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Aim Location Taxon Methods Results Main Conclusion We reconstructed the genetic patterns and identified the main genetic breaks of several taxa across California and Baja California coast. Additionally, we evaluated the contribution of different variables to the level of structure.California and Baja California coast.Fish, invertebrates, algae, seagrass and mammals.We generated a map to reconstruct the genetic patterns using genetic information (Fst index and phylogenetic clades distribution) from a literature review of population genetics publications from 2000 to 2023. For the analysis of genetic connectivity drivers, we explored the effect of different variables representing life history traits, reproductive strategies and biogeographic variables and generated five working hypotheses which were evaluated with generalized linear models (GLMs).We identified 42 genetic breaks from 63 species across our study area. The largest number of breaks occurs from 27° N to 29° N and from 31° N to 35° N. This range includes transition zones between ecoregions such as Punta Eugenia, Baja California, Mexico and Point Conception, California, USA. We also identified Ensenada, Baja California region as a barrier to gene flow. From a transboundary perspective, we found 40 species with connectivity between California and Baja California, including 14 commercial and or recreational species. We found none of the variables explored had a clear effect on the level of genetic differentiation of the species assessed in the region.Genetic breaks among different taxa do not distribute randomly across the latitudinal range from California and Baja California coastal area, rather they are mainly located in transition zones between marine ecoregions. The challenge to identify specific variables that explain general genetic patterns highlights the complexity that drives population connectivity processes in marine species. [ABSTRACT FROM AUTHOR]

In reports on stock assessments for rockfish species on the West Coast of the United States, the need for additional biological data to provide more accurate estimates of population abundance is commonly cited. Improvement of population estimates is important because those data are used to set catch quotas along this coast of the nation. The recreational charter boat fleet in the state of California has historically landed large amounts of rockfish species; however, vessels in this fleet discard carcasses once fillets have been removed from fish. These carcasses could be a valuable source of age, length, and sex data, with a standardized measurement method used to relate the post-fillet length of carcasses to the pre-fillet length. To determine the feasibility of a program to collect rockfish carcasses for biological data, specimens of 4 rockfish species were captured off the central coast of California and measured before and after filleting. Pre-fillet lengths were accurately predicted on the basis of post-fillet elongate length for blue (Sebastes mystinus), gopher (S. carnatus), copper (S. caurinus), and vermilion (S. miniatus) rockfish. A high percentage (87.5%) of the carcasses had identifiable gonads, a fortunate result because the availability of sex data on measured specimens is an important consideration for species with dimorphic growth. This new data source based on information from carcasses can be used to enhance the length-at-age and life history data available for stock assessments or other biological studies of rockfish populations. [ABSTRACT FROM AUTHOR]

Chinook salmon (Oncorhynchus tshawytscha) display remarkable life history diversity, underpinning their ability to adapt to environmental change. Maintaining life history diversity is vital to the resilience and stability of Chinook salmon metapopulations, particularly under changing climates. However, the conditions that promote life history diversity are rapidly disappearing, as anthropogenic forces promote homogenization of habitats and genetic lineages. In this study, we use the highly modified Yuba River in California to understand if distinct genetic lineages and life histories still exist, despite reductions in spawning habitat and hatchery practices that have promoted introgression. There is currently a concerted effort to protect federally listed Central Valley spring‐run Chinook salmon populations, given that few wild populations still exist. Despite this, we lack a comprehensive understanding of the genetic and life history diversity of Chinook salmon present in the Yuba River. To understand this diversity, we collected migration timing data and GREB1L genotypes from hook‐and‐line, acoustic tagging, and carcass surveys of Chinook salmon in the Yuba River between 2009 and 2011. Variation in the GREB1L region of the genome is tightly linked with run timing in Chinook salmon throughout their range, but the relationship between this variation and entry on spawning grounds is little explored in California's Central Valley. We found that the date Chinook salmon crossed the lowest barrier to Yuba River spawning habitat (Daguerre Point Dam) was tightly correlated with their GREB1L genotype. Importantly, our study confirms that ESA‐listed spring‐run Chinook salmon are spawning in the Yuba River, promoting a portfolio of life history and genetic diversity, despite the highly compressed habitat. This work highlights the need to identify and protect this life history diversity, especially in heavily impacted systems, to maintain healthy Chinook salmon metapopulations. Without protection, we run the risk of losing the last vestiges of important genetic variation. [ABSTRACT FROM AUTHOR]

Multiple studies in a range of taxa have found links between structural variants and the development of ecologically important traits. Such variants are becoming easier to find due, in large part, to the increase in the amount of genome-wide sequence data in nonmodel organisms. The salmonids (salmon, trout, and charr) are a taxonomic group with abundant genome-wide datasets due to their importance in aquaculture, fisheries, and variation in multiple ecologically important life-history traits. Previous research on rainbow trout (Oncorhynchus mykiss) has documented a large pericentric (∼55 Mb) chromosomal inversion (CI) on chromosome 5 (Omy05) and a second smaller (∼14 Mb) chromosome inversion on Omy20. While the Omy05 inversion appears to be associated with multiple adaptive traits, the inversion on Omy20 has received far less attention. In this study, we re-analyze RAD-seq and amplicon data from several populations of rainbow trout (O. mykiss) to better document the structure and geographic distribution of variation in the Omy20 CI. Moreover, we utilize phylogenomic techniques to characterize both the age- and the protein-coding gene content of the Omy20 CI. We find that the age of the Omy20 inversion dates to the early stages of O. mykiss speciation and predates the Omy05 inversion by ∼450,000 years. The 2 CIs differ further in terms of the frequency of the homokaryotypes. While both forms of the Omy05 CI are found across the eastern Pacific, the ancestral version of the Omy20 CI is restricted to the southern portion of the species range in California. Furthermore, the Omy20 inverted haplotype is comparable in genetic diversity to the ancestral form, whereas derived CIs typically show substantially reduced genetic diversity. These data contribute to our understanding of the age and distribution of a large CI in rainbow trout and provide a framework for researchers looking to document CIs in other nonmodel species. [ABSTRACT FROM AUTHOR]

Understanding past coastal variability is valuable for contextualizing modern changes in coastal settings, yet existing Holocene paleoceanographic records for the North American Pacific Coast commonly originate from offshore marine sediments and may not represent the dynamic coastal environment. A potential archive of eastern Pacific Coast environmental variability is the intertidal mussel species Mytilus californianus. Archaeologists have collected copious stable isotopic (δ18O and δ13C) data from M. californianus shells to study human history at California's Channel Islands. When analyzed together, these isotopic data provide windows into 9000 years of Holocene isotopic variability and M. californianus life history. Here we synthesize over 6000 δ18O and δ13C data points from 13 published studies to investigate M. californianus shell isotopic variability across ontogenetic, geographic, seasonal, and millennial scales. Our analyses show that M. californianus may grow and record environmental information more irregularly than expected due to the competing influences of calcification, ontogeny, metabolism, and habitat. Stable isotope profiles with five or more subsamples per shell recorded environmental information ranging from seasonal to millennial scales, depending on the number of shells analyzed and the resolution of isotopic subsampling. Individual shell profiles contained seasonal cycles and an accurate inferred annual temperature range of ~ 5°C, although ontogenetic growth reduction obscured seasonal signals as organisms aged. Collectively, the mussel shell record reflected millennial-scale climate variability and an overall 0.52‰ depletion in δ18Oshell from 8800 BP to the present. The archive also revealed local-scale oceanographic variability in the form of a warmer coastal mainland δ18Oshell signal (-0.32‰) compared to a cooler offshore islands δ18Oshell signal (0.33‰). While M. californianus is a promising coastal archive, we emphasize the need for high-resolution subsampling from multiple individuals to disentangle impacts of calcification, metabolism, ontogeny, and habitat and more accurately infer environmental and biological patterns recorded by an intertidal species. [ABSTRACT FROM AUTHOR]

Objective: Protecting biodiversity is important for preserving ecosystem functions and services, and understanding the diversity present in a system is necessary for effective conservation. Lampreys display extensive diversity in morphology and life history strategy. The extent of this diversity and the underlying genetic patterns have not yet been fully characterized. Uncertainty about species boundaries and operational taxonomic units hinders lamprey management and conservation. Limited data have been collected on California lampreys (Lampetra spp. and Entosphenus spp.), but evidence suggests widespread population decline across the west coast of North America. Study objectives were to identify which nominal species are present at study sites across northern and central California, determine whether current taxonomic classifications accurately and sufficiently describe lamprey diversity in California, and characterize the biogeographic distribution of genetically distinct lamprey lineages across the study area. Methods: To achieve these objectives, this study utilized DNA barcoding, phylogenetic analysis, and species delimitation analysis. Lamprey individuals (N = 87) from 19 sites in the Sacramento–San Joaquin River basin, San Francisco Bay, and Klamath River basin were sequenced for the mitochondrial cytochrome b (cyt b) gene, and the data were combined with publicly available lamprey cyt b sequences for analysis. Result: Results showed relatively deep phylogenetic divergence between Lampetra and Entosphenus. Distinct and genetically divergent lineages were observed within Lampetra, while distinct but genetically similar lineages were observed within Entosphenus. This study revealed novel Lampetra lineages in the Napa River and Alameda Creek, and results suggest that the biogeographic distribution of lamprey diversity may follow patterns observed in other native fishes. Species delimitation results indicated that at least seven separate candidate species of Lampetra can be found in California, suggesting that California holds more species‐level diversity than the expected three nominal Lampetra species known to occur in the state. Conclusion: These results highlight the underestimated diversity of lampreys in California and the need for further assessment of taxonomic classifications and operational taxonomic unit designations of California lampreys. Impact statementLampreys are ecologically and culturally significant. Populations are thought to be declining across the west coast of North America, but a lack of research impedes monitoring and conservation of lampreys in California. This study investigated lampreys in California using DNA sequences and found more diversity than expected. By determining how many genetically different types of lampreys are present and where these various lampreys are found across the study area, this research paves the way for conservation and protection of lampreys and the numerous benefits they contribute. [ABSTRACT FROM AUTHOR]

While cross‐species comparisons of birds suggest that as latitude decreases or elevation increases, clutch size decreases and the duration of developmental stages and parental attentiveness increases, studies comparing populations of the same species are rare. We studied populations of house wrens, Troglodytes aedon, at high and low elevations in California and Costa Rica, collecting data on clutch size, the duration of incubation and nestling periods, parental attentiveness, nestling growth rate, and nesting success. Our data support results from cross‐species comparisons, but also revealed unanticipated results from low elevation temperate zone house wrens in the southwest. This population had prolonged incubation and nestling periods similar to those found in the tropics. We also found that temperate zone females, especially those at our higher elevation site, spent more of their day incubating than did tropical females. Nest temperature at our high elevation temperate zone site was higher than that at all other tropical sites. Age at fledging did not differ between sites. Total feeding rates per chick and male feedings per chick did not vary between sites. Nest success rates showed the predicted effect of latitude, but not the predicted effects of elevation. Our results extend low elevation house wren research into the southwestern US and contribute the first intraspecific elevational comparison in the Neotropics. Data from our low elevation southwestern site present a unique suite of life history traits that align more with tropical house wrens, although with a larger clutch size, and point to food limitation and/or high predation pressure as being possible drivers of some of these differences. These results highlight the need for additional studies of house wrens and other broadly distributed species at a more diverse array of sites to better understand which forces drive the evolution of different life history strategies across major biogeographical gradients. [ABSTRACT FROM AUTHOR]

Simple Summary: North American bean thrips, Caliothrips fasciatus, native to California (U.S.), is a regular contaminant of navel oranges exported from California. Despite more than 100 years of accidental shipments overseas, this polyphagous thrips has not established outside of its native range. Understanding why this thrips has not successfully invaded other parts of the world may be explained, in part, by the effects of temperature on fitness. This study investigated the effects of nine fluctuating temperatures that averaged 8, 10, 15, 20, 25, 30, 32, 35, and 37 °C over a 24 h period on the developmental and reproductive biology of C. fasciatus to better understand the effects of temperature on these critical life history characters and how temperature may influence the invasion potential of this thrips. North American bean thrips, Caliothrips fasciatus, native to California U.S., has been detected inside the navels of navel oranges exported from California for more than 120 years. Despite this long history of accidental movement into new areas, this thrips has failed to establish populations outside of its native range. The cold accumulation hypothesis postulates that increasing levels of cold stress experienced by thrips overwintering inside navels is compounded when harvested fruit is shipped under cold storage conditions. Consequently, the fitness of surviving thrips is compromised, which greatly diminishes invasion potential. At the time this study was conducted, the effects of temperature on C. fasciatus fitness were unknown. To address this shortcoming, the effects of nine fluctuating temperatures that averaged 8, 10, 15, 20, 25, 30, 32, 35, and 37 °C over a 24 h period on the developmental and reproductive biology of C. fasciatus were evaluated. One linear and five nonlinear regression functions were fit to egg-to-adult development rate data for parent and offspring thrips to characterize thermal performance curves. Estimates of minimum, optimal, and maximum temperature thresholds for development were in the ranges of −4.37–6.52 °C (i.e., Tmin), 31.19–32.52 °C (i.e., Topt), and 35.07–37.98 °C (i.e., Tmax), respectively. Degree day accumulation to complete development, estimated from linear regression, ranged 370.37–384.61. Average development times for eggs, first and second instar larvae, propupae, pupae, and adult longevity, and mean lifetime fecundity of females were significantly affected by temperature. These biological responses to temperature may provide insight into how this abiotic variable affects the invasion potential of C. fasciatus. [ABSTRACT FROM AUTHOR]

It is known that climatic factors can influence the reproductive performance of small mammal populations. However, this information has not been available for the big-eared woodrat (Neotoma macrotis), a keystone species that inhabits the California central coast ranges south to Mexico and the oak woodlands (Quercus spp.) of the western Sierra Nevada foothills. From 2002 to 2014, we livetrapped woodrats on 1.1-ha study plots in coastal-central California and recorded their age and reproductive status. We analyzed these data by a capture-mark-recapture (CMR) framework to estimate state-specific recapture probability (p) and monthly apparent survival (S) of juvenile, non-reproductive, and reproductive adult female woodrats, and the influence of rain and temperature on S and transition probability (Ψ) of the three states. Rainfall from the previous season did not markedly affect survival rates of the states, with one exception: it decreased the survival of nonreproductive woodrats. Nearly all breeding occurred during the cool, wet winter season. Juvenile woodrats had at least a 0.55 probability of breeding by their first winter, conditional on survival. Temperature during the breeding season had a marked negative influence on transition probability. During winter, survival of nonreproductive adult females was significantly higher than for juvenile and reproductive females, indicating a cost of reproduction. Physiological effects and diminished diet quality due to further climate warming could reduce the reproductive success of female big-eared woodrats with negative consequences on population growth and persistence. [ABSTRACT FROM AUTHOR]

From 2000 to 2013, an inventory was conducted by introductory entomology classes from the College of Marin (COM) with the twin goals of describing this insect community and enhancing students' educational experiences. General collecting was the main method, supplemented by rearing of immature stages and by light, pitfall, and pan trapping. After specimens were processed and identified, literature review provided information on five key life history traits of the species: area of origin, range, habitat, feeding habit, and dietary specificity. Four-hundred ninety species or morphospecies were recorded from 12 orders and 133 families. Diptera was the order with the most species. For 449 species with information available, 45% were plant feeders, 21% were predators, and 17% were parasites. For 274 species with information on dietary breadth, 57% were generalists and 43% were specialists. One species and four distinctive populations of other species were endemic to the site. Thirty-nine species had distributions likely restricted to the sand dunes of the immediate Pacific Coastal slope. Groups of species shared with adjacent habitats were also important components of the community. Findings are compared with the information available from other sand dune faunas. The diversity and uniqueness of this community warrant continued conservation efforts, especially the removal of invasive plant species. Students received benefits beyond those expected from the standard introductory course. Recommendations are made for improvement of the description of this community and for the more efficient integration of inventory of local insect faunas into general entomology classes. [ABSTRACT FROM AUTHOR]

Surfperches (Family Embiotocidae) are viviparous temperate reef fishes that brood their young. This life history trait translates into limited dispersal, strong population structure, and an unusually strong potential for local adaptation in a marine fish. As part of the California Conservation Genomics Project (CCGP), we sequenced the genome of the Black Surfperch, Embiotoca jacksoni , to establish a genomic model for understanding phylogeographic patterns of marine organisms in California. These patterns, in turn, may inform the design of marine protected areas using dispersal models based on genomic data. The genome of E. jacksoni is typical of marine fishes at less than 1Gb (genome size = 635 Mb), and our assembly is near-chromosome level (contig N50 = 6.5Mb, scaffold N50 = 15.5 Mb, BUSCO = 98.1%). Within the context of the CCGP, the genome will be used as a reference for future whole genome resequencing projects aimed at enhancing our knowledge of the population structure of the species, and efficacy of Marine Protected Areas across the state. [ABSTRACT FROM AUTHOR]

Keystone species are known to play a critical role in kelp forest health, including the well-known killer whales, sea otter, sea urchin, kelp trophic cascade in the Aleutian Islands, Alaska, USA. In California, a major player in the regulation of sea urchin abundance, and in turn, the health of kelp forests ecosystems, is a large wrasse, the California Sheephead, Semicossyphus pulcher. We present a reference genome for this ecologically important species that will serve as a key resource for future conservation research of California's inshore marine environment utilizing genomic tools to address changes in life-history traits, dispersal, range shifts, and ecological interactions among members of the kelp forest ecological assemblages. Our genome assembly of S. pulcher has a total length of 0.794 Gb, which is similar to many other marine fishes. The assembly is largely contiguous (N50 = 31.9 Mb) and nearly complete (BUSCO single-copy core gene content = 98.1%). Within the context of the California Conservation Genomics Project (CCGP), the genome of S. pulcher will be used as an important reference resource for ongoing whole genome resequencing efforts of the species. [ABSTRACT FROM AUTHOR]

The Mad River Hatchery supports one of the most important fisheries for steelhead Oncorhynchus mykiss in California. Although the Mad River Hatchery has stated goals of operating an integrated hatchery program that addresses demographic and genetic risks, very little monitoring of these goals has taken place. We applied parentage‐based tagging methods to assess the origin (wild versus hatchery), age structure, and spawn‐date heritability of steelhead returning to the Mad River Hatchery. We generated single nucleotide polymorphism genotypes at 96 loci for all adult steelhead broodstock spawned at Mad River Hatchery over a 9‐year period (2009–2017; N = 1,572) and identified 965 trios (mother, father, and offspring) using parentage analysis. Although the hatchery attempts to release 100% adipose‐fin‐clipped hatchery steelhead, our analysis uncovered a large difference in the proportion of hatchery‐origin broodstock individuals as estimated by pedigrees (0.87) and traditional adipose fin clipping (0.58). This difference presumably resulted from failure to clip or identify a clip in 100% of hatchery‐produced fish. Our analysis revealed the complete age structure of six cohorts of hatchery broodstock and showed substantial differences in different years for Mad River Hatchery steelhead. Pedigree‐based estimates of narrow‐sense heritability for spawn date were 0.242 to 0.470, indicating moderate to high heritability, and highlighting the opportunity for a strong response to selection on this trait imposed by hatchery spawning. The application of parentage‐based tagging provided critical information for understanding life history variation and the efficacy of management actions for Mad River Hatchery steelhead and provides a framework for minimizing domestication selection and associated reductions in fitness for naturally spawning fish in this integrated population. [ABSTRACT FROM AUTHOR]

Vocal territory defense can vary within a species due to many factors such as sex and breeding status, influencing territory size and thus population density across a landscape. Therefore, understanding what influences variation in territorial vocalizations can help to illuminate trade‐offs between territoriality and other life history demands, which benefits our general understanding of animal ecology as well as helps to inform emerging passive acoustic monitoring approaches. Here, we investigated how sex and breeding status affected territoriality and vocal behavior in the California spotted owl Strix occidentalis occidentalis in the Sierra Nevada, California, USA, using high‐resolution acoustic/GPS tags. We discovered that territorial vocal behavior was related to breeding status and to a lesser extent sex. Breeding owls with fledged young had a less diverse vocal repertoire, produced fewer and quieter territorial calls, and typically called only when close to their nest. Males were also more likely to engage in territorial calling than females. Breeding spotted owls also maintained significantly smaller territories – but utilized larger home ranges – than non‐breeding individuals. Our results suggest that breeding spotted owls may reduce their investment in territorial behaviors to mitigate the demands and risks associated with rearing young. Further, our results have important implications for the passive acoustic monitoring of spotted owls and, more broadly, highlight the utility of using multiple call types to detect species of interest. [ABSTRACT FROM AUTHOR]

Daphnia, an ecologically important zooplankton species in lakes, shows both genetic adaptation and phenotypic plasticity in response to temperature and fish predation, but little is known about the molecular basis of these responses and their potential interactions. We performed a factorial experiment exposing laboratory-propagated Daphnia pulicaria clones from two lakes in the Sierra Nevada mountains of California to normal or high temperature (15°C or 25°C) in the presence or absence of fish kairomones, then measured changes in life history and gene expression. Exposure to kairomones increased upper thermal tolerance limits for physiological activity in both clones. Cloned individuals matured at a younger age in response to higher temperature and kairomones, while size at maturity, fecundity and population intrinsic growth were only affected by temperature. At the molecular level, both clones expressed more genes differently in response to temperature than predation, but specific genes involved in metabolic, cellular, and genetic processes responded differently between the two clones. Although gene expression differed more between clones from different lakes than experimental treatments, similar phenotypic responses to predation risk and warming arose from these clone-specific patterns. Our results suggest that phenotypic plasticity responses to temperature and kairomones interact synergistically, with exposure to fish predators increasing the tolerance of Daphnia pulicaria to stressful temperatures, and that similar phenotypic responses to temperature and predator cues can be produced by divergent patterns of gene regulation. [ABSTRACT FROM AUTHOR]

CaliPopGen is a database of population genetic data for native and naturalized eukaryotic species in California, USA. It summarizes the published literature (1985–2020) for 5,453 unique populations with genetic data from more than 187,394 individuals and 448 species (513 species plus subspecies) across molecular markers including allozymes, RFLPs, mtDNA, microsatellites, nDNA, and SNPs. Terrestrial habitats accounted for the majority (46.4%) of the genetic data. Taxonomic groups with the greatest representation were Magnoliophyta (20.31%), Insecta (13.4%), and Actinopterygii (12.85%). CaliPopGen also reports life-history data for most included species to enable analyses of the drivers of genetic diversity across the state. The large number of populations and wide taxonomic breadth will facilitate explorations of ecological patterns and processes across the varied geography of California. CaliPopGen covers all terrestrial and marine ecoregions of California and has a greater density of species and georeferenced populations than any previously published population genetic database. It is thus uniquely suited to inform conservation management at the regional and state levels across taxonomic groups. Measurement(s) genetic variation Technology Type(s) DNA sequencing Factor Type(s) Kingdom • Phylum • TaxonGroup • MarkerType • SampleSize • GeneTarget • NumMarkers • YearStart • YearEnd • PopName • LongitudeDD • LatitudeDD • CoordError • HabitatType • Lifespan • Fecundity • LifetimeReprodOutput • AgeSexMat • NumBreedingEvents • ReprodMode • BodyLength • AdultMass • CANativeStatus • CESAStatus • SSCStatus • ESAStatus • LifeCycle • AdultHeight • SelfCompatibility • MonoeciousDioecious • Asexual • PollinationMode • SeedDispMode • MassPerSeed • CAEndemicStatus Sample Characteristic - Organism eukaryota Sample Characteristic - Location California [ABSTRACT FROM AUTHOR]

Offspring size is a key functional trait that can affect subsequent life history stages; in many species, it exhibits both local adaptation and phenotypic plasticity. Variation among populations in offspring size may be explained by various factors, including local climatic conditions. However, geographic variation in climate may be partitioned into long‐term and interannual sources of variation, which may differ in their effects on population mean offspring size. To assess environmental correlates of offspring size, we evaluated geographic variation in seed mass among 88 populations representing 6 species of Streptanthus (Brassicaceae) distributed across a broad climatic gradient in California. We examined the effects of temperature‐mediated growing season length and precipitation on population mean seed mass to determine whether it is best explained by (1) long‐term mean climatic conditions; (2) interannual climate anomalies (i.e., deviations in climate from long‐term means) during the year of seed development, or (3) interactions between climate variables. Both long‐term mean climate and climate anomalies in the year of collection were associated with population mean seed mass, but their effects differed in direction and magnitude. Relatively large seeds were produced at chronically wet sites but also during drier‐than‐average years. This contrast indicates that these associations may be generated by different mechanisms (i.e., adaptive evolution vs. phenotypic plasticity) and may be evidence of countergradient plasticity in seed mass. In addition, populations occurring in locations characterized by relatively long growing seasons produced comparatively large seeds, particularly among chronically dry sites. This study highlights the need to consider that the responses of seed mass to long‐term versus recent climatic conditions may differ and that climate variables may interact to predict seed mass. Such considerations are especially important when using these patterns to forecast the long‐ and short‐term responses of seed mass to climate change. The results presented here also contribute to our broader understanding of how climate drives long‐term (e.g., local adaptation) and short‐term (e.g., phenotypic plasticity) variation in functional traits, such as offspring size across landscapes. [ABSTRACT FROM AUTHOR]

Intentional introductions of non-native fishes can severely affect native communities. Wakasagi (Hypomesus nipponensis, referred to as Japanese Pond Smelt) are native to Japan and were once separated from their non-native congener the endangered Delta Smelt (Hypomesus transpacificus) of the San Francisco Estuary (hereon "estuary") of California. Wakasagi were introduced into California reservoirs in the 20th century as forage fish. Wakasagi have since expanded their distribution downstream to the estuary, but less is known about Wakasagi's current distribution status, biology in the estuary, and negative influences on Delta Smelt. In this study, we took a comparative approach by synthesizing long-term field monitoring surveys, modeling environmental associations, and quantifying phenology, growth, and diets of Wakasagi and Delta Smelt to describe abundance and range, trends of co-occurrence, and shared ecological roles between smelt species. We found Wakasagi in greatest abundance in the upper watershed below source reservoirs, and in the northern regions of the estuary with the most co-occurrence with Delta Smelt; however, their range extends to western regions of the estuary, and we found evidence of an established population that annually spawns and rears in the estuary. We found these smelt species have similar ecological roles demonstrated by overlaps in habitat use (e.g., an association with higher turbidities and higher outflow), phenology, growth, and diets. Despite similarities, earlier hatching and rearing of Wakasagi during cooler months and reduced growth during warmer drought years suggest this species is unlike typical non-natives (e.g., Centrarchids), and they exhibit a similar sensitivity to environmental variability as Delta Smelt. This sensitivity may be why Wakasagi abundance remains relatively low in the estuary. [ABSTRACT FROM AUTHOR]

The distributions of marine ectotherms are governed by physiological sensitivities to long-term trends in seawater temperature and dissolved oxygen. Short-term variability in these parameters has the potential to facilitate rapid range expansions, and the resulting ecological and socioeconomic consequences may portend those of future marine communities. Here, we combine physiological experiments with ecological and demographic surveys to assess the causes and consequences of sudden but temporary poleward range expansions of a marine ectotherm with considerable life history plasticity (California market squid, Doryteuthis opalescens). We show that sequential factors related to resource accessibility in the core range—the buildup of large populations as a result of competitive release and climate-associated temperature increase and oxygen loss that constrain aerobic activity—may drive these expansions. We also reveal that poleward range expansion alters the body size—and therefore trophic role—of invading populations, with potential negative implications for socioeconomically valuable resident species. To help forecast rapid range expansions of marine ectotherms, we advocate that research efforts focus on factors impacting resource accessibility in core ranges. Determining how environmental conditions in receiving ecosystems affect body size and how body size is related to trophic role will help refine estimates of the impacts of future marine communities. [ABSTRACT FROM AUTHOR]

The larval stage of the California newt (Taricha torosa) has been little studied despite the presence and abundance of the species throughout much of California. During the 2017–2018 time period, the diet and life history characteristics of this cohort of stream-dwelling newt larvae were examined, using gut contents and stable isotopes, in order to better understand the ecological niche and trophic relationships of the life stage. Our results suggest that the newt larvae consume Chironomidae as a major part of their diet and that this reliance decreases as the larvae age. Newt larvae also feed more widely and abundantly as they age. The isotopic data suggest that as larvae get larger, they alter their diet but that the relationships to both carbon source (dC) and trophic level (dN) are complex. [ABSTRACT FROM AUTHOR]

Natural selection shapes the evolution of antipredator traits in prey. However, selection in the wild depends on ecological context, including features of predator and prey populations, making field studies of selection critical to understanding how predators shape selection on prey defences. Threespine stickleback (Gasterosteus aculeatus) is a classic system to study the effects of predators on the natural selection of prey. In lakes and rivers, fish predators have been shown to impose selection against low plated adult stickleback phenotypes and genotypes. We directly measured selection by predatory salmonids on the Ectodysplasin‐A (Eda) gene in estuary stickleback from California. Despite previous studies showing a positive correlation between predator presence and frequency of the Eda "complete" allele in estuary populations, we found that Eda "low" genotypes were not significantly more frequent in salmonid predator diets. Further, we found no evidence of changes in Eda genotype frequencies across generations that would suggest directional selection driven by predators. Prior selection studies have examined the effects of large resident trout on adult stickleback. In contrast, predators in this study were juvenile anadromous salmonids, which only ate juvenile stickleback whose plate phenotypes had not fully developed. Thus, in this case, predator life history and stickleback ontogeny may preclude strong selection on stickleback armour. Our results underscore the importance of selection studies in the wild for understanding the context‐dependent nature of selection in natural populations. [ABSTRACT FROM AUTHOR]

People seek reliable natural resources despite climate change. Diverse habitats and biologies stabilize productivity against disturbances like climate, prompting arguments to promote climate‐resilient resources by prioritizing complex, less‐modified ecosystems. These arguments hinge on the hypothesis that simplifying and degrading ecosystems will reduce resources' climate resilience, a process liable to be cryptically evolving across landscapes and human generations, but rarely documented. Here, we examined the industrial era (post 1848) of California's Central Valley, chronicling the decline of a diversified, functional portfolio of salmon habitats and life histories and investigating for empirical evidence of lost climate resilience in its fishery. Present perspectives indicate that California's dynamic, warming climate overlaid onto its truncated, degraded habitat mosaic severely constrains its salmon fishery. We indeed found substantial climate constraints on today's fishery, but this reflected a shifted ecological baseline. During the early stages of a stressor legacy that transformed the landscape and ‐‐ often consequently ‐‐ compressed salmon life history expression, the fishery diffused impacts of dry years across a greater number of fishing years and depended less on cool spring‐summer transitions. The latter are important given today's salmon habitats, salmon life histories, and resource management practices, but are vanishing with climate change while year‐to‐year variation in fishery performance is rising. These findings give empirical weight to the idea that human legacies influence ecosystems' climate resilience across landscapes and boundaries (e.g., land/sea). They also raise the question of whether some contemporary climate effects are recent and attributable not only to increasing climate stress, but to past and present human actions that erode resilience. In general, it is thus worth considering that management approaches that prioritize complex, less‐modified ecosystems may stabilize productivity despite increasing climate stress and such protective actions may be required for some ecological services to persist into uncertain climate futures. [ABSTRACT FROM AUTHOR]

California pistachios are threatened by several stink bug species (Hemiptera: Pentatomidae), including the native Thyanta pallidovirens (Stål) and Chlorochroa uhleri (Stål), as well as the invasive Nezara viridula (L.). In pistachio, control tactics often target specific life stages, which makes knowledge about life histories fundamental to successful IPM programs. For that purpose, life history parameters of these stink bug species were assessed. Nymphal development and survivorship at seven constant temperatures, upper and lower development thresholds, thermal constants, adult longevity and fecundity, and life table parameters were evaluated. No species completed development at 15°C or 35°C. For N. viridula, egg to adult development was fastest at 30°C, whereas for T. pallidovirens there was no significant difference between 27.5 and 30°C and C. uhleri development was similar between 25 and 30°C. Egg to adult survival was highest at 22.5°C and 27.5°C. The thermal requirements as degree-days (DD) to complete immature development were estimated to be 714.3, 370.4, and 434.8 for C. uhleri, T. pallidovirens, and N. viridula, respectively. For C. uhleri, life table calculations produced a value of 56.7 d for mean generation time (To), 24.89 for net reproductive rate (Ro) and 0.057 for the intrinsic rate of increase (r). Thyanta pallidovirens had a To of 39.9 d, a Ro of 81.10 and a r of 0.11. The results are discussed with respect to the improvement of IPM in California pistachios, and the information presented may contribute to the control of these pest species in other ecosystems. [ABSTRACT FROM AUTHOR]

Bass describes the fascinating life history, behavior, and neurobiology of the California singing fish, including its remarkable vocal abilities. [ABSTRACT FROM AUTHOR]

Parasites may influence their hosts in multiple ways, ranging from physiological changes and behavioral modifications, to altering life history traits. One fitness component that is often considered in relation to parasitism is host fecundity. The larval acanthocephalan parasite, Profilicollis altmani, commonly infects the Pacific mole crab, Emerita analoga; yet this parasite's effect on the crab's fecundity is unknown. Consequently, we examined the effects of acanthocephalan parasitism on the fecundity of this mole crab species. Crabs were collected from the swash intertidal zone in Monterey Bay, CA, and the following parameters were quantified: crab body size (carapace length) and weight, egg‐bearing status (nongravid and gravid), egg number and diameter, total volume and weight of egg mass, and their developmental stages (from newly laid eggs to recognizable zoea larval stage). Parasite prevalence, intensity of infection, and body size of larval cystacanths (measured as volume) were assessed. Host fecundity was positively correlated with both body size and body weight. No differences in egg weight were found between uninfected and infected crabs. Similarly, no difference in crab body weight at various embryonic developmental phases was documented between uninfected and infected crabs. Cystacanth volumes in infected nongravid and infected gravid crabs were not significantly different. Our study suggests that the parasite P. altmani does not have any appreciable effect on the fecundity of E. analoga and that female mole crabs undergo normal reproduction and maintain robust population sizes in their natural environments. Our findings thus appear to moderate the pervasive notion of a major impact of parasitism on host reproduction. [ABSTRACT FROM AUTHOR]

Premise: Does the seed size–seed number allocation trade‐off model apply to long‐term persistent soil seed banks? This trade‐off between seed size versus number of seeds produced is usually applied at a single population on an annual basis. Our question is how this model might apply to close relatives that produce dormant seed forming long‐term persistent soil seed banks. These two criteria allow a focus on divergent evolution of conspecifics and permits us to isolate seed size in the spectrum of life history traits that may be influencing seed traits, and on how seed size influences accumulation and persistence in the soil. Methods: In California, Arctostaphylos species only produce physiologically dormant seed that are fire‐stimulated and that vary in seed size permitting seed size–seed bank density relationship as a test of the seed size–seed number allocation model. Soil seed banks of 10 species of Arctostaphylos were sampled with fruit volumes ranging from 21–1063 mm3. Seed bank density was determined by hand extraction from soil samples. Results: We found that seed bank densities were significantly negatively related to fruit or seed size. Conclusions: Rather than an issue of allocational trade‐off between size and number, we interpret these results as reflecting seed predation and postfire seedling establishment. Seed bank densities, even after decades, generally were less than one or two‐year's seed production, suggesting intense seed predation. Burial by scatter‐hoarding rodents provided sufficient seeds deep enough for survival of fire. Variation on seed size suggests seedling establishment constraints, but it needs further research. [ABSTRACT FROM AUTHOR]

In this issue of Molecular Ecology, Tepolt et al. (2021) illustrate how the genetic architecture of adaptation and life history influence invasive success. A marvel of many invasive species is that they are incredibly successful despite evolutionary expectations that they will have low adaptive potential and suffer inbreeding depression due to initially small founding population sizes. Determining the combinations of ecoevolutionary factors that permit this apparent "genetic paradox of invasions" is an ongoing endeavour of invasive species research. Tepolt et al. (2021) study the European green crab in its invasive range on the North American west coast. Following a single introduction into California, this crab quickly spread across a wide latitude gradient, despite low diversity in the original founding population. Adaptation of this crab to clinal variation in temperature appeared largely driven by an inferred chromosomal inversion. This inversion exists as a balanced polymorphism in the European home range of green crabs and is associated with thermal tolerance. Tepolt et al. (2021) therefore demonstrate that adaptive evolution post introduction need not be impeded by bottlenecks if variation at key parts of the genome is available and can be maintained in introduced populations. Moreover, Tepolt et al. (2021) show how chromosomal inversions acting as large‐effect loci might facilitate rapid responses to selection in introduced populations. [ABSTRACT FROM AUTHOR]

Predation on parasites is a common interaction with multiple, concurrent outcomes. Free‐living stages of parasites can comprise a large portion of some predators' diets and may be important resources for population growth. Predation can also reduce the density of infectious agents in an ecosystem, with resultant decreases in infection rates. While predator–parasite interactions likely vary with parasite transmission strategy, few studies have examined how variation in transmission mode influences contact rates with predators and the associated changes in consumption risk.To understand how transmission mode mediates predator–parasite interactions, we examined associations between an oligochaete predator Chaetogaster limnaei that lives commensally on freshwater snails and nine trematode taxa that infect snails. Chaetogaster is hypothesized to consume active (i.e. mobile), free‐living stages of trematodes that infect snails (miracidia), but not the passive infectious stages (eggs); it could thus differentially affect transmission and infection prevalence of parasites, including those with medical or veterinary importance. Alternatively, when infection does occur, Chaetogaster can consume and respond numerically to free‐living trematode stages released from infected snails (cercariae). These two processes lead to contrasting predictions about whether Chaetogaster and trematode infection of snails correlate negatively ('protective predation') or positively ('predator augmentation').Here, we tested how parasite transmission mode affected Chaetogaster–trematode relationships using data from 20,759 snails collected across 4 years from natural ponds in California. Based on generalized linear mixed modelling, snails with more Chaetogaster were less likely to be infected by trematodes that rely on active transmission. Conversely, infections by trematodes with passive infectious stages were positively associated with per‐snail Chaetogaster abundance.Our results suggest that trematode transmission mode mediates the net outcome of predation on parasites. For trematodes with active infectious stages, predatory Chaetogaster limited the risk of snail infection and its subsequent pathology (i.e. castration). For taxa with passive infectious stages, no such protective effect was observed. Rather, infected snails were associated with higher Chaetogaster abundance, likely owing to the resource subsidy provided by cercariae. These findings highlight the ecological and epidemiological importance of predation on free‐living stages while underscoring the influence of parasite life history in shaping such interactions. [ABSTRACT FROM AUTHOR]

This article discusses the importance of community-based archaeology and collaboration with indigenous communities in California. It highlights the challenges and opportunities of working with tribal descendant communities in cultural resource management projects. The focus is on the Muwekma Ohlone Tribe, a previously federally recognized tribe, and their efforts to protect and learn from ancestral remains and sites. The article also presents specific research projects conducted by the Muwekma Tribe, including studies on life histories, demographics of children, enculturation practices, and medicinal plant usage. These collaborative efforts aim to understand the cultural and behavioral patterns of the Ohlone community and contribute to a broader understanding of the past. [Extracted from the article]

Síi Túupentak (CA-SCA-565/H) is a late precontact ancestral Ohlone village and cemetery site in Central California (ca. 540–145 cal. BP). Integration of proteomic, genomic, and osteological analyses provided highly confident biological sex estimates for remains of most individuals at this site (65 of 76), spanning all age groups, from perinatal infants to aged adults. Based on these relatively comprehensive data, it was possible to generate sex-specific Kaplan-Meier survival curves for this burial population of sedentary hunter-gatherers. As was common among societies predating modern Western medicine and antibiotics, infant mortality was high for both males and females. However, male infants (from birth to 5 years of age) appear to have died at nearly twice the rate of female infants (10 of 33 males vs. 5 of 32 females) and had a mean age of survival at birth of only 19 years, compared to 30 years for females. The difference in male and female survival was statistically significant by log-rank test (p = 0.005). Compared to survival curves for other societies predating modern Western medicine and antibiotics, including American-era historical deaths recorded for a cemetery in San Francisco, this bias is larger than might be expected. We suspect the pattern of sex-biased infant mortality at Síi Túupentak could relate to an intrinsic survival advantage for female infants, combined with extrinsic factors such as environmental pathogens, nutritional stress, and gendered differences in weaning patterns detected through stable isotope analyses. Using isotopic data on weaning ages and ethnographic accounts of gendered foraging activities, we focus on the potential role of sex-biased differences in weaning patterns and highlight potential demographic and social implications. Broader application of proteomic and genomic sex estimation would allow sex-biased differences in nutrition and health, as well as social and cultural aspects of male and female life histories, to be compared across a wide range of archaeologically known hunter-gatherer societies. [ABSTRACT FROM AUTHOR]

Steelhead (Oncorhynchus mykiss expressing an anadromous life history) in the Sacramento and San Joaquin rivers and their tributaries in California's Central Valley (CCV) belong to a Distinct Population Segment (DPS) that is listed as threatened under the US Endangered Species Act. Although contemporary management and recovery plans include numerous planned and ongoing efforts seeking to aid in DPS recovery--such as gravel augmentation, manipulation of spring flows, and restoration of rearing and spawning habitat--a paucity of data precludes the possibility of evaluating the effect of these actions on populations of Steelhead in CCV streams. Knowledge gaps relating to historic and current abundance, population-specific ratios of resident and anadromous life-history expression, and the influence of hatchery-reared fish remain largely unaddressed. This is partly a result of aspects of Steelhead biology that make them difficult to monitor, including the multitude of factors that contribute to the expression of anadromy, polymorphic populations, and migration periods that coincide with challenging field conditions. However, these gaps in understanding are also partly the result of an institutional focus on Chinook Salmon (Oncorhynchus tshawytscha) and a pervasive notion that actions benefiting Chinook populations will also benefit Steelhead populations. To evaluate these gaps and to suggest approaches for assessing DPS recovery actions, we review available data and existing monitoring efforts, and consider the actions necessary to inform the development of targeted O. mykiss monitoring programs. Current management and recovery goals focus on abundance estimates of Steelhead only, yet current monitoring is insufficient for reliable estimates. We argue that a reallocation of monitoring resources to better understand the interaction between resident O. mykiss and Steelhead would provide better data to estimate the vital rates needed to evaluate the effects of recovery actions. [ABSTRACT FROM AUTHOR]

Where freshwater species populations are in decline, conservation management requires rapid, cost‐effective approaches to develop recommendations, particularly at broad geographical scales or where species‐specific information is lacking. The umbrella species approach, typically applied to terrestrial taxa, is one potentially useful option to inform large‐scale freshwater management efforts.A quantitative, integrated approach is proposed for selecting suites of umbrella fish species over diverse spatial scales using a combination of species ranges, life‐history traits, and species vulnerability scores. The approach also uses expert opinion to validate methods and results.This approach was applied to native fishes in California, and results for two river basins are explored in the context of instream flow management. These examples illustrate how the results could help address two common instream flow management challenges in California: (i) the lack of information related to species‐specific flow requirements in basins with many species; and (ii) the need to move beyond a single species approach to flow management. In addition, the results indicate that the protection of native fishes in California would provide co‐benefits for other aquatic and riparian taxa.A key benefit of this approach is that the data used to select suites of umbrella species (e.g. species ranges, life‐history traits, climate vulnerabilities) are widely available at varying degrees of specificity for most freshwater fishes. Therefore, this flexible approach could be applied in other regions to aid managers in making freshwater conservation decisions, such as for instream flow strategies, in an efficient and cost‐effective manner. [ABSTRACT FROM AUTHOR]

The developmental time of pink hibiscus mealybug, Maconellicoccus hirsutus (Green), immatures was investigated on the host plant Cucurbita moschata Duchesne ex Poiret variety 'Black Futsu.' Because host plant species influences developmental rates of M. hirsutus, understanding the life history of this specific host plant has implications for the mass rearing protocols of its natural enemy, Anagyrus callidusTriapitsyn, Andreason and Perring, currently being released in California, United States. Fruit from 'Black Futsu' squash were infested with first instar pink hibiscus mealybug and kept at 26.6 ± 2°C, 50 ± 10% RH, and 0:24 (L:D) h photoperiod for the duration of the experiment. Every 24 h the life stages of pink hibiscus mealybug individuals on the squash were recorded. After adult eclosion, observations of adult females continued until the first eggs hatched, which revealed an average pre-oviposition period of 7.2 ± 0.1 d and an average length of the egg stage of 7.0 ± 0.0 d. The average developmental times for both sexes were similar from the egg stage through the second instar.Third instar females took nearly twice as long (7.2 d) to develop into adults as did third instar males. However, females have just three immature instars while males have four.The males spent an average of 4.5 ± 0.3 d as third instars and 4.8 ± 0.4 d as fourth instars before developing into winged adults. On average, female immature developmental time was 27.8 ± 0.2 d from egg to adult and male developmental time was 29.4 ± 0.2 d from egg to adult.The implications of these results on rearing A. callidus are discussed. [ABSTRACT FROM AUTHOR]

Straying has been difficult to study directly in natural steelhead Oncorhynchus mykiss populations. We analyzed an opportunistic sample of seven adult steelhead from a small basin on the Big Sur coast of California to determine their life history traits, including whether they were strays. Otolith natural tags (87Sr/86Sr) and genetic stock identification indicated that all seven adults were strays from at least six different sources. Three adults strayed from nearby streams (<72 km) on the Big Sur coast, while three strayed from distant sources, including the Klamath River (680 km to the north); the source of one stray could not be identified. Six strays were progeny of steelhead mothers, but one was the offspring of a nonanadromous mother. Six were female and one was male, and all that could be genotyped were homozygous (n = 4) or heterozygous (n = 2) for the anadromy‐associated haplotype in a migration‐associated genomic region. While the opportunistic nature and small size of the sample prevents us from inferring the rate of straying into the basin, our study nonetheless demonstrates that steelhead may stray across greater distances than generally has been appreciated and that nonanadromous females can produce anadromous offspring that stray, thus providing connectivity among basins. [ABSTRACT FROM AUTHOR]

The transition to motherhood in mammals is marked by changes in females' perception of and responsiveness to sensory stimuli from infants. Our understanding of maternally induced sensory plasticity relies most heavily on studies in uniparental, promiscuous house mice and rats, which may not be representative of rodent species with different life histories. We exposed biparental, monogamous California mouse (Peromyscus californicus) mothers and ovariectomized virgin females to one of four acoustic and olfactory stimulus combinations (Control: clean cotton and white noise; Call: clean cotton and pup vocalizations; Odor: pup-scented cotton and white noise; Call + Odor: pup-scented cotton and pup vocalizations) and quantified females' behavior and Fos expression in select brain regions. Behavior did not differ between mothers and ovariectomized virgins. Among mothers, however, those exposed to the Control condition took the longest to sniff the odor stimulus, and mothers exposed to the Odor condition were quicker to sniff the odor ball compared to those in the Call condition. Behavior did not differ among ovariectomized virgins exposed to the different conditions. Fos expression differed across conditions only in the anterior hypothalamic nucleus (AHN), which responds to aversive stimuli: among mothers, the Control condition elicited the highest AHN Fos and Call + Odor elicited the lowest. Among ovariectomized virgin females, Call elicited the lowest Fos in the AHN. Thus, reproductive status in California mice alters females' behavioral responses to stimuli from pups, especially odors, and results in the inhibition of defense circuitry in response to pup stimuli. [ABSTRACT FROM AUTHOR]

Demographic models enhance understanding of drivers of population growth and inform conservation efforts to prevent population declines and extinction. For species with complex life histories, however, parameterizing demographic models is challenging because some life stages can be difficult to study directly. Integrated population models (IPMs) empower researchers to estimate vital rates for organisms that have cryptic or widely dispersing early life stages by integrating multiple demographic data sources. For a stream‐inhabiting frog (Rana boylii) that is declining through much of its range in Oregon and California, USA, we collected egg‐mass counts and capture–mark–recapture data on adults from two populations in California to fit IPMs that estimate adult abundance and the survival rate of both marked and unobserved life stages. Estimates of adult abundance based on long‐term monitoring of egg‐mass counts showed that study populations fluctuated greatly inter‐annually but were stable at longer timescales (i.e., decades). Adult female survival during 5–6 yr of capture–mark–recapture study periods was nearly equal in each population. Survival rate of R. boylii eggs to the subadult stage is low on average (0.002) but highly variable among years depending on post‐oviposition stream flow. Population viability analysis showed that survival of adult and subadult life stages has the greatest proportional effect on population growth; the survival of egg and tadpole life stages, however, is more malleable by management interventions. For example, simulations showed head‐starting of tadpoles, salvaging stranded egg masses, and limiting aseasonal pulsed flows could dramatically reduce the threat of extirpation. This study demonstrates the value of integrating multiple demographic data sources to construct models of population dynamics in species with complex life histories. [ABSTRACT FROM AUTHOR]

Populations of Chinook Salmon Oncorhynchus tshawytscha in California are in decline due to the combined effects of habitat degradation, water diversions, and climate change. Reduced life history diversity within these populations inhibits their ability to respond to these stressors. Putah Creek, a small creek in California's Central Valley that once supported Chinook Salmon, is undergoing restoration to provide spawning habitats for this imperiled species. Beginning in 2014, increasing numbers of Chinook Salmon spawned throughout the creek, and emigrating juveniles were observed in the following months. Here we used otolith annual growth bands and microchemistry to investigate the age structure and natal origins of the adult spawners. Most individuals were 2 or 3 years old, and they originated from at least seven different natal sources, overwhelmingly from Central Valley hatcheries (~88%). These findings highlight that straying fall‐run Central Valley Chinook Salmon can rapidly utilize restored habitats, potentially establishing new populations. However, to facilitate local adaptations, straying rates and gene flow will have to be managed over time. Reconnecting migratory pathways and restoring many small and diverse streams, like Putah Creek, provides an opportunity to increase life history diversity, strengthening the recovery and resilience of Chinook Salmon. [ABSTRACT FROM AUTHOR]

Downstream migration of smolts is a critical aspect of the life history pathway for anadromous salmonids. Timing of downstream migration can vary along latitudinal and climatic gradients. Steelhead Oncorhynchus mykiss occur over a broad range of climate and hydrologic conditions, but relatively little is known about migration timing of smolts in the southern extent of the species' range. Using a 19‐year data set (1994–2014) of smolt arrivals collected in a downstream migrant trap at the Vern Freeman Diversion facility on the Santa Clara River, one of the largest coastal watersheds in southern California, I report patterns of migration and potential environmental drivers determining migration timing. Large sections of the Santa Clara River and the confluences of its perennial tributaries are intermittent except during winter and spring stormflows, limiting migration opportunities. If tributaries were connected, smolts were regularly encountered in the downstream migrant trap between March and May, with rare observations of downstream migrants in January (0.1%) or February (0.3%). Although these migration data are limited by low smolt abundance and sampling efficiency during high‐flow events, potential environmental drivers were identified as cues for smolt migration timing in this region. Day length was a consistent predictor of smolt migration, while hydrology was both a constraint and a cue, with migrants only arriving after tributaries had reconnected to the main stem and with many arrivals occurring weeks or months after storm events had passed. Smolt migration was not consistently synchronized with periods when intermittent sections of the main stem were wetted and passable to the ocean. Between 0% and 70% of smolts arrived at the Vern Freeman Diversion after natural flows were likely insufficient for passage to the ocean. Smolt migration is a critical piece of the management puzzle for southern California steelhead, and these data will serve to inform effective management strategies and research needs for the successful recovery of the species. [ABSTRACT FROM AUTHOR]

One of the strongest biological impacts of climate change has been the movement of species poleward and upward in elevation. Yet, what is not clear is the extent to which the spatial distribution of locally adapted lineages and ecologically important traits may also shift with continued climate change. Here, we take advantage of a transplant experiment mimicking up‐slope seed dispersal for a suite of ecologically diverse populations of yellow monkeyflower (Mimulus guttatus sensu lato) into a high‐elevation common garden during an extreme drought period in the Sierra Nevada mountains, California, USA. We use a demographic approach to quantify fitness and test for selection on life history traits in local versus lower‐elevation populations and in normal versus drought years to test the potential for up‐slope migration and phenotypic selection to alter the distribution of key life history traits in montane environments. We find that lower‐elevation populations tend to outperform local populations, confirming the potential for up‐slope migration. Although selection generally favored some local montane traits, including larger flowers and larger stem size at flowering, drought conditions tended to select for earlier flowering typical of lower‐elevation genotypes. Taken together, this suggests that monkeyflower lineages moving upward in elevation could experience selection for novel trait combinations, particularly under warmer and drier conditions that are predicted to occur with continued climate change. [ABSTRACT FROM AUTHOR]

The timing of life history events, such as germination and reproduction, influences ecological and selective environments throughout the life cycle. Many organisms evolve responses to seasonal environmental cues to synchronize these key events with favourable conditions. Often the fitness consequences of each life history transition depend on previous and subsequent events in the life cycle. If so, shifts in environmental cues can create cascading effects throughout the life cycle, which can influence fitness, selection on life history traits, and population viability.We examined variation in cue responses for contingent life history expression and fitness in a California native wildflower, Streptanthus tortuosus, by manipulating seasonal germination timing in a common garden experiment. We also manipulated chilling exposure to test the role of vernalization cues for seasonal life history contingency.Plants germinating early in the growing season in autumn were more likely to flower in the first year and less likely to perennate than later germinants in spring. First‐year reproduction and overall fitness was the highest for autumn cohorts. Sensitivity analyses showed that optimal germination date depended on survival beyond the first year and fruit production in later years.Experimental chilling exposure induced first‐year flowering in spring germinants, demonstrating that seasonal life history contingency is mediated by a vernalization requirement. This requirement reduced fitness of spring germinants without increasing survival or later fecundity and may be maladaptive. Such mismatches between cues and fitness may become more pervasive as predicted climate change reduces exposure to chilling, shortens growing seasons, and increases severity of summer drought.Synthesis. Shifts in germination timing in seasonal environments can cause cascading effects on trait expression and fitness that extend beyond the first year of the life cycle. Climate change is likely to shift seasonal conditions, influencing such life history contingency, with significant impacts on trait expression, fitness, and population persistence. These shifts may cause strong natural selection on cue sensitivity and life history expression, but it is an open question whether populations have the potential for rapid adaptation in response to this selection. [ABSTRACT FROM AUTHOR]

Intense fishing pressure has led to changes in species composition, demography and the over‐exploitation of many coastal fishes. To restore populations, artificial reefs (ARs) are used with the assumption that new habitat will increase fish productivity. Kelp bass (Paralabrax clathratus), barred sand bass (P. nebulifer) and California sheephead (Semicossyphus pulcher) are three important recreational gamefish species in southern California. Home ranging behaviour, space use and spawning‐related activity of these three species were quantified on a large AR. Kelp bass used the largest amount of area, but space use was similar among species. While no spawning behaviour could be determined for sheephead, kelp bass exhibited two different activity patterns during spawning months and barred sand bass migrated (indicative of spawning). Results of this study indicate that this large AR is providing suitable habitat for these species, and spawning‐related activity could be a sign that this AR is meeting essential life history demands. [ABSTRACT FROM AUTHOR]

Partial migration is a common phenomenon wherein populations include migratory and resident individuals. Whether an individual migrates or not has important ecological and management implications, particularly within protected populations. Within partially migratory populations of Oncorhynchus mykiss, migration is highly correlated with a specific genomic region, but it is unclear how well this region predicts migration at the individual level. Here, we relate sex and life history genotype, determined using >400 single nucleotide polymorphisms (SNPs) on the migratory-linked genomic region, to life history expression of marked juvenile O. mykiss from two tributaries to the South Fork Eel River, northern California. Most resident fish were resident genotypes (57% resident, 37% heterozygous, 6% migratory genotype) and male (78%). Most migratory fish were female (62%), but were a mixture of genotypes (30% resident, 45% heterozygous, 25% migratory genotype). Sex was more strongly correlated with life history expression than genotype, but the best-supported model included both. Resident genotypes regularly migrated, highlighting the importance of conserving the full suite of life history and genetic diversity in partially migratory populations. [ABSTRACT FROM AUTHOR]

We made extensive observations in the shallows off sandy beaches along the southern California coastline from 2013-2018 using SCUBA. The common diurnal behavior of young-of-the-year (YOY) of giant sea bass, Stereolepis gigas, were documented, in detail, and categorized while they occupied their unique nursery areas. We identified and described the frequently observed behaviors referred to as 1) "kelping", 2) "resting", 3) "traveling", and 4) "burying". Finally, through direct observation, mysid shrimp were confirmed as the primary diet of young-of-the-year of the giant sea bass off southern California. This is the first study to provide a behavioral overview of the YOY of this internationally listed, endangered species, and it bridges important gaps in our understanding of their early life history. [ABSTRACT FROM AUTHOR]

Expansion of native junipers, Juniperus Linnaeus (Cupressaceae), is altering landscapes in the western U.S., prompting extensive management efforts to counter this spread and the negative effects on impacted ecosystems. Our studies investigating sources of seed mortality in western juniper, Juniperus occidentalis Hooker; Utah juniper, Juniperus osteosperma (Torrey) Little); and California juniper, Juniperus californica Carrière, have revealed a number of previously unreported seed-attacking arthropods. One of the most commonly encountered insects at collection sites in California and Nevada are cone-boring cosmet moths (Cosmopterigidae) in the genus Periploca Braun, 1919. DNA analysis of insect adults and immatures both reared and dissected from juniper berries definitively associated Periploca adults with their immature stages and with seed damage while also screening for parasitoid DNA to reveal parasitoid-host relationships. Sequence data for Periploca adults and larvae revealed the presence of three species of Periploca attacking juniper berries at our survey locations. These have been identified as P. atrata Hodges, 1962, commonly referred to as the juniper cone moth, along with P. juniperi Hodges, 1978, and P. serrulata Hodges, 1978. Previously unreported details regarding the life histories of these three species of Periploca, all of which were encountered in western, Utah, and California juniper, were revealed. In addition, berry dissections, rearing efforts, and DNA sequence data have linked numerous parasitoids to juniper berry-infesting Periploca. These fi ndings develop a more refined understanding of the genus Periploca and the arthropod community influencing juniper seed production, which can provide potentially valuable tools for the ongoing management of juniper expansion. [ABSTRACT FROM AUTHOR]

A thorough understanding of the life cycles underlying the demography of wild species is limited by the difficulty of observing hidden life-history traits, such as embryonic development. Major aspects of embryonic development, such as the rate and timing of development, and maternal-fetal interactions can be critical features of early-life fitness and may impact population trends via effects on individual survival. While information on development in wild snakes and lizards is particularly limited, the repeated evolution of viviparity and diversity of reproductive mode in this clade make it a valuable subject of study. We used field-portable ultrasonography to investigate embryonic development in two sympatric garter snake species, Thamnophis sirtalis and Thamnophis elegans in the Sierra Nevada mountains of California. This approach allowed us to examine previously hidden reproductive traits including the timing and annual variation in development and differences in parental investment in young. Both species are viviparous, occupy similar ecological niches, and experience the same annual environmental conditions. We found that T. sirtalis embryos were more developmentally advanced than T. elegans embryos during June of three consecutive years. We also found that eggs increased in volume more substantially across developmental stages in T. elegans than in T. sirtalis, indicating differences in maternal provisioning of embryos via placental transfer of water. These findings shed light on interspecific differences in parental investment and timing of development within the same environmental context and demonstrate the value of field ultrasonography for pursuing questions relating to the evolution of reproductive modes, and the ecology of development. [ABSTRACT FROM AUTHOR]

Advancement in timing of important life history events for birds due to climate change presents conservation and monitoring challenges. Song and other vocal activity are strong indicators of avian phenology because they correspond to territorial defense and mate attraction during the breeding season. We combined data from 2 projects using point counts and automated sound recorders to survey passerines during the breeding season in northern California, USA (553 sites, 2009-2011). We used multi-species occupancy modeling to estimate how detection probability based on vocalizations varied over the course of the breeding season. We estimated dates of peak vocal activity, which we reasoned were indicative of reproductive phenology. We demonstrated a strong unimodal relationship between vocal activity and survey date for 8 focal species for which average detectability peaked on June 21 (90% Cl: June 19-June 22). Although we found no difference in peak dates of average detectability for migrants vs. residents, the variability of this estimate was lowest for Neotropical migrants compared to residents and elevational migrants. This finding supports previous research suggesting that long-distance migrants may be less flexible in adapting their phenology and more vulnerable to climate change. For an 80% power standard, we found that repeating our level of survey effort on an annual basis would allow detection of an advancement of average peak vocal activity by as small as 2.2 days over 10 yr for the focal species. We could detect smaller average shifts of 0.8 day decade ' for this group or 1.6 days decade-1 for all passerines over 20 yr. Monitoring vocal phenology of birds through occupancy modeling of survey data from the breeding season is an efficient approach to assessing climate change impacts because species occupancies and measures of community- level diversity can be simultaneously estimated. [ABSTRACT FROM AUTHOR]

Advancement in timing of important life history events for birds due to climate change presents conservation and monitoring challenges. Song and other vocal activity are strong indicators of avian phenology because they correspond to territorial defense and mate attraction during the breeding season. We combined data from 2 projects using point counts and automated sound recorders to survey passerines during the breeding season in northern California, USA (553 sites, 2009-2011). We used multi-species occupancy modeling to estimate how detection probability based on vocalizations varied over the course of the breeding season. We estimated dates of peak vocal activity, which we reasoned were indicative of reproductive phenology. We demonstrated a strong unimodal relationship between vocal activity and survey date for 8 focal species for which average detectability peaked on June 21 (90% CI: June 19-June 22). Although we found no difference in peak dates of average detectability for migrants vs. residents, the variability of this estimate was lowest for Neotropical migrants compared to residents and elevational migrants. This finding supports previous research suggesting that long-distance migrants may be less flexible in adapting their phenology and more vulnerable to climate change. For an 80% power standard, we found that repeating our level of survey effort on an annual basis would allow detection of an advancement of average peak vocal activity by as small as 2.2 days over 10 yr for the focal species. We could detect smaller average shifts of 0.8 day decade-1 for this group or 1.6 days decade-1 for all passerines over 20 yr. Monitoring vocal phenology of birds through occupancy modeling of survey data from the breeding season is an efficient approach to assessing climate change impacts because species occupancies and measures of communitylevel diversity can be simultaneously estimated. [ABSTRACT FROM AUTHOR]

The pet ferret (Mustela putorius furo) is at the center of a controversy over how domesticated carnivores should be regulated and managed, and in general, how the impacts of introduced mammals can be minimized. California is presented as a case study because it contains the largest state population of pet ferrets, is subject to repeated petitions to repeal the ownership ban, and has diverse wildlife communities vulnerable to exotic animal introductions. The impacts of ferrets upon native wildlife and ecosystems, agribusiness, and human health and safety were compiled from a thorough review of the published literature and the analysis of four surveys of U.S. state agencies, including our unpublished survey data. Results highlight two primary concerns: the ferret can easily escape confinement, and could impact native bird populations, as do feral cats; and human safety concerns, especially with infants, because of the proclivity of the ferret to bite. The requirements for introduction and establishment of an exotic animal are discussed in relation to the case studies of feral ferret populations and applicable life history traits. While the pet ferret may lack the genetic rigor and instincts to be an effective predator and invader, the European polecat (M. p. putorius) and ferret-polecat hybrids can and do exploit vulnerable ecosystems such as islands. Regulatory strategies and environmental impact mitigation measures are presented: methods for minimizing the risk of release and for quantifying risk/benefits in general; addressing gaps in regulation, enforcement, funding, and information sharing; mitigating human health and safety concerns by mandatory sterilization /vaccination and pet owner education; and improving monitoring of invasive species and adequacy of emergency response and eradication measures. [ABSTRACT FROM AUTHOR]

Abiotic factors and species introductions can alter food web timing, disrupt life cycles, and change life history expressions and the temporal scale of population dynamics in zooplankton communities. We examined physical, trophic, and zooplankton community dynamics in the San Francisco Estuary, California, a highly altered Mediterranean climate waterway, across a 43-year dataset (1972-2014). Before invasion by the suspension-feeding overbite clam ( Potamocorbula amurensis) in the mid-1980s, the estuary demonstrated monomictic thermal mixing in which winter turbidity and cool temperatures contributed to seasonally low productivity, followed by a late-spring-summer clearing phase with warm water and peak phytoplankton blooms that continued into early winter. Following the clam invasion, we observed a shift in peak phytoplankton bloom timing, with peak productivity now occurring in May compared to June prior to the invasion. Peak abundance of several zooplankton taxa ( Eurytemora affinis, Pseudodiaptomus, other calanoids, and non-copepods) also shifted to earlier in the season. We present the first evidence of a shift in the timing of peak abundance for zooplankton species that are key prey items of delta smelt ( Hypomesus transpacificus), a federally threatened pelagic fish species. These timing shifts may have exacerbated well-documented food limitations of delta smelt due to declines in primary productivity since the invasion of the overbite clam. Future conservation efforts in the estuary should consider measures designed to restore the timing and magnitude of pre-invasion phytoplankton blooms. [ABSTRACT FROM AUTHOR]

Shelled pteropods are cosmopolitan, free-swimming organisms of biogeochemical and commercial importance. They are widely used as sentinel species for the overall response of marine ecosystems to environmental stressors associated with climate change and changes in ocean chemistry. However, currently we are unable to project the effects of climate change on shelled pteropods at the population level, due to the missing spatio-temporal characterization of the response of pteropods to environmental stressors, and the limited information on the pteropod life history and life-cycle. In this study, we implement a shelled pteropod Individual-Based Model (IBM), i.e. we simulate a pteropod population as a set of discrete individuals over several generations, life-stages (eggs, larvae, juveniles and adults) and as a function of temperature, food availability, and aragonite saturation state. The model is able to provide an abundance signal that is consistent with the abundance signal measured in the temperate region. In addition, the modeled life-stage progression matches the reported size spectrum across the year, with two major spawning periods in spring and fall, and maturation in March and September. Furthermore, our IBM correctly predicts the abundance maxima of younger, smaller and potentially more susceptible life-stages in spring and winter. Thus, our model provides a tool for advancing our understanding of the response of pteropod populations to future environmental changes. • First shelled pteropod individual-based model (IBM) based on Limacinidae species. • Shelled pteropod IBM reproduces the abundance signal measured at temperate latitudes. • The pteropod IBM provides the life-stage composition, and life-stage progression of populations. • IBM might be used for quantifying ongoing and future effects of climate change. [ABSTRACT FROM AUTHOR]