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In the past few decades, the discrete dynamics of difference maps have attained the remarkable attention of researchers owing to their incredible applications in different domains, like cryptography, secure communications, weather forecasting, traffic flow models, neural network models, and population biology. In this article, a generalized chaotic system is proposed, and superior dynamics is disclosed through fixed point analysis, time-series evolution, cobweb representation, period-doubling, period-3 window, and Lyapunov exponent properties. The comparative bifurcation and Lyapunov plots report the superior stability and chaos performance of the generalized system. It is interesting to notice that the generalized system exhibits superior dynamics due to an additional control parameter β . Analytical and numerical simulations are used to explore the superior dynamical characteristics of the generalized system for some specific values of parameter β . Further, it is inferred that the superiority in dynamics of the generalized system may be efficiently used for better future applications. [ABSTRACT FROM AUTHOR]

Genotype and phenotype in mobile organisms can be defined by various factors such as environmental, biological and geographical. Brown noddies Anous stolidus are pan-tropical seabirds breeding at different times, with migratory and resident populations in six islands throughout 20° of latitude in the Southwestern Atlantic Ocean. If environmental heterogeneity plays a key role in their population biology, we would expect significant genetic structure among colonies. However, absence of genetic structure between phenotypically different populations could play a scenario of ecological plasticity. To test these hypotheses, we used a model-based integrative approach combining genetic (mtDNA and ultraconserved elements) and morphological data of the brown noddy (n = 122) along with environmental variables and isotopic niches. We uncovered low levels of genetic structure, with 16 haplotypes for mtDNA and a signal of an ancient population expansion. Ultraconserved elements indicated that all colonies belong to the same genetic population (K = 1) and revealed substantial endogamy. However, phenotype differed both by biometric measures and isotopic niches between most pairs of populations. Although individuals from the northernmost colony are larger than the others, they are genetically similar, indicating a wide reaction norm for this species. Our results indicate the Southwestern Atlantic populations of the brown noddy are panmictic, but ecologically and morphologically diverse. [ABSTRACT FROM AUTHOR]

Fire blight, caused by the bacterial pathogen Erwinia amylovora, continues to be a devastating disease affecting commercial apple and pear plantings in almost all areas of the world, with recent incursions into Korea and China. During the past two decades, significant gains in knowledge of E. amylovora and fire blight disease have been achieved, in topic areas such as genetic and genomic diversity, host-pathogen interactions, host resistance, and disease management. As we look forward to the next two decades and beyond of fire blight research, we summarize the current research knowledge in topics focused on E. amylovora pathogen and population biology and propose research questions that we hope can guide the field forward to gain the necessary understanding that will lead to sustainable management of this disease. [ABSTRACT FROM AUTHOR]

Single gamete cell sequencing together with long-read sequencing can reliably produce chromosome-level phased genomes. In this study, we employed PacBio HiFi and Hi-C sequencing on a male Landrace pig, coupled with single-sperm sequencing of its 102 sperm cells. A haplotype assembly method was developed based on long-read sequencing and sperm-phased markers. The chromosome-level phased assembly showed higher phasing accuracy than methods that rely only on HiFi reads. The use of single-sperm sequencing data enabled the construction of a genetic map, successfully mapping the sperm motility trait to a specific region on chromosome 1 (105.40–110.70 Mb). Furthermore, with the assistance of Y chromosome-bearing sperm data, 26.16 Mb Y chromosome sequences were assembled. We report a reliable approach for assembling chromosome-level phased genomes and reveal the potential of sperm population in basic biology research and sperm phenotype research. An improved pig genome assembly is reported, using single sperm sequencing to reconstruct chromosome haplotypes, and with improved Y chromosome sequence. [ABSTRACT FROM AUTHOR]

The goal of evolutionary biology is to explain the diversity of the entire sweep of the natural world; population biology only examines tiny slices of time of a few individuals of single species. What gives the tiny scale of population biology its relevance to evolutionary biology is the following assumption: processes identical or similar to those observed in a given population biology study are operative in unexamined individuals in the same species, have been operative throughout the history of the species, and are operative in other species. Without this assumption, population biology studies are just very detailed descriptions of a handful of individuals of a species. Population biology lacks the means to test its jusifying assumption. It is tested by the comparative method, studies of convergent evolution across species. The comparative method has its own blind spots, mainly its inability to examine intraspecific variation, heritability, and fitness directly, exactly the purview of population biology. Population and comparative biology thus provide complementary sources of direct evidence regarding evolutionary process. Both, along with optimality models, evo-devo studies of the variants that can or can't be produced in development, together with assumptions about unseeable ancestral populations, make up essential parts of a maximally well-supported evolutionary explanation. Recognizing this essential epistemic interdependence shows why it is necessary to select sources of evidence from across population, comparative, optimality, and developmental studies, leading to collaboration rather than criticism across these fields, and stronger explanations accounting for the evolution of diversity in organismal form and function. [ABSTRACT FROM AUTHOR]

Hydrothermal vents host fragmented habitats and are increasingly becoming the target of deep-sea mining projects for their mineral resources. Managing a future sustainable exploitation requires a good understanding of the resilience of biological populations to natural and anthropogenic disturbances, hence a better knowledge of species life history traits and their capacity to replenish local populations or colonise distant sites. In this context, we studied the reproductive biology and recruitment patterns of three main representative hydrothermal vent limpets of the South West Pacific back-arc basins, Lepetodrilus schrolli, Lepetodrilus fijiensis and Shinkailepas tollmanni, in relation to habitats and environmental conditions. Limpets were collected in Bathymodiolus and Ifremeria nautilei habitats at several vent sites in the Manus, North Fiji and Lau back-arc basins, and the Futuna Volcanic Arc during the CHUBACARC cruise in 2019. Population structure, gonad morphology, and gametogenesis were analysed for each species, and fecundity was analysed for the two Lepetodrilus species. Both Lepetodrilus spp. were gonochoric and displayed a sexual size dimorphism with females larger than males. Gametogenesis was continuous or quasi-continuous with all stages of oocyte development present in the gonad and a maximum oocyte size of 124 µm for L. schrolli and 126 µm for L. fijiensis. Fecundity varied between 52 and 205 with a mean of 119 ± 74 (SD) matured oocytes per female in L. schrolli and between 80 and 605 with a mean of 366 ± 183 (SD) matured oocytes per female in L. fijiensis, and was independent of the limpet size for both species. Shinkailepas tollmanni is also a gonochoric gastropod with continuous gametogenesis and a maximum oocyte size of 153 µm. For each species, size-frequency distributions were consistent with a continuous recruitment although episodic larval supply could blur the signal. There was no evidence of an influence of the habitat type nor environmental conditions on population structures. [ABSTRACT FROM AUTHOR]

The goal of this perspective is to review how seagrass research has evolved over the past half century to our current state of knowledge. We review how our knowledge of seagrass ecosystems changed from the pre-1970s when so little was known about seagrasses and how it progressed during the next 5 decades when seagrass knowledge rapidly expanded. Here, we concentrate on accomplishments in the areas of reproductive biology and ecology, population biology, seagrass-animal relationships, conservation and restoration, and mapping and monitoring. We also look ahead and discuss some areas that are ripe for future research, especially those employing new mapping and monitoring technologies, improved restoration methods that include multiple genetic variants, rhizosphere studies that result in a deeper understanding of microbial effects on nitrogen availability, sulfide levels and carbon sequestration, and how changing climatic regimes and tropicalization will likely affect temperate and tropical seagrass-dominated ecosystems. [ABSTRACT FROM AUTHOR]

Growth curve models play an instrumental role in quantifying the growth of biological processes and have immense practical applications across all disciplines. The most popular growth metric to capture the species fitness is the "Relative Growth Rate" in this domain. The different growth laws, such as exponential, logistic, Gompertz, power, and generalized Gompertz or generalized logistic, can be characterized based on the monotonic behavior of the relative growth rate (RGR) to size or time. Thus, in this case, species fitness can be determined truly through RGR. However, in nature, RGR is often non-monotonic and specifically bell-shaped, especially in the situation when a species is adapting to a new environment [1]. In this case, species may experience with the same fitness (RGR) for two different time points. The species precise growth and maturity status cannot be determined from this RGR function. The instantaneous maturity rate (IMR), as proposed by [2], helps to determine the correct maturity status of the species. Nevertheless, the metric IMR suffers from severe drawbacks; (i) IMR is intractable for all non-integer values of a specific parameter. (ii) The measure depends on a model parameter. The mathematical expression of IMR possesses the term "carrying capacity" which is unknown to the experimenter. (iii) Note that for identifying the precise growth status of a species, it is also necessary to understand its response when the populations are deflected from their equilibrium position at carrying capacity. This is an established concept in population biology, popularly known as the return rate. However, IMR does not provide information on the species deflection rate at the steady state. Hence, we propose a new growth measure connected with the species return rate, termed the "reverse of relative of relative growth rate" (henceforth, RRRGR), which is treated as a proxy for the IMR, having similar mathematical properties. Finally, we introduce a stochastic RRRGR model for specifying precise species growth and status of maturity. We illustrate the model through numerical simulations and real fish data. We believe that this study would be helpful for fishery biologists in regulating the favorable conditions of growth so that the species can reach a steady state with optimum effort. [ABSTRACT FROM AUTHOR]

Life-history traits are used as proxies of fitness in insects including Drosophila. Egg size is an adaptive and ecologically important trait potentially with genetic variation across different populations. However, the low throughput of manual measurement of egg size has hampered the widespread use of this trait in evolutionary biology and population genetics. We established a method for accurate and high throughput measurement of Drosophila egg size using large particle flow cytometry (LPFC). The size estimates using LPFC are accurate and highly correlated with the manual measurements. The measurement of egg size is high throughput (average of 214 eggs measured per minute) and viable eggs of a specific size can be sorted rapidly (average of 70 eggs per minute). Sorting by LPFC does not reduce the survival of eggs making it a suitable approach for sorting eggs for downstream analyses. This protocol can be applied to any organism within the detectable size range (10–1500 µm) of the large particle flow cytometers. We discuss the potential applications of this method and provide recommendations for optimizing the protocol for other organisms. [ABSTRACT FROM AUTHOR]

Narrowly endemic species are particularly vulnerable to catastrophic events. Compared to widespread species, they may also be less capable of adapting to shifts in environmental pressures as a result of specialisation on a narrow range of local condition and limited ability to disperse. However, life-history traits, such as preferential outcrossing and high fecundity can maintain genetic diversity and evolutionary potential, and boost species resilience. The endangered Grevillea bedggoodiana (Enfield Grevillea) is an understorey shrub restricted to an area of ca. 150 km2 in south-eastern Australia with a legacy of large-scale anthropogenic disturbance. Prior to this study little was known about its biology and population structure. Here, its breeding system was assessed through a controlled pollination experiment at one of its central populations, and eight populations were sampled for genetic analysis with microsatellite markers. The species was found to be preferentially outcrossing, with no evidence of pollination limitation. In most populations, allelic richness, observed heterozygosity and gene diversity were high (Ar: 3.8–6.3; Ho: 0.45–0.65, He: 0.60 − 0.75). However, the inbreeding coefficients were significant in at least four populations, ranging from Fi -0.061 to 0.259 despite high outcrossing rates. Estimated reproductive rates varied among sampled populations but were independent of gene diversity and inbreeding. Despite its small geographic range, the species' populations showed moderate differentiation (AMOVA: FST = 0.123), which was largely attributable to isolation by distance. We interpret these results as suggesting that G. bedggoodiana is reproductively healthy and has maintained high levels of genetic diversity despite recent disturbance. [ABSTRACT FROM AUTHOR]

Over the past two decades, the range of the desert wheatear has expanded and the species has started breeding in northwestern Kazakhstan. There are, however, almost no studies on the breeding biology of this northwesternmost population. In this paper, we provided data on the breeding biology and space use of the desert wheatear near the village of Isatai, Atyrau Region, Kazakhstan. In 2012–2016, no fewer than 17 breeding pairs bred each year as a dense settlement next to Isatai within a 650 × 470 m plot. The local density was thus 0.55 pairs per ha, and the distance between the neighboring pairs was usually less than 100 m. Such dense settlements seem to be unusual for the desert wheatear in Kazakhstan. We assume that the local features of limited cattle grazing may have caused the formation of this dense settlement. At the same time, the habitat and nest site selections, as well as the breeding phenology, of the desert wheatear in the vicinity of Isatai are generally the same as in southern Kazakhstan (i.e., in the central part of the species' range). [ABSTRACT FROM AUTHOR]

Climate change is a primary driver of tropical mangroves colonizing temperate salt marshes in the Gulf of Mexico. Studies indicate that threshold temperatures of adult and sapling Avicennia germinans survival range from −7 to −10 °C and survival can depend on life history stage during a freeze event. We performed a growth chamber study to explore responses to varying freezing temperature regimes when produced at two different latitudes with varying salinity and nutrient conditions. Propagules were collected from Corpus Christi and South Padre Island, Texas. In Corpus Christi Bay, propagules were harvested from fertilized maternal shrubs (nitrogen, phosphorus, and controls) in an ongoing fertilization experiment (2017 to present). A 2-h hard freeze treatment (−8 °C), resulted in 20% survival across latitude and nutrient treatments. The lower latitude propagules, which were harvested from the hypersaline South Padre Island A. germinans, had higher survival rates after –2 °C exposure, grew significantly taller as seedlings over 20 weeks, and produced more leaves after −8 °C exposure. Propagules from nitrogen-treated shrubs grew taller following −2 °C exposure. In all treatments, propagule weight was a significant covariate predictor of seedling height and leaf production. Avicennia germinans populations may not be decimated by a single −8 °C freeze, and populations could possibly experience rapid recruitment from surviving propagules after a freeze, leading to local adaptation. Growth benefits from fertilized parent plants indicate that propagules from high nutrient areas may be "hotspots" of future A. germinans expansion. [ABSTRACT FROM AUTHOR]

Aristotle is often named as the first zoologist or biologist because of his writings on animals. Although Aristotle's major intention in these books was to illustrate his ideas of how knowledge and understanding might advance, at least one modern biologist (C. Darwin) has recognized Aristotle's depth and breadth as being of surviving merit. Of greater surprise is the ongoing attention that his works continue to receive, including publications in contemporary scientific journals. This review identifies 38 peer-reviewed papers on various topics from Aristotle's biological writings that have been published during the last 50 years. These papers are described according to content (genetics, population biology, anatomy, brain, movement), specific creatures (fish, scorpions, elephants, insects, birds), publication outlet, distribution over the fifty year period surveyed, and visible trends in the topics studied. It is concluded that, in the highly-competitive field of peer-reviewed scientific publication and citation, Aristotle's biology continues to excite the interest of scientists and remains salient to modern science itself. [ABSTRACT FROM AUTHOR]

Ceratitis capitata (Wiedemann) is a polyphagous plant pest organism causing serious damage on more than 300 fruit types. Although the medfly is present in Europe, it is so far not established in Germany. In the years 2015–2017, an official survey was conducted by the German Federal Plant Protection Organisations to elucidate the current occurrence of this organism in Germany. While in 2015 only small numbers of flies were captured in traps situated in all German Federal States, a peak of 188 specimens could be trapped in 2016 with a decline to 29 specimens in 2017. Highest abundance of the fruit fly was detected in Southern Germany and at a single spot east of Berlin. The present study aimed to identify the origin of the trapped fruit flies and to assess the general potential of the species for overwintering in Germany. Using two approaches with cytochrome oxidase subunit I (COI), Sanger barcoding sequencing first and subsequent analysis of ten small simple repeat microsatellite loci from literature, the worldwide spread of C. capitata describing three phases could be retraced by analysing samples from Germany and 11 other countries. German and French populations were found to build the most recent stage of this species distribution. Specimens trapped in Germany obviously resulted from different introduction events. They most strongly resembled populations from France and Croatia but were not identical to these populations. We found strong evidence that specimens captured between 2016 and 2017 could not overwinter in Germany. [ABSTRACT FROM AUTHOR]

A system of sites indexed by N are each assigned an initial fitness value in [0, 1]. Each unit of time an environment is sampled for the system and a proposed fitness, uniform in [0, 1], is sampled for each site, all independent of each other and the past. The environment is good with probability p and is bad otherwise. The fitness of each site is then updated to the maximum or the minimum of its current fitness and the proposed fitness according to whether the environment is good or bad. We study the empirical fitness distribution, a probability-valued Markov process, and prove that it converges in distribution to a unique stationary distribution. Under the stationary distribution the system exhibits a self-similar (typically) non-smooth site-exchangeable behavior whereas the fitness distribution for each site is smooth. Our analysis is done by identifying a class of iterated function systems for which we prove ergodicity and provide a probabilistic representation of the stationary distribution. This also yields a close connection to the fractals literature. [ABSTRACT FROM AUTHOR]

Individual-based studies where animals are monitored through space and time enable explorations of ecology, demography, evolutionary biology, movements, and behavior. Here, we review 70 years of research on an endangered African herbivore, the giraffe, based on individual spot pattern recognition, and profile an example of a long-term photographic mark–recapture study of Masai giraffes in Tanzania. We illustrate how individual-based data can be used to examine the fitness consequences (variation in survival and reproduction) of extrinsic environmental factors or intrinsic traits in an evolutionary ecology framework. These data also allow the study of social structure, space use, life histories, and health. The giraffe offers an excellent opportunity to study dynamics of an ungulate species with a highly fission–fusion social system using spot pattern recognition. [ABSTRACT FROM AUTHOR]

Background: In the last decade, genomic studies have identified and replicated thousands of genetic associations with measures of health and disease and contributed to the understanding of the etiology of a variety of health conditions. Proteins are key biomarkers in clinical medicine and often drug-therapy targets. Like genomics, proteomics can advance our understanding of biology. Methods and Results: In the setting of the Cardiovascular Health Study (CHS), a cohort study of older adults, an aptamer-based method that has high sensitivity for low-abundance proteins was used to assay 4979 proteins in frozen, stored plasma from 3188 participants (61% women, mean age 74 years). CHS provides active support, including central analysis, for seven phenotype-specific working groups (WGs). Each CHS WG is led by one or two senior investigators and includes 10 to 20 early or mid-career scientists. In this setting of mentored access, the proteomic data and analytic methods are widely shared with the WGs and investigators so that they may evaluate associations between baseline levels of circulating proteins and the incidence of a variety of health outcomes in prospective cohort analyses. We describe the design of CHS, the CHS Proteomics Study, characteristics of participants, quality control measures, and structural characteristics of the data provided to CHS WGs. We additionally highlight plans for validation and replication of novel proteomic associations. Conclusion: The CHS Proteomics Study offers an opportunity for collaborative data sharing to improve our understanding of the etiology of a variety of health conditions in older adults. [ABSTRACT FROM AUTHOR]

The use of remote camera traps has accelerated rapidly in the field of large carnivore science since the 1990s. Members of the Hyaenidae are important components of functional ecosystems in Africa and parts of the Middle East and South Asia, and make good candidates for study using camera traps. However, camera trap studies of hyenas remain rare in the literature when compared to species like tigers Panthera tigris, leopards Panthera pardus, and snow leopards Panthera uncia. In this paper, we examine the published use of camera traps for hyenas (n = 34 studies implemented between 2007 and 2020) and examine the logistical challenges of using camera traps, such as individual identification, limited sexual dimorphism, and complex social structures, for studies of hyena population biology, behavioral ecology, and conservation. We highlight what these challenges may mean for data analyses and interpretation. We also suggest potential benefits of further camera trap studies of this taxonomic family, including new insights into social behavior, range extensions, and robust density estimates. [ABSTRACT FROM AUTHOR]

Quambalaria are fungal pathogens of Corymbia, Eucalyptus and related genera of Myrtaceae. They are smut fungi (Ustilaginomycota) described from structures that resemble conidia and conidiophores. Whether these spore forms have asexual or sexual roles in life cycles of Quambalaria is unknown. An epidemic of Q. pitereka destroyed plantations of Corymbia in New South Wales and Queensland (Australia) in 2008. We sampled 177 individuals from three plantations of C. variegata and used AFLPs to test hypotheses that the epidemic was spread by asexual reproduction and dominated by a single genotype. There was high genotypic diversity across ≥600 AFLP loci in the pathogen populations at each plantation, and evidence of sexual reproduction based on neighbour-net analyses and rejection of linkage disequilibrium. The populations were not structured by host or location. Our data did not support a hypothesis of asexual reproduction but instead that Q. pitereka spreads exclusively by sexual reproduction, similar to life cycles of other smut fungi. Epidemics were exacerbated by monocultures of Corymbia established from seed collected from a single provenance. This study showcases an example of an endemic pathogen, Q. pitereka, with a strictly outbreeding life cycle that has caused epidemics when susceptible hosts were planted in large monoculture plantations. [ABSTRACT FROM AUTHOR]

Showing that the arithmetic mean number of offspring for a trait type often fails to be a predictive measure of fitness was a welcome correction to the philosophical literature on fitness. While the higher mathematical moments (variance, skew, kurtosis, etc.) of a probability-weighted offspring distribution can influence fitness measurement in distinct ways, the geometric mean number of offspring is commonly singled out as the most appropriate measure. For it is well-suited to a compounding (multiplicative) process and is sensitive to variance in offspring number. The geometric mean thus proves to be a predictively efficacious measure of fitness in examples featuring discrete generations and within- or between-generation variance in offspring output. Unfortunately, this advance has subsequently led some to conclude that the arithmetic mean is never (or at best infrequently) a good measure of fitness and that the geometric mean should accordingly be the default measure of fitness. We show not only that the arithmetic mean is a perfectly reasonable measure of fitness so long as one is clear about what it refers to (in particular, when it refers to growth rate), but also that it functions as a more general measure when properly interpreted. It must suffice as a measure of fitness in any case where the geometric mean has been effectively deployed as a measure. We conclude with a discussion about why the mathematical equivalence we highlight cannot be dismissed as merely of mathematical interest. [ABSTRACT FROM AUTHOR]

Opioid use disorder (OUD) has become a serious leading health issue in the USA leading to addiction, disability, or death by overdose. Research has shown that OUD can lead to a chronic lifelong disorder with greater risk for relapse and accidental overdose deaths. While the prescription opioid epidemic is a relatively new phenomenon, illicit opioid use via heroin has been around for decades. Recently, additional illicit opioids such as fentanyl have become increasingly available and problematic. We propose a mathematical model that focuses on illicit OUD and includes a class for recovered users but allows for individuals to either remain in or relapse back to the illicit OUD class. Therefore, in our model, individuals may cycle in and out of three different classes: illicit OUD, treatment, and recovered. We additionally include a treatment function with saturation, as it has been shown there is limited accessibility to specialty treatment facilities. We used 2002–2019 SAMHSA and CDC data for the US population, scaled to a medium-sized city, to obtain parameter estimates for the specific case of heroin. We found that the overdose death rate has been increasing linearly since around 2011, likely due to the increased presence of fentanyl in the heroin supply. Extrapolation of this overdose death rate, together with the obtained parameter estimates, predict that by 2038 no endemic equilibrium will exist and the only stable equilibrium will correspond to the absence of heroin use disorder in the population. There is a range of parameter values that will give rise to a backward bifurcation above a critical saturation of treatment availability. We show this for a range of overdose death rate values, thus illustrating the critical role played by the availability of specialty treatment facilities. Sensitivity analysis consistently shows the significant role of people entering treatment on their own accord, which suggests the importance of removing two of the most prevalent SAMHSA-determined reasons that individuals do not enter treatment: financial constraints and the stigma of seeking treatment for heroin use disorder. [ABSTRACT FROM AUTHOR]

We studied the Ngaio flat mite, Brevipalpus ferraguti Ochoa & Beard, on Myoporum laetum (Scrophulariaceae), a common introduced plant used as hedgerows in gardens and green areas of the Mediterranean, where the mite causes considerable damage. We first describe the damage, and then the patterns of mite seasonal abundance and spatial distribution. Finally, we address the development of the female insemination system at the population level. Damage occurs on both sides of the leaves, starting with a uniform stippling and bronzing and ending in the leaves drying out and extensive defoliation that coincides with summer. Mite population peaked between June and August, maintained moderate levels in autumn and winter and reached its lowest density in early spring. Active motile immatures and eggs were present throughout the year. Females and motile immature forms were more abundant on the abaxial (lower) leaf surface, but eggs were deposited on both surfaces indistinctly, suggesting that females actively move to the adaxial (upper) surface in summer to oviposit. All the developmental stages were aggregated on the leaves throughout the year regardless of their population density. Our study suggests that a binomial or presence-absence sampling, examining only the number of females on the abaxial surface, can accurately estimate the total mite density levels. Only 23.5% of females possessed a fully developed spermatheca, whereas in 76.5% of the cases the seminal receptacle was not present or not developed. Females with a complete spermatheca were less abundant in summer. Average temperatures and host plant species affected the occurrence of this reproductive structure. [ABSTRACT FROM AUTHOR]

In the 1960s, theoretical biologist Richard Levins criticised modellers in his own discipline of population biology for pursuing the "brute force" strategy of building hyper-realistic models. Instead of exclusively chasing complexity, Levins advocated for the use of multiple different kinds of complementary models, including much simpler ones. In this paper, I argue that the epistemic challenges Levins attributed to the brute force strategy still apply to state-of-the-art climate models today: they have big appetites for unattainable data, they are limited by computational tractability, and they are incomprehensible to the human modeller. Along the lines Levins described, this uncertainty generates a trade-off between realistic, precise models with predictive power and simple, highly idealised models that facilitate understanding. In addition to building ensembles of highly complex dynamical models, climate modellers can address model uncertainty by comparing models of different types, such as dynamical and data-driven models, and by systematically comparing models at different levels of what climate modellers call the model hierarchy. Despite its age, Levins' paper remains incredibly insightful and should be considered an important entry into the philosophy of computational modelling. [ABSTRACT FROM AUTHOR]

For sea snakes as for many types of animals, long-term studies on population biology are rare and hence, we do not understand the degree to which annual variation in population sizes is driven by density-dependent regulation versus by stochastic abiotic factors. We monitored three populations of turtle-headed sea snakes (Emydocephalus annulatus) in New Caledonia over an 18-year period. Annual recruitment (% change in numbers) showed negative density-dependence: that is, recruitment increased when population densities were low, and decreased when densities were high. Windy weather during winter increased survival of neonates, perhaps by shielding them from predation; but those same weather conditions reduced body condition and the reproductive output of adult snakes. The role for density-dependence in annual dynamics of these populations is consistent with the slow, K-selected life-history attributes of the species; and the influence of weather conditions on reproductive output suggests that females adjust their allocation to reproduction based on food availability during vitellogenesis. [ABSTRACT FROM AUTHOR]

As the debate about holism and reductionism in ecology has ebbed in the last twenty years, this article aims to reassess the traditional opposition between holistic and reductionist epistemologies during the development of population biology. The history of the notion of carrying capacity, the upper demographic limit of a viable population, will be analyzed as a paradigmatic case of the progressive imposition of reductionist strategies, from both an epistemological and a semantic point of view, since the middle of the twentieth century. Then, Richard Looijen's reduction of the carrying capacity concept to the niche partitioning theory will be assessed and rebuked for both empirical and logical reasons. Eventually, some recent "weak" and "hard" emergent conceptualizations of the notion of carrying capacity, in logistic map models or in coupled niche-population systems, will be presented in order to show how they call into question the nature and the use of the notion of carrying capacity as a predefined ecological limit. [ABSTRACT FROM AUTHOR]

The scope of this paper can be clarified by means of a well-known phenomenon that is usually called 'industrial melanism': the fact that the melanic form of the peppered moth became dominant in industrial areas in England in the second half of the nineteenth century. Such changes in relative phenotype frequencies are important explananda for population biologists. Apart from trying to explain such changes over time, population biologists also often try to explain differences between populations, e.g. why yellow shell colour is dominant in certain colonies of land snails and almost absent in other colonies. The causal explanations that are given to address such explananda are the objects of analysis in this paper. Our primary aim is to explicate their structure: we want to capture the typical ingredients of causal explanations in population biology, and their organisation. Based on this explication, we discuss how natural selection fits into recent mechanical philosophy of science, and engage in the debate on the nature of evolutionary theory. [ABSTRACT FROM AUTHOR]

The Swedish wolf population has rebounded from near extinction in the 1960s to around 365 individuals in 2020, after the implementation of the Hunting Act (jaktlagen) in 1966. This recent increase in the wolf population has evoked a serious divide between "pro-wolf" and "anti-wolf" Swedish citizens. Despite the continuous efforts by the Swedish government to reconcile this antagonism, the conflicts are persistent with a sign of impasse. In this paper, we present a modelling tool, which can bring transparent and "structured dialogue to the opposing positions." This approach includes a stylized framework for quantitative modelling of stakeholders' satisfaction levels regarding their preferred size of the wildlife population in question, based on the concept of satisfaction functions. We argue that this framework may contribute to conflict resolution by bringing a common understanding among stakeholders, facilitate a societal discourse, and potentially help to assess likely support for conservation policies. We present a showcase application of this modeling tool in the context of the conflict over the Swedish wolf conservation policies. The model is informed using a thorough literature review as well as interviews, which identified relevant stakeholder groups and respective drivers of their attitudes towards wolves. [ABSTRACT FROM AUTHOR]

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Understanding and predicting responses to increased mortality is important for conservation biology and population management strategies. In stage-structured populations, increased mortality of a particular stage can have the counterintuitive effect of causing increased abundance in one or more stages (called stage-specific overcompensation in density) or the whole population (called a hydra effect). We analyzed an n-stage, single-species, ordinary differential equation model in order to explore the mechanisms driving overcompensation in density and hydra effects in stage-structured populations. We find that in the absence of inter-stage competition, overcompensation in density only occurs if intra-stage competition in one stage is sufficiently strong to cause overcompensation in the maturation or reproductive rate of that stage (i.e., increased input causes decreased output for that stage). When there is inter-stage competition, overcompensation in density can also be driven by sufficiently strong inter-stage competition, even in the absence of overcompensation in any ecological rate. Hydra effects arise under the same conditions and are more likely to be caused by sufficiently strong intra-stage competition. We interpret our results in terms of the direct and indirect effects between stages, which helps clarify the relationships between stage-specific overcompensation in density, overcompensation in ecological rates and hydra effects. [ABSTRACT FROM AUTHOR]

The spatial distribution of phenotypes across the environment has important consequences for population biology, community ecology, and evolution. Populations of pumpkinseed sunfish (Centrarchidae: Lepomis gibbosus) have repeatedly diversified between the littoral and pelagic habitats of postglacial lakes, but we know little about the natural history of pumpkinseed in exposed rocky littoral shorelines relative to those in sheltered littoral bays. We addressed three general questions with respect to the pumpkinseed found in exposed littoral shoreline relative to conspecifics from sheltered littoral and pelagic habitats: (1) What phenotype is associated with the exposed littoral shoreline? (2) What is their summer diet? (3) What is the condition of pumpkinseed from exposed littoral shorelines? Reference sheltered littoral and pelagic pumpkinseed were phenotypically and ecologically differentiated in a pattern consistent with several previous studies; pelagic pumpkinseed had deeper bodies, smaller jaws (narrower oral jaw width and shorter premaxilla), and a more terminal mouth, as well as having more zooplankton and less insects in their diet. Pumpkinseed from exposed shoreline habitat had jaw and body shape phenotypes, as well as diets, that were similar to sheltered littoral reference pumpkinseed in some traits while others were more intermediate. We found no evidence that differences between habitats in phenotype or diet translated into differences in body condition at the end of the summer growing season, suggesting that exposed littoral shorelines are unlikely to be an ecological 'sink' habitat. This study expands our understanding of the spatial distributions of polyphenic pumpkinseed, and their habitat use in postglacial lakes. [ABSTRACT FROM AUTHOR]

The investigation of the temporal dynamics of marine benthonic populations is an important tool to evaluate whether and how they are responding to environmental changes. Here we compared the population biology and reproduction of Hepatus pudibundus in Ubatuba Bay after a 20-year gap. The first samplings were done in September 1995 − August 1996 (hereafter 1ºP), and the second, in September 2016 − August 2017 (hereafter 2ºP). In both periods, five sites were trawled aboard a shrimp fishing boat. We captured 865 crabs in the 1ºP and 4222 in the 2ºP. The mean individual size of each demographic group, the size at the onset of sexual maturity, and the growth rate of females was lower in the 2ºP. The reproductive and recruitment periods were continuous. Our comparable data on population features taken 20-years apart showed adjustments regarding the sizes and abundance of mature individuals of H. pudibundus of Ubatuba Bay, indicating that this species is resilient to the anthropogenic impacts in the region. [ABSTRACT FROM AUTHOR]

We studied the population biology and natural history of the endangered Swallowtail butterfly, Euryades corethrus to establish parameters for its conservation. We used capture-mark-recapture techniques and observations to study demography, mobility, foraging strategies, and sexual behavior. We captured 588 males and 367 females. Daily captures varied from zero to 44 per sex; sex ratio was male-biased. Abundance estimates showed that the population peaked during early spring and summer. Survival probability related to age, while temperature negatively affected recapture probability. Wing size varied throughout the study similarly for males and females, and both sexes displayed similar mobility. The distribution of flowers along sampling transects was not homogenous; Aristolochia sessilifolia was the only host plant recorded. The number of butterfly captures was higher in meadows and shrublands when compared to swamplands. Both the presence of flowers and host plants increased the chances of capturing individuals. The results shown here are relevant to design conservation strategies for the species, suggesting that classic conservation strategies, aimed to maintain a single patch of habitat protecting a single population, may not be the best strategy for the E. corethrus. [ABSTRACT FROM AUTHOR]

The southeastern Brazilian highlands harbor a high number of endemic and threatened species of animals and plants, including two species of Pampasatyrus butterflies (Satyrinae: Pronophilina). As for many other threatened Brazilian butterflies, there is virtually no biological information available for these butterflies. A mark-recapture study was carried out for two consecutive years (2017 and 2018) to study population parameters, movement, natural history and threats for the two Pampasatyrus species. The results showed that population parameters of both species are similar to those of satyrine butterfly species from temperate regions, including a single flight season, short adult lifespan and a typical pattern of protandry (adult males flying before females). Moreover, adults were shown to have high habitat fidelity, being restricted to natural grassland, and are mostly sedentary. Both studied species are seriously threatened by human-caused impacts, including urban expansion, presence of non-native large grazing animals, uncontrolled tourism and natural and man-made fires. Although none of these impacts have been directly measured, a fire that consumed more than 70% of the study area in the winter of 2017 did not cause the extinction of the populations of both species, as evidenced by population numbers in 2018. The present study contributes important data on the population biology and ecology of these two threatened butterflies, providing information that can be used for future management plans of these species and their habitats. [ABSTRACT FROM AUTHOR]

This review summarizes and analyzes data on the threespine stickleback Gasterosteus aculeatus L. of the White Sea, which is currently the most abundant fish in the region and, therefore, plays an important role in inshore and offshore communities. The threespine stickleback was abundant in the 1920s–1940s; its numbers declined significantly between the late 1960s and late 1990s and have increased again since then, showing a positive correlation with water temperature. In order to reveal the mechanisms of changes in the population of this species and to assess its role in the marine ecosystems, various aspects of the population biology of the species (interannual and seasonal population dynamics, spatial heterogeneity, age and sex structure, lipid and fatty acid status, homing, and fluctuating asymmetry), as well as its interactions with other organisms (feeding characteristics of adults and juveniles, role in feeding predatory fish, association with eelgrass, parasite composition and spatial distribution, and relationships with competing species) are analyzed. [ABSTRACT FROM AUTHOR]

While the link between amyloid β (Aβ) accumulation and synaptic degradation in Alzheimer's disease (AD) is known, the consequences of this pathology on population coding remain unknown. We found that the entropy, a measure of the diversity of network firing patterns, was lower in the dorsal CA1 region in the APP/PS1 mouse model of Aβ pathology, relative to controls, thereby reducing the population's coding capacity. Our results reveal a network level signature of the deficits Aβ accumulation causes to the computations performed by neural circuits. [ABSTRACT FROM AUTHOR]

Ecology in principle is tied to evolution, since communities and ecosystems result from evolution and ecological conditions determine fitness values (and ultimately evolution by natural selection). Yet the two disciplines of evolution and ecology were not unified in the twentieth-century. The architects of the Modern Synthesis, and especially Julian Huxley, constantly pushed for such integration, but the major ideas of the Synthesis—namely, the privileged role of selection and the key role of gene frequencies in evolution—did not directly or immediately translate into ecological science. In this paper I consider five stages through which the Synthesis was integrated into ecology and distinguish between various ways in which a possible integration was gained. I start with Elton's animal ecology (1927), then consider successively Ford's ecological genetics in the 1940s, the major textbook Principles of animal ecology edited by Allee et al. (1949), and the debates over the role of competition in population regulation in the 1950s, ending with Hutchinson's niche concept (1959) and McArthur and Wilson's Principles of Island Biogeography (1967) viewed as a formal transposition of Modern Synthesis explanatory schemes. I will emphasize the key role of founders of the Synthesis at each stage of this very nonlinear history. [ABSTRACT FROM AUTHOR]

This paper examines the history of animal behavior studies after the synthesis period. Three episodes are considered: the adoption of the theory of natural selection, the mathematization of ideas, and the spread of molecular methods in behavior studies. In these three episodes, students of behavior adopted practices and standards developed in population ecology and population genetics. While they borrowed tools and methods from these fields, they made distinct uses (inclusive fitness method, evolutionary theory of games, emphasis on individual selection) that set them relatively apart and led them to contribute, in their own way, to evolutionary theory. These episodes also highlight some limitations of "conjunction narratives" centered on the relation between a discipline and the modern synthesis. A trend in conjunction narratives is to interpret any development related to evolution in a discipline as an "extension," an "integration," or as a "delayed" synthesis. I here suggest that this can lead to underestimate discontinuities in the history of evolutionary biology. [ABSTRACT FROM AUTHOR]

Dollar spot, caused by four Clarireedia species (formerly Sclerotinia homoeocarpa), is a devastating disease that affects many turfgrass species throughout North America. Proper classification and genetic diversity of Clarireedia spp. was debated for the past several decades until recently when the organism was reclassified in 2018. Previous studies have shown that there is little genetic diversity except for isolates obtained from warm season hosts in Florida and the southern United States. Our research confirms the presence of isolates obtained from cool-season (C3) turfgrass species which are consistent with the recently classified species Clarireedia jacksonii; and a second, distinct sub-group of isolates obtained solely from warm-season (C4) turfgrass species, which are consistent with the recently classified species Clarireedia monteithiana. Additionally, we have documented the coexistence of these two species throughout the transition zone of the United States, extending as far north as Virginia, with both species present among adjacent stands of C3 and C4 turfgrass species in the same locale. Despite previous documentation of genetically distinct isolates occurring in the United States, there have been no reports on the variability in growth of the two named species over a range of temperatures, nor have these species been evaluated for their ability to infect both C3 and C4 turfgrass species. The effects of temperature on the lack of in vitro isolate growth for both C. jacksonii and C. monteithiana isolates were most noticeable at 10 and 35 °C, where all isolates exhibited little to no growth after 60 h. Cross inoculation experiments showed that both species are capable of infecting and inciting disease on both the preferred and alternative host, and that C. jacksonii isolates are more virulent on both C3 and C4 host grasses than C. monteithiana isolates. The results of this study will have implications for dollar spot management strategies on bermudagrass as well as an increased need for turfgrass breeders to develop dollar spot resistance cultivars of bermudagrass, particularly for those used in climates extending north of the transition zone. [ABSTRACT FROM AUTHOR]

With recent increases in the numbers of reintroduction projects, it has become crucial to know the main factors that allow colonization of new areas and prevent the extinction of small and reintroduced populations. Dispersal is one of the most important phenomena in population biology with consequences to the proportion of individuals that keep breeding in the natal population and the number of individuals that move to other populations to breed. We studied changes in offspring sex ratio and differences in dispersal patterns between the sexes in a reintroduced population of osprey (Pandion haliaetus). Results showed that at the beginning of the colonization process breeding pairs produced more males, which dispersed shorter distances and were more philopatric than females. However, with increasing breeding population size over the years, the offspring production was skewed to females, which dispersed longer distances from their natal area and tended to breed in different areas. Here we suggest that changes in offspring sex ratio during colonization processes, together with differences in dispersal pattern between sexes, could influence colonization rate and the probability of success of future reintroduction projects. [ABSTRACT FROM AUTHOR]

In the interwar years the Gran Paradiso ibex population followed two subsequent, contrasting trends: a steady rise once the national park was established in 1922, followed by a precipitous fall after the Fascist regime took direct control of conservation in 1934, which almost led to the colony's extinction. This paper addresses the issue of how models taken from population ecology may inform historical narratives. The data for the interwar years were analyzed using a statistical model based on climate and population density, which has proved reliable for most of the post-World War II period. The article highlights the pivotal role of anthropic variables in determining the inter-war trends and how these are best analyzed using historical scholarship. [ABSTRACT FROM AUTHOR]

Opioid addiction has become a global epidemic and a national health crisis in recent years, with the number of opioid overdose fatalities steadily increasing since the 1990s. In contrast to the dynamics of a typical illicit drug or disease epidemic, opioid addiction has its roots in legal, prescription medication—a fact which greatly increases the exposed population and provides additional drug accessibility for addicts. In this paper, we present a mathematical model for prescription drug addiction and treatment with parameters and validation based on data from the opioid epidemic. Key dynamics considered include addiction through prescription, addiction from illicit sources, and treatment. Through mathematical analysis, we show that no addiction-free equilibrium can exist without stringent control over how opioids are administered and prescribed, in which case we estimate that the epidemic would cease to be self-sustaining. Numerical sensitivity analysis suggests that relatively low states of endemic addiction can be obtained by primarily focusing on medical prevention followed by aggressive treatment of remaining cases—even when the probability of relapse from treatment remains high. Further empirical study focused on understanding the rate of illicit drug dependence versus overdose risk, along with the current and changing rates of opioid prescription and treatment, would shed significant light on optimal control efforts and feasible outcomes for this epidemic and drug epidemics in general. [ABSTRACT FROM AUTHOR]

Even though the idea that modes of speciation other than allopatric speciation are possible in nature is now widespread, compelling examples of ecological speciation in sympatry remain rare. We studied an undescribed radiation of haplochromine cichlids in a young crater lake in western Uganda, and in the small river that is nearby but has currently no known surface connection to the lake. We describe two different modes of speciation that occurred in this cichlid lineage within the past 1,500-10,000 years. Not constrained by gene flow, allopatric divergence between river and lake cichlids affects many different morphological traits as well as nuptial colouration—muted in the river, but intensified and polymorphic in lake cichlids—and neutral genetic differentiation. More surprisingly, we demonstrate a case for sympatric speciation within the small lake that is associated with dramatic differences in male breeding colouration (yellow with bright red-chest versus bright blue) and subtle differences in microhabitat, feeding regime and morphology. Reproductive isolation by assortative mating is suggested by significant differentiation between yellow and blue males in neutral markers of gene flow despite complete sympatry. We hypothesize speciation is mediated by divergent selection on sexual signalling between microhabitats. [ABSTRACT FROM AUTHOR]

Stability results are presented for a class of differential and difference inclusions, so-called positive Lur'e inclusions which arise, for example, as the feedback interconnection of a linear positive system with a positive set-valued static nonlinearity. We formulate sufficient conditions in terms of weighted one-norms, reminiscent of the small-gain condition, which ensure that the zero equilibrium enjoys various global stability properties, including asymptotic and exponential stability. We also consider input-to-state stability, familiar from nonlinear control theory, in the context of forced positive Lur'e inclusions. Typical for the study of positive systems, our analysis benefits from comparison arguments and linear Lyapunov functions. The theory is illustrated with examples. [ABSTRACT FROM AUTHOR]

Organismic drift in lotic waters can have major impact on population dynamics. It is influenced by a variety of interacting abiotic and biotic factors, and species often have evolved specific strategies for drift avoidance and compensation. We studied downstream and upstream movements of larval fire salamanders (Salamandra salamandra) within three first-order streams in Germany using up- and downstream traps. We tested several predictions related to the influence of body size, water flow and inclination on the number of upstream and downstream moving larvae. Larval fire salamanders actively moved upstream in all creeks, however, in much lower numbers than downstream. The total body lengths of upstream and downstream moving larvae did not differ significantly; in contrast, downstream drifting larvae were smaller compared to non-drifting larvae collected randomly from the creeks in-between traps. There was no negative effect of the amount of water flow on larval upward movements, but significantly more larvae drifted downstream with the increasing water flow volume. There was no effect of inclination on the amount of either upstream or downstream movements. Our results indicate that upstream movements are a side product of a principle rheotactic behaviour, which prevents larvae from being drifted downstream. [ABSTRACT FROM AUTHOR]

Ecological specialisation, e.g. in terms of prey preferences, can have important implications for population biology. Bee-eaters are considered diet specialists; they hunt aerial insects, particularly hymenopterans. However, the Blue-cheeked bee-eater (Merops persicus) has been considered a special case, as it preferentially feeds upon dragonflies (Odonata). Here we review current literature on the diet of the Blue-cheeked bee-eater, and conclude that this species is not as restricted to dragonflies as previously suggested. Instead, populations in different parts of the breeding and wintering ranges seem to specialise on various types of insects (such as wasps, bees, dragonflies, butterflies and mosquitoes). [ABSTRACT FROM AUTHOR]

Bird exclusion experiments consistently show that birds exhibit strong top-down control of arthropods, including ants and the honeydew-producing insects (HPIs) that they tend. However, it remains unclear whether the results of these small-scale bird exclosure experiments can be extrapolated to larger spatial scales. In this study, we use a natural bird removal experiment to compare the prevalence of ants and HPIs between Guam, an island whose bird community has been extirpated since the 1980s due to the introduction of the brown tree snake, and two nearby islands (Rota and Saipan) that have more intact bird assemblages. Consistent with smaller-scale bird exclosure experiments, we show that (1) forest trees from Guam are significantly more likely to host HPIs than trees from Saipan and (2) ants are nearly four times as abundant on Guam than on both Saipan and Rota. The prevalence of HPIs varied slightly based on tree species identity, although these effects were not as strong as island-level effects associated with bird loss. Ant community composition differed between Guam and the other two islands. These results corroborate past observational studies showing increased spider densities on Guam and suggest that trophic changes associated with landscape-level bird extirpation may also involve alterations in the abundance of ants and HPIs. This study also provides a clear example of the strong indirect effects that invasive species can have on natural food webs. [ABSTRACT FROM AUTHOR]

This paper investigates an SIS epidemic model with variable population size including a vaccination program. Dynamics of the endemic equilibrium of the model are obtained, and it will be shown that this equilibrium exists and is locally asymptotically stable when R0>1. In this case, the disease uniformly persists, and moreover, using a geometric approach we conclude that the model is globally asymptotically stable under some conditions. Also, a numerical discussion is given to verify the theoretical results. [ABSTRACT FROM AUTHOR]

The fungus Puccinia coronata Corda. is the causal agent of crown rust on oats (Avena sativa) and grasses and the disease is a major problem in oat production causing devastating yield losses. The population biology of P. coronata in oat fields and on the aecial host in central Sweden was studied to get a deeper understanding of the role of the aecial hosts in the epidemiology of the disease. Samples were collected from the aecial hosts common buckthorn (Rhamnus cathartica) and alder buckthorn (Frangula alnus), and three adjacent spring oat (Avena sativa) fields. Microsatellite markers were used to evaluate the relationships between populations sampled from the different hosts. According to our results F. alnus can be excluded as a part of the oat crown rust disease cycle. The results further show that samples collected from the aecial host were genetically separate from the population sampled in adjacent oat fields. Concurrently, the genotypic variation of P. coronata observed within oat fields was high. No population differentiation was observed within or between samples collected from different fields within the region, suggesting that airborne spores from other than the sampled specimens of the aecial hosts were contributing to the genetic diversity of P. coronata f. sp. avenae in the selected oat fields. [ABSTRACT FROM AUTHOR]

The degree of genetic diversity of the steppe field mouse was estimated on the basis of the mtDNA control region variability data. Polymorphism of this mtDNA marker in S. witherbyi was more pronounced than previously assumed. The steppe field mouse population from the northern shore of Lake Manych-Gudilo includes several mitochondrial lines, which may be due to the existence of several migration flows to this area from Southwest Asia. [ABSTRACT FROM AUTHOR]

Human population growth and sea-level rise are increasing the demand for protection of coastal property against shoreline erosion. Living shorelines are designed to provide shoreline protection and are constructed or reinforced using natural elements. While living shorelines are gaining popularity with homeowners, their ability to provide ecological services (e.g., habitat provision and trophic transfer) is not well understood, and information is needed to improve coastal and resource management decision-making. We examined benthic community responses to living shorelines in two case-study subestuaries of Chesapeake Bay using a before-after control-impact study design. At Windy Hill, a bulkhead was removed and replaced by three tombolos, sand fill, and native marsh vegetation. At Lynnhaven, 25 m of eroding marsh shoreline was stabilized with coir logs, sand fill, and native marsh vegetation. Communities of large (> 3 mm) infauna adjacent to living shorelines at both locations tended to increase in biomass by the end of the study period. Community compositions changed significantly following living shoreline construction at Windy Hill, reflecting a trend toward higher density and biomass of large bivalves at living shorelines compared to pre-construction. Increasing trends in density and biomass of clams and simultaneously decreasing density and decreasing trends in biomass of polychaetes suggest a transition toward stable infaunal communities at living shorelines over time, though longer-term studies are warranted. [ABSTRACT FROM AUTHOR]