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Aquatic insects were collected from Arizona during 2022, and museum specimens and observations posted to online platforms were reviewed to support new records. Notes and records are provided for 8 species of aquatic Coleoptera and Hemiptera. Three species are reported for the first time from the United States in Arizona: Hydaticus rimosus (Dytiscidae), Neobidessus youngi (Dytiscidae), and Rhagovelia ignota (Veliidae). Two additional species are new state records for Arizona: Copelatus debilis (Dytiscidae) and Meridiorhantus calidus (Dytiscidae). Distributional notes are provided for Abedus breviceps (Belostomatidae) and Rhagovelia choreutes (Veliidae). A form of Copelatus distinctus (Dytiscidae) with greatly reduced striae is illustrated. [ABSTRACT FROM AUTHOR]

Aquatic insects were collected from Arizona during 2022, and museum specimens and observations posted to online platforms were reviewed to support new records. Notes and records are provided for 8 species of aquatic Coleoptera and Hemiptera. Three species are reported for the first time from the United States in Arizona: Hydaticus rimosus (Dytiscidae), Neobidessus youngi (Dytiscidae), and Rhagovelia ignota (Veliidae). Two additional species are new state records for Arizona: Copelatus debilis (Dytiscidae) and Meridiorhantus calidus (Dytiscidae). Distributional notes are provided for Abedus breviceps (Belostomatidae) and Rhagovelia choreutes (Veliidae). A form of Copelatus distinctus (Dytiscidae) with greatly reduced striae is illustrated. [ABSTRACT FROM AUTHOR]

Belostoma minor (Palisot de Beauvois, 1805) and Mesovelia polhemusi Spangler, 1990 are reported for the first time from the continental United States, in southern Florida. Ten species of Belostomatidae (water bugs) belonging to the genus Belostoma Latreille, 1807 are now reported from the United States, with three species documented in Florida; the record of a fourth species, B. flumineum Say, 1832, in Florida is doubtful. Four species of Mesoveliidae (water treaders) belonging to the genus Mesovelia Mulsant and Rey, 1852 are now documented from Florida and the United States. I provide keys to species of the genera Belostoma and Mesovelia in the northern Caribbean Bioregion, representing southern Florida, the Greater Antilles, and the Lucayan Archipelago. [ABSTRACT FROM AUTHOR]

The predator-permanence hypothesis predicts that as hydroperiod increases in lentic ecosystems, biotic interactions—mainly predation—replace physical factors like drying as the main determinant of community structure and population dynamics. We propose that the same transition occurs over time in seasonally flooded ecosystems that are connected to permanent water bodies. To test for evidence of successional changes that are similar to spatial changes in the relative importance of drying and predation, we used a 12-y time series of snail density, predator density, and water depth at 4 sites arranged along a nutrient gradient in a subtropical, seasonally flooded wetland, the Florida Everglades, USA. The rate of change in snail population size was negatively correlated with their density at all 4 sites, suggesting that density-dependent factors such as resource limitation regulate snail dynamics. The strength of the relationship varied among sites such that when water depth changes were less important, snail population size was more important in predicting changes in snail population size. At the site that consistently had the greatest snail density, crayfish density negatively affected the rate of snail population change, suggesting that crayfish predation may limit snail population growth in areas with more or higher-quality resources that support larger snail populations. Tethering studies were also conducted, which revealed higher snail mortality in the wet season, primarily because crushing predators (e.g., molluscivorous fishes) were more common at that time and added to the chronic mortality by entry-based predators (e.g., crayfish, which access snails through their aperture). In summary, 3 of the sites resembled temporary or permanent fishless ponds where snail populations were primarily structured by abiotic factors, intraspecific competition, and invertebrate predators (e.g., crayfish) during the wet season, whereas 1 site showed evidence that snail populations were also influenced by molluscivorous fish. This temporal change in importance of water permanence factors to fish that affected population dynamics supports the spatial pattern proposed by the predator-permanence hypothesis. [ABSTRACT FROM AUTHOR]

Patch size is one of the most important factors affecting the distribution and abundance of species, and recent research has shown that patch size is an important niche dimension affecting community structure in aquatic insects. Building on this result, we examined the impact of patch size in conjunction with presence of larval anurans on colonization by aquatic insects. Hyla chrysoscelis (Cope's gray treefrog) larvae are abundant and early colonists in fishless lentic habitats, and these larvae can fill multiple ecological roles. By establishing larvae in mesocosms prior to colonization, we were able to assess whether H. chrysoscelis larvae have priority effects on aquatic insect assemblages. We conducted a series of three experiments in naturally colonized experimental landscapes to test whether (1) H. chrysoscelis larval density affects insect colonization, (2) variation in patch size affects insect colonization, and (3) the presence and larval density of H. chrysoscelis shift colonization of insects between patches of different size. Larval density independently had almost no effect on colonization, while patch size had species‐specific effects consistent with prior work. When larvae and patch size were tested in conjunction, patch size had numerous, often strong, species‐specific effects on colonization; larval density had effects largely limited to the assemblages of colonizing beetles and water bugs, with few effects on individual species. Higher larval densities in large mesocosms shifted some insect colonization to smaller patches, resulting in higher beta diversity among small patches in proximity to high density large mesocosms. This indicates establishing H. chrysoscelis larvae prior to insect colonization can likely create priority effects that slightly shape insect communities. Our results support the importance of patch size in studying species abundances and distributions and also indicate that colonization order plays an important role in determining the communities found within habitat patches. [ABSTRACT FROM AUTHOR]

The Everglades is a large subtropical wetland that has been modified heavily by humans and now is undergoing restoration. Aquatic and semiaquatic Heteroptera (Hemiptera) in the infraorders Gerromorpha and Nepomorpha were collected in the Florida Everglades using standardized 1-m2 throw-traps. Sampling efforts were conducted in marshes distributed from southern Everglades National Park, north throughout the Water Conservation Areas to Loxahatchee National Wildlife Refuge. In total, 12,833 individuals were identified representing 17 species in 13 genera and 8 families (Belostomatidae, Corixidae, Gerridae, Mesoveliidae, Naucoridae, Nepidae, Veliidae). The naucorid Pelocoris femoratus (Palisot de Beauvois) (Hemiptera: Naucoridae) was by far the most abundant species, whereas 2 other species, Belostoma lutarium (Stål) (Hemiptera: Belostomatidae) and Neogerris hesione Kirkaldy (Hemiptera: Gerridae), were widespread but less abundant. Two species, Abedus immaculatus (Say) (Hemiptera: Belostomatidae) and Pelocoris balius La Rivers (Hemiptera: Naucoridae) had localized distributions, whereas all other species were collected rarely. We discuss the abundance and distribution of species recorded, along with unique traits and the biology of the aquatic Heteroptera in the Everglades and implications for the restoration of the Everglades. [ABSTRACT FROM AUTHOR]

Running the gauntlet of predators consumes critical time and energy resources, as all species are vulnerable to one or, typically, more predators at some life stage. Prey employ a vast array of mechanisms to avoid predation, and predators, likewise, come in a bewildering variety. Thus, defensive adaptations are rarely one size fits all. Considerable work has addressed multi‐predator consumptive effects, but we now know that non‐consumptive effects of predators can dramatically impact individuals, (meta)populations, and (meta)communities. However, little is known regarding the community‐wide dynamics of non‐consumptive effects generated by multiple predators. Predator avoidance by choosing a patch that is free of a particular predator or predators can be the most effective strategy if conditions at colonization are a reliable predictor of absence, which is often true for fish in freshwater systems. We experimentally manipulated composition of the predator assemblage in aquatic mesocosms in a substitutive design, with zero, one, two, or three caged predatory fish species (one benthic, one pelagic, and one surface fish) at constant density and biomass, and assayed responses of naturally colonizing aquatic insects. We addressed three related questions; first, how do members of a diverse assemblage of colonizing aquatic insects respond to this variation in species and species combinations, second, do individual species (and higher taxa), respond differently to single vs. multiple predator species (species richness), and third how do any responses to fish species and species combinations, and effects on species richness, translate into community‐wide changes in the composition of colonists. Prey had varied responses to specific predators or combinations of predators, resulting in distinct community composition across treatments and higher β‐diversity with predators. Prey showed emergent multi‐predator effects, where certain species only responded to predator species combinations, but not to any individual predator, and stronger effects of multiple predator vs. single‐predator treatments, despite strong responses to individual predators in many taxa. Habitat selection effects can range from the individual to the metacommunity, and the dynamics of habitat selection in response to predators is a complex function of predator identity, density, richness, species composition, and patch spatial context. [ABSTRACT FROM AUTHOR]

1. Predators have effects on prey populations through both consumptive and non‐consumptive effects. Predator's presence is expected to drive variation in prey oviposition habitat selection behaviour, but differences in biotic and abiotic characteristics of habitats, or trait variation, may produce geographic variation in species interactions. 2. We conducted a series of experiments in two geographic locations, Mississippi and Missouri, USA, to assess oviposition responses of Culex mosquitoes (prey) to the presence of Notonecta irrorata (predator). We first tested whether mosquitoes in each location respond to the presence of N. irrorata, with follow‐up experiments to determine whether mosquitoes respond to variation in N. irrorata density, whether N. irrorata from each location generate different responses by the same Culex population, and whether diet and consumption of conspecifics affect oviposition. 3. We found that Culex restuans in Missouri had reduced oviposition when N. irrorata were present. In Mississippi, C. restuans did not respond to the presence of N. irrorata from either Mississippi or Missouri, to the variation in density of N. irrorata, or to N. irrorata that had been fed larval mosquitoes. 4. Our study documents the first instance of geographic variation in oviposition response of a prey species to a predator species. [ABSTRACT FROM AUTHOR]

The article discusses effects of acid deposition on animals that have acted through trophic relationships, with reduced calcium availability in prey possibly being a limiting factor for forest songbirds. It mentions territory size decreased as calcium concentrations of potential prey increased, regardless of watershed; and also mentions calcium limitation can be a determinant of territory size in some landscapes.

Predators are a particularly critical component of habitat quality, as they affect survival, morphology, behavior, population size, and community structure through both consumptive and non‐consumptive effects. Non‐consumptive effects can often exceed consumptive effects, but their relative importance is undetermined in many systems. Our objective was to determine the consumptive and non‐consumptive effects of a predaceous aquatic insect, Notonecta irrorata, on colonizing aquatic beetles. We tested how N. irrorata affected survival and habitat selection of colonizing aquatic beetles, how beetle traits contributed to their vulnerability to predation by N. irrorata, and how combined consumptive and non‐consumptive effects affected populations and community structure. Predation vulnerabilities ranged from 0% to 95% mortality, with size, swimming, and exoskeleton traits generating species‐specific vulnerabilities. Habitat selection ranged from predator avoidance to preferentially colonizing predator patches. Attraction of Dytiscidae to N. irrorata may be a natural ecological trap given similar cues produced by these taxa. Hence, species‐specific habitat selection by prey can be either predator‐avoidance responses that reduce consumptive effects, or responses that magnify predator effects. Notonecta irrorata had both strong consumptive and non‐consumptive effects on populations and communities, while combined effects predicted even more distinct communities and populations across patches with or without predators. Our results illustrate that an aquatic invertebrate predator can have functionally unique consumptive effects on prey, attracting and repelling prey, while prey have functionally unique responses to predators. Determining species‐specific consumptive and non‐consumptive effects is important to understand patterns of species diversity across landscapes. [ABSTRACT FROM AUTHOR]

Abiotic conditions are important considerations in the species sorting process, which ultimately determines the distribution and abundance of species. Freshwater ecosystems will be impacted by ongoing temperature rise and other anthropogenically induced changes, such as nutrient enrichment and eutrophication. Changing characteristics of freshwater habitats will likely impact organisms in numerous ways, including through effects on colonization dynamics. Species are expected to colonize habitat patches where fitness will be the highest for themselves and their offspring, and how habitat selection interacts with changing environments remains an important question. We conducted a warming experiment to test the habitat selection preferences of aquatic beetles and hemipterans between habitat patches (mesocosms) of varying temperatures (via heaters), nutrient addition, and their interaction. Overall, insect abundance and richness were higher in unheated patches, with taxon‐specific variation in response to heating. Although nutrients had limited effects on environmental conditions in mesocosms, their addition had no significant effects on insects. Insect assemblages had unique structures across heating treatments, with lower beta diversity and higher effective numbers of species in the warmest mesocosms. Our data support the importance of spatial variation in abiotic factors during the habitat selection process, and in determining species distributions and abundances as shallow lentic ecosystems are impacted by rising global temperatures. [ABSTRACT FROM AUTHOR]

Structure of natural communities is shaped by both abiotic characteristics and the ongoing processes of community assembly. Important to this process are the habitat selection behaviors and subsequent survival of colonists, both in the context of temporal changes in the abiotic characteristics and priority effects driven by earlier colonists. Aquatic beetles are prevalent in temporary freshwater systems, form speciose assemblages, and are often early colonists of temporary ponds. While beetles have the potential to influence community structure through post‐colonization interactions (predation and competition), our goal was to determine whether the presence of beetle assemblages (versus patches without beetles) influences the colonization and oviposition of a diverse group of animals in a naturally colonized experimental landscape. We established mesocosms that either contained existing beetle assemblages or contained no beetles and assessed abundances of subsequent colonists. Treefrogs, Hyla chrysoscelis, and mosquitoes, Culex restuans, both deposited fewer eggs in patches containing beetle assemblages, while two beetles, Copelatus glyphicus and Paracymus, colonized those patches at lower rates. One beetle, Helophorus linearis, colonized patches containing beetle assemblages at higher rates, while two beetles, Berosus infuscatus and Tropisternus lateralis, exhibited no colonization differences between treatments. Overall, there were no differences in the assemblage structure or richness of beetles that colonized patches. Our results illustrate the importance of species‐specific habitat selection behavior in determining the species composition of habitat patches, while emphasizing the role of priority effects in influencing patterns of community assembly. Habitat selection in response to abiotic and biotic characteristics of habitat patches can potentially create greater spatiotemporal niche separation among the numerous, often closely related species (phylogenetically and trophically), that can be simultaneously found in similar patches across landscapes. [ABSTRACT FROM AUTHOR]

Aquatic and semiaquatic Heteroptera (Hemiptera) in the infraorders Gerromorpha and Nepomorpha were collected from the University of Mississippi Field Station (UMFS) in north-central Mississippi from May 2014 until August 2019. UMFS encompasses over 200 ponds, springs, wetlands, and streams in the headwaters of the Little Tallahatchie River. We collected insects from mesocosm experiments and natural water bodies in order to survey and document the aquatic and semiaquatic Heteroptera of UMFS. A total of 20,304 individuals were collected representing 43 species in 20 genera and 10 families (Belostomatidae, Corixidae, Gerridae, Hebridae, Hydrometridae, Mesoveliidae, Naucoridae, Nepidae, Notonectidae, Veliidae). We compare mesocosms and natural water bodies in terms of species present and their abundances, and we also provide notes on the abundance, distribution, and habitats of some species, with new state records for three species. [ABSTRACT FROM AUTHOR]

Positive correlation of species richness with area is ubiquitous in nature, but the processes driving that relationship, as well as those constraining typical patterns, remain elusive. Patch size variation is pervasive in natural systems, and it is thus critical to understand how variation in patch size, as well as its potential interaction with factors like predation and isolation, affects community assembly. We crossed patch quality (fish presence/absence) with patch size to the examine effects of quality, size, and their interaction on colonization by aquatic insects. Overall, beetles favored small, fishless patches, but individual species sorted across patch size while hemipterans aggregated into large, fishless patches, producing sorting between Coleoptera and Hemiptera. Both patch size and predation risk generated significant variation in community structure and diversity. Patch size preferences for the 14 most abundant species and preeminence of species turnover in patterns of β-diversity reinforce patch size as a driver of regional species sorting via habitat selection. Species sorting at the immigration stage plays a critical role in community assembly. Identifying patch size as a component of perceived quality establishes patch size as a critical niche dimension and alters our view of its role in assembly dynamics and the maintenance of local and regional diversity. [ABSTRACT FROM AUTHOR]

Disturbances and variation in abiotic habitat conditions greatly affect populations and communities. The multitude of processes that occur in natural systems offers the possibility that the trajectories of ephemeral habitats and the effects of disturbances can be slowed or reversed. Hydroperiod is a defining characteristic in freshwater systems, with temporary ponds supporting distinct communities of organisms with plastic developmental trajectories and complex lifecycles that allow them to cope with the vagaries of pond duration.Despite work on the effects of pond drying on aquatic animals, little consideration has been given to filling, which can extend the duration of small, drying ponds. Our goal was to assess how increasing the volume of small ponds affects the developmental trajectories of larval amphibians living in these habitats. We conducted a field mesocosm experiment to assess how filling of ponds early, midway and late in the larval period affected the survival and development of the barking treefrog, Hyla gratiosa. We hypothesised that filling early in the larval stage would provide the most benefits, producing more and larger metamorphs than filling later in development.We found that through various effects on survival, metamorphosis, habitat quality and competition, increasing volume early in development produced more and larger metamorphs with faster growth rates than any other treatment, whereas filling late in development produced few, small, slow growing metamorphs.Our results provide support for the role of stressors in initiating metamorphosis and also show that increased pond volumes early in larval development can provide benefits to Hyla populations in terms of compensatory growth, but filling late in development has little benefit. [ABSTRACT FROM AUTHOR]

Abstract: Populations and communities are often greatly affected by disturbances and variation in abiotic habitat conditions. Many of these effects are contingent on relatively predictable, yet still variable, environmental conditions that drive the life history strategies and development pathways of organisms in those habitats. However, much focus has been placed on aspects of such changes that cause mortality or movement from patches, whereas a multitude of outcomes can occur in natural systems. In lentic freshwater habitats, hydroperiod is a defining environmental characteristic, with temporary ponds supporting distinct communities of organisms with complex life cycles and plastic developmental trajectories. Little consideration has been given to the effects of refilling of ponds with variable hydroperiods, as lengthening the hydroperiod can extend the time organisms spend in their aquatic stages, allowing for the acquisition of more resources. We hypothesised that increasing the volume of small ponds and adding competitors (Ambystoma maculatum) at the time of filling would interactively affect the development and phenotypic expression of Ambystoma talpoideum. We introduced larval A. talpoideum to experimental mesocosms and manipulated water level (small, low volume mesocosms; filled, full mesocosms) and the addition of competitors (A. maculatum) at the time of filling in a 2 × 2 factorial design. We found that low volume mesocosms were dominated by metamorphs, while filling resulted in a more even mix of metamorphs, larvae and paedomorphs in full mesocosms. Filling resulted in larger metamorphs and paedomorphs, but did not affect larvae, whereas addition of A. maculatum shortened the larval period of metamorphs. We provide evidence that changes in abiotic habitat conditions, such as variation in the volume of ponds, can shift the development and phenotype of organisms. This plasticity may allow species to ensure the success of populations under both improvement and deterioration of environmental conditions. Hence, phenotypes like paedomorphic A. talpoideum can breed sooner than metamorphs, theoretically maximising the fitness of both individuals and populations. [ABSTRACT FROM AUTHOR]

Abstract: Predation risk and resource abundance are two primary characteristics that determine species abundances and community composition. Colonizing organisms should attempt to minimize the risk of mortality and maximize growth through selection of patches with the highest expected fitness. However, maximizing fitness across multiple gradients of patch quality involves accurate cue assessment, integration and behavioural responses that consider multiple factors that affect fitness simultaneously. Our goal was to simultaneously and factorially assess the effects of predation risk and resource abundance among an assemblage of aquatic insects to determine the relative importance of each factor, and whether the two factors interact to affect colonization, oviposition and community assembly. We conducted a field mesocosm experiment in which we crossed predator density (0, 1, 2 fish, Fundulus chrysotus) with supplemental nutrient abundance (0, 4, 8 g rabbit chow) in a 3 × 3 factorial design. We then assayed colonization by natural populations of aquatic beetles and oviposition by natural populations of Culex mosquitoes. We observed species‐specific responses, with many species avoiding fish and some selecting habitats with more nutrients. Nutrients and predator presence only interactively affected oviposition by Culex mosquitoes, and the effect of fish presence exceeded that of nutrients in all but one analysis. Our results illustrate the primacy of predation risk in generating colonization patterns and structuring communities in aquatic habitats, but that colonization responses to variation in multiple components of patch quality are often species‐specific. Simultaneous assessments of multiple aspects of patch quality allow for the determination of potential interactions among cue sources and the relative importance of various patch characteristics to colonizers. A plain language summary is available for this article. [ABSTRACT FROM AUTHOR]

Ovipositing amphibians select breeding sites that determine their offspring's larval habitat. Preference-performance theory predicts that adults will select habitat patches that match the expected performance of their offspring in those patches. Many amphibians breed in temporary ponds immediately after they fill, and one species, Hyla chrysoscelis (Cope's Gray Treefrogs), selects between breeding sites based on patch age differences of as little as 7 d. Prior work established that H. chrysoscelis have better larval performance in more recently filled ponds, but not in ponds less than 15 d after filling or among ponds that differed in age by less than 65 d. Our objective was to determine experimentally whether larval H. chrysoscelis performance varies across short time scales after filling (3- and 23-d-old ponds) and across two larval densities (15 and 30 larvae per mesocosm). Higher larval densities reduced metamorph mass and body condition, but did not otherwise affect larval performance. There were lower survival, shorter larval periods, and slightly lower mass and body condition among larvae from 3-d-old ponds than those in 23-d-old ponds. These mixed performance differences across our two levels of habitat age might not necessarily be representative of what happens in natural systems, however, where older ponds have more established communities of competitors and predators. [ABSTRACT FROM AUTHOR]

Colonisation is a critical process driving the abundances and diversity of species in spatially discrete communities. Although patch size and patch quality are well known as determinants of post-colonisation species richness and abundance, less is known about how patch size affects colonisation., Patch size and quality may not be independent, so assessment of potential interactions is necessary for understanding patterns of species abundance in natural systems. In freshwater systems, presence and identity of predators is a dominant determinant of patch quality, with larger habitat patches often supporting larger and more diverse predator assemblages., To examine potential interactions, we manipulated patch size and quality (fish presence/absence) using naturally colonised experimental landscapes and assayed oviposition by Culex mosquitoes., Culex restuans selected patches that were smaller, did not contain fish, and had higher temperatures. We demonstrate that patch size, along with patch quality, can generate patterns of abundance at the colonisation stage that are contradictory to traditional patch size-based models of species distributions. [ABSTRACT FROM AUTHOR]

1. Habitat selection by colonizing organisms is an important factor in determining species abundance and community dynamics at multiple spatial scales. Many organisms select habitat patches based on intrinsic patch quality, but patches exist in complex landscapes linked by dispersal and colonization, forming metapopulations and metacommunities. Perceived patch quality can be influenced by neighbouring patches through spatial contagion, wherein perceived quality of one patch can extend beyond its borders and either increase or decrease the colonization of neighbouring patches and localities. These spatially explicit colonization dynamics can result in habitat compression, wherein more colonists occupy a patch or locality than in the absence of spatial context dependence. 2. Previous work on contagion/compression focused primarily on the role of predators in driving colonization patterns. Our goal was to determine whether resource abundance can drive multi-scale colonization dynamics of aquatic beetles through the processes of contagion and compression in naturally colonized experimental pools. 3. We established two levels (high/low quality) of within-patch resource abundances (leaf litter) using an experimental landscape of mesocosms and assayed colonization by 35 species of aquatic beetles. Patches were arranged in localities (sets of two patches), which consisted of a combination of two patch-level resource levels in a 2 x 2 factorial design, allowing us to assay colonization at both locality and patch levels. 4. We demonstrate that patterns of species abundance and richness of colonizing aquatic beetles are determined by patch quality and context-dependent processes at multiple spatial scales. Localities that consisted of at least one high-quality patch were colonized at equivalent rates that were higher than localities containing only low-quality patches, displaying regional reward contagion. In localities that consisted of one high and one low-quality patch, reward contagion produced by higher leaf litter levels resulted in greater abundance of beetles in such localities, which then compressed into the highest quality patches. 5. Our results provide further support for the critical roles of habitat selection and spatial context, particularly the quality of neighbouring habitat patches, in generating patterns of species abundances and community structure across landscapes. [ABSTRACT FROM AUTHOR]

Trophic interactions are critical determinants of community structure and ecosystem function. In freshwater habitats, top predators are traditionally viewed as drivers of ecosystem structure, shaping populations of consumers and primary producers. The temporary nature of small water bodies makes them dependent on colonization by many organisms, particularly insects that form highly diverse predator assemblages. We conducted mesocosm experiments with naturally colonizing populations of aquatic beetles to assess how prey (zooplankton) abundances influenced colonization and assemblages of natural populations of aquatic beetles. We experimentally demonstrate that zooplankton populations can be proximate regulators of predator populations and assemblages via prey-density-dependent predator recruitment. Our results provide support for the importance of prey populations in structuring predator populations and the role of habitat selection in structuring communities. We indicate that traditional views of predators as drivers of ecosystem structure in many systems may not provide a comprehensive picture, particularly in the context of highly disturbed or ephemeral habitats. [ABSTRACT FROM AUTHOR]

Oviposition site selection by breeding amphibians determines larval habitat for their offspring. Many amphibians breed in temporary ponds, which vary in hydroperiod and levels of competition, predation, and resource abundance. Newly filled ponds have fewer competitors and predators and more periphyton and phytoplankton, which are more palatable food sources for anuran larvae. We tested for oviposition site preference between old and new water pools in Hyla chrysoscelis , a species known to have better larval performance in newly filled pools. Consistent with larval performance and the observation that anurans often breed in ponds immediately after they fill, H. chrysoscelis selectively oviposited in new pools. Conductivity was significantly lower and dissolved oxygen significantly higher in new versus old pools, and these may be cues of pond age and productivity, respectively. We demonstrate that adult oviposition site selection preferences in our study match larval performance differences seen in previous work and that this preference is not simply for newly filled ponds but for ponds with a recent influx of water. These results further suggest novel ways for land managers to increase amphibian populations. Draining ponds will increase their attractiveness to breeding females who simultaneously avoid fish and choose new water. [ABSTRACT FROM AUTHOR]

Polymorphisms play critical roles in allowing organisms to adapt to novel environments while enabling ecological speciation under divergent selection. Ambystoma maculatum, the spotted salamander, exhibits a unique polymorphism in the structure and appearance of its egg masses with two common morphs, white and clear. Amphibian egg jelly layers mediate interactions between embryos and the environment and are more responsive to ecological pressures of natural selection than other egg coat components. The A. maculatum egg mass polymorphism was hypothesized to be adaptive with regard to varying dissolved nutrient levels in ponds. We conducted two mesocosm experiments, collected field data, and constructed a population projection model to determine how dissolved nutrient levels affect embryonic and larval development and relate to the distribution of the morphs in natural ponds. We found that upon hatching there was an interaction between nutrient level and egg mass morph wherein individuals from white morphs were larger in low nutrient habitats. This interaction persisted throughout the larval stage, and along with the higher abundance of white morphs in ponds with low conductivity, we demonstrate that the white morph is advantageous in low nutrient environments. Our findings provide evidence for the role of environmental heterogeneity in enabling the persistence of a structural egg mass polymorphism, with maintenance occurring across multiple scales and persistence across its range. This indicates that polymorphisms can maximize performance in heterogeneous environments, while persisting over long timescales without leading to sympatric speciation. [ABSTRACT FROM AUTHOR]

Predators play an extremely important role in natural communities. In freshwater systems, fish can dominate sorting both at the colonization and post-colonization stage. Specifically, for many colonizing species, fish can have non-lethal, direct effects that exceed the lethal direct effects of predation. Functionally diverse fish species with a range of predatory capabilities have previously been observed to elicit functionally equivalent responses on oviposition in tree frogs. We tested this hypothesis of functional equivalence of non-lethal effects for four predatory fish species, using naturally colonizing populations of aquatic beetles. Among taxa other than mosquitoes, and with the exception of the chemically camouflaged pirate perch, Aphredoderus sayanus, we provide the first evidence of variation in colonization or oviposition responses to different fish species. Focusing on total abundance, Fundulus chrysotus, a gape-limited, surface-feeding fish, elicited unique responses among colonizing Hydrophilidae, with the exception of the smallest and most abundant taxa, Paracymus, while Dytiscidae responded similarly to all avoided fish. Neither family responded to A. sayanus. Analysis of species richness and multivariate characterization of the beetle assemblages for the four fish species and controls revealed additional variation among the three avoided species and confirmed that chemical camouflage in A. sayanus results in assemblages essentially identical to fishless controls. The origin of this variation in beetle responses to different fish is unknown, but may involve variation in cue sensitivity, different behavioral algorithms, or differential responses to species-specific fish cues. The identity of fish species occupying aquatic habitats is crucial to understanding community structure, as varying strengths of lethal and non-lethal effects, as well as their interaction, create complex landscapes of predator effects and challenge the notion of functional equivalence. [ABSTRACT FROM AUTHOR]

Predators affect prey through both consumptive and non-consumptive effects (NCEs), and prey typically face threats from multiple simultaneous predators. While different predators have a variety of NCEs on prey, little is known regarding effects of simultaneous multiple predators on demographic habitat selection. Demographic habitat selection is unique among NCEs, especially in discrete habitat patches; decisions directly affect both distribution and abundance of species across habitat patches, rather than simply abundance and performance within patches. Our goal was to determine strength of avoidance responses to multiple species/species combinations of predatory fish, and responses to predator richness. We assessed responses of ovipositing grey treefrogs (Hyla chrysoscelis) to three predatory fish species and substitutive combination of species. In single-species treatments, treefrogs avoided only one species, Notemigonus crysoleucas. All two-species combinations, and the three-species combination, were avoided, including the Fundulus chrysotus × Noturus phaeus combination, of which neither were avoided alone. This suggests emergent properties of multiple predators, with potential interactive effects among cues themselves or in the perception of cues by treefrogs. Our results indicate effects of multiple predators are not predictable based on individual effects, and illustrate the importance and complexity of effects of demographic habitat selection on distribution and abundance. [ABSTRACT FROM AUTHOR]

Avoiding detection is perhaps the ultimate weapon for both predators and prey. Chemosensory detection of predators via waterborne or airborne cues (predator‐released kairomones) is a key prey adaptation in aquatic ecosystems. Pirate perch, Aphredoderus sayanus, a largely insectivorous mesopredatory fish, are considered to be chemically camouflaged because they are unavoided by all colonizing organisms tested, including treefrogs and aquatic insects, despite stronger predatory effects on target taxa than several avoided fish. To address the mechanism behind camouflage we used aquatic insect colonization as a bioassay to test (1) whether increasing pirate perch density/biomass leads to increased avoidance, and (2) whether pirate perch mask heterospecific fish kairomones. Insect abundances, species richness, and community structure showed no response to pirate perch density. Last, pirate perch did not mask the kairomones of heterospecific predatory fish. Results support the idea that fish kairomones are species‐specific, and chemical camouflage is driven by a unique chemical signature that is either undetectable or has no negative associations for colonists. [ABSTRACT FROM AUTHOR]

Abstract: Two of the most important factors determining community structure and diversity within and among habitat patches are patch size and patch quality. Despite the importance of patch size in existing paradigms in island biogeography, metapopulation biology, landscape ecology, and metacommunity ecology, and growing conservation concerns with habitat fragmentation, there has been little investigation into how patch size interacts with patch quality. We crossed three levels of patch size (1.13 m2, 2.54 m2 and 5.73 m2) with two levels of patch quality (fish presence/absence, green sunfish [Lepomis cyanellus] and golden shiners [Notemigonus crysoleucus]) in six replicate experimental landscapes (3 × 2 × 6 = 36 patches). Both fish predators have been previously shown to elicit avoidance in ovipositing treefrogs. We examined how patch size and patch quality, as well as the interaction between size and quality, affected female oviposition preference and male calling site choice in a natural population of treefrogs (Hyla chrysoscelis). Females almost exclusively oviposited in the largest fishless patches, indicating that females use both risk, in the form of fish predators, and size itself, as components of patch quality. Females routinely use much smaller natural and experimental patches, suggesting that the responses to patch size are highly context dependent. Responses to fish were unaffected by patch size. Male responses largely mimicked those of females, but did not drive female oviposition. We suggest that patch size itself functions as another aspect of patch quality for H. chrysoscelis, and serves as another niche dimension across which species may behaviorally sort in natural systems. Because of strong, shared avoidance of fish (as well as other predators), among many colonizing taxa, patch size may be a critical factor in species sorting and processes of community assembly in freshwater habitats, allowing species to behaviorally segregate along gradients of patch size in fishless ponds. Conversely, lack of variation in patch size may concentrate colonization activity, leading to intensification of species interactions and/or increased use of lesser quality patches. [ABSTRACT FROM AUTHOR]