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Abstract 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 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 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 Colonizing organisms actively choosing habitats face a bewildering array of choices regarding patch quality, whether choosing for themselves, offspring, or both. Decisions are especially critical when selecting patches for long‐term use (demographic habitat selection). Thus, identifying higher quality patches based on available cues, and integrating information across multiple axes of patch quality, is critical to survival, performance, and fitness. Two critical axes of patch quality for ovipositing gray treefrogs, revealed by prior experiments, are predation risk and patch size. We utilized a unique design presenting two, suboptimal patch choices: small fishless pools and large pools with fish. Our goal was to gain an understanding of the relative priority of these two important patch characteristics for treefrogs by presenting only compromise choices and comparing these results to expectations generated by a previous experiment. In the absence of optimal patches, treefrogs increased their use of both large pools with fish and especially small fishless patches, both of which are unused when larger fishless patches are available. These results reaffirm the primacy of predation, especially the presence of fish, vividly illustrating the spatial context dependence of habitat selection behavior, as well as the complexity of the decisions faced by colonizing and ovipositing organisms in complex landscapes.

Abstract Although consumptive effects of predators have long been central to ecology, predation‐risk effects have emerged as major components of predator–prey interactions. Both consumptive and predation‐risk effects should vary with predator functional traits (e.g., hunting mode, gape size), where consumption rates and induction of morphological and behavioral defenses correlate with prey‐specific predator threat. Ambush predators, in contrast with active predators, may face selection pressure to be cryptic to avoid detection by prey. Thus, ambush predators may change prey density through consumptive effects but have reduced or absent predation‐risk effects. We performed two mesocosm experiments with free‐roaming and caged predators to explore post‐colonization interactions of the chemically camouflaged, large‐gaped, ambush predator, pirate perch (Aphredoderus sayanus), active, large‐gaped green sunfish (Lepomis cyanellus), and active, small‐gaped golden topminnow (Fundulus chrysotus), with larval gray treefrogs (Hyla chrysoscelis) and mole salamanders (Ambystoma talpoideum). We examined the consumptive and predation‐risk effects of each predator on amphibian mortality, growth rates, tail morphology, and polyphenisms. Large‐gaped pirate perch and green sunfish had strong, equivalent consumptive effects, but only the free‐roaming active predator, green sunfish, suppressed the growth of survivors through risk‐induced trait responses. Caged green sunfish induced much stronger non‐consumptive mortality than pirate perch in gray treefrogs, an effect that was absent for mole salamanders; golden topminnows had intermediate effects. Tail defenses were a function of prey mortality and only manifested in free‐roaming predator treatments, suggesting the necessity of predator attacks or conspecific alarm signals. Likewise, mole salamander polyphenism was unaffected by caged predators, whereas free‐roaming green sunfish prevented all metamorphosis. Free‐roaming golden topminnows increased the proportion of individuals remaining as larvae, and pirate perch increased the proportion of paedomorphs and metamorphs. Overall, the prey had positively correlated anti‐predator responses across life stages, suggesting multicomponent defenses. Predator effects varied with functional traits with large‐gaped predators having strong consumptive effects, but active predators causing stronger risk‐induced changes in growth compared to cryptic ambush predators, which provides more evidence for chemical camouflage. Our results emphasize the role of hunting mode and gape size in determining consumptive and predation‐risk effects, and that predation‐risk effects cannot be reliably predicted from consumptive effects.