Abstract Acoustic interference is a critical factor driving the evolution of communication systems. In mixed-species choruses, competition for acoustic space is expected to drive signal differentiation among heterospecific signals. The acoustic space partitioning hypothesis proposes that species differentiate their signals to reduce overlap and thereby reduce acoustic interference. Despite ongoing debates in niche theory, studies in animal communication have remained disconnected from these conversations, and no critical evaluation of this hypothesis has been conducted. We performed a systematic review to assess empirical support for acoustic space partitioning and evaluate the conceptual and methodological approaches used to test it. We found that two-thirds of studies conclude that the acoustic space is partitioned, albeit with a strong taxonomic bias toward anurans. However, studies rarely account for key assumptions of the hypothesis, including co-signaling, limited acoustic space, and signal masking at the receiver. Without explicit evidence of conditions for acoustic interference, signal differentiation alone is insufficient to infer that competition is driving partitioning, since this outcome may also arise from alternative processes. By integrating sensory ecology, we provide a framework to reconcile signal-structure differentiation with receiver perception, thereby improving our understanding of how communication systems evolve in mixed-species choruses.

Abstract Commonly shared patterns of introduction and spread into new environmental conditions are often poorly understood, even though a better understanding of invasion history and niche dynamics among closely related invasive species could give practitioners valuable information to prevent and mitigate the impact of biological invasions. For this study, we investigate the invasion history and niche patterns among congeneric invasive species. We synthesize public occurrence data for five invasive alien anurans ( Eleutherodactylus coqui, E. planirostris, E. johnstonei, E. antillensis, and E. martinicensis ) to reconstruct their historic introductions and evaluate evidence for climatic niche shifts between their native and established non-native ranges. By pairing these data with current and future climate projections, we compare patterns of range shifts under future climate scenarios. Our results highlight different temporal and geographic introduction histories in invasive Eleutherodactylus , but a strong signal of colonizing broader invasive climatic niches, specifically into colder environmental conditions. Under future climate scenarios, suitable habitats for most of the non-native regions are likely to increase, although this increase is restricted under scenarios with high greenhouse gas emissions. Our results reveal that despite different invasion histories, the ability to spread into colder regions may be a conserved trait among the most widespread Eleutherodactylus anurans. This study ultimately shows that commonalities among closely related invasive species can provide clues about their ability to expand into areas with particular abiotic conditions, a pattern likely to be widespread, offering a potentially valuable opportunity to deploy targeted prevention strategies.

Species interactions are fundamental to ecological and evolutionary processes, shaping ecosystem dynamics and driving biodiversity. Among those, interactions between flies and amphibians are common in tropical areas, yet most aspects of their ecology and evolution are understudied. Using the PRISMA method, we systematically review the literature to examine the direct and indirect threats imposed by Diptera flies attacking amphibians and the behavioral, physiological, and acoustic defenses they elicit. We delve, for instance, into the eavesdropping behavior of some dipteran species, which use anuran calls as cues for host-seeking, and the potential impacts on frog communication systems. As flies can be disease vectors, we investigate pathogen transmission to amphibians as an indirect cost imposed by flies attacking them and examine the role of species specificity in these dynamics. Finally, we address how human activities are currently impacting these long-established interactions between dipterans and amphibians. We focus on potential disruptions caused by habitat alteration, the presence of invasive species, and climate change. By synthesizing existing knowledge of the threats imposed by flies on amphibians, we shed light on these groups of growing conservation concern given their current escalating extinction rates. Ultimately, our findings provide valuable insights into the intricacies of species interactions and underscore the urgent need for comprehensive studies mitigating the adverse effects of anthropogenic disturbances on these clades.

To attract mates, organisms relying on advertisement signals must encode relevant information and transmit it to target receivers, yet the effectiveness of this process is mediated by the environment. The acoustic adaptation hypothesis (AAH) proposes that habitat properties impose selective forces on acoustic signal design to enhance transmission efficiency. In tropical forests, pronounced vertical heterogeneity in microhabitats creates a variety of conditions for signalers, raising the question of how calling height influences signal transmission efficiency across forest strata. To investigate how vertical microhabitat variation modulates signal transmission, we experimentally broadcast the advertisement calls of 24 species from a Neotropical anuran community from both the understory and the relatively understudied dimension of the forest, the canopy. Across species, calls showed lower transmission performance in the canopy than in the understory, regardless of the species' natural calling height. The transmission performance did not consistently differ among species occupying different vertical strata, nor did it align with the predictions from the AAH. Although our results are inconsistent with AAH, they suggest that habitat properties that vary with height, such as vegetation architecture and background noise, likely modulate signal transmission, increasing excess attenuation, degradation, and reverberation. This study emphasizes that the complex nature of vertical forest microhabitats may affect signal transmission in different forest types and sensory modalities, ultimately modulating the evolution of signal design.

Frog-biting mosquitoes (Culicidae) and midges (Corethrellidae) are old hematophagous lineages that originated over 200 million years ago and provide an ideal opportunity to broaden our understanding of the evolution of host specialization and sensory ecology. While most mosquito research has targeted medically important species, which preferentially feed on mammals and birds, a subset specializes in ectothermic hosts, particularly amphibians. Some of these species locate calling male frogs by exploiting their advertisement calls, a host-seeking strategy that contrasts sharply with the use of chemical, thermal and olfactory cues by endotherm-feeding species. Such interactions can influence frog signaling evolution, alter parasite transmission dynamics and shape ecological networks. Globally, understanding amphibian-feeding Culicomorpha is critical for integrating evolutionary, ecological and conservation perspectives. Yet research is disproportionately concentrated in the Neotropics, where species diversity, host associations and behavioral adaptations have been comparatively well documented. In this review, we synthesize current knowledge on frog-biting mosquitoes and midges in the Oriental region and compare these findings with those from Japan, as these regions share a similar amphibian lineage. A particular focus is given to India, a country hosting high anuran biodiversity hotspots, making it an ideal setting to study the ecology and evolution of frog-biting midges and mosquitoes. By providing an overview of the status of our knowledge of these groups in the Oriental region, we identify gaps to stimulate future research. Ultimately, this review offers a foundation for researchers to develop projects focusing on fertile research venues that will advance our understanding of frog-biting mosquitoes and midges.

Unlike organisms equipped with tympanal ears, mosquitoes hear using their antennae, which are lightweight sensory structures capable of detecting sound. Here, we study the antennae of two species - Aedes aegypti and Uranotaenia lowii - known to use hearing for different functions. Through the use of geometrically comprehensive computational models, we find that architectural features in the mosquito antenna provide mechanisms that promote the detection of species and sex specific acoustic targets amidst the non-target signals produced by their own wingbeats. Structurally, we find that the increased surface area of sensory hairs provides enhanced sensitivity while the tapering effect of intersegmental variation affects the tuning response. These features result in the highest antennal sensitivity through vibration at specific natural frequency modes that correspond to frequencies associated with their acoustic targets. STATEMENT OF SIGNIFICANCE: Our study provides valuable insights into the remarkable architectural design of mosquito antennae and its role in auditory adaptations. By dissecting the intricate geometry of antennal architecture in Aedes aegypti and Uranotaenia lowii, we uncover mechanisms that enhance sensitivity to specific acoustic cues while mitigating interference from wingbeat noise. This research builds upon and extends the existing understanding, providing a deeper comprehension of how mosquitoes navigate their acoustic environment. Our findings have significant implications for understanding sensory adaptations in insects and may inspire the development of bioinspired sensing technologies. We believe our work will interest a broad audience by offering new perspectives on the intersection of biomechanics and sensory biology, which can also find applications in the design of bioinspired architected materials.

A survey of Corethrellidae from two countries in the Neotropical Region, Cuba and Colombia, was performed. Four new species are described from Cuba (Corethrella parallela Amaral & Pinho sp. nov., Corethrella doryphallica Amaral & Pinho sp. nov., Corethrella trivittata Amaral & Pinho sp. nov., and Corethrella coronata Amaral & Pinho sp. nov.), and two from Colombia (Corethrella compacta Amaral & Pinho sp. nov. and Corethrella obtusa Amaral & Pinho sp. nov.). New records from these countries also expand the known distribution of eight additional species.

Sexual size variation in adult holometabolous insects may arise from selective pressures impacting ontogenetic stages associated with diverse habitats and resource use. In addition, scaling relations of these sexually dimorphic traits play an important role in morphological diversification. In mosquitoes, given the sexual differences in feeding strategies, investigations of the ontogeny of sexually dimorphic traits are of particular interest to understanding their reproductive biology and implementing early sex-separating technologies for vector control. However, our current knowledge of the morphological scaling of body parts over development across sexes is centered around a few well-known species of anthropophilic mosquitoes. In general, there is a noticeable gap in our understanding of the developmental biology of mosquitoes with limited medical consequences. One such mosquito is Uranotaenia lowii (Diptera: Culicidae), a species of growing interest due to its unique host use of feeding exclusively on frogs by eavesdropping on their mating calls. This study takes a step forward toward filling this gap by investigating sexual size dimorphism during the ontogeny of Ur. lowii. We examined larval and pupal stages to focus on traits that allow sex identification to evaluate various sex-sorting techniques that provide a foundation for experimental manipulation. We found that sex identification in Ur. lowii is possible during both larval and pupal stages. In the fourth larval instar, thorax length, abdomen length, and total body length differ significantly between the sexes, showing allometric scaling. In the pupal stage, the allometry of the head and thorax to body size remains consistent, as these parts fuse into the cephalothorax. Successful sorting based on cephalothorax length enables highly accurate pupal sex identification. This research sheds light on the biology of Ur. lowii, an understudied mosquito species, and lays the foundation for future studies on the developmental and reproductive biology of frog-biting mosquitoes.

ABSTRACT Predation can alter diverse ecological processes, including host–parasite interactions. Selective predation, whereby predators preferentially feed on certain prey types, can affect prey density and selective pressures. Studies on selective predation in infected populations have primarily focused on predators preferentially feeding on infected prey. However, there is substantial evidence that some predators preferentially consume uninfected individuals. Such different strategies of prey selectivity likely modulate host–parasite interactions, changing the fitness payoffs both for hosts and their parasites. Here we investigated the effects of different types of selective predation on infection dynamics and host evolution. We used a host–parasite system in the laboratory (Daphnia dentifera infected with the horizontally transmitted fungus, Metschnikowia bicuspidata) to artificially manipulate selective predation by removing infected, uninfected, or randomly selected prey over approximately 8–9 overlapping generations. We collected weekly data on population demographics and host infection and measured susceptibility from a subset of the remaining hosts in each population at the end of the experiment. After 6 weeks of selective predation pressure, we found no differences in host abundance or infection prevalence across predation treatments. Counterintuitively, populations with selective predation on infected individuals had a higher abundance of infected individuals than populations where either uninfected or randomly selected individuals were removed. Additionally, populations with selective predation for uninfected individuals had a higher proportion of individuals infected after a standardized exposure to the parasite than individuals from the two other predation treatments. These results suggest that selective predation can alter the abundance of infected hosts and host evolution.

Species interactions are defined by the behavioral strategies deployed by the parties involved. However, a barrier to fully understanding the processes shaping those strategies has been the limited knowledge about the diverse and complex ways in which species can interact. Here, we perform a systematic review to examine the natural history and evolutionary ecology of the interactions between two large clades with a long evolutionary history together: Diptera and Amphibians. We outline three main strategies that have evolved multiple times within Diptera: (a) adult flies feeding on amphibian blood (micropredators), (b) fly larvae feeding on anuran eggs (egg predators), and (c) fly larvae acting as parasites or parasitoids of adult frogs (myiasis). We provide a synthesis of the distinct phylogenetic and biogeographical signatures of these strategies and identify current gaps in our understanding of these complex interactions. Ultimately, this work emphasizes the intricate nature of trophic strategies that can arise between invertebrates and vertebrates.

Sexual selection often favors the evolution of conspicuous mating displays. Emitting such overt displays carries the risk of interception by eavesdropping enemies, i.e. predators, parasitoids and parasites that exploit communication systems to find and attack their signaling victims. Yet, many signalers respond to variation in perceived eavesdropper risk, protecting themselves through risk-dependent inducible defenses to mitigate potential costs. Given that signalers are embedded in communication networks in which they interact with other signalers, target receivers and multiple eavesdropping enemies, here we investigated how variation in signaling and defensive strategies impacted by an eavesdropping enemy (frog-biting midges; Diptera: Corethrellidae) affects other receivers in a communication network. Ultimately, we aimed to determine whether and to what extent effects that cascade throughout the network shape relative fitness among chorusing males. Using female choice experiments with túngara frogs (Engystomops pustulosus) and predation experiments with eavesdropping, fringe-lipped bats (Trachops cirrhosus), we show that variation in the call elaboration and defensive strategies of competing males shapes their relative fitness. Defensive strategies targeting eavesdropping frog-biting midges indirectly shift a male's relative attractiveness to females and predatory bats, though the mechanisms and impacts are context and receiver specific. These findings showcase how the frequency-dependent effects of micropredation can dynamically shape variation in secondary sexual characteristics and thus influence the mechanisms driving sexual selection.

Predators use prey-emitted cues to assess and localize potential food sources. Sexual advertisement calls offer conspicuous cues for eavesdropping predators. While the ontogeny of predatory behaviour is key for survival and can determine adult responses, our understanding of the development of the responses to prey-emitted cues is limited. Here, we measured the responses of juvenile and adult fringe-lipped bats ( Trachops cirrhosus ) to the acoustic advertisement calls of co-occurring anurans. We confirmed that adult bats modulate their foraging behaviour based on their prey’s acoustic cues associated with prey palatability. The responses of juvenile bats revealed that ontogeny plays an important role in bat predatory responses. In contrast to adults, prey palatability did not predict predatory behaviour in juveniles, which responded strongly to poisonous toads and little to some palatable frog species, suggesting that avoidance of poisonous species is learned through experience. Despite these differences, both juveniles and adults appeared to attend to acoustic cues related to body size. Our results support the hypothesis that, over development, acoustic preferences of eavesdropping predators become more closely aligned with advantageous foraging outcomes. Overall, these results offer the first evidence of developmental changes refining decision-making in an eavesdropping predator in the wild.

Salinity can be an environmental stressor for anurans, as their highly permeable skin makes them prone to osmotic stress when exposed to saline conditions. However, certain anuran species have colonized areas near saltwater habitats, suggesting an ability to acclimate to saline conditions. Here, we evaluated physiological and behavioral responses to saline conditions in adult Cuban treefrogs (Osteopilus septentrionalis), an invasive anuran found throughout Florida. To examine their response to salinity, adult frogs were maintained in two treatments simulating a freshwater (0.5 ppt) or brackish (8.0 ppt) environment for 6 weeks. To assess their physiological response to this potential stressor, all frogs were submerged in a brackish solution to quantify individual weight change every 2 weeks. We found that frogs maintained in brackish solution lost more weight at Weeks 2 and 6 when compared to Week 0, suggesting that salinity may be an environmental stressor for Cuban treefrogs. Yet, the weight change at Week 4 was similar to the pre-exposure period, which may indicate that constant exposure to salinity may alter their physiological response to saline conditions. To supplement the physiological analyses, we investigated avoidance behavior toward saline conditions by offering individuals a choice between freshwater or brackish environments. Our results showed that Cuban treefrogs chose freshwater environments more frequently and may thus avoid saline ones. This study reveals that salinity may induce plastic and avoidance responses in Cuban treefrogs, potentially allowing them to expand their range into areas typically stressful for most anurans.

Many studies on mosquito biology rely on laboratory-reared colonies, emphasizing the need for standardized protocols to investigate critical aspects such as disease biology, mosquito behavior, and vector control methods. While much knowledge is derived from anthropophilic species from genera like

Many studies on mosquito biology rely on laboratory-reared colonies, emphasizing the need for standardized protocols to investigate critical aspects such as disease biology, mosquito behavior, and vector control methods. While much knowledge is derived from anthropophilic species from genera like Anopheles, Aedes, and Culex, there is a growing interest in studying mosquitoes that feed on non-human hosts. This interest stems from the desire to gain a deeper understanding of the evolution of diverse host range use and host specificity. However, there is currently a limited number of comprehensive protocols for studying such species. Considering this gap, we present a protocol for rearing Uranotaenia lowii, a mosquito species specialized in feeding on anuran amphibians by eavesdropping on host-emitted sound cues. Additionally, we provide instructions for successfully shipping live specimens to promote research on this species and similar ones. This protocol helps fill the current gap in comprehensive guidelines for rearing and maintaining colonies of anuran host-biting mosquitoes. It serves as a valuable resource for researchers seeking to establish colonies of mosquito species from the Uranotaeniini tribe. Ultimately, this protocol may facilitate research on the evolutionary ecology of Culicidae, as this family has recently been proposed to have originated from a frog-feeding ancestor. Key features • Rearing and maintenance of colonies of non-human host-biting mosquitoes that feed on frogs using host-emitted acoustic cues. • Provides shipping guidelines aimed to enhance the establishment of colonies by new research groups and specimen exchanges between labs.

Flexible signalling behaviour is widespread, with adjustments often enhancing gains or reducing costs of signalling based on the current state of the signaller's local communication network. Male tungara frogs call within multispecies communication networks containing conspecifics (both target receivers and rivals) and eavesdropping predators. These diverse players all exert an influence on male calling strategies. We investigated the degree to which patterns of changes in call characteristics across individual tungara frog calling bouts were influenced by callers' social environment, body condition, and ambient temperature. Most call bouts exhibited two distinct phases, an initial steep increase in call amplitude (the rise) followed by a longer period of more gradual amplitude increase (the plateau). Rises were completed more quickly when males called in denser choruses, while call amplitude increases during plateau phases were greater for males in better body condition. Males also produced more complex calls and increased complexity sooner when calling in denser choruses. Our results suggest that the social environment is the main driver of within-bout calling patterns. This could be due to (i) increased call effort required when competing in denser choruses, (ii) dilution effects provided by nearby rivals releasing callers from eavesdropping risk or, likely, (iii) a combination of both.

ABSTRACT Most mosquito and midge species use hearing during acoustic mating behaviors. For frog-biting species, however, hearing plays an important role beyond mating as females rely on anuran calls to obtain blood meals. Despite the extensive work examining hearing in mosquito species that use sound in mating contexts, our understanding of how mosquitoes hear frog calls is limited. Here, we directly investigated the mechanisms underlying detection of frog calls by a mosquito species specialized on eavesdropping on anuran mating signals: Uranotaenia lowii. Behavioral, biomechanical and neurophysiological analyses revealed that the antenna of this frog-biting species can detect frog calls by relying on neural and mechanical responses comparable to those of non-frog-biting species. Our findings show that in Ur. lowii, contrary to most species, males do not use sound for mating, but females use hearing to locate their anuran host. We also show that the response of the antennae of this frog-biting species resembles that of the antenna of species that use hearing for mating. Finally, we discuss our data considering how mosquitoes may have evolved the ability to tap into the communication system of frogs.

Emitting conspicuous signals into the environment to attract mates comes with the increased risk of interception by eavesdropping enemies. As a defence, a commonly described strategy is for signallers to group together in leks, diluting each individual's risk. Lekking systems are often highly social settings in which competing males dynamically alter their signalling behaviour to attract mates. Thus, signalling at the lek requires navigating fluctuations in risk, competition and reproductive opportunities. Here, we investigate how behavioural defence strategies directed at an eavesdropping enemy have cascading effects across the communication network. We investigated these behaviours in the túngara frog ( Engystomops pustulosus ), examining how a calling male's swatting defence directed at frog-biting midges indirectly affects the calling behaviour of his rival. We found that the rival responds to swat-induced water ripples by increasing his call rate and complexity. Then, performing phonotaxis experiments, we found that eavesdropping fringe-lipped bats ( Trachops cirrhosus ) do not exhibit a preference for a swatting male compared to his rival, but females strongly prefer the rival male. Defences to minimize attacks from eavesdroppers thus shift the mate competition landscape in favour of rival males. By modulating the attractiveness of signalling prey to female receivers, we posit that eavesdropping micropredators likely have an unappreciated impact on the ecology and evolution of sexual communication systems.