Hearing sensitivity: An underlying mechanism for niche differentiation in gleaning bats

Tropical ecosystems are known for high species diversity. Adaptations permitting niche differentiation enable species to coexist. Historically, research focused primarily on morphological and behavioral adaptations for foraging, roosting, and other basic ecological factors. Another important factor, however, is differences in sensory capabilities. So far, studies mainly have focused on the output of behavioral strategies of predators and their prey preference. Understanding the coexistence of different foraging strategies, however, requires understanding underlying cognitive and neural mechanisms. In this study, we investigate hearing in bats and how it shapes bat species coexistence. We present the hearing thresholds and echolocation calls of 12 different gleaning bats from the ecologically diverse Phyllostomid family. We measured their auditory brainstem responses to assess their hearing sensitivity. The audiograms of these species had similar overall shapes but differed substantially for frequencies below 9 kHz and in the frequency range of their echolocation calls. Our results suggest that differences among bats in hearing abilities contribute to the diversity in foraging strategies of gleaning bats. We argue that differences in auditory sensitivity could be important mechanisms shaping diversity in sensory niches and coexistence of species

DNA methylation predicts age and provides insight into exceptional longevity of bats

Exceptionally long-lived species, including many bats, rarely show overt signs of aging, making it difficult to determine why species differ in lifespan. Here, we use DNA methylation (DNAm) profiles from 712 known-age bats, representing 26 species, to identify epigenetic changes associated with age and longevity. We demonstrate that DNAm accurately predicts chronological age. Across species, longevity is negatively associated with the rate of DNAm change at age-associated sites. Furthermore, analysis of several bat genomes reveals that hypermethylated age- and longevity-associated sites are disproportionately located in promoter regions of key transcription factors (TF) and enriched for histone and chromatin features associated with transcriptional regulation. Predicted TF binding site motifs and enrichment analyses indicate that age-related methylation change is influenced by developmental processes, while longevity-related DNAm change is associated with innate immunity or tumorigenesis genes, suggesting that bat longevity results from augmented immune response and cancer suppression

DNA methylation predicts age and provides insight into exceptional longevity of bats

This work was supported by a Paul G. Allen Frontiers Group grant to S.H., the University of Maryland, College of Computer, Mathematical and Natural Sciences to G.S.W., an Irish Research Council Consolidator Laureate Award to E.C.T., a UKRI Future Leaders Fellowship (MR/T021985/1) to S.C.V. and a Discovery Grant from the Natural Sciences and Engineering Research Council (NSERC) of Canada to P.A.F. S.C.V. and P.D. were supported by a Max Planck Research Group awarded to S.C.V. by the Max Planck Gesellschaft, and S.C.V. and E.Z.L. were supported by a Human Frontiers Science Program Grant (RGP0058/2016) awarded to S.C.V. L.J.G. was supported by an NSERC PGS-D scholarship.Exceptionally long-lived species, including many bats, rarely show overt signs of aging, making it difficult to determine why species differ in lifespan. Here, we use DNA methylation (DNAm) profiles from 712 known-age bats, representing 26 species, to identify epigenetic changes associated with age and longevity. We demonstrate that DNAm accurately predicts chronological age. Across species, longevity is negatively associated with the rate of DNAm change at age-associated sites. Furthermore, analysis of several bat genomes reveals that hypermethylated age- and longevity-associated sites are disproportionately located in promoter regions of key transcription factors (TF) and enriched for histone and chromatin features associated with transcriptional regulation. Predicted TF binding site motifs and enrichment analyses indicate that age-related methylation change is influenced by developmental processes, while longevity-related DNAm change is associated with innate immunity or tumorigenesis genes, suggesting that bat longevity results from augmented immune response and cancer suppression.Publisher PDFPeer reviewe

Vocal learning: A language-relevant trait in need of a broad cross-species approach

Although humans are unmatched in their capacity to produce speech and learn language, comparative approaches in diverse animalmodelsareabletoshedlightonthebiologicalunderpinnings of language-relevant traits. In the study of vocal learning, a trait crucial for spoken language, passerine birds have been the dominant models, driving invaluable progress in understanding the neurobiology and genetics of vocal learning despite being only distantly related to humans. To date, there is sparse evidence that our closest relatives, nonhuman primates have the capability to learn new vocalisations. However, a number of other mammals have shown the capacity for vocal learning, such as some cetaceans, pinnipeds, elephants, and bats, and we anticipate that with further study more species will gain membership to this (currently) select club. A broad, cross-species comparison of vocal learning, coupled with careful consideration of the components underlying this trait, is crucial to determine how human speech and spoken language is biologically encoded and how it evolved. We emphasise the need to draw on the pool of promising species that havethusfarbeenunderstudiedorneglected.Thisisbynomeansa call for fewer studies in songbirds, or an unfocused treasure-hunt, but rather an appeal for structured comparisons across a range of species, considering phylogenetic relationships, ecological and morphological constrains, developmental and social factors, and neurogenetic underpinnings. Herein, we promote a comparative approachhighlightingtheimportanceofstudyingvocallearningina broad range of model species, and describe a common framework for targeted cross-taxon studies to shed light on the biology and evolution of vocal learning

Personality-related survival and sampling bias in wild cricket nymphs

The study of adaptive individual behavior (“animal personality”) focuses on whether individuals differ consistently in (suites of correlated) behavior(s) and whether individual-level behavior is under selection. Evidence for selection acting on personality is biased toward species where behavioral and life-history information can readily be collected in the wild, such as ungulates and passerine birds. Here, we report estimates of repeatability and syndrome structure for behaviors that an insect (field cricket; Gryllus campestris ) expresses in the wild. We used mark-recapture models to estimate personality-related survival and encounter probability and focused on a life-history phase where all individuals could readily be sampled (the nymphal stage). As proxies for risky behaviors, we assayed maximum distance from burrow, flight initiation distance, and emergence time after disturbance; all behaviors were repeatable, but there was no evidence for strong syndrome structure. Flight initiation distance alone predicted both daily survival and encounter probability: bolder individuals were more easily observed but had a shorter life span. Individuals were also somewhat repeatable in the habitat temperature under which they were assayed. Such environment repeatability can lead to upward biases in estimates of repeatability in behavior; this was not the case. Behavioral assays were, however, conducted around the subject’s personal burrow, which could induce pseudorepeatability if burrow characteristics affected behavior. Follow-up translocation experiments allowed us to distinguish individual and burrow identity effects and provided conclusive evidence for individual repeatability of flight initiation distance. Our findings, therefore, forcefully demonstrate that personality variation exists in wild insects and that it is associated with components of fitness