Communication and Social Influences on Foraging in Bats

Using social information can be an efficient way to respond to changing situations or to learn skills. Other benefits of foraging in a group, such as social facilitation, have also been reported. Furthermore, individuals foraging near conspecifics may use acoustic communication to mediate interactions. Many bat species (Order Chiroptera) are gregarious, and many tropical frugivorous bats rely on seasonally-abundant foods such that following conspecifics to a food source could benefit "followers" without harming "leaders." Animal-eating bats do not typically share food, but information obtained from experienced foragers could help facilitate development of prey acquisition skills in young bats. Additionally, communicative vocalizations serving various social functions have been reported in diverse bat species. Despite the opportunities for social learning and information transfer that many bats experience, few studies have attempted to determine if these phenomena occur in bats. Similarly, despite research on echolocation and some communicative calls, the context and function of social calls emitted by flying, foraging bats have received relatively little study. In this dissertation, I examine interactions between individuals in a foraging context and the impact of these interactions on the individuals' behavior. Specifically, I used pairs of big brown bats (Eptesicus fuscus) to test whether insectivorous bats can acquire a new foraging skill via social learning and what social cues might facilitate learning. I then describe the context of and attribute function to social calls emitted by bats in pairs. Finally, I examine the effects of social context on the foraging behavior of the frugivorous short-tailed fruit bat (Carollia perspicillata) presented with a food-finding task. My results provide the first evidence of the role of social learning (via attention to feeding buzzes and interaction with experienced individuals) in the development of foraging skills in young insectivorous bats. I also report a repertoire of social calls produced by foraging big brown bats and present evidence that males use social calls to defend food and increase their foraging success. Finally, I present evidence that social facilitation increases foraging performance in short-tailed fruit bats. These findings contribute to our knowledge of the social aspects of foraging in group-living animals

Automated acoustic identification of bat species

Automated acoustic identification of bat species Recent improvements in bat survey methods in Portugal, especially automatic recording stations, have led to an analysis problem due to the amount of data obtained. In this thesis we propose to develop an automated analysis and classification method for bat echolocation calls by developing a computer program based on statistical models and using a reference database of bat calls recorded in Portugal to quickly analyze and classify large amounts of recordings. We recorded 2968 calls from 748 bats of 20 (of the 25) bat species known in mainland Portugal and coded a program in R that automatically detects bat calls in a recording, isolates the calls from the background noise and measures 19 parameters from each call. A two stage hierarchical classification bat call scheme was implemented based on logistic regression models and ensembles of artificial neural networks. In the first stage calls were classified in six major groups with individual correct classification rates that varied between 93% and 100%. In the second stage calls were classified in species or groups of species with classification rates that varied between 50% and 100%; ### Identificação acústica automatizada de espécies de morcegos Desenvolvimentos recentes nas metodologias de monitorização de morcegos utilizadas em Portugal, especialmente estações de gravação automáticas, conduziram a um problema de análise devido à quantidade de dados obtida. Nesta tese propomos desenvolver um método automatizado de análise e classificação de pulsos de ecolocalização de morcegos através do desenvolvimento de um programa de computador baseado em modelos estatísticos e utilizando uma base de dados de pulsos de morcegos gravados em Portugal continental para rapidamente analisar e classificar grandes quantidades de gravações. Gravámos 2968 pulsos de 748 morcegos de 20 (das 25) espécies de morcegos conhecidas em Portugal continental e codificámos em R um programa para automaticamente detectar pulsos de morcego numa gravação, isolar os pulsos do ruído de fundo e medir 19 parâmetros de cada pulso. Foi implementado um esquema hierárquico de classificação de pulsos em duas etapas baseado em modelos de regressão logística e conjuntos de redes neuronais artificiais. Numa primeira etapa os pulsos foram classificados em seis grupos com taxas individuais de classificações correctas que variaram entre 93% e 100%. Numa segunda fase os pulsos foram classificados em espécies ou grupos de espécies com taxas de classificação correctas que variaram entre 50% e 100%

Spatial encoding in primate hippocampus during free navigation.

The hippocampus comprises two neural signals-place cells and θ oscillations-that contribute to facets of spatial navigation. Although their complementary relationship has been well established in rodents, their respective contributions in the primate brain during free navigation remains unclear. Here, we recorded neural activity in the hippocampus of freely moving marmosets as they naturally explored a spatial environment to more explicitly investigate this issue. We report place cells in marmoset hippocampus during free navigation that exhibit remarkable parallels to analogous neurons in other mammalian species. Although θ oscillations were prevalent in the marmoset hippocampus, the patterns of activity were notably different than in other taxa. This local field potential oscillation occurred in short bouts (approximately .4 s)-rather than continuously-and was neither significantly modulated by locomotion nor consistently coupled to place-cell activity. These findings suggest that the relationship between place-cell activity and θ oscillations in primate hippocampus during free navigation differs substantially from rodents and paint an intriguing comparative picture regarding the neural basis of spatial navigation across mammals

Spatial, demographic, and phylogenetic patterns of Bartonella diversity in bats

Includes bibliographical references.2015 Summer.Much recent attention has focused on bats as potentially exceptional reservoirs of pathogens. Bats are known to carry zoonotic viruses deadly to humans with no apparent signs of pathology, however the evolutionary and physiological processes that are behind this ability remain largely unknown. Despite this uncertainty, bats’ long lifespans, deep evolutionary history, sociality, and migratory behavior make them a fascinating system in which to study patterns of diversity in viruses, bacteria, and other infectious organisms. This thesis explores ecological and evolutionary processes that structure the diversity of infectious bacteria in bats. I focus on Bartonella, a genus of vector-borne intracellular bacteria, because of its high prevalence and genetic diversity within bats. I examined the structure of Bartonella species assemblages in Eidolon spp. fruit bats across Africa and Madagascar using newly developed molecular and statistical tools. The results from this examination indicate that fruit bats from distant geographic locations host similar communities of Bartonella; I attribute this to widespread dispersal and communal roosting behavior in Eidolon spp. bats. To understand how Bartonella diversity has evolved and is structured geographically, I assembled a global dataset of Bartonella genotypes from bats and their ectoparasites. Using this dataset, I analyzed the contributions of cospeciation and sympatry among host species to the diversity of Bartonella in bats. Continued development of this research could provide a model system for the study of ecological and evolutionary processes contributing to pathogen diversification and infection dynamics in natural systems

Adaptive evolution of butterfly wing shape: from morphology to behaviour

International audienceButterflies display extreme variation in wing shape associated with tremendous ecological diversity. Disentangling the role of neutral versus adaptive processes in wing shape diversification remains a challenge for evolutionary biologists. Ascertaining how natural selection influences wing shape evolution requires both functional studies linking morphology to flight performance, and ecological investigations linking performance in the wild with fitness. However, direct links between morphological variation and fitness have rarely been established. The functional morphology of butterfly flight has been investigated but selective forces acting on flight behaviour and associated wing shape have received less attention. Here, we attempt to estimate the ecological relevance of morpho-functional links established through biomechanical studies in order to understand the evolution of butterfly wing morphology. We survey the evidence for natural and sexual selection driving wing shape evolution in butterflies, and discuss how our functional knowledge may allow identification of the selective forces involved, at both the macro-and micro-evolutionary scales. Our review shows that although correlations between wing shape variation and ecological factors have been established at the macro-evolutionary level, the underlying selective pressures often remain unclear. We identify the need to investigate flight behaviour in relevant ecological contexts to detect variation in fitness-related traits. Identifying the selective regime then should guide experimental studies towards the relevant estimates of flight performance. Habitat, predators and sex-specific behaviours are likely to be major selective forces acting on wing shape evolution in butterflies. Some striking cases of morphological divergence driven by contrasting ecology involve both wing and body morphology, indicating that their interactions should be included in future studies investigating co-evolution between morphology and flight behaviour

Photoluminescence in fur

Linda Reinhold researched photoluminescence (fluorescence and/or phosphorescence) in the fur of Wet Tropic mammals. She found that photoluminescence is common, the luminophores include porphyrins, the photoluminescence easily degrades, and nocturnal vertebrates do not respond to it. These results dispel recent assumptions that photoluminescent fur is a rare, visually functional trait