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Neotropical Bats (neotropical + bat)
Selected AbstractsNested distributions of bat flies (Diptera: Streblidae) on Neotropical bats: artifact and specificity in host-parasite studiesECOGRAPHY, Issue 3 2009Bruce D. Patterson We examined the structure of ectoparasitic bat fly infestations on 31 well-sampled bat species, representing 4 Neotropical families. Sample sizes varied from 22 to 1057 bats per species, and bat species were infested by 4 to 27 bat fly species. Individual bats supported smaller infracommunities (the set of parasites co-occurring on an individual host), ranging from 1 to 5 fly species in size, and no bat species had more than 6 bat fly species characteristically associated with it (its primary fly species). Nestedness analyses used system temperature (BINMATNEST algorithm) because it is particularly well-suited for analysis of interaction networks, where parasite records may be nested among hosts and host individuals simultaneously nested among parasites. Most species exhibited very low system temperatures (mean 3.14°; range 0.14,12.28°). Simulations showed that nested structure for all 31 species was significantly stronger than simulated values under 2 of the 3 null hypotheses, and about half the species were also nested under the more stringent conditions of the third null hypothesis. Yet this structure disappears when analyses are restricted to "primary" associations of fly species (flies on their customary host species), which exclude records thought to be atypical, transient, or potential contaminants. Despite comprising a small fraction of total parasite records, such anomalies represent a considerable part of the statistical state-space, offering the illusion of significant ecological structure. Only well understood and well documented systems can make distinctions between primary and other occurrence records. Generally, nestedness appears best developed in host-parasite systems where infestations are long-term and accumulate over time. Dynamic, short-term infestations by highly mobile parasites like bat flies may appear to be nested, but such structure is better understood in terms of host specificity and accidental occurrences than in terms of prevalence, persistence, or hierarchical niche relations of the flies. [source] Ecological correlates of vulnerability to fragmentation in Neotropical batsJOURNAL OF APPLIED ECOLOGY, Issue 1 2008Christoph F. J. Meyer Summary 1In the face of widespread human-induced habitat fragmentation, identification of those ecological characteristics that render some species more vulnerable to fragmentation than others is vital for understanding, predicting and mitigating the effects of habitat alteration on biodiversity. We compare hypotheses on the causes of interspecific differences in fragmentation sensitivity using distribution and abundance data collected on 23 species of Neotropical bats. 2Bats were captured over a 2-year period on 11 land-bridge islands in Gatún Lake, Panama, and on the adjacent mainland. We derived a series of explanatory variables from our capture data and from the literature: (1) natural abundance in continuous forest, (2) body mass, (3) trophic level, (4) dietary specialization, (5) vertical stratification, (6) edge-sensitivity, (7) mobility, (8) wing morphology (aspect ratio and relative wing loading) and (9) ecologically scaled landscape indices (ESLIs). After phylogenetic correction, these variables were used separately and in combination to assess their association with two indices of fragmentation sensitivity, species prevalence (proportion of islands occupied) as well as an index of change in abundance. 3Model selection based on Akaike's information criterion identified edge-sensitivity as the best correlate of vulnerability to fragmentation. Natural abundance and mobility or traits linked to mobility (relative wing loading and ESLI) received limited support as predictors. Vulnerability of gleaning animalivorous bats is probably caused by a combination of these traits. 4Synthesis and applications. Our findings emphasize the importance of a local-scale approach in developing predictive models of species fragmentation sensitivity and indicate that risk assessments of Neotropical bats could be based on species tolerance to habitat edges and mobility-related traits. We suggest that, in order to be effective, management efforts should aim to minimize the amount of edge-habitat and reduce the degree of fragment-matrix contrast. Moreover, if high bat diversity is to be preserved in fragmented Neotropical landscapes, conservation measures regarding reserve design should assure spatial proximity to source populations in larger tracts of continuous forest and a low degree of remnant isolation. [source] Morphological characterization of the testicular cells and seminiferous epithelium cycle in six species of Neotropical batsJOURNAL OF MORPHOLOGY, Issue 8 2009Mateus R. Beguelini Abstract We know little about the process of spermatogenesis in bats, a great and diverse clade of mammals that presents different reproductive strategies. In the present study, spermatogenesis in six species of Neotropical bats was investigated by light microscopy. On the basis of chromatin condensation, nuclear morphology, relative position to the basal membrane and formation of the flagellum, three types of spermatogonia were recognized: dark type A (Ad), pale type A (Ap), and type B; the development of spermatids was divided into seven steps. With the exception of Myotis nigricans, the seminiferous epithelium cycle of the other five species studied was similar to those of other mammals, showing gradual stages by the tubular morphology method. Asynchrony was observed in the seminiferous epithelium cycle of M. nigricans, shown by overlapping stages and undefined cycles. The frequencies found in the three phases of the cycle were variable with the greatest frequency occurring in the postmeiotic phase (>50%) and the least in the meiotic phase (<10%). The similarities observed in the five species of Phyllostomidae appeared to be related to their phylogenetic relationship and shorter divergence times, whereas the differences in M. nigricans appeared to be related to its greater phylogenetic distance because the Vespertilionidae family diverged earlier. J. Morphol., 2009. © 2009 Wiley-Liss, Inc. [source] DNA barcoding of Neotropical bats: species identification and discovery within GuyanaMOLECULAR ECOLOGY RESOURCES, Issue 2 2007ELIZABETH L. CLARE Abstract Sequence diversity in the cytochrome c oxidase subunit 1 gene has been shown to be an effective tool for species identification and discovery in various groups of animals, but has not been extensively tested in mammals. We address this gap by examining the performance of DNA barcodes in the discrimination of 87 species of bats from Guyana. Eighty-one of these species showed both low intraspecific variation (mean = 0.60%), and clear sequence divergence from their congeners (mean = 7.80%), while the other six showed deeply divergent intraspecific lineages suggesting that they represent species complexes. Although further work is needed to examine patterns of sequence diversity at a broader geographical scale, the present study validates the effectiveness of barcoding for the identification of regional bat assemblages, even highly diverse tropical faunas. [source] Reduced-impact Logging has Little Effect on Temporal Activity of Frugivorous Bats (Chiroptera) in Lowland AmazoniaBIOTROPICA, Issue 3 2009Steven J. Presley ABSTRACT Reduced-impact logging (RIL) represents a viable option for sustainable use of Neotropical lowland forests while minimizing negative effects on local biodiversity. Many Neotropical bats of the family Phyllostomidae provide ecosystem services associated with pollination and seed dispersal that promote the regeneration of disturbed areas; therefore, effects of RIL on these species is of particular concern. We determined patterns of temporal activity, degree of temporal overlap of activity, and dispersion in peaks of activity for seven abundant species of frugivorous bat in Tapajós National Forest, Pará, Brazil. In addition, we evaluated the effects of RIL at a harvest level of 18.7 m3/ha and habitat physiognomy on temporal patterns of activity for these species. Bats were surveyed for four nights at each of 96 sites for a total sampling effort of 64,512 net-m-h. Sites were distributed among four experimental blocks, two blocks of unlogged forest and two blocks of forest subjected to RIL. Half of the sites in each management type were in forest gaps and half were in closed-canopy forest. In general, species exhibited similar patterns of activity, and greater than expected temporal overlap in activity among species. RIL and forest physiognomy had little effect on activity patterns of species. RIL in Amazonia removes fewer trees than do naturally occurring treefalls and such changes in habitat structure do not alter activity patterns of frugivorous bats. Evidence suggests that RIL does not have an appreciable adverse effect on frugivorous bats in Amazonia. RESUMO A exploração madeireira de impacto reduzido é uma opção viável para o uso sustentável de florestas de planícies tropicais, ao passo em que também minimizam os efeitos sobre a biodiversidade local e processos ecossistêmicos. Avaliações dos efeitos de regimes de derrubada de árvores geralmente se baseiam em respostas em nível populacional ou de comunidades e ignoram respostas comportamentais que podem ter consequências críticas em processos ecossistêmicos locais. Muitos dos morcegos neotropicais filostomídeos proporcionam serviços ecossistêmicos associados à polinização e dispersão de sementes, que promovem regeneração de áreas degradadas. Por esse motivo, os efeitos da exploração madeireira de impacto reduzido, sobre essas espécies, devem ter sua importância considerada. Nós avaliamos padrões temporais de atividade, grau de sobreposição temporal de atividade, e dispersão nos picos de atividade de sete espécies de morcegos frugívoros abundantes na Floresta Nacional de Tapajós, Pará, Brasil. Além disso, avaliamos os efeitos da exploração madeireira de impacto reduzido e da fisionomia de habitat (lacunas florestais e locais de dossel fechado) nos padrões temporais de atividade desses morcegos. Em geral, as espécies exibiram padrões de atividade similares, o que resulta em uma sobreposição temporal maior do que a esperada na atividade das espécies. A exploração madeireira de impacto reduzido e a fisionomia florestal tiveram pouco efeito nos padrões de atividades das espécies observadas. A exploração madeireira ora apresentada (2-4 árvores/ha) se propõe a um impacto menor que o associado às quedas naturais de árvores na Amazônia e aparenta não alterar a estrututra dos habitats de forma significativa à atividade das espécies de morcegos aqui estudadas. Consequentemente, não há evidências para acreditar que a exploração madeireira impacto reduzido possua efeitos adversos em espécies abundantes de morcegos frugívoros na Amazônia ou em suas capacidades de continuar a promover a regeneração de áreas degradadas via polinização ou dispersão de sementes. [source] | ||||||||||