Biodiversity (original) (raw)
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Journal of Applied …, 2007
1. It is difficult to establish conservation priorities for cryptic species when their ecological requirements are confounded by problems with species identification. In some cases, such as Chiroptera, cryptic taxa may actually consist of both widespread, abundant species and localized, rare species. Discrimination between these species may be facilitated by phenotypic, species-specific traits such as echolocation calls. Echolocation studies supported by genetic data have revealed that one of the most abundant bat species in Europe actually consists of two cryptic species: Pipistrellus pipistrellus and P. pygmaeus . 2. We recorded echolocation calls from both species along road transects in Switzerland to study their distribution and abundance. Using Ecological Niche Factor Analysis and discriminant analysis, we characterized species-specific habitat requirements, built habitat suitability maps and examined interspecific differences in niche parameters. 3. The presence of P. pygmaeus was associated with landscape matrices comprising large rivers and lakes, human settlements and open woodland. P. pipistrellus utilized similar habitat matrices but was far more tolerant to deviations from its optimal habitat. P. pygmaeus occupied a much narrower ecological niche, encompassed mainly within that of its sister taxon. 4. Synthesis and applications. P. pipistrellus is ranked as 'not threatened' in Switzerland. The results from this study indicate an abundance approximately 30 times higher than that of P. pygmaeus . In contrast, P. pygmaeus is distributed patchily and occurs at comparatively low densities. We recommend reclassification of P. pygmaeus as 'rare and potentially threatened'. Conservation of P. pygmaeus should focus on the management of riparian woodland in areas with a high probability of occurrence. This study emphasizes the need to recognize the potential existence of cryptic taxa so that effective conservation management of rare species can be put into place before they are seriously endangered.
Latitudinal Diversity Gradients in New World Bats: Are They a Consequence of Niche Conservatism?
The increase in species diversity from the Poles to the Equator is a major biogeographic pattern, but the mechanisms underlying it remain obscure. Our aim is to contribute to their clarification by describing the latitudinal gradients in species richness and in evolutionary age of species of New World bats, and testing if those patterns may be explained by the niche conservatism hypothesis. Maps of species ranges were used to estimate species richness in a 100 x 100 km grid. Root distances in a molecular phylogeny were used as a proxy for the age of species, and the mean root distance of the species in each cell of the grid was estimated. Generalised additive models were used to relate latitude with both species richness and mean root distance. This was done for each of the three most specious bat families and for all Chiroptera combined. Species richness increases towards the Equator in the whole of the Chiroptera and in the Phyllostomidae and Molossidae, families that radiated in the tropics, but the opposite trend is observed in the Vespertilionidae, which has a presumed temperate origin. In the whole of the Chiroptera, and in the three main families, there were more basal species in the higher latitudes, and more derived species in tropical areas. In general, our results were not consistent with the predictions of niche conservatism. Tropical niche conservatism seems to keep bat clades of tropical origin from colonizing temperate zones, as they lack adaptations to survive cold winters, such as the capacity to hibernate. However, the lower diversity of Vespertilionidae in the Neotropics is better explained by competition with a diverse pre-existing community of bats than by niche conservatism.
Diversity and Distributions, 2014
Aim To identify characteristics of a human-modified landscape that promote taxonomic (TD), functional (FD) and phylogenetic (PD) dimensions of bat biodiversity. Location Caribbean lowlands of northeastern Costa Rica. Methods During the dry and wet seasons, we quantified TD (Simpson's diversity), as well as FD and PD (Rao's quadratic entropy) of phyllostomid bat assemblages at 15 sites that represented a forest loss and fragmentation gradient. FD was estimated separately for each of seven functional components that reflect particular niche axes (e.g. diet, foraging strategy) and for all functional components combined (FD all). PD was based on relatedness of species derived from a supertree. We identified the best explanatory landscape characteristics of each dimension using hierarchical partitioning. Results Landscape effects were dimension and season specific. During the dry season, TD and PD increased with increasing proportions of pasture or size of forest patches, whereas FD all decreased with increasing size of forest patches. During the wet season, TD increased with increasing forest patch size, whereas FD all and PD increased with increasing compactness of forest patches and decreasing proximity. Decomposition of FD into separate functional components revealed different landscape effects on ecological aspects of assemblages. Main conclusions One dimension of biodiversity was not a good surrogate for another. Rather, decomposition of biodiversity into different dimensions and functional components facilitated identification of the aspects of assemblages that are most affected by forest conversion and fragmentation. Areas with intermediate amounts of forest and pasture during the dry season harboured highest diversity from taxonomic, functional and phylogenetic perspectives. During the wet season, areas with large, compact forest patches promoted the dimensions of biodiversity. Placement of areas with even amounts of forest and pasture adjacent to large, compact forest patches (e.g. reserves) may maintain high biodiversity of bats and the ecosystem functions that they provide throughout the year.
Taxonomic and Phylogenetic Determinants of Functional Composition of Bolivian Bat Assemblages
Understanding diversity patterns and the potential mechanisms driving them is a fundamental goal in ecology. Examination of different dimensions of biodiversity can provide insights into the relative importance of different processes acting upon biotas to shape communities. Unfortunately, patterns of diversity are still poorly understood in hyper-diverse tropical countries. Here, we assess spatial variation of taxonomic, functional and phylogenetic diversity of bat assemblages in one of the least studied Neotropical countries, Bolivia, and determine whether changes in biodiversity are explained by the replacement of species or functional groups, or by differences in richness (i.e., gain or loss of species or functional groups). Further , we evaluate the contribution of phylogenetic and taxonomic changes in the resulting patterns of functional diversity of bats. Using well-sampled assemblages from published studies we examine noctilionoid bats at ten study sites across five ecoregions in Bolivia. Bat assemblages differed from each other in all dimensions of biodiversity considered; however , diversity patterns for each dimension were likely structured by different mechanisms. Within ecoregions, differences were largely explained by species richness, suggesting that the gain or loss of species or functional groups (as opposed to replacement) was driving dis-similarity patterns. Overall, our results suggest that whereas evolutionary processes (i.e., historical connection and dispersal routes across Bolivia) create a template of diversity patterns across the country, ecological mechanisms modify these templates, decoupling the observed patterns of functional, taxonomic and phylogenetic diversity in Bolivian bats. Our results suggests that elevation represents an important source of variability among diversity patterns for each dimension of diversity considered. Further, we found that neither phyloge-netic nor taxonomic diversity can fully account for patterns of functional diversity, highlighting the need for examining different dimensions of biodiversity of bats in hyperdiverse ecosystems.
Molecular species identification boosts bat diversity
Frontiers in Zoology, 2007
The lack of obvious morphological differences between species impedes the identification of species in many groups of organisms. Meanwhile, DNA-based approaches are increasingly used to survey biological diversity. In this study we show that sequencing the mitochondrial protein-coding gene NADH dehydrogenase, subunit 1 (nd1) from 534 bats of the Western Palaearctic region corroborates the promise of DNA barcodes in two major respects. First, species described with classical taxonomic tools can be genetically identified with only a few exceptions. Second, substantial sequence divergence suggests an unexpected high number of undiscovered species.
Ecography, 2006
Habitat selection as a mechanism of resource partitioning in two cryptic bat species Pipistrellus pipistrellus and Pipistrellus pygmaeus. Á Ecography 29: 697 Á708. Ecomorphological studies of bat communities often reveal the spatial and temporal coexistence of morphologically similar species, leading to suggestions that these communities are structured by non-deterministic processes. However, the diversification of echolocation call structure in bats allows for considerable morphological similarity while still permitting niche differentiation based on specialisation for prey type and habitat structure. The recent separation of a common Palaearctic bat, the pipistrelle, into Pipistrellus pipistrellus and P. pygmaeus, which are sympatrically distributed throughout their range, raises the question as to whether these two morphologically similar species partition resources in time and space. To test the hypothesis that the coexistence of these cryptic species is facilitated by differential habitat use, 14 P. pipistrellus, and 12 P. pygmaeus were radio-tracked from adjacent maternity roosts, in northeast Scotland, from May to September 2002/2003. The two species showed distinct habitat partitioning with P. pygmaeus foraging predominantly in riparian woodland and over water, and P. pipistrellus foraging along woodland edges and short isolated tree lines. Inter-specific overlap in habitat use was low and consequently foraging ranges were segregated spatially. The degree of habitat partitioning revealed in these species, which show considerable overlap in echolocation call parameters and functional morphology, suggests that morphological features, whilst useful in separating chiropteran species into coarsegrained foraging guilds, may not predict fine-grained ecological segregation.
Molecular Phylogenetics and Evolution, 2002
Conflicting phylogenetic signals of two data sets that analyse different portions of the same molecule are unexpected and require an explanation. In the present paper we test whether (i) differential evolution of two mitochondrial genes or (ii) cryptic diversity can better explain conflicting results of two recently published molecular phylogenies on the same set of species of long-eared bats (genus Plecotus). We sequenced 1714 bp of three mitochondrial regions (16S, ND1, and D-loop) of 35 Plecotus populations from 10 European countries. A likelihood ratio test revealed congruent phylogenetic signals of the three data partitions. Our phylogenetic analyses demonstrated that the existence of a previously undetected Plecotus lineage caused the incongruities of previous studies. This lineage is differentiated on the species level and lives in sympatry with its sister lineage, Plecotus auritus, in Switzerland and Northern Italy. A molecular clock indicates that all European Plecotus species are of mid or late Pliocene origin. Plecotus indet. was previously described as an intergrade between P. auritus and Plecotus austriacus since it shares morphological characters with both. It is currently known from elevations above 800 m a.s.l. in the Alps, the Dinarian Alps and the Pindos mountains in Greece. Since we could demonstrate that incongruities of two molecular analyses simply arose from the mis-identification of one lineage, we conclude that molecular phylogenetic analyses do not free systematists from a thorough inclusion of morphological and ecological data.
A synthesis of ecological and evolutionary determinants of bat diversity across spatial scales
BMC Ecology
Background: Diversity patterns result from ecological to evolutionary processes operating at different spatial and temporal scales. Species trait variation determine the spatial scales at which organisms perceive the environment. Despite this knowledge, the coupling of all these factors to understand how diversity is structured is still deficient. Here, we review the role of ecological and evolutionary processes operating across different hierarchically spatial scales to shape diversity patterns of bats-the second largest mammal order and the only mammals with real flight capability. Main body: We observed that flight development and its provision of increased dispersal ability influenced the diversification, life history, geographic distribution, and local interspecific interactions of bats, differently across multiple spatial scales. Niche packing combined with different flight, foraging and echolocation strategies and differential use of air space allowed the coexistence among bats as well as for an increased diversity supported by the environment. Considering distinct bat species distributions across space due to their functional characteristics, we assert that understanding such characteristics in Chiroptera improves the knowledge on ecological processes at different scales. We also point two main knowledge gaps that limit progress on the knowledge on scale-dependence of ecological and evolutionary processes in bats: a geographical bias, showing that research on bats is mainly done in the New World; and the lack of studies addressing the mesoscale (i.e. landscape and metacommunity scales). Conclusions: We propose that it is essential to couple spatial scales and different zoogeographical regions along with their functional traits, to address bat diversity patterns and understand how they are distributed across the environment. Understanding how bats perceive space is a complex task: all bats can fly, but their perception of space varies with their biological traits.
Unveiling the Hidden Bat Diversity of a Neotropical Montane Forest
PLOS ONE, 2016
Mountain environments, characterized by high levels of endemism, are at risk of experiencing significant biodiversity loss due to current trends in global warming. While many acknowledge their importance and vulnerability, these ecosystems still remain poorly studied, particularly for taxa that are difficult to sample such as bats. Aiming to estimate the amount of cryptic diversity among bats of a Neotropical montane cloud forest in Talamanca Range-southeast Central America-, we performed a 15-night sampling campaign, which resulted in 90 captured bats belonging to 8 species. We sequenced their mitochondrial cytochrome c oxidase subunit I (COI) and screened their inter-and intraspecific genetic variation. Phylogenetic relations with conspecifics and closely related species from other geographic regions were established using Maximum Likelihood and Bayesian inference methods, as well as median-joining haplotype networks. Mitochondrial lineages highly divergent from hitherto characterized populations (> 9% COI dissimilarity) were found in Myotis oxyotus and Hylonycteris underwoodi. Sturnira burtonlimi and M. keaysi also showed distinct mitochondrial structure with sibling species and/or populations. These results suggest that mountains in the region hold a high degree of endemicity potential that has previously been ignored in bats. They also warn of the high extinction risk montane bats may be facing due to climatic change, particularly in isolated mountain systems like Talamanca Range.