Cynopterus

Abstract: We constructed DNA-hybridisation matrices comparing 18 genera of Megachiroptera and an outgroup microchiropteran, and eight species of Pteropus and two related genera. Three species each of Megachiroptera and Microchiroptera, two of Primates, and an outgroup armadillo were compared in another matrix; additional representatives of other mammalian orders figured in a further set of experiments. Among the megachiropterans examined, Nyctimene and Paranyctimene comprise the sister-group to other pteropodids. Of the 'macroglossines', only Macroglossus and Syconycteris are associated apart from typical pteropodines, while the four remaining nectar-feeders (Eonycteris, Megaloglossus, Melonycteris, Notopteris) are independently linked with non-nectar-feeding clades. Thus, Megaloglossus is the nearest relative of Lissonycteris, with Epomophorus and Rousettus successive sister-groups to both, while Eonycteris is the sister of all four; Melonycteris and Pteralopex form a trichotomy with the closely related Acerodon and Pteropus, and Notopteris is the sister-taxon to all four. It therefore appears that anatomical specialisations for nectar- and pollen-feeding evolved (or were lost) several times within Pteropodidae. Cynopterus and Dobsonia represent additional clades within the Pteropodinae, with which Thoopterus and Aproteles are respectively paired. Comparisons among species of Pteropus and related genera suggest that Acerodon may be congeneric with Pteropus, but that Pteralopex clearly is not. The ordinal-level matrices support bat monophyly: no order tested is closer to either of the chiropteran suborders than they are to each other, and bats are separated from Primates by at least two nodes. On the basis of previous rate determinations for mammals, we estimate that the African grouping (Epomophorus, Megaloglossus, Lissonycteris) is mid-Miocene in origin, that the two major pteropodid subfamilies (Nyctimeninae and Pteropodinae, including 'Macroglossinae') separated in the Early Miocene, and that the divergence of chiropteran suborders dates from the latest Cretaceous or earliest Palaeocene. Arrangement of genera within Pteropodidae supports the family's Australo-Pacific or south-east Asian origin.

Abstract: This study investigated allozyme and morphometric variability within the genus Cynopterus, with particular emphasis on C. nusatenggara, which is endemic to Wallacea, the area encompassing the Oriental-Australian biogeographic interface. The genetic distances between Cynopterus species are small by mammalian standards and suggest that this genus has undergone a recent series of speciation events. The genetic distance between populations of C. nusatenggara is strongly correlated with both the contemporary sea-crossing distance between islands and the estimated sea crossing at the time of the last Pleistocene glacial maximum, 18,000 b.p. This observation, together with low levels of population substructure within islands as shown by F-statistics, indicates that the sea is a primary and formidable barrier to gene exchange. The genetic distance and the great-circle geographical distance between the populations of C. nusatenggara are not correlated, although a principal-coordinates analysis of genetic distance reveals relationships between the populations that are similar to their geographical arrangement. A strong negative correlation exists between the level of heterozygosity within island populations of C. nusatenggara and the minimum sea-crossing distance to the nearest large source population. This is interpreted as reflecting an isolation effect of the sea, leading to reduced heterozygosity in populations that have larger sea barriers between them and the large source islands. Independently of this, heterozygosity is negatively associated with longitude, which in turn is associated with systematic changes in the environment such as a gradual decline in rainfall from west to east. The association between heterozygosity and longitude is interpreted as reflecting an association between genetic and environmental variance and supports the niche-width theory of genetic variance. Morphometric variability did not show any of the main effects demonstrated in the genetic data. Furthermore, there was no evidence that, at the level of individuals, genetic and morphometric variability were associated.

Abstract: The extent to which response to environmental change is mediated by species-specific ecology is an important aspect of the population histories of tropical taxa. During the Pleistocene glacial cycles and associated sea level fluctuations, the Sunda region in Southeast Asia experienced concurrent changes in landmass area and the ratio of forest to open habitat, providing an ideal setting to test the expectation that habitat associations played an important role in determining species’ response to the opportunity for geographic expansion. We used mitochondrial control region sequences and six microsatellite loci to compare the phylogeographic structure and demographic histories of four broadly sympatric species of Old World fruit bats in the genus, Cynopterus . Two forest-associated species and two open-habitat generalists were sampled along a latitudinal transect in Singapore, peninsular Malaysia, and southern Thailand. Contrary to expectations based on habitat associations, the geographic scale of population structure was not concordant across ecologically similar species. We found evidence for long and relatively stable demographic history in one forest and one open-habitat species, and inferred non-coincident demographic expansions in the second forest and open-habitat species. Thus, while these results indicate that Pleistocene climate change did not have a single effect on population structure across species, a correlation between habitat association and response to environmental change was supported in only two of four species. We conclude that interactions between multiple factors, including historical and contemporary environmental change, species-specific ecology and interspecific interactions, have shaped the recent evolutionary histories of Cynopterus fruit bats in

Abstract: Data are presented on temperature regulation and rate of metabolism in three Bornean bats, Cynopterus brachyotis, Eonycteris spelaea , and Hipposideros galeritus . These species maintain core body temperature at 36.5, 34.0, and 31.9°C, respectively, a sequence also found in the level of basal rate of metabolism, namely 92, 73, and 55% of the values expected from mass, respectively. These data and those available in the literature demonstrate that much of the variation in basal rate among bats correlates with food habits, independent of phylogeny. Thus, Cynopterus , like other frugivorous species, has the highest basal rate reported here, and Hipposideros , an insectivorous species, has a low basal rate. The intermediate basal rate in Eonycteris may reflect a large mass (52 g) for a nectarivorous species. The variation in basal rate may be understood principally in terms of the phenology of foods used. Previous estimates for basal rate of metabolism and minimal thermal conductance of Neotropical bats have been readjusted for temperature and pressure.