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The repetitive landscapes of mammalian genomes typically display high Class I (retrotransposon) transposable element (TE) content, which usually comprises around half of the genome. In contrast, the Class II (DNA transposon) contribution is typically small (<3% in model mammals). Most mammalian genomes exhibit a precipitous decline in Class II activity beginning roughly 40 Ma. The first signs of more recently active mammalian Class II TEs were obtained from the little brown bat, Myotis lucifugus, and are reflected by higher genome content (∼5%). To aid in determining taxonomic limits and potential impacts of this elevated Class II activity, we performed 454 survey sequencing of a second Myotis species as well as four additional taxa within the family Vespertilionidae and an outgroup species from Phyllostomidae. Graph-based clustering methods were used to reconstruct the major repeat families present in each species and novel elements were identified in several taxa. Retrotransposons remained the dominant group with regard to overall genome mass. Elevated Class II TE composition (3–4%) was observed in all five vesper bats, while less than 0.5% of the phyllostomid reads were identified as Class II derived. Differences in satellite DNA and Class I TE content are also described among vespertilionid taxa. These analyses present the first cohesive description of TE evolution across closely related mammalian species, revealing genome-scale differences in TE content within a single family.

Habitat loss and resultant fragmentation are major threats to biodiversity, particularly in tropical and subtropical ecosystems. It is increasingly urgent to understand fragmentation effects, which are often complex and vary across taxa, time and space. We determined whether recent fragmentation of Atlantic forest is causing population subdivision in a widespread and important Neotropical seed disperser: Artibeus lituratus (Chiroptera: Phyllostomidae). Genetic structure within highly fragmented forest in Paraguay was compared to that in mostly contiguous forest in neighbouring Misiones, Argentina. Further, observed genetic structure across the fragmented landscape was compared with expected levels of structure for similar time spans in realistic simulated landscapes under different degrees of reduction in gene flow. If fragmentation significantly reduced successful dispersal, greater population differentiation and stronger isolation by distance would be expected in the fragmented than in the continuous landscape, and genetic structure in the fragmented landscape should be similar to structure for simulated landscapes where dispersal had been substantially reduced. Instead, little genetic differentiation was observed, and no significant correlation was found between genetic and geographic distance in fragmented or continuous landscapes. Furthermore, comparison of empirical and simulated landscapes indicated empirical results were consistent with regular long-distance dispersal and high migration rates. Our results suggest maintenance of high gene flow for this relatively mobile and generalist species, which could be preventing or significantly delaying reduction in population connectivity in fragmented habitat. Our conclusions apply to A. lituratus in Interior Atlantic Forest, and do not contradict broad evidence that habitat fragmentation is contributing to extinction of populations and species, and poses a threat to biodiversity worldwide.

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Microsatellites are often the marker of choice for population genetic studies at intermediate spatial and temporal scales. Developing large numbers of markers has traditionally been technically difficult, and this has limited our ability to investigate evolutionary phenomena that emerge across short temporal scales. Moreover, few markers tend to successfully amplify across species boundaries. As rapid advancements in high-throughput sequencing make microsatellite development cost- and time-effective, new avenues for evolutionary, population genetic and chromosome linkage mapping research are emerging. We used a published PERL script and second-generation sequencing to rapidly and affordably develop microsatellite loci for a widespread phyllostomid bat, Artibeus lituratus, for which no markers were previously available. We used Roche FLX (Titanium) Genome Sequencing to randomly sequence ∼101 Mb (255,065 unique reads) of genomic DNA for A. lituratus, within which we discovered 30,100 microsatellite loci. We designed primers for 19,395 loci that contained suitable flanking regions. We ordered primers for 96 loci, 90 of which produced a single PCR product in A. lituratus. We genotyped 52 loci, and 45 were polymorphic in A. lituratus. We tested cross-species amplification for 96 loci in six additional phyllostomid species: A. planirostris, A. fimbriatus, A. phaeotis, Enchisthenes hartii, Sturnira lilium, and Carollia perspicillata. Cross-species amplification was successful for at least one species for 87 loci (A. fimbriatus), and in all species, at least 66 loci were amplified. These markers will not only facilitate future work on these seven species, but also illustrate the utility of this high-throughput method for development of primers across many species simultaneously.