Consumption of spiders by the little brown bat (Myotis lucifugus) and the long-eared bat (Myotis evotis) in the Rocky Mountains of Alberta

Intraspecific variation in diet and/or foraging behaviour is one way in which species are able to occupy wide geographical areas with variable environments. <i>Myotis lucifugus</i> (Le Conte, 1831), a primarily aerial insectivorous bat, consumes spiders in low temperatures at the start and end of summer in Northwest Territories, but in Alaska, it consumes spiders all summer, even during high aerial-insect abundance. There are no competitors of <i>M. lucifugus</i> in Alaska, but there are in Northwest Territories, suggesting that aerial insect abundance and competition from gleaning bats influences when <i>M. lucifugus</i> consumes spiders. In the Kananaskis area of the Rocky Mountains of Alberta, we investigated spider consumption by <i>M. lucifugus</i>, and <i>Myotis evotis</i> (H. Allen, 1864), a species more adept at gleaning, to better understand when bats consume spiders. Fecal sample analysis indicated that <i>Myotis evotis</i> consumed spiders all season long, with greater consumption when the bats were caught near water. <i>Myotis lucifugus</i> did not consume spiders at all. This suggests that <i>M. lucifugus</i> opportunistically consumes spiders when encountered, but does not encounter them in Kananaskis where it forages primarily over open water, unlike in Northwest Territories where it forages in the interior of forests and may encounter spiders more frequently.

Rapid Biodiversity Sampling for Bat Assemblages in Northwestern Nevada

Bat (Chiroptera) assemblages in the western North America remain understudied despite their importance to ecosystem function and vulnerability to multiple anthropogenic stressors. We present the first large-scale survey that we are aware of for bat fauna in the Black Rock Plateau of northwestern Nevada in the northern Great Basin Desert. We conducted surveys using both acoustic and mist net methods, documenting 14 species across 19 sites sampled during a four-night period in August 2016. We surveyed over water sources, usually surrounded by cliff and canyon habitat, and in salt desert scrub, sagebrush, and woodland habitats, detecting multiple sensitive bat species (spotted bat Euderma maculatum, little brown bat Myotis lucifugus, canyon bat Parastrellus hesperus) in the canyon habitats of the High Rock region. We analyzed regional species diversity and present the utility of using multiple detection methods to enhance understanding of Chiroptera biodiversity at both local and regional scales. Our results demonstrate the utility of “BioBlitz” approaches in documenting local and regional diversity and provide insight into areas with species assemblages or vulnerable species. Knowledge of these sites is increasingly important for future disease surveillance and population monitoring.

Genomic signatures of evolutionary rescue in bats surviving white-nose syndrome

Rapid evolution of advantageous traits following abrupt environmental change can help populations grow and avoid extinction through evolutionary rescue. Here, we provide the first genetic evidence for rapid evolution in bat populations affected by white-nose syndrome (WNS). By comparing genetic samples from before and after little brown bat populations were decimated by WNS, we identified signatures of soft selection on standing genetic variation. This selection occurred at multiple loci in genes linked to hibernation behavior rather than immune function, suggesting that differences in hibernation strategy have allowed these bats to survive infection with WNS. Through these findings, we suggest that evolutionary rescue can be a conservationrelevant process even in slowly reproducing taxa threatened with extinction.

Molecular parallelism in fast-twitch muscle proteins in echolocating mammals

Detecting associations between genomic changes and phenotypic differences is fundamental to understanding how phenotypes evolved. By systematically screening for parallel amino acid substitutions, we detected known as well as novel cases (Strc, Tecta, and Cabp2) of parallelism between echolocating bats and toothed whales in proteins that could contribute to high-frequency hearing adaptations. Our screen also showed that echolocating mammals exhibit an unusually high number of parallel substitutions in fast-twitch muscle fiber proteins. Both echolocating bats and toothed whales produce an extremely rapid call rate when homing in on their prey, which was shown in bats to be powered by specialized superfast muscles. We show that these genes with parallel substitutions (Casq1, Atp2a1, Myh2, and Myl1) are expressed in the superfast sound-producing muscle of bats. Furthermore, we found that the calcium storage protein calsequestrin 1 of the little brown bat and the bottlenose dolphin functionally converged in its ability to form calcium-sequestering polymers at lower calcium concentrations, which may contribute to rapid calcium transients required for superfast muscle physiology. The proteins that our genomic screen detected could be involved in the convergent evolution of vocalization in echolocating mammals by potentially contributing to both rapid Ca2+ transients and increased shortening velocities in superfast muscles.

Temperature-dependent consumption of spiders by little brown bats (Myotis lucifugus), but not northern long-eared bats (Myotis septentrionalis), in northern Canada

Intraspecific variation in diet has been observed in many species, including the geographically widespread little brown bat (Myotis lucifugus (Le Conte, 1831)). Spider consumption by M. lucifugus is more common in northern regions of their distribution, possibly due to reduced availability of aerial prey during low temperatures. However, in previously studied northern regions, M. lucifugus was the only bat species captured. The purpose of our study was to examine whether there is overlap in the diet and morphology of M. lucifugus and the northern long-eared bat (Myotis septentrionalis (Trouessart, 1897)), a species that commonly gleans prey, in the Northwest Territories, Canada. There were significant differences in the dietary composition and wing morphology of the two species, suggesting partitioning of resources. Both species consumed spiders, although unlike M. septentrionalis, the probability of M. lucifugus consuming spiders was significantly greater at low temperatures. Myotis lucifugus demonstrated a different pattern of spider consumption than in other northern regions where it consumes spiders throughout the summer, suggesting the possibility of resource competition where M. lucifugus overlaps with M. septentrionalis. Further research is needed to determine whether arthropods are seasonally limiting at high latitudes and to examine how these species capture nonaerial prey, including spiders.