Dispersal, mating events and fine-scale genetic structure in the lesser flat-headed bats

Bat mating systems-A review and recategorisation

Mating systems, influenced by the social and ecological environment and individual attributes, are fundamental components of animal social organisation, impacting behaviour, animal distribution, ecosystem processes, individual reproductive success, and population dynamics. Bats are of particular interest for studies of mating systems as they are thought to exhibit a greater diversity in mating systems than any other mammalian order, and thus make great models for improving our fundamental understanding of causes and consequences of social organisation. Here, we review the current knowledge of bat mating systems. Our analyses show that research on bat mating systems has not kept pace with research on bats in general and that traditional typologies do not accommodate the mating system of several species. Therefore, we propose an alternative, functional framework to categorise mating systems of bats and by extension of other taxa. We argue that mating systems can be classified according to a male reproductive skew continuum, with an increasing skew from monogamy to true lekking. We include an additional category of lek-like mating system along the continuum to account for previous trans-categorical cases that have the appearance of resource defence but are functionally akin to a lek. The new framework has a total of seven categories: promiscuity, monogamy, female defence polygyny, resource defence polygyny, a lek-like mating system, exploded classical lek, and clustered classical lek. Applying this framework to bats reveals that lek mating systems are more prevalent in bats than previously recognised. It is our aim that this review and the proposed framework provide a greater understanding of bat mating systems particularly and provoke research into the factors that shape mating systems across animal taxa more generally.

High genetic connectivity among large populations of Pteronotus gymnonotus in bat caves in Brazil and its implications for conservation

Bat caves in the Neotropical region harbor exceptional bat populations (> 100,000 individuals). These populations play a wider role in ecological interactions, are vulnerable due to their restriction to caves, and have a disproportionate conservation value. Current knowledge of bat caves in Brazil is still small. However, systematic monitoring of some bat caves in northeastern Brazil shows that they experience strong population fluctuations over short periods of time, suggesting large-scale movements between roosts and a much broader use of the landscape than previously considered. Spatio-temporal reproductive connectivity between distant populations would change our understanding of the use of roosts among bat species in Brazil, and important gaps in knowledge of long-distance bat movements in the country would be filled. Here, we used ddRADseq data to analyze the genetic structure of Pteronotus gymnonotus across nine bat caves over 700 km. Our results indicate the lack of a clear geographic structure with gene flow among all the caves analyzed, suggesting that P. gymnonotus uses a network of bat caves geographically segregated hundreds of kilometers apart. Facing strong anthropogenic impacts and an underrepresentation of caves in conservation action plans worldwide, the genetic connectivity demonstrated here confirms that bat caves are priority sites for bat and speleological conservation in Brazil and elsewhere. Moreover, our results demonstrate a warning call: the applied aspects of the environmental licensing process of the mining sector and its impact must be reviewed, not only in Brazil, but wherever this licensing process affects caves having exceptional bat populations.

Dispersal ability predicts spatial genetic structure in native mammals persisting across an urbanization gradient

As the rate of urbanization continues to increase globally, a growing body of research is emerging that investigates how urbanization shapes the movement-and consequent gene flow-of species in cities. Of particular interest are native species that persist in cities, either as small relict populations or as larger populations of synanthropic species that thrive alongside humans in new urban environments. In this study, we used genomic sequence data (SNPs) and spatially explicit individual-based analyses to directly compare the genetic structure and patterns of gene flow in two small mammals with different dispersal abilities that occupy the same urbanized landscape to evaluate how mobility impacts genetic connectivity. We collected 215 white-footed mice (Peromyscus leucopus) and 380 big brown bats (Eptesicus fuscus) across an urban-to-rural gradient within the Providence, Rhode Island (U.S.A.) metropolitan area (population =1,600,000 people). We found that mice and bats exhibit clear differences in their spatial genetic structure that are consistent with their dispersal abilities, with urbanization having a stronger effect on Peromyscus mice. There were sharp breaks in the genetic structure of mice within the Providence urban core, as well as reduced rates of migration and an increase in inbreeding with more urbanization. In contrast, bats showed very weak genetic structuring across the entire study area, suggesting a near-panmictic gene pool likely due to the ability to disperse by flight. Genetic diversity remained stable for both species across the study region. Mice also exhibited a stronger reduction in gene flow between island and mainland populations than bats. This study represents one of the first to directly compare multiple species within the same urban-to-rural landscape gradient, an important gap to fill for urban ecology and evolution. Moreover, here we document the impacts of dispersal capacity on connectivity for native species that have persisted as the urban landscape matrix expands.