Turner, G. G. | bioRxiv Science

bioRxiv2023

Drivers of population dynamics of at-risk populations change with pathogen arrival

Successful wildlife conservation in an era of rapid global change requires understanding determinants of species population abundance and growth. However, when populations are faced with novel stressors, factors associated with healthy and growing populations can change, necessitating a shift in conservation strategies. For example, emerging infectious diseases can cause conditions previously beneficial or neutral to host populations to increase disease impacts. Here, we paired a population dataset of 265 colonies of the federally endangered Indiana bat (Myotis sodalis) with 50.7 logger-years of environmental data to explore factors that affected colony response to white-nose syndrome (WNS), an emerging fungal disease. We found wide variation in colony responses to WNS, ranging from extirpation to stabilization and persistence. Simulating future population dynamics suggests that most extirpations have already occurred, as the pathogen has been present for several years in most colonies, and that small colonies were more susceptible to extirpation than large ones. Further, while temperature and humidity conditions of hibernacula appeared unassociated with Indiana bat colony growth prior to WNS, extirpation risk following pathogen arrival was elevated in colonies that used colder and wetter hibernacula. Additionally, rates of decline were greater in colder hibernacula, opposite the association for a sympatric bat species. Overall, this study illustrates that emerging infectious diseases can change the factors associated with host population abundance and optimal growth, including through novel environmental associations, which can vary across host species. Consideration of these shifting associations and intrinsic differences between impacted host species will be essential to successful species conservation.

ecology↗

bioRxiv2019

Genome-wide changes in genetic diversity in a Myotis lucifugus population affected by white-nose syndrome

Novel pathogens can cause massive declines in populations, and even extirpation of hosts. But disease can also act as a selective pressure on survivors, driving the evolution of resistance or tolerance. Bat white-nose syndrome (WNS) is a rapidly spreading wildlife disease in North America. The fungus causing the disease invades skin tissues of hibernating bats, resulting in disruption of hibernation behavior, premature energy depletion, and subsequent death. We used whole-genome sequencing to investigate changes in allele frequencies within a population of Myotis lucifugus in eastern North America to search for genetic resistance to WNS. Our results show low FST values within the population across time, i.e. prior to WNS (Pre-WNS) compared to the population that has survived WNS (Post-WNS). However, when dividing the population with a geographical cut-off between the states of Pennsylvania and New York, a sharp increase in values on scaffold GL429776 is evident in the Post-WNS samples. Genes present in the diverged area are associated with thermoregulation and promotion of brown fat production. Thus, although WNS may not have subjected the entire M. lucifugus population to selective pressure, it may have selected for specific alleles in Pennsylvania through decreased gene flow within the population. However, the persistence of remnant sub-populations in the aftermath of WNS is likely due to multiple factors in bat life history.

evolutionary biology↗