Spatial genetic structure in American black bears (Ursus americanus): female philopatry is variable and related to population history

Abstract

Previously, American black bears (Ursus americanus) were thought to follow the pattern of female philopatry and male-biased dispersal. However, recent studies have identified deviations from this pattern. Such flexibility in dispersal patterns can allow individuals greater ability to acclimate to changing environments. We explored dispersal and spatial genetic relatedness patterns across ten black bear populations-including long established (historic), with known reproduction >50 years ago, and newly established (recent) populations, with reproduction recorded <50 years ago-in the Interior Highlands and Southern Appalachian Mountains, United States. We used spatially explicit, individual-based genetic simulations to model gene flow under scenarios with varying levels of population density, genetic diversity, and female philopatry. Using measures of genetic distance and spatial autocorrelation, we compared metrics between sexes, between population types (historic and recent), and among simulated scenarios which varied in density, genetic diversity, and sex-biased philopatry. In empirical populations, females in recent populations exhibited stronger patterns of isolation-by-distance (IBD) than females and males in historic populations. In simulated populations, low-density populations had a stronger indication of IBD than medium- to high-density populations; however, this effect varied in empirical populations. Condition-dependent dispersal strategies may permit species to cope with novel conditions and rapidly expand populations. Pattern-process modeling can provide qualitative and quantitative means to explore variable dispersal patterns, and could be employed in other species, particularly to anticipate range shifts in response to changing climate and habitat conditions.

Landscape genetics of wolverines (Gulo gulo): scale-dependent effects of bioclimatic, topographic, and anthropogenic variables

“…Also, wolverines may establish their home ranges in proximity of their natal range ( Hedmark et al 2007 ; Bischof et al 2016 ; Aronsson and Persson 2018 ). These behavioral characteristics can lead to strong spatial-genetic correlations at fine spatial scales, because related individuals tend to be closer geographically than unrelated individuals (see, e.g., Wang et al 2017 ; Kristensen et al 2018 , for other species). Because these are endogenous (i.e., landscape-independent) processes, they explain the relatively high percentage of pure spatial components in our small-scale analysis, despite the high mobility of the species.…”

Analysing the recolonisation of a highly fragmented landscape by wild boar using a landscape genetic approach

“…Landscape genetic studies benefit from an individual-based approach, often using datasets with specific coordinates of sample locations (Cushman et al 2006, Holderegger and Wagner 2008, Segelbacher et al 2010, Parks et al 2015, Kristensen et al 2018). As we did not have the exact coordinates from each sample, we opted to conduct the landscape genetic analysis using a subset of samples which could be allocated to an area of a municipality within a GMU of less than 40 km 2 and used repeated random point locations in these areas to determine the influence of landscape variables.…”

Forecasting Seasonal Habitat Connectivity in a Developing Landscape

“…Female bears do not typically disperse far from their natal ranges [49,50]. However, this philopatry may be density dependent and females may disperse further in recently established black bear range [51]. Given that we could only model female home range movement, our model is a conservative approximation of movement and connectivity for our study area.…”