Dispersal, gene flow, and population genetic structure in the pygmy rabbit (Brachylagus idahoensis)

Abstract

Dispersal and gene flow are significant components of metapopulation structure and dynamics. We examined gene flow in the pygmy rabbit (Brachylagus idahoensis), a sagebrush specialist that occurs in small, isolated populations in the Great Basin region and is believed to have limited dispersal abilities. We examined genetic diversity, gene flow, and population genetic structure, and investigated the effects of putative barriers to gene flow in 8 sample locations within 2 study areas in Idaho during 2002-2006. Potential barriers included secondary roads, highways, creeks, and agricultural pastures. Distance between sample locations ranged from 0.5 to 32 km. We expected that gene flow would be limited and that moderate levels of genetic structure would be apparent among sample locations separated by barriers and distances over several kilometers. However, analyses based on 15 microsatellite loci from 239 rabbits revealed low to moderate levels of genetic differentiation among sample locations. Bayesian cluster analyses suggested that sample locations separated by ,14 km comprised 1 genetic cluster with high levels of gene flow among sample locations within clusters. We documented no significant evidence of a sex bias in dispersal based on sex-specific F ST among sample locations, and relatedness (r), mean assignment index (mAI), and variance of assignment index (vAI) within sample locations; however, spatial autocorrelation suggested that juvenile females might disperse farther than males. These results indicate that dispersal capabilities of pygmy rabbits greatly exceed previous estimates, and that creeks and roads were not effective barriers to gene flow in our study areas.

Quantitative analysis of connectivity in populations of a semi‐aquatic mammal using kinship categories and network assortativity

“…Bayesian clustering algorithms like Structure have been used in previous studies of recent fragmentation (Blair et al, ; Estes‐Zumpf et al, ; Riley et al, ). However, in certain populations, for example in contact zones of ancient lineages, clustering methods will reflect both ancient and recent population divergence, making it difficult to determine the genetic structure specifically due to recent barriers.…”

“…In particular, the detection of barriers to gene flow has been a topic of major interest (Storfer et al, ; Storfer, Murphy, Spear, Holderegger, & Waits, ). Barriers that alter connectivity among populations can be as old as mountain ridges but they can also be more recent barriers, generally of anthropogenic origin, such as roads (Estes‐Zumpf, Rachlow, Waits, & Warheit, ; Riley et al, ) and river dams (Ardren & Bernall, ; Deiner, Garza, Coey, & Girman, ; Gouskov, Reyes, Wirthner‐Bitterlin, & Vorburger, ; Raeymaekers et al, ; Taylor, Stamford, & Baxter, ; Wofford, Gresswell, & Banks, ). While the analysis of old barriers is relevant to study the evolution of species, understanding the effect of more recent barriers may be crucial for their conservation.…”

Plant protein and secondary metabolites influence diet selection in a mammalian specialist herbivore

“…We analyzed data from the 2 field sites independently because (1) they were separated by approximately 180 km, (2) the dominant sagebrush at each site had different chemical profiles (Ulappa 2011), and (3) pygmy rabbits from each site were far enough apart to be considered genetically distinct (Estes-Zumpf et al 2010). We analyzed all 30 pairs of plants from the Camas Prairie site, whereas we analyzed 35 of the 40 pairs from the Leadore site because 5 pairs from the latter were damaged during Total Kjeldahl Nitrogen analysis.…”

Habitat specialists as conservation umbrellas: Do areas managed for greater sage‐grouse also protect pygmy rabbits?

“…We buffered each trusted location by 3 km, which is approximately equal to the median natal dispersal distance documented for the species (Estes-Zumpf and Rachlow 2009, Estes-Zumpf et al 2010 and also close to one estimate of the width of an average female home range (Sanchez and Rachlow 2008). We buffered each trusted location by 3 km, which is approximately equal to the median natal dispersal distance documented for the species (Estes-Zumpf and Rachlow 2009, Estes-Zumpf et al 2010 and also close to one estimate of the width of an average female home range (Sanchez and Rachlow 2008).…”