Dispersal and gene flow among pygmy rabbit (Brachylagus idahoensis) populations in Idaho and southwestern Montana


Estes-Zumpf, Wendy A.. (2008). Dispersal and gene flow among pygmy rabbit (Brachylagus idahoensis) populations in Idaho and southwestern Montana. Theses and Dissertations Collection, University of Idaho Library Digital Collections.

Dispersal and gene flow among pygmy rabbit (Brachylagus idahoensis) populations in Idaho and southwestern Montana
Estes-Zumpf, Wendy A.
Pygmy rabbit--Dispersal--Idaho Pygmy rabbit--Dispersal--Montana Pygmy rabbit--Idaho--Genetics Pygmy rabbit--Montana--Genetics
Natural Resources
Dispersal influences the genetic and demographic structure of wildlife populations. In addition, patterns of dispersal and gene flow can be affected by the dispersal capabilities of a species, putative barriers or filters to movement, and the quality, quantity, and configuration of habitat. We studied dispersal behavior 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. Habitat loss and fragmentation and the tendency for local extinctions make knowledge of the dispersal patterns and capabilities of pygmy rabbits critical for conservation planning.;Despite the importance of dispersal to maintaining wildlife populations, information on dispersal patterns can be difficult to obtain due to logistical constraints associated with various different techniques. To gain a more accurate and more complete understanding of the dispersal patterns of pygmy rabbits, we used field techniques (radio-telemetry and mark-recapture) and genetic techniques at several spatial scales to investigate the dispersal capabilities and influence of putative barriers to gene flow in this species.;At the local scale, we studied natal dispersal behavior in pygmy rabbits by following movements of individual juvenile rabbits using radio-telemetry. We first designed a radio-transmitter attachment method that increased retention time, but also would be shed safely if juveniles were not recaptured for transmitter removal (Chapter 1). Using our transmitter attachment method we studied dispersal of 61 juveniles during 2004-2006. Dispersal occurred rapidly when juveniles were between 2.5 and 12 weeks-of-age. Both males and females exhibited a high rate of dispersal (males = 90%; females = 80%), however, median natal dispersal distances for females (1.0 km; range = 0.03-6.5 km) were greater than for males (2.9 km; range = 0.02-11.9 km). Dispersing juveniles crossed gravel roads and perennial streams, however, rabbits tended to initiate dispersal movements away from nearby streams (Chapter 2).;We also examined genetic diversity, gene flow, and population genetic structure, and investigated the effects of putative barriers to gene flow within 2 study areas in the Lemhi Valley and Camas Prairie, Idaho. Population genetic analyses were conducted using microsatellite markers developed specifically for the pygmy rabbit (Chapter 3). We found relatively low levels of genetic differentiation among sample locations. Bayesian cluster analyses suggested that sample locations separated by <14 km comprised one genetic cluster with high levels of gene flow among sample locations within clusters. We documented no significant evidence of a sex-bias in dispersal (Chapter 4). We then compared inferences about dispersal behavior made using field techniques and genetic techniques and determined that, in general, field and genetic techniques indicated similar dispersal patterns (Chapter 5).;Lastly, we examined the influence of landscape features on recent and historic patterns of gene flow at regional and landscape scales (Chapter 6). We quantified genetic diversity and population differentiation in pygmy rabbits from 19 populations across Idaho and 6 populations in southwestern Montana using 16 microsatellite loci and a 509 bp fragment of the mitochondrial control region. Genetic diversity was lowest on the periphery of the species range in Montana. In general, the Snake and Salmon Rivers appear to have severely limited gene flow among populations of pygmy rabbits in both recent and historic times. The Continental Divide, however, does not appear to be a barrier to gene flow, with gene flow likely occurring across lower elevation passes that support sagebrush vegetation. Overall, we determined that pygmy rabbits have a greater biological potential for maintaining gene flow than previously perceived, however, rapid landuse changes in the sagebrush steppe may lead to greater isolation of remaining rabbit populations.
Thesis (Ph. D., Natural Resources)--University of Idaho, May 2008.
Major Professor:
Janet L. Rachlow.
Defense Date:
May 2008.
Format Original:
xvii, 165 leaves :ill., maps (some col.) ;29 cm.

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