|COSENTINO, BRADLEY - Hobart College|
|SCHOOLEY, ROBERT - University Of Illinois|
|MCCARTHY, ALISON - Hobart College|
|SIERZEGA, KEVIN - University Of Illinois|
Submitted to: Molecular Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/9/2015
Publication Date: 12/16/2015
Citation: Cosentino, B., Schooley, R.L., Bestelmeyer, B.T., Mccarthy, A.J., Sierzega, K. 2015. Rapid genetic restoration of a keystone species exhibiting delayed demographic response. Molecular Ecology. 24:6120-6133.
Interpretive Summary: Low genetic diversity can increase the probability of local extinction and limit adaptation to environmental change. Limited genetic diversity is associated with initial, small populations that originate from only a few source populations, called founder effects. Founder effects may be common when species colonize a site following environmental restoration. To test for founder effects, we compared the genetic structure of populations of the grassland specialist kangaroo rat D. spectabilis between sites treated wither herbicides to remove shrubs and remnant grasslands that serve as source populations. We also examined how the genetic response to restoration depended on treatment age, area, and connectivity to source populations. Theresults indicated that founder effects during colonization of treated sites were weak or absent. Moreover, our results suggested founder effects were not mitigated by treatment area or connectivity. Our study shows that genetic diversity can be recovered rapidly after habitat restoration and that founder effects are not inevitable for animals colonizing restored habitat in fragmented landscapes.
Technical Abstract: Genetic founder effects are often expected when animals colonize restored habitat in fragmented landscapes, but empirical data on genetic responses to restoration are limited. We examined the genetic response of banner-tailed kangaroo rats (Dipodomys spectabilis) to landscape-scale grassland restoration in the Chihuahuan Desert of New Mexico, USA. Dipodomys spectabilis is a grassland specialist and keystone species. At sites treated with herbicide to remove shrubs, colonization by D. spectabilis is slow and populations persist at low density for =10 years (=6 generations). Persistence at low density and low gene flow may cause strong founder effects. We compared genetic structure of D. spectabilis populations between treated sites and remnant grasslands, and we examined how the genetic response to restoration depended on treatment age, area, and connectivity to source populations. Allelic richness and heterozygosity were similar between treated sites and remnant grasslands. Allelic richness at treated sites was greatest early in the restoration trajectory, and genetic divergence did not differ between recently colonized and established populations. These results indicated that founder effects during colonization of treated sites were weak or absent. Moreover, our results suggested founder effects were not mitigated by treatment area or connectivity. Dispersal is negatively density-dependent in D. spectabilis, and we hypothesize that high gene flow may occur early in the restoration trajectory when density is low. Our study shows genetic diversity can be recovered more rapidly than demographic components of populations after habitat restoration and that founder effects are not inevitable for animals colonizing restored habitat in fragmented landscapes.