Abstract
Forest fragmentation may negatively affect plants through reduced genetic diversity and increased population structure due to habitat isolation, decreased population size, and disturbance of pollen‐seed dispersal mechanisms. However, in the case of tree species, effective pollen‐seed dispersal, mating system, and ecological dynamics may help the species overcome the negative effect of forest fragmentation. A fine‐scale population genetics study can shed light on the postfragmentation genetic diversity and structure of a species. Here, we present the genetic diversity and population structure of Cercis canadensis L. (eastern redbud) wild populations on a fine scale within fragmented areas centered around the borders of Georgia–Tennessee, USA. We hypothesized high genetic diversity among the collections of C. canadensis distributed across smaller geographical ranges. Fifteen microsatellite loci were used to genotype 172 individuals from 18 unmanaged and naturally occurring collection sites. Our results indicated presence of population structure, overall high genetic diversity (H E = 0.63, H O = 0.34), and moderate genetic differentiation (F ST = 0.14) among the collection sites. Two major genetic clusters within the smaller geographical distribution were revealed by STRUCTURE. Our data suggest that native C. canadensis populations in the fragmented area around the Georgia–Tennessee border were able to maintain high levels of genetic diversity, despite the presence of considerable spatial genetic structure. As habitat isolation may negatively affect gene flow of outcrossing species across time, consequences of habitat fragmentation should be regularly monitored for this and other forest species. This study also has important implications for habitat management efforts and future breeding programs.
Highlights
Habitat fragmentation involves discontinuities in the distribution of an organism due to geographical and/or geological barriers, and/or human activities (Kolb & Diekmann, 2005; Kwak, Velterop, & Andel, 1998)
Long-term evolutionary success and species survival is influenced by population size, genetic diversity, allelic richness, fitness, and substantial gene flow, which are of fundamental importance in plant ecology, evolution, and conservation (Leimu, Mutikainen, Koricheva, & Fischer, 2006)
Our study, which is part of a larger population assessment effort for C. canadensis in the United States, has revealed high levels of genetic diversity and allelic richness, moderate genetic differentiation, presence of genetic structure, and high gene flow between C. canadensis wild populations distributed within fragmented forest patches in eastern Tennessee and along the Georgia–Tennessee border
Summary
Habitat fragmentation involves discontinuities in the distribution of an organism due to geographical and/or geological barriers, and/or human activities (Kolb & Diekmann, 2005; Kwak, Velterop, & Andel, 1998). C. canadensis is well adapted to mesic, semiarid to sometimes in xeric environments This self-incompatible tree can grow as a shade-tolerant understory tree in closed forests (the mid- to deep southern United States), open woodlands, and forest borders (northern region of the species distribution) in full sunlight. Our hypothesis was that despite increased habitat fragmentation, wild populations of C. canadensis at local levels would have high genetic diversity with the presence of population structure and moderate-to-high gene flow To test this hypothesis, previously developed microsatellite loci (Wadl et al, 2012) were used to achieve the following objectives: (a) to evaluate the fine-scale genetic diversity present within C. canadensis populations occurring in eastern Tennessee and along the Georgia–Tennessee border and (b) to infer fine-scale patterns in the spatial distribution and gene flow of C. canadensis Tennessee and on the Georgia–Tennessee border
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
