Evaluating range genetics in black cherry (Prunus serotina) and the genetic status of an enigmatic relative, Alabama cherry (Prunus alabamensis)

Abstract

Premise of the study: Isolation by distance (IBD) is a genetic pattern in which populations geographically closer to one another are more genetically similar to each other than populations which are further apart. Black cherry (Prunus serotina Ehrh.) (Rosaceae) is a forest tree species widespread in eastern North America, and found sporadically in the southwestern United States, Mexico, and Guatemala. This tree is both commercially important as timber for furniture and ecologically important as a source of nutrition for local wildlife. IBD has been studied in relatively few North American plant taxa, and no study has rigorously sampled across the range of such a widespread species. In this research we evaluated IBD and overall genetic structure in eastern black cherry (Prunus serotina Ehrh. subsp. serotina), the widespread black cherry subspecies of eastern North America. Methods: Dense sampling across the eastern black cherry range was made possible by genotyping 15 microsatellite loci in 439 herbarium samples from all portions of the range. Mantel tests and STRUCTURE analyses were performed to evaluate the hypothesis of IBD and overall genetic structure. Key results: Mantel tests demonstrated no isolation by distance at any distance class, and STRUCTURE analyses revealed no clear geographic pattern of genetic groups. 2 Conclusions: The lack of detectable large-scale genetic structure across the range of eastern black cherry suggests widespread gene flow in this taxon. This is consistent with P. serotina's status as a disturbance-associated species, and for comparison further studies should include species characteristic of low-disturbance forests.