Abstract Detail

Population Genetics/Genomics

Wyatt, Graham [1], Trapnell, Dorset [2].

Phylogeography and range-wide patterns of genetic variation in Asimina triloba (Annonaceae).

Among the most important ecological processes for evolutionary persistence of species are dispersal and colonization, which enable species to undergo range modifications in response to changing environmental conditions. Understanding historical patterns of plant dispersal and range expansion during the warming climate that ensued after the last glacial maximum (~20,000 years before present) provides insight into species’ capacity to modify their ranges. Some tree species with apparently limited seed dispersal migrated remarkably long distances after glacial retreat in the late Pleistocene, a phenomenon known as Reid’s Paradox. We employed genetic markers and analytical approaches to explore this phenomenon in a North American tree species with large edible fruits. Asimina triloba (pawpaw) occurs in 26 states extending from the eastern U.S. westward to Nebraska and Texas, and spanning a latitudinal gradient from Florida to the Great Lakes region and southern Ontario, well north of the southern limit of the Laurentide Ice Sheet. We sampled 82 populations covering an east-west distance of 1,643 km and a north-south distance of 1,320 km. DNA was extracted from leaf samples and characterized with nine microsatellite loci. Sampled populations that were within 1 km of known pre-Columbian population centers were designated “anthropogenic” while others were designated as “wild.” Global Fst = 0.369 among all populations. The effective number of alleles per population decreased significantly with increasing latitude, consistent with post-glacial range expansion northward, but observed heterozygosity remained consistent across the same latitudinal gradient. Anthropogenic populations were characterized by significantly fewer total and effective numbers of alleles than wild populations. Private alleles were observed in 25 populations, although none occurred in populations at latitudes beyond 40° N. Clonal richness, diversity, and evenness decreased at higher latitudes. Principal components and structure analyses reveal genetically distinct clusters of populations on either side of the Appalachian Mountains, which may explain the absence of significant isolation by distance.  Ecological niche modeling indicates that there were likely two Pleistocene (~22,000 years before present) refugia: one on the Gulf of Mexico and the other on the southeastern Atlantic Coast which is consistent with present-day genetic data for A. triloba populations.

1 - University of Georgia, Department of Plant Biology, Miller Plant Sciences Building, Athens, GA, 30602, USA
2 - University of Georgia, Plant Biology, 2502 Miller Plant Sciences, Athens, GA, 30602

population genetics
Asimina triloba.

Presentation Type: Poster This poster will be presented at 5:30 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PPG013
Abstract ID:754
Candidate for Awards:Genetics Section Poster Award

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