Abstract Detail

Population Genetics/Genomics

Hosseinalizadehnobarinezhad, Mahboubeh [1], Wallace, Lisa [2].

Genetic variability among populations of Chamaecrista fasciculata (Fabaceae) occurs at small spatial scales in the Southeastern U.S.

Studies of population genetic structure enable understanding of how environmental factors influence gene flow and local adaptation. Widely distributed species are ideal systems for understanding local changes because they occupy diverse habitats and experience varied interspecific interactions that could lead to the evolution of adaptive variation. Chamaecrista fasciculata (Fabaceae) has a wide geographic range in the eastern U.S., extending from Minnesota to the Gulf Coast and from the east coast to New Mexico. Regional morphological and ecological variants are commonly recognized in this species, and past studies have shown that populations in the Southeast exhibit greater morphological variability than those in other areas. Some studies have identified local adaptation among widely spaced populations, but few studies have surveyed southernmost populations. To gain a better understanding of intraspecific variation across geographic space for this species, we collected data at 14 microsatellite loci from samples in twenty six populations in the Southeast. We hypothesized that populations would be genetically structured, following an isolation by distance pattern. Genetic diversity was high across populations (mean percent polymorphic loci = 95%; Ho = 0.495; He = 0.526). Analysis of molecular variance indicated that variation is partitioned within individuals (62%), among individuals within populations (25%) and among populations (13%). Additionally, a significant correlation between genetic and geographic distance was found in a Mantel test (R = 0.29, p = 0.00232). A Mantel correlogram revealed significant  correlations at the shortest distance classes (0-70 Km), non-significant correlations at intermediate distance classes (70 to 150 Km), and negative significant correlation at largest distance clasess (150-260 Km). Latitude, but not longitude, was found to be a significant factor in explaining the observed pattern of population differentiation, which suggests long distance gene flow along a latitudinal gradient. These results suggest considerable genetic structure among populations of C. fasciculata and potential for local adaptation in a relatively small geographic area.

1 - Mississippi State University , Biological Sciences, MS, 39762, USA
2 - Old Dominion University, Biological Sciences, Mills Godwin Building Rm. 110, Norfolk, VA, 23529, United States

genetic structure
gene flow
Genetic diversity
local adaptation
Chamaecrista fasciculata .

Presentation Type: Oral Paper
Number: 0001
Abstract ID:262
Candidate for Awards:Margaret Menzel Award

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