Abstract Detail

Population Genetics/Genomics

Van Natto, Alyson [1], Eckert, Chris [1].

Mating system and hybridization combine to effect range-wide genetic structure in a coastal endemic plant.

The genetic structure of natural plant populations are the result of evolutionary factors acting through space and time, but decomposing the contributions to genetic variation remains challenging. In this study, we investigated the effects of peripherality, mating system and hybridization on the range-wide genetic structure of Abronia umbellata, a pink-flowered Pacific coastal dune endemic. The species ranges from San Quintín, Baja California to Coos Bay, Oregon and occurs as disjunct populations in Washington and on Vancouver Island in Canada. The species exhibits striking mating system differentiation across the range with obligately outcrossing populations south of San Francisco and highly selfing populations to the north. Abronia umbellata co-occurs with two congeners, and putatively hybridizes with the yellow-flowered A. latifolia and magenta-flowered A. maritima. We predicted that because of genetic drift and inbreeding, peripherality and selfing would decrease genetic variation within A. umbellata populations, and that gene flow from hybridization and introgression would increase genetic variation. Genetic analyses of sequence variation at nine single-copy genes revealed mixed results. As expected, northern disjunct populations and selfing populations had low genetic variation and populations with evidence of introgression showed signs of slightly greater genetic variation. Unexpectedly, we found that selfing populations were genetically differentiated from outcrossing populations but not from one another, which might be attributed to the relatively young evolutionary age of the selfing populations. Most surprising was that the southern edge population had the highest genetic variation of all populations and was genetically unique. However, analyses revealed that although the southern edge population contained no congeners, there was possible hybridization with A. maritima in the past. Finally, evidence of hybridization was found in every population where outcrossing A. umbellata co-occurred with a congener, but hybridization does not substantially influence genetic structure among A. umbellata populations, because deep introgression appears uncommon. Overall, our results provide insight into how multiple factors can influence a species’ range-wide genetic structure.

1 - Queen's University, Biology, 116 Barrie St, Kingston, ON, K7L 3N6, Canada

population genetics
Genetic variation
Genetic differentiation
Mating system

Presentation Type: Oral Paper
Number: PGG1001
Abstract ID:819
Candidate for Awards:None

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