Abstract Detail



Population Genetics/Genomics

Naranjo, Andre [1], Payton, Adam [2], SOLTIS, PAMELA S. [3], Soltis, Douglas [4], Gitzendanner, Matt [5], Judd, Walter [6].

Population Genetics, Speciation and Hybridization in Annual Dicerandra (Lamiaceae), a Southeastern North American Endemic.

Understanding patterns of speciation and subsequent gene flow clarifies the evolutionary origins and history of species endemic to the southeastern coastal plain of the U.S. We therefore used Dicerandra as a model to explore these concepts because of its endemism and threatened status. Using microsatellite-based population level analyses of 42 populations from four of the annual species (D. linearifolia var. linearifoliaD. linearifolia var. robustiorD. fumellaD. odoratissima, and D. radfordiana) and ecological niche models built using locality data from FLAS herbarium and iDigBio, we were able to address the questions of population structure, gene flow, and hybridization. Strong support was found for the species-level recognition of the recently described D. fumella from the Florida panhandle. Dicerandra linearifolia var. linearifolia showed some regional cohesion of populations, but there was no consistent geographic pattern to the clustering of populations. Dicerandra radfordiana showed consistent clustering in analyses with proximate populations of D. odoratissima. Given that D. radfordiana is found at the southeastern extreme of the range of D. odoratissima these populations may represent the beginning of speciation by isolation. While there are morphological and bioclimatic niche distinctions between D. odoratissima and D. radfordiana, there is no molecular support for a distinct D. radfordiana entity. As a result, the taxonomic circumscription of D. radfordiana at the species rank is in question. Overall, there is significant genetic diversity found at the population level for all Dicerandra annuals. The isolated nature of many populations of Dicerandra, limited dispersal capability, and frequent visitation from generalist pollinators produce conditions where drift can cause significant differentiation between populations within the same geographic area. Obligate outcrossing and the potential for multi-generational populations resulting from recruitment from the seed bank are likely stabilizing factors maintaining heterozygosity within populations. Additionally, predicted niche occupancy profiles built from niche models show abiotic niche differentiation between members of the clade. We expect to see results similar to these in other obligate outcrossing taxa native to this imperiled ecosystem.


1 - University of Florida, Biology, 220 Bartram Hall P.O. Box 118525, Gainesville, FL, 32611, USA
2 - 427 SW 5th Street, Gainesville, FL, 32601, United States
3 - University Of Florida, Florida Museum Of Natural History, Po Box 117800, Gainesville, FL, 32611, United States
4 - University of Florida, Biology, Gainesville, FL
5 - University Of Florida, Florida Museum Of Natural History, Po Box 117800, Gainsville, FL, 32611, United States
6 - University Of Florida, Department Of Biology, 220 Bartram Hall, PO Box 118525, Gainesville, FL, 32611, United States

Keywords:
endemicity
gene flow
Mints
sand scrub
genetic structure
Niche Modeling.

Presentation Type: Oral Paper
Number: 0002
Abstract ID:160
Candidate for Awards:None


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