Abstract Detail



Ecological factors that drive patterns of population genetic structure in plants

Trapnell, Dorset [1], Wyatt, Graham [2], Hamrick, James [3], Schmidt, John Paul [4].

Refugia – it’s not always what you think.

Genetic variation is often partitioned among plant populations distributed across a landscape, resulting in patterns of genetic structure in neutral markers.  Genetic divergence of conspecific populations is one signature of microevolutionary processes that, given enough time, can ultimately lead to macroevolutionary events and increases in biological diversification.  The degree of genetic structure and the pace at which it develops are closely linked with life history traits such as growth form, pollination syndromes, and seed dispersal mechanisms.  However, other factors such as changing climatic conditions can leave long-lasting signatures within plant populations.  Here we present studies illustrating contrasting effects of climate change since the last glacial maximum (LGM) on two North American woody plants.  Asimina triloba (Annonaceae), whose common name is Pawpaw, is a widespread North American understory tree species that occurs in 26 states in the eastern U.S.  Ceratiola ericoides (Empetraceae), whose common name is Sandhill Rosemary, is a narrowly distributed long-lived evergreen shrub found only in three states in the southeastern U.S.  Like many plant species that retreated to southern refugia during the colder, drier LGM and then underwent extensive range expansion subsequent to glacial retreat, A. triloba genetic data and ecological niche modelling suggest that the species persisted in two or three refugia.  Descendants of a western refugium now occupy the Mississippi, Ohio and Missouri watersheds while descendants of the eastern refugium have expanded along the eastern seaboard from Georgia to New York.  As an interesting contrast, the genetic signatures of Ceratiola ericoides populations suggest that this species was in fact more widespread and probably had a continuous distribution during the LGM but is presently contracted into two to three refugia until its preferred cooler, drier climate returns.  Given enough time, populations in different refugia become more genetically divergent as they experience independent evolutionary trajectories.  The signatures of these processes often persist subsequent to the return of more favorable climatic conditions and as the species expands its range beyond glacial refugia.


1 -
2 - University of Georgia, 2502 Miller Plant Sciences Bldg, Athens, Georgia, 30602, United States
3 - University Of Georgia, Department Of Plant Biology, Miller Plant Sciences Building, Athens, GA, 30602, United States
4 - University of Georgia, Odum School of Ecolgoy, Athens, Georgia, 30602, United States

Keywords:
Asimina triloba
Ceratiola ericoides
genetic structure
last glacial maximum
population genetics
phylogeography
refugia.

Presentation Type: Colloquium Presentations
Number: 0012
Abstract ID:197
Candidate for Awards:None


Copyright © 2000-2019, Botanical Society of America. All rights reserved