Recent Topics Posters
Gruhn, Jennifer A. , Jimenez, Ivan , Hiser, Kenneth M. , Wen, Jun , Ricklefs, Robert E. .
Time of Separation and Cold Tolerance ofAsian-American Disjunct Plants.
Wolfe’s 1975 “boreotropical flora” hypothesis suggests that the uppermost part of the Northern Hemisphere was characterized by a tropical environment in the early Tertiary, with land bridges interconnecting Asia, Europe, and North America. It further posits that, as Earth’s climate cooled in the middle to late Tertiary, less cold-tolerant taxa either became extinct or moved south, “tracking” warmer conditions. The existence of a boreotropical flora is consistent with fossil and molecular phylogenetic data across several plant taxa. Here we test a prediction that follows from Wolfe’s hypothesis: if cold tolerance of Asian-American disjunct taxa have been conserved over time (as suggested by previous work), and cooling temperatures caused disjunction events, then cold tolerance should be related to disjunction time across Asian-American disjunct taxa. We used GBIF data to define the native geographic ranges of 110 species belonging to 56 Asian-American disjunct monophyletic groups and Worldclim data to estimate the minimum temperature of the coldest month, a proxy for cold tolerance, within those ranges. Disjunction dates, compiled from the literature, ranged from 1 to 89 Ma and values for cold tolerance from -24.0 to 16.4Â°C. As predicted, we found a positive relationship, (slope=0.79 Ma/C Â± 95% C.I. = 0.6, p-value=0.013, r2=0.11, n=56),between disjunction time and cold tolerance across Asian-American disjunct groups, with earlier disjunction times corresponding to plant groups that are presently less cold tolerant. These findings further our understanding of how niche conservatism, habitat tracking, and global climate shape current biogeographic patterns.
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1 - Washington University in St. Louis, Department of Evolution, Ecology, and Population Biology, 1 Brookings Drive, Campus Box 1137, St. Louis, MO, 63130, USA
2 - Missouri Botanical Garden, Center for Conservation and Sustainable Development, P.O. Box 299, St. Louis, MO, 63166, USA
3 - National Park Service, Yellowstone National Park, P.O. Box 168, Yellowstone National Park, WY, 82190, USA
4 - Smithsonian Institution, Botany, MRC-166 National Museum Of Natural History, 10th St. & Constitution Ave., NW, MRC 166, Washington/DC, N/A, 20013-7012, USA
5 - University of Missouri - St. Louis, Department of Biology, 8001 Natural Bridge Road, St. Louis, MO, 63121, USA
Asian-American disjunct taxa
global climate change
Presentation Type: Recent Topics Poster
Location: Khorassan Ballroom/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 5:30 PM