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Abstract Detail


Simpson, Andrew G. [1], Axsmith, Brian J. [2].

Forest to desert or forest to forest: how the character of climate change affects lineage survivorship in the context of dispersal adaptations.

Increasingly, scientists are linking ecology and evolutionary biology by finding evidence for macroecological explanations of patterns of evolutionary diversification and extinction, with particular attention given to geographic range size and related factors. Multiple studies now link ecological traits, such as seed dispersal, to macroevolutionary trends mediated by macroecological factors. However, while patterns of diversification and extinction must necessarily affect ecological parameters such as community composition, relatively little work has been done investigating the character and tempo of these ecological changes.
We here compare the rates of survival and range collapse in floras in the United States from the Miocene through the Pliocene. Climatic changes endured by floras of eastern North America have been different in character from those endured by western North American floras; while climate in the east has become cooler from the Miocene to the present overall, eastern North America remains a wet temperate forest while most of western North America has transitioned to steppe or desert during the same interval. As a result, we predicted that floristic change in the east should be dominated by dispersal-mediated metapopulation dynamics with animal-mediated dispersal being useful in resisting extinction due to climate change. Western floristic change would instead be driven by broad climatic tolerance and not by dispersal.
Preliminary data suggest the opposite, however. There appears to be a relationship between animal dispersal and lineage survivorship in eastern North American floras (Alum Bluff, Brandon, Brandywine, Citronelle), but is not statistically significant. By contrast, a partial taxon list from the Clarkia flora of eastern Idaho alone implies that there is a statistically significant association between animal dispersal and survivorship. If these results bear out with the inclusion of additional data from Clarkia as well as other western North American floras (including the Latah, Purple Mountain, and Stewart Valley floras), then we suggest that the abundance of refugia in eastern North America relaxed the need for effective long-distance dispersal, while more severe secular climate change in the west resulted in fewer refugia located farther part, with animal dispersal thus being more valuable in enabling colonization and, ultimately, survivorship.

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1 - National Museum of Natural History, Paleobiology, Washington, DC, USA
2 - University of South Alabama, Biology, 5871 USA Drive North, Rm 124, Mobile, AL, 36688, USA

none specified

Presentation Type: Oral Paper
Session: 25, Cretaceous/Cenozoic/collections paleobotany
Location: Sundance 3/Omni Hotel
Date: Tuesday, June 27th, 2017
Time: 11:30 AM
Number: 25006
Abstract ID:199
Candidate for Awards:None

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