These authors led this study and supervised AK.
THE ROLE OF CLIMATIC TOLERANCES AND SEED TRAITS IN REDUCED EXTINCTION RATES OF TEMPERATE POLYGONACEAE
Version of Record online: 16 APR 2014
© 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.
Volume 68, Issue 7, pages 1856–1870, July 2014
How to Cite
Kostikova, A., Salamin, N. and Pearman, P. B. (2014), THE ROLE OF CLIMATIC TOLERANCES AND SEED TRAITS IN REDUCED EXTINCTION RATES OF TEMPERATE POLYGONACEAE. Evolution, 68: 1856–1870. doi: 10.1111/evo.12400
- Issue online: 1 JUL 2014
- Version of Record online: 16 APR 2014
- Accepted manuscript online: 13 MAR 2014 03:45PM EST
- Manuscript Accepted: 25 FEB 2014
- Manuscript Received: 12 AUG 2013
- Swiss National Science Foundation. Grant Numbers: 3100A0–122433, 3100A0–138282
- climate tolerance;
- distribution model;
- latitudinal richness gradient;
- molecular rates;
The latitudinal diversity gradient (LDG) is one of the most striking and consistent biodiversity patterns across taxonomic groups. We investigate the species richness gradient in the buckwheat family, Polygonaceae, which exhibits a reverse LDG and is, thus, decoupled from dominant gradients of energy and environmental stability that increase toward the tropics and confound mechanistic interpretations. We test competing age and evolutionary diversification hypotheses, which may explain the diversification of this plant family over the past 70 million years. Our analyses show that the age hypothesis, which posits that clade richness is positively correlated with the ecological and evolutionary time since clade origin, fails to explain the richness gradient observed in Polygonaceae. However, an evolutionary diversification hypothesis is highly supported, with diversification rates being 3.5 times higher in temperate clades compared to tropical clades. We demonstrate that differences in rates of speciation, migration, and molecular evolution insufficiently explain the observed patterns of differential diversification rates. We suggest that reduced extinction rates in temperate clades may be associated with adaptive responses to selection, through which seed morphology and climatic tolerances potentially act to minimize risk in temporally variable environments. Further study is needed to understand causal pathways among these traits and factors correlated with latitude.