Diversification ofCeanothus(Rhamnaceae) in the California Floristic Province
High diversity and endemism in the California Floristic Province (CFP) are an alleged response to the late Cenozoic advent of Mediterranean-type climate in this region.Ceanothuscomprises two divergent subgenera with centers of diversity in the CFP. We reconstruct the evolution ofCeanothusby using DN...
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Veröffentlicht in: | International journal of plant sciences 2011-11, Vol.172 (9), p.1137-1164 |
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Sprache: | eng |
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Zusammenfassung: | High diversity and endemism in the California Floristic Province (CFP) are an alleged response to the late Cenozoic advent of Mediterranean-type climate in this region.Ceanothuscomprises two divergent subgenera with centers of diversity in the CFP. We reconstruct the evolution ofCeanothusby using DNA sequence data from the nuclear gene nitrate reductase. We find that the timing of diversification events is related to geological and climatic history. In both subgenera, diversification is characterized by recent divergence of extant taxa and geographically structured phylogenetic relationships. A strong north-south divergence of subgenusCerastesacross the Transverse Ranges indicates that phylogenetic relationships may be structured by climatically divergent regions of the CFP. Divergence-time estimation suggests that the age of extant diversification in both subgenera is ∼6 Ma. This agrees with the fossil record but predates the hypothesized Quaternary (2-Ma) origin of Mediterranean-type climate in the region. |
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ISSN: | 1058-5893 1537-5315 |
DOI: | 10.1086/662028 |