期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1995
卷号：92
期号：13
页码：5832-5835
DOI：10.1073/pnas.92.13.5832
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Pleistocene glaciations have been suggested as major events influencing speciation rates in vertebrates. Avian paleontological studies suggest that most extant species evolved in the Pleistocene Epoch and that species' durations decreased through the Pleistocene because of heightened speciation rates. Molecular systematic studies provide another data base for testing these predictions. In particular, rates of diversification can be determined from molecular phylogenetic trees. For example, an increasing rate of speciation (but constant extinction) requires shorter intervals between successive speciation events on a phylogenetic tree. Examination of the cumulative distribution of reconstructed speciation events in mtDNA phylogenies of 11 avian genera, however, reveals longer intervals between successive speciation events as the present time is approached, suggesting a decrease in net diversification rate through the Pleistocene Epoch. Thus, molecular systematic studies do not indicate a pulse of Pleistocene diversification in passerine birds but suggest, instead, that diversification rates were lower in the Pleistocene than for the preceding period. Documented habitat shifts likely led to the decreased rate of diversification, although from molecular evidence we cannot discern whether speciation rates decreased or extinction rates increased.
