Avise J C, Walker D, Johns G C
Department of Genetics, University of Georgia, Athens 30602-7223, USA.
Proc Biol Sci. 1998 Sep 22;265(1407):1707-12. doi: 10.1098/rspb.1998.0492.
An approach applied previously to avian biotas is extended in this paper to other vertebrate classes to evaluate Pleistocene phylogeographic effects and to estimate temporal spans of the speciation process (speciation durations) from mitochondrial (mt) DNA data on extant taxa. Provisional molecular clocks are used to date population separations and to bracket estimates of speciation durations between minimum and maximum values inferred from genetic distances between, respectively, extant pairs of intraspecific phylogroups and sister species. Comparisons of genetic-distance trends across the vertebrate classes reveal the following: (i) speciation durations normally entail at least two million years on average; (ii) for mammals and birds, Pleistocene conditions played an important role in initiating phylogeographic differentiation among now-extant conspecific populations as well as in further sculpting pre-existing phylogeographic variety into many of today's sister species; and (iii) for herpetofauna and fishes, inferred Pleistocene biogeographic influences on present-day taxa differ depending on alternative but currently plausible mtDNA rate calibrations.
本文将先前应用于鸟类生物群的一种方法扩展到其他脊椎动物类群，以评估更新世系统发育地理学效应，并根据现存分类群的线粒体（mt）DNA数据估计物种形成过程的时间跨度（物种形成持续时间）。临时分子钟用于确定种群分离的时间，并确定从现存种内系统发育群对和姊妹物种之间的遗传距离推断出的物种形成持续时间估计值的最小值和最大值范围。对各脊椎动物类群遗传距离趋势的比较揭示了以下几点：（i）物种形成持续时间平均通常至少需要200万年；（ii）对于哺乳动物和鸟类，更新世条件在引发现存同种种群之间的系统发育地理分化以及将先前存在的系统发育地理多样性进一步塑造为当今许多姊妹物种方面发挥了重要作用；（iii）对于两栖爬行动物和鱼类，根据目前合理的替代线粒体DNA速率校准，推断出的更新世生物地理学对当今分类群的影响有所不同。
