Systematics and Evolutionary Tempo and Mode in African Bovidae: Tribes Alcelaphini, Hippotragini, Reduncini

非洲羚羊有望成为大型哺乳动物中最全面的进化研究对象。在过去的2000万年里，羚羊所包含的现存和灭绝的物种比其他任何已知的大型哺乳动物都要多。它们的化石记录不仅在物种丰富度方面，而且在与之相关的年代估计和古环境数据方面都是例外的。Vrba和DeSalle通过研究现存物种的DNA分子，以及现存和灭绝物种的头骨特征，分析了具有丰富的现存和化石代表的三个主要羚羊类群的系统发育关系树。成对物种之间的DNA变化将与化石记录中同一谱系的绝对日期进行比较。这将允许1)估计谱系中分子变化的速率，2)估计通过谱系分支的新物种起源的绝对日期；3)这些演化事件的性质与同期古环境变化的性质比较。强大的复合数据集将测试关于进化如何发生的各种假设。其中一个假设是，物种的系统发育是否同步（如果广泛的气候变化提供了启动许多谱系进化变化的共同驱动力，就可以预测），还是随时间的随机分布。人类家族，人科，在同一时期和非洲地区进化。事实上，到目前为止，与早期人类遗骸一起发现的最丰富的大型哺乳动物化石正是正在研究的羚羊群。因此，原始人进化反应的性质和时间将与共同进化的大型哺乳动物谱系进行比较。理解人类进化的丰富的物理和生物背景是理解人类起源的必要条件。

The African antelopes promise the most comprehensive evolutionary studies in large mammals. Antelopes include more living and extinct species than does any other large mammal group known over the past 20 million years. Their fossil record is exceptional not only in terms of species-richness, but also in the wealth of dating estimates and paleoenvironmental data associated with it. Vrba and DeSalle are analyzing the phylogenetic relationship trees of three major antelope groups with abundant living and fossil representatives, by studying DNA molecules of living species, and skull characters of living and extinct species. DNA changes between pairs of species will be compared with absolute dates for the same lineages in the fossil record. This will allow 1) estimates of rates of molecular change in lineages and 2) estimates of absolute dates of the origins of new species by lineage-branching; and 3) comparison of nature of these evolutionary events with the nature of coincident paleoenvironmental changes. The powerful compound data set will test various, hypotheses of how evolution occurs. One such hypothesis whether there is synchronization across phylogenies of speciations (predicted if wide-spread climatic changes provide the common driving force that initiates evolutionary changes in many lineages) versus random distribution against time. The Family of humans, Hominidae, evolved over the same time period and African areas. In fact, by far the most abundant large mammal fossils found together with early hominid remains are the very antelope groups under study. Thus, the nature and timing of evolutionary responses in hominids will be compared with those of the co-evolving large mammal lineages. A comprehension of the rich physical and biological context of human evolution is necessary for understanding human origins.