Barrio E, Ayala F J
Department of Ecology and Evolutionary Biology, University of California, Irvine 92717, USA.
Mol Phylogenet Evol. 1997 Feb;7(1):79-93. doi: 10.1006/mpev.1996.0375.
The Drosophila obscura group consists of several dozen Nearctic and Palearctic species, with a phylogeny that remains largely unresolved in spite of numerous morphological, cytogenetic, and molecular investigations. We have partially sequenced two genes, Gpdh (about 1000 bp) and Sod (about 700 bp) in 12-13 species and 1 subspecies in order to settle the issues. Difficulties in resolving the phylogeny emanate from the rapid sequence of successive radiations. Nevertheless, the following conclusions are warranted: (1) The Palearctic species include two monophyletic subgroups, subobscura (which may be the most ancient clade of the whole group) and obscura, plus two other species with unresolved phylogenetic positions, D. bifasciata and D. subsilvestris; (2) the Nearctic species form a monophyletic group consisting of two monophyletic sister clades, the affinis subgroup and the pseudoobscura subgroup. The Palearctic radiation may have resulted from adaptation to expanding temperate forests in the Old World. A second radiation occurred during the colonization of the deciduous forests of the New World by the descendants of a single lineage that soon split into the affinis and pseudoobscura subgroups.
果蝇隐种组由几十种新北区和古北区物种组成，尽管进行了大量形态学、细胞遗传学和分子研究，但其系统发育关系在很大程度上仍未得到解决。为了解决这些问题，我们对12 - 13个物种和1个亚种的两个基因Gpdh（约1000 bp）和Sod（约700 bp）进行了部分测序。解决系统发育问题的困难源于连续辐射的快速序列。然而，以下结论是合理的：（1）古北区物种包括两个单系亚组，即亚暗果蝇亚组（可能是整个组中最古老的分支）和暗果蝇亚组，另外还有两个系统发育位置未解决的物种，即双带果蝇和亚林果蝇；（2）新北区物种形成一个单系群，由两个单系姐妹分支组成，即近缘亚组和拟暗果蝇亚组。古北区的辐射可能是由于对旧世界不断扩张的温带森林的适应。第二次辐射发生在一个单一谱系的后代对新世界落叶林的殖民过程中，该谱系很快分裂为近缘亚组和拟暗果蝇亚组。
