Kirsch J A, Pettigrew J D
University of Wisconsin Zoological Museum, Madison, Wisconsin 53706, USA.
Philos Trans R Soc Lond B Biol Sci. 1998 Mar 29;353(1367):381-8. doi: 10.1098/rstb.1998.0216.
We conducted a series of parallel DNA-hybridization experiments on a small group of bats (species of Pteropus, Rhinolophus, Noctilio and Pteronotus) and outgroups (Lemur, Cynocephalus, Didelphis), using whole-genome labels and tracers made from extracts enriched with AT and two levels of GC content. FITCH (additive phylogenetic trees) topologies were constructed from the four sets of comparisons, indexed as both delta Tmode and delta NPHs (normalized percentage of hybridization). Based on our previous work showing that the shared AT bias of pteropodids and some microchiropterans may affect the rank-ordering of taxa based on either AT- or GC-rich labels, our expectation was that the resulting trees would show differing topologies when generated from tracers made with the variously enriched DNA extracts. Whereas there was some variation among the trees, most of them grouped the bats together, and almost all paired the representative megachiropteran and rhinolophoid microchiropteran as sister-taxa in contrast to the other microchiropterans. As the pteropodid-rhinolophoid relationship is an unexpected and unlikely one, we attribute this association to an AT bias that was not obviated even by our most GC-rich labels, and suggest that such a bias may compromise the truth of some molecular trees. Accordingly, we believe the broader issue of bat monophyly remains unresolved by DNA-hybridization and probably also by gene-sequencing studies.
我们对一小群蝙蝠（狐蝠属、菊头蝠属、夜蛾属和无尾蹄蝠属的物种）以及外类群（狐猴、鼯猴、负鼠）进行了一系列平行DNA杂交实验，使用了由富含AT和两种GC含量水平的提取物制成的全基因组标签和示踪剂。基于四组比较构建了FITCH（加法系统发育树）拓扑结构，以δTmode和δNPHs（杂交标准化百分比）进行索引。根据我们之前的研究表明，狐蝠科和一些小蝙蝠亚目的共同AT偏差可能会影响基于富含AT或GC的标签对分类单元的排序，我们预期当用不同富集程度的DNA提取物制成的示踪剂生成树时，得到的树会显示出不同的拓扑结构。虽然树之间存在一些差异，但大多数将蝙蝠归为一类，并且几乎所有的树都将代表性的大蝙蝠和菊头蝠类小蝙蝠配对为姐妹分类单元，与其他小蝙蝠不同。由于狐蝠科 - 菊头蝠类的关系是意想不到且不太可能的，我们将这种关联归因于即使是我们最富含GC的标签也无法消除的AT偏差，并表明这种偏差可能会损害一些分子树的真实性。因此，我们认为蝙蝠单系性这个更广泛的问题仍未通过DNA杂交解决，可能基因测序研究也无法解决。
