MOLECULAR PHYLOGENETIC STUDY OF DROSOPHILA

Throckmorton（1966,1975）在内部物种形态学和生物地理学的基础上，提出了亲果蝇科物种群之间的系统发育关系假说，该假说已被许多进化生物学家广泛接受。另一方面，Grimaldi（1990）最近通过对许多外部形态特征的钙化分析，提出了另一个与Throckmorton截然不同的假设。因此，我们通过乙醇脱氢酶（ADH）和线粒体ND2基因的核苷酸序列重新研究了果蝇科物种之间的进化关系。从这些序列得到的分子系统发育树与Grimaldi的假设有很大的不同。总的来说，我们的结果支持斯罗克莫顿的假设。然而，我们的树为理解果蝇的系统发育提供了一些新的知识，这些知识在Throckmorton和Grimaldi的假设中都没有指出。其中，关于夏威夷果蝇起源的信息非常有趣。夏威夷果蝇起源于移民的假说- Hirtodrosohila辐射（Throckmorton, 1975）已被许多果蝇学家广泛接受。然而，在这项研究中，这个群体被发现与从移民- Hirtodrosohila谱系中分化出来的virilis- repleta谱系的物种关系更密切。

On the basis of internal marphology and biogeography, Throckmorton (1966,1975) proposed a hypothesis for phylogenetic relationships between the species group of the family Droso-philidae, which has been widely accepted by many evolutionary biologists. On the other hand, using a caldistic analysis of many external morphological traits, Grimaldi (1990) recently put forward another hypothesis that was very different from Throckmorton's. We therefore re- examined phlogenetic relationships between the species of the family Drosophilidae by nucleotide sequences of the alcohol dehydrogenase (ADH) and the mitochondrial ND2 genes. The molecular phylogenetic trees obtained from these sequences were significantly different from Grimaldi's hypothesis. On the whole, our results supported the Throckmorton's hypothesis. However, our trees offered some new knowledege for understanding Drosophila phylogeny which have not been pointed out neither in Throckmorton's or Grimaldi's hypotheses. Among those, a information for the origin of Hawaiian drosophilids is very interesting. The hypothesis that Hawaiian drosophilids originated in the immigrans- Hirtodrosohila radiation (Throckmorton, 1975) has been widely accepted by many drosophilists. In this study, however, this group is found to be more closely related to the species of the virilis- repleta lineage that diverged from the immigrans- Hirtodrosohila lineage.