Skupski M P, Jackson D A, Natvig D O
Department of Biology, University of New Mexico, Albuquerque 87131, USA.
Fungal Genet Biol. 1997 Feb;21(1):153-62.
We examined the phylogenetic relationships among five heterothallic species of Neurospora using restriction fragment polymorphisms derived from cosmid probes and sequence data from the upstream regions of two genes, al-1 and frq. Distance, maximum likelihood, and parsimony trees derived from the data support the hypothesis that strains assigned to N. sitophila, N. discreta, and N. tetrasperma form respective monophyletic groups. Strains assigned to N. intermedia and N. crassa, however, did not form two respective monophyletic groups, consistent with a previous suggestion based on analysis of mitochondrial DNAs that N. crassa and N. intermedia may be incompletely resolved sister taxa. Trees derived from restriction fragments and the al-1 sequence position N. tetrasperma as the sister species of N. sitophila. None of the trees produced by our data supported a previous analysis of sequences in the region of the mating type idiomorph that grouped N. crassa and N. sitophila as sister taxa, as well as N. intermedia and N. tetrasperma as sister taxa. Moreover, sequences from al-1, frq, and the mating-type region produced different trees when analyzed separately. The lack of consensus obtained with different sequences could result from the sorting of ancestral polymorphism during speciation or gene flow across species boundaries, or both.
我们利用来自黏粒探针的限制性片段多态性以及两个基因（al-1和frq）上游区域的序列数据，研究了五种异宗配合的脉孢菌属物种之间的系统发育关系。从数据推导得到的距离树、最大似然树和简约树支持以下假说：被归类为嗜坐脉孢菌、离散脉孢菌和四孢脉孢菌的菌株分别形成单系类群。然而，被归类为间型脉孢菌和粗糙脉孢菌的菌株并未分别形成两个单系类群，这与之前基于线粒体DNA分析提出的观点一致，即粗糙脉孢菌和间型脉孢菌可能是尚未完全分化的姐妹分类单元。从限制性片段和al-1序列推导得到的树将四孢脉孢菌定位为嗜坐脉孢菌的姐妹物种。我们的数据所生成的树均不支持之前对交配型特异区域序列的分析结果，该分析将粗糙脉孢菌和嗜坐脉孢菌归为姐妹分类单元，同时也将间型脉孢菌和四孢脉孢菌归为姐妹分类单元。此外，对al-1、frq和交配型区域的序列进行单独分析时，会产生不同的树。不同序列之间缺乏一致性可能是由于物种形成过程中祖先多态性的分选，或物种边界间的基因流动，或两者兼而有之。
