Avise J C, Shapira J F, Daniel S W, Aquadro C F, Lansman R A
Department of Molecular and Population Genetics, University of Georgia, Athens 30602.
Mol Biol Evol. 1983 Dec;1(1):38-56. doi: 10.1093/oxfordjournals.molbev.a040301.
We address the problem of the possible significance of biological speciation to the magnitude and pattern of divergence of asexually transmitted characters in bisexual species. The empirical data for this report consist of restriction endonuclease site variability in maternally transmitted mitochondrial DNA (mtDNA) isolated from 82 samples of Peromyscus polionotus and P. leucopus collected from major portions of the respective species' ranges. Data are analyzed together with previously published information on P. maniculatus, a sibling species to polionotus. Maps of restriction sites indicate that all of the variation observed can be reasonably attributed to base substitutions leading to loss or gain of particular recognition sites. Magnitude of mtDNA sequence divergence within polionotus (maximum approximately equal to 2%) is roughly comparable to that observed within any of five previously identified mtDNA assemblages in maniculatus. Sequence divergence within leucopus (maximum approximately equal to 4%) is somewhat greater than that within polionotus. Consideration of probable evolutionary links among mtDNA restriction site maps allowed estimation of matriarchal phylogenies within polionotus and leucopus. Clustering algorithms and qualitative Wagner procedures were used to generate phenograms and parsimony networks, respectively, for the between-species comparisons. Three simple graphical models are presented to illustrate some conceivable relationships of mtDNA differentiation to speciation. In theoretical case I, each of two reproductively defined species (A and B) is monophyletic in matriarchal genealogy; the common female ancestor of either species can either predate or postdate the speciation. In case II, neither species is monophyletic in matriarchal genotype. In case III, species B is monophyletic but forms a subclade within A which is thus paraphyletic with respect to B. The empirical results for mtDNA in maniculatus and polionotus appear to conform closely to case III. These theoretical and empirical considerations raise a number of questions about the general relationship of the speciation process to the evolution of uniparentally transmitted traits. Some of these considerations are presented, and it is suggested that the distribution patterns of mtDNA sequence variation within and among extant species should be of considerable relevance to the particular demographies of speciation.
我们探讨了生物物种形成对于双性物种中性传播性状分化程度及模式的潜在重要性这一问题。本报告的实证数据包括从分别采集自白足鹿鼠（Peromyscus polionotus）和白足鼠（P. leucopus）各自分布范围主要区域的82个样本中分离出的母系遗传线粒体DNA（mtDNA）的限制性内切酶位点变异性。这些数据与之前发表的关于鹿鼠（P. maniculatus）（白足鹿鼠的近缘物种）的信息一同进行分析。限制性位点图谱表明，观察到的所有变异都可合理归因于碱基替换导致特定识别位点的丢失或获得。白足鹿鼠内mtDNA序列分化程度（最大值约为2%）大致与之前在鹿鼠中鉴定出的五个mtDNA组合中的任何一个内观察到的程度相当。白足鼠内的序列分化程度（最大值约为4%）比白足鹿鼠内的略大。考虑mtDNA限制性位点图谱之间可能的进化联系，从而估计了白足鹿鼠和白足鼠内的母系系统发育。聚类算法和定性的瓦格纳程序分别用于生成种间比较的聚类图和简约网络。提出了三个简单的图形模型来说明mtDNA分化与物种形成的一些可想象的关系。在理论情况I中，两个由生殖定义的物种（A和B）在母系谱系中都是单系的；任一物种的共同雌性祖先可以早于或晚于物种形成。在情况II中，两个物种在母系基因型中都不是单系的。在情况III中，物种B是单系的，但在A内形成一个亚分支，因此A相对于B是并系的。鹿鼠和白足鹿鼠中mtDNA的实证结果似乎与情况III非常相符。这些理论和实证考量引发了一些关于物种形成过程与单亲遗传性状进化的一般关系的问题。呈现了其中一些考量，并表明现存物种内部和之间mtDNA序列变异的分布模式应该与物种形成的特定种群统计学有相当大的相关性。
