Arellano Elizabeth, González-Cozátl Francisco X, Rogers Duke S
Centro de Educación Ambiental e Investigación Sierra de Huautla, Universidad Autónoma del Estado de Morelos, Avenida Universidad 1001, Champila, Cuernavaca, Morelos, C.P. 62210, Mexico.
Mol Phylogenet Evol. 2005 Nov;37(2):529-40. doi: 10.1016/j.ympev.2005.07.021. Epub 2005 Sep 26.
We estimated phylogenetic relationships among 16 species of harvest mice using sequences from the mitochondrial cytochrome b (cyt b) gene. Gene phylogenies constructed using maximum parsimony (MP), maximum likelihood (ML) and Bayesian inference (BI) optimality criteria were largely congruent and arranged taxa into two groups corresponding to the two recognized subgenera (Aporodon and Reithrodontomys). All analyses also recovered R. mexicanus and R. microdon as polyphyletic, although greater resolution was obtained using ML and BI approaches. Within R. mexicanus, three clades were identified with high nodal support (MP and ML bootstrap, Bremer decay and Bayesian posterior probabilities). One represented a subspecies of R. mexicanus from Costa Rica (R. m. cherrii) and a second was distributed in the Sierra Madre Oriental of Mexico. The third R. mexicanus clade consisted of mice from southern Mexico southward to South America. Polyphyly between the two moieties of R. microdon corresponded to the Isthmus of Tehuantepec in southern Mexico. Populations of R. microdon microdon to the east of the isthmus (Chiapas, Mexico) grouped with R. tenuirostris, whereas samples of R. m. albilabris to the west in Oaxaca, Mexico, formed a clade with R. bakeri. Within the subgenus Reithrodontomys, all analyses recovered R. montanus and R. raviventris as sister taxa, a finding consistent with earlier studies based on allozymes and cyt b data. There was also strong support (ML and BI criteria) for a clade consisting of ((R. megalotis, R. zacatecae) (R. sumichrasti)). In addition, cytb gene phylogenies (MP, ML, and BI) recovered R. fulvescens and R. hirsutus (ML and BI) as basal taxa within the subgenus Reithrodontomys. Constraint analyses demonstrated that tree topologies treating the two subgenera (Aporodon and Reithrodontomys) as monophyletic (ML criterion) was significantly better (p>0.036) and supported polyphyly of R. mexicanus (both ML and MP criteria - p>0.013) and R. microdon (MP criterion only for certain topologies; p>0.02). Although several species-level taxa were identified based on multiple, independent data sets, we recommended a conservative approach which will involve thorough analyses of museum specimens including material from type localities together with additional sampling and data from multiple, nuclear gene markers.
我们利用线粒体细胞色素b（cyt b）基因的序列，估计了16种收获鼠之间的系统发育关系。使用最大简约法（MP）、最大似然法（ML）和贝叶斯推断（BI）最优标准构建的基因系统发育树在很大程度上是一致的，并将分类单元分为两组，对应于两个公认的亚属（Aporodon和Reithrodontomys）。所有分析还发现墨西哥收获鼠（R. mexicanus）和小齿收获鼠（R. microdon）是多系的，不过使用ML和BI方法获得了更高的分辨率。在墨西哥收获鼠中，鉴定出了三个具有高节点支持度的分支（MP和ML自展值、布勒默衰减值以及贝叶斯后验概率）。一个分支代表来自哥斯达黎加的墨西哥收获鼠亚种（R. m. cherrii），另一个分布在墨西哥东马德雷山脉。第三个墨西哥收获鼠分支由来自墨西哥南部向南至南美洲的小鼠组成。小齿收获鼠两个部分之间的多系性对应于墨西哥南部的特万特佩克地峡。地峡以东的小齿收获鼠指名亚种（R. m. microdon）种群（墨西哥恰帕斯州）与细吻收获鼠（R. tenuirostris）归为一组，而墨西哥瓦哈卡州以西的白唇小齿收获鼠（R. m. albilabris）样本与巴氏收获鼠（R. bakeri）形成一个分支。在Reithrodontomys亚属内，所有分析都发现蒙塔努斯收获鼠（R. montanus）和活跃收获鼠（R. raviventris）是姐妹分类单元，这一发现与早期基于等位酶和cyt b数据的研究一致。对于一个由（（巨耳收获鼠（R. megalotis）、萨卡特卡斯收获鼠（R. zacatecae））（苏米氏收获鼠（R. sumichrasti）））组成的分支也有很强的支持（ML和BI标准）。此外，cytb基因系统发育树（MP、ML和BI）将棕褐收获鼠（R. fulvescens）和多毛收获鼠（R. hirsutus）（ML和BI）恢复为Reithrodontomys亚属内的基部分类单元。约束分析表明，将两个亚属（Aporodon和Reithrodontomys）视为单系的树形拓扑结构（ML标准）显著更好（p>0.036），并支持墨西哥收获鼠的多系性（ML和MP标准均为 - p>0.013）和小齿收获鼠的多系性（仅在某些树形拓扑结构下MP标准适用；p>0.02）。尽管基于多个独立数据集鉴定出了几个物种级分类单元，但我们建议采用一种保守的方法，这将涉及对博物馆标本进行全面分析，包括来自模式产地的材料，以及来自多个核基因标记的额外采样和数据。
