Fuzzy boundaries: color and gene flow patterns among parapatric lineages of the western shovel-nosed snake and taxonomic implication.
Fuzzy boundaries: color and gene flow patterns among parapatric lineages of the western shovel-nosed snake and taxonomic implication.
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DOI：
10.1371/journal.pone.0097494
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发表时间：
2014
期刊：
影响因子：
3.7
通讯作者：
Vandergast AG
中科院分区：
文献类型：
--
作者：
Wood DA;Fisher RN;Vandergast AG
随着物种分布日益减少和受到威胁，准确描绘谱系多样性变得越来越重要。在上个世纪，亚种类别经常被用来表示物种范围内的表型变异，并为理解谱系分化提供一个框架，通常被认为是早期的物种形成。虽然这一类别在很大程度上已被废弃，但在缺乏其他信息的情况下，以前认识到的亚种经常作为保护政策和管理的重要单位。在这项研究中，我们在遗传数据的基础上评估了铲鼻蛇的表型亚种假设，并考虑了基因流等进化过程如何影响表型和遗传模式之间可能的不一致。我们使用传统的系统发育和贝叶斯聚类分析来推断全范围的遗传结构，并使用空间显式分析来检测可能的谱系接触边界位置。多位点分析支持三个历史上孤立的群体，当代基因交换水平低至中等。遗传数据不支持表型亚种作为排他群体，我们在假定三个亚种接触的区域检测到不一致的模式。基于遗传和表型证据，我们认为该类群物种水平的多样性被低估了，我们建议识别两个物种：Chionactis occipitalis和C. annulata。此外，我们建议保留两个亚种名称（c.a.a annulata和c.a.k lauberi），这反映了物种内遗传和表型变异的区域变化。我们的结果突出了在谱系中验证分类学界限的困难，谱系是在一个依赖时间的连续过程中进化的。
Accurate delineation of lineage diversity is increasingly important, as species distributions are becoming more reduced and threatened. During the last century, the subspecies category was often used to denote phenotypic variation within a species range and to provide a framework for understanding lineage differentiation, often considered incipient speciation. While this category has largely fallen into disuse, previously recognized subspecies often serve as important units for conservation policy and management when other information is lacking. In this study, we evaluated phenotypic subspecies hypotheses within shovel-nosed snakes on the basis of genetic data and considered how evolutionary processes such as gene flow influenced possible incongruence between phenotypic and genetic patterns. We used both traditional phylogenetic and Bayesian clustering analyses to infer range-wide genetic structure and spatially explicit analyses to detect possible boundary locations of lineage contact. Multilocus analyses supported three historically isolated groups with low to moderate levels of contemporary gene exchange. Genetic data did not support phenotypic subspecies as exclusive groups, and we detected patterns of discordance in areas where three subspecies are presumed to be in contact. Based on genetic and phenotypic evidence, we suggested that species-level diversity is underestimated in this group and we proposed that two species be recognized, Chionactis occipitalis and C. annulata. In addition, we recommend retention of two subspecific designations within C. annulata (C. a. annulata and C. a. klauberi) that reflect regional shifts in both genetic and phenotypic variation within the species. Our results highlight the difficultly in validating taxonomic boundaries within lineages that are evolving under a time-dependent, continuous process.
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