MORPHOLOGICAL SHIFTS OF SOME ISOLATED POPULATIONS OF EUTAMIAS (RODENTIA: SCIURIDAE) IN DIFFERENT CONGENERIC ASSEMBLAGES
MORPHOLOGICAL SHIFTS OF SOME ISOLATED POPULATIONS OF EUTAMIAS (RODENTIA: SCIURIDAE) IN DIFFERENT CONGENERIC ASSEMBLAGES
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不同同属组合中一些孤立的真鼠类（啮齿类：鼠科）种群的形态变化
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发表时间：
1981
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通讯作者：
Bruce D. Patterson
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作者：
Bruce D. Patterson
形态进化的生态决定因素是我们理解生物多样性的核心。这一论点的关键在于复杂形态的进化惯性。由于它们整合在基因组中，精细的形态结构在很大程度上不受混淆的短期变异性的影响，这种变异性经常困扰着更具可塑性的生态属性的研究。（参见：Wiens，1977）。一个由多基因和多效性组成的相互关联的遗传系统，由于环境的力量，对选择环境中的非定向变化的反应不如对普遍选择更透明的简单遗传结构。通过这种方式，复杂的形态系统抑制了环境“噪音”的影响，从而允许识别那些塑造物种进化轨迹的环境特征。虽然重要的是要认识到，更柔顺的属性，特别是行为，是重要的启动力量在进化变化（迈尔，1974年），复杂的形态结构可以提供一个保守的记录占主导地位的选择压力。本研究探讨了形态变化表现出孤立的种群的花栗鼠（属Eutamias）在不同的环境中，主要是在其他物种的花栗鼠的存在或不存在。如果真的是花栗鼠进化过程中的一个主要因素，那么，只要有足够的时间，我们不仅可以在相对可塑的性状上，而且还可以在更基本的属性上找到这种选择的结果。分类特征（颅和下颌形态方面）形成这些变化的参考框架。本文探讨的假设，种群的Eutamias表现出的基因组组织的模式，结构与同类物种的竞争。具体而言，形态模式与竞争压力下进化的三种假设的预测进行了比较：生态位变异假设（货车Valen，1965），字符位移（Brown和Wilson，1956）和趋同（例如，Karr和James，1975年）。
Ecological determinants of morphological evolution are central to our understanding of biotic diversification. The crux of this argument lies in the evolutionary inertia of complex morphologies. Because of their integration in the genome, elaborate morphological structures are largely immune to the confounding short-term variability that often plagues studies of more malleable ecological attributes .(cf. Wiens, 1977). An interconnected genetic system comprised of polygeny and pleiotropy is, by force of circumstances, less responsive to nondirected changes in the selective milieu than are simpler genetic architectures more transparent to prevailing selection. In this way, intricate morphological systems dampen the effects of environmental "noise," thereby permitting the identification of those environmental features shaping the evolutionary trajectories of species. While it is important to recognize that more pliant attributes, especially behaviors, are important initiating forces in evolutionary change (Mayr, 1974), complex morphological structures can provide a conservative record of predominating selective pressures. This study examines the morphological shifts exhibited by isolated populations of chipmunks (genus Eutamias) in response to environments that differ chiefly in terms of the presence or absence of other species of chipmunks. If interspecific competition among Eutamias has truly been a predominant factor in the evolution of chipmunks, then, given sufficient time, we can expect to find the results of such selection not only in relatively plastic characters but also in more fundamental attributes. Taxonomic characters (aspects of cranial and mandibular morphology) form the frame of reference for these shifts. This paper examines the hypothesis that populations of Eutamias exhibit patterns of genomic organization that are structured by competition with congeneric species. Specifically, morphological patterns are compared with predictions of three hypotheses for evolution under competitive pressures: the niche variation hypothesis (Van Valen, 1965), character displacement (Brown and Wilson, 1956), and convergence (e.g., Karr and James, 1975).