CONSERVED PHENOTYPIC VARIATION PATTERNS, EVOLUTION ALONG LINES OF LEAST RESISTANCE, AND DEPARTURE DUE TO SELECTION IN FOSSIL RODENTS
CONSERVED PHENOTYPIC VARIATION PATTERNS, EVOLUTION ALONG LINES OF LEAST RESISTANCE, AND DEPARTURE DUE TO SELECTION IN FOSSIL RODENTS
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DOI：
10.1111/j.0014-3820.2006.tb00514.x
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发表时间：
2006-08
期刊：
影响因子：
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通讯作者：
S. Renaud;J. Auffray;J. Michaux
中科院分区：
文献类型：
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作者：
S. Renaud;J. Auffray;J. Michaux
摘要在一组生物体中，由于内部发育的限制，某些形态比其他形态更容易产生。这种限制可以引导进化的变化到对应于最大的种内变异的方向。然而，长期的进化产出取决于这些种内变异模式随时间的稳定性，以及内部约束和选择机制之间的相互作用。为了解决这些问题，表型方差协方差矩阵的结构和形态进化的方向之间的关系进行了研究，使用化石啮齿动物的牙齿。这里考虑的一个谱系导致Stephanomys，一个高度专门化的属，其特征是牙齿模式，据说有利于吃草。Stephanomys进化的背景下，定向选择相关的全球变冷的气候趋势，导致欧洲西南部草原的比例越来越大。最初的分歧（高达6.5百万年）是引导沿着方向最大的种内变异，而6.5百万年后，形态进化偏离的方向有利于内部的限制。这种偏离“最小抗性品系”的现象可能是环境退化的结果，环境退化导致选择梯度足够强，足以压倒对表型进化的限制。然而，在稳定选择的背景下，这些限制实际上是进化的通道，就像姬鼠的血统一样。在过去的1000万年里，这个谱系保留了原始的饮食和牙齿模式。有限的形态发生变化，但根据种内变异的主要模式。这些最小的阻力线指导长期形态进化的重要性，可以解释在小鼠进化的一些牙齿模式的平行进化。
Abstract Within a group of organisms, some morphologies are more readily generated than others due to internal developmental constraints. Such constraints can channel evolutionary changes into directions corresponding to the greatest intraspecific variation. Long term evolutionary outputs, however, depend on the stability of these intraspecific patterns of variation over time and from the interplay between internal constraints and selective regimes. To address these questions, the relationship between the structure of phenotypic variance covariance matrices and direction of morphological evolution was investigated using teeth of fossil rodents. One lineage considered here leads to Stephanomys, a highly specialized genus characterized by a dental pattern supposedly favoring grass eating. Stephanomys evolved in the context of directional selection related to the climatic trend of global cooling causing an increasing proportion of grasslands in southwestern Europe. The initial divergence (up to ∼6.5 mya) was channeled along the direction of greatest intraspecific variation, whereas after 6.5 mya, morphological evolution departed from the direction favored by internal constraints. This departure from the “lines of least resistance” was likely the consequence of an environmental degradation causing a selective gradient strong enough to overwhelm the constraints to phenotypic evolution. However, in a context of stabilizing selection, these constraints actually channel evolution, as exemplified by the lineage of Apodemus. This lineage retained a primitive diet and dental pattern over the last 10 myr. Limited morphological changes occurred nevertheless in accordance with the main patterns of intraspecific variation. The importance of these lines of least resistance directing long-term morphological evolution may explain parallel evolution of some dental patterns in murine evolution.