Evolution of extreme ontogenetic allometric diversity and heterochrony in pythons, a clade of giant and dwarf snakes
Evolution of extreme ontogenetic allometric diversity and heterochrony in pythons, a clade of giant and dwarf snakes
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DOI：
10.1111/evo.13382
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发表时间：
2017-12-01
期刊：
影响因子：
3.3
通讯作者：
Keogh, J. Scott
中科院分区：
文献类型：
--
作者：
Esquerre, Damien;Sherratt, Emma;Keogh, J. Scott
个体发育异速生长（物种在其生命过程中如何随体型变化）以及异时性（形状、大小和年龄之间的解耦）是生物多样性的主要贡献因素。然而，宏观进化的异速生长和异时性趋势仍未得到很好的理解，因为先前的研究集中在少数密切相关的物种群体上。在此，我们重点测试关于异速生长进化的假设，以及异速生长和异时性如何在整个物种丰富且多样的分支水平上驱动形态多样化。蟒蛇是一个有用的研究体系，因为它们具有极其多样且适应性良好的表型以及极大的体型差异。我们从1191个标本中收集了44种蟒蛇里40种的详细表型数据。我们使用了一系列分析来测试改变形态多样性的异速生长轨迹的变化。异时性是蟒蛇分支内初始分化的主要驱动因素，而异速生长轨迹斜率的变化使得在分化历史后期探索新的表型成为可能。我们发现异速生长系数具有高度的可进化性，并且个体发育异速生长与生态之间存在关联，这表明异速生长是易变且具有适应性的，而不是对可能表型的一种限制。
Ontogenetic allometry, how species change with size through their lives, and heterochony, a decoupling between shape, size, and age, are major contributors to biological diversity. However, macroevolutionary allometric and heterochronic trends remain poorly understood because previous studies have focused on small groups of closely related species. Here, we focus on testing hypotheses about the evolution of allometry and how allometry and heterochrony drive morphological diversification at the level of an entire species-rich and diverse clade. Pythons are a useful system due to their remarkably diverse and well-adapted phenotypes and extreme size disparity. We collected detailed phenotype data on 40 of the 44 species of python from 1191 specimens. We used a suite of analyses to test for shifts in allometric trajectories that modify morphological diversity. Heterochrony is the main driver of initial divergence within python clades, and shifts in the slopes of allometric trajectories make exploration of novel phenotypes possible later in divergence history. We found that allometric coefficients are highly evolvable and there is an association between ontogenetic allometry and ecology, suggesting that allometry is both labile and adaptive rather than a constraint on possible phenotypes.