Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada.
Proc Biol Sci. 2013 Jun 5;280(1763):20130849. doi: 10.1098/rspb.2013.0849. Print 2013 Jul 22.
Diversity and disparity are unequally distributed both phylogenetically and geographically. This uneven distribution may be owing to differences in diversification rates between clades resulting from processes such as adaptive radiation. We examined the rate and distribution of evolution in feeding biomechanics in the extremely diverse and continentally distributed South American geophagine cichlids. Evolutionary patterns in multivariate functional morphospace were examined using a phylomorphospace approach, disparity-through-time analyses and by comparing Brownian motion (BM) and adaptive peak evolutionary models using maximum likelihood. The most species-rich and functionally disparate clade (CAS) expanded more efficiently in morphospace and evolved more rapidly compared with both BM expectations and its sister clade (GGD). Members of the CAS clade also exhibited an early burst in functional evolution that corresponds to the development of modern ecological roles and may have been related to the colonization of a novel adaptive peak characterized by fast oral jaw mechanics. Furthermore, reduced ecological opportunity following this early burst may have restricted functional evolution in the GGD clade, which is less species-rich and more ecologically specialized. Patterns of evolution in ecologically important functional traits are consistent with a pattern of adaptive radiation within the most diverse clade of Geophagini.
多样性和差异在系统发育和地理上的分布是不均匀的。这种不均匀的分布可能是由于不同分支之间的多样化速率的差异，这是由于适应辐射等过程造成的。我们研究了在南美分布广泛的地理雀鲷中，摄食生物力学的进化速率和分布。利用分支形态空间方法、随时间变化的离散度分析以及通过最大似然法比较布朗运动（BM）和适应峰进化模型，研究了多变量功能形态空间中的进化模式。与 BM 预测和其姊妹分支（GGD）相比，物种最丰富且功能差异最大的分支（CAS）在形态空间中扩张得更有效率，进化得更快。CAS 分支的成员还表现出功能进化的早期爆发，这与现代生态角色的发展相对应，可能与以快速口腔颌力学为特征的新型适应峰的殖民化有关。此外，在这种早期爆发之后，生态机会的减少可能限制了 GGD 分支的功能进化，因为 GGD 分支的物种较少，生态专业化程度较高。生态重要功能特征的进化模式与地理雀鲷中最具多样性的分支的适应辐射模式一致。
