Decoupling of morphological disparity and taxic diversity during the adaptive radiation of anomodont therapsids

Ruta, Marcello and Angielczyk, Kenneth D. and Fröbisch, Jörg and Benton, Michael J. (2013) Decoupling of morphological disparity and taxic diversity during the adaptive radiation of anomodont therapsids. Proceedings of the Royal Society B: Biological Sciences, 280 (1768). pp. 1-9. ISSN 0962-8452

Full content URL: http://dx.doi.org/10.1098/rspb.2013.1071

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Abstract

Adaptive radiations are central to macroevolutionary theory. Whether triggered by acquisition of new traits or ecological opportunities arising from mass extinctions, it is debated whether adaptive radiations are marked by initial expansion of taxic diversity or of morphological disparity (the range of anatomical form). If a group rediversifies following a mass extinction, it is said to have passed through a macroevolutionary bottleneck, and the loss of taxic or phylogenetic diversity may limit the amount of morphological novelty that it can subsequently generate. Anomodont therapsids, a diverse clade of Permian and Triassic herbivorous tetrapods, passed through a bottleneck during the end-Permian mass extinction. Their taxic diversity increased during the Permian, declined significantly at the Permo–Triassic boundary and rebounded during the Middle Triassic before the clade's final extinction at the end of the Triassic. By sharp contrast, disparity declined steadily during most of anomodont history. Our results highlight three main aspects of adaptive radiations: (i) diversity and disparity are generally decoupled; (ii) models of radiations following mass extinctions may differ from those triggered by other causes (e.g. trait acquisition); and (iii) the bottleneck caused by a mass extinction means that a clade can emerge lacking its original potential for generating morphological variety.

Keywords:Anomodontia, bottleneck, Dicynodontia, disparity, diversity, Permian extinction
Subjects:C Biological Sciences > C300 Zoology
C Biological Sciences > C182 Evolution
F Physical Sciences > F641 Palaeontology
C Biological Sciences > C181 Biodiversity
Divisions:College of Science > School of Life Sciences
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ID Code:11616
Deposited On:15 Aug 2013 09:19

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