Megaevolutionary dynamics and the timing of evolutionary innovation in reptiles

Tiago R Simões,Oksana Vernygora,Stephanie E Pierce,Michael W Caldwell

doi:10.1038/s41467-020-17190-9

Tiago R Simões, Oksana Vernygora + Show 2 more

Open Access

https://doi.org/10.1038/s41467-020-17190-9

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Journal: Nature Communications	Publication Date: Jul 3, 2020
Citations: 71	License type: open-access

Affiliation: Harvard University, University of Alberta

Abstract

The origin of phenotypic diversity among higher clades is one of the most fundamental topics in evolutionary biology. However, due to methodological challenges, few studies have assessed rates of evolution and phenotypic disparity across broad scales of time to understand the evolutionary dynamics behind the origin and early evolution of new clades. Here, we provide a total-evidence dating approach to this problem in diapsid reptiles. We find major chronological gaps between periods of high evolutionary rates (phenotypic and molecular) and expansion in phenotypic disparity in reptile evolution. Importantly, many instances of accelerated phenotypic evolution are detected at the origin of major clades and body plans, but not concurrent with previously proposed periods of adaptive radiation. Furthermore, strongly heterogenic rates of evolution mark the acquisition of similarly adapted functional types, and the origin of snakes is marked by the highest rates of phenotypic evolution in diapsid history.

Highlights

The origin of phenotypic diversity among higher clades is one of the most fundamental topics in evolutionary biology
These punctuated evolutionary patterns have prompted the idea that the origin and early evolution of major clades and phenotypic innovations would be necessarily associated with high rates of phenotypic evolution and expansion in phenotypic disparity in deep time[1,2,3,4,5]
Adaptive radiations are traditionally believed to be responsible for the origin of most of Earth’s taxonomic and phenotypic diversity, usually associated with the first stages of the evolution of major clades[2,3]

Summary

Introduction

The origin of phenotypic diversity among higher clades is one of the most fundamental topics in evolutionary biology. When observed at sufficiently broad scales of time, new patterns emerge generating alternative models to the classical ideas described above: episodic radiations, when seemingly early bursts at the origin of major clades represent smaller episodic events of rapid evolution throughout evolutionary history (e.g., in echinoids)[17]; and constructive radiations, when there is a long chronological gap between the origin of clades and new body plans (associated with high evolutionary rates and phenotypic disparity), and the actual period of taxonomic diversification (e.g., in early metazoans)[1,20].

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