Saturday, January 13, 2018

[Herpetology • 2017] Arboreality Constrains Morphological Evolution but Not Species Diversification in Vipers

Stejneger's Pitviper (Trimeresurus stejnegeri

 Alencar, Martins, Burin & Quental, 2017
    DOI: 10.1098/rspb.2017.1775 

An increase in ecological opportunities, either through changes in the environment or acquisition of new traits, is frequently associated with an increase in species and morphological diversification. However, it is possible that certain ecological settings might prevent lineages from diversifying. Arboreality evolved multiple times in vipers, making them ideal organisms for exploring how potentially new ecological opportunities affect their morphology and speciation regimes. Arboreal snakes are frequently suggested to have a very specialized morphology, and being too large, too small, too heavy, or having short tails might be challenging for them. Using trait-evolution models, we show that arboreal vipers are evolving towards intermediate body sizes, with longer tails and more slender bodies than terrestrial vipers. Arboreality strongly constrains body size and circumference evolution in vipers, while terrestrial lineages are evolving towards a broader range of morphological variants. Trait-dependent diversification models, however, suggest similar speciation rates between microhabitats. Thus, we show that arboreality might constrain morphological evolution but not necessarily affect the rates at which lineages generate new species.

KEYWORDS: speciation, divergent selection, snakes, Ornstein–Uhlenbeck

The arboreal Stejneger's Pitviper (Trimeresurus stejnegeri).

Photo: M. Martins 

Laura Rodrigues Vieira de Alencar, Marcio Martins, Gustavo Burin and Tiago Bosisio Quental. 2017. Arboreality Constrains Morphological Evolution but Not Species Diversification in Vipers. Proceedings of the Royal Society B: Biological Sciences. 284(1869)  DOI: 10.1098/rspb.2017.1775 


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