Ecomorphological diversification in squamates from conserved pattern of cranial integration

Watanabe, A., Fabre, A.-C., Felice, R. N., Maisano, J. A., Müller, J., Herrel, A., & Goswami, A.

Ecomorphological diversification in squamates from conserved pattern of cranial integration

2019

Proceedings of the National Academy of Sciences

Animals
Biological Evolution
Ecosystem
Feeding Behavior physiology
Fossils anatomy & histology
Index Medicus
Lizards anatomy & histology physiology
Phenotype
Phylogeny
Skull anatomy & histology physiology
Snakes anatomy & histology physiology
Squamata
Geometric morphometrics
Integration and modularity
Macroevolution
Skull

English

Factors intrinsic and extrinsic to organisms dictate the course of morphological evolution but are seldom considered together in comparative analyses. Among vertebrates, squamates (lizards and snakes) exhibit remarkable morphological and developmental variations that parallel their incredible ecological spectrum. However, this exceptional diversity also makes systematic quantification and analysis of their morphological evolution challenging. We present a squamate-wide, high-density morphometric analysis of the skull across 181 modern and extinct species to identify the primary drivers of their cranial evolution within a unified, quantitative framework. Diet and habitat preferences, but not reproductive mode, are major influences on skull-shape evolution across squamates, with fossorial and aquatic taxa exhibiting convergent and rapid changes in skull shape. In lizards, diet is associated with the shape of the rostrum, reflecting its use in grasping prey, whereas snakes show a correlation between diet and the shape of posterior skull bones important for gape widening. Similarly, we observe the highest rates of evolution and greatest disparity in regions associated with jaw musculature in lizards, whereas those forming the jaw articulation evolve faster in snakes. In addition, high-resolution ancestral cranial reconstructions from these data support a terrestrial, nonfossorial origin for snakes. Despite their disparate evolutionary trends, lizards and snakes unexpectedly share a common pattern of trait integration, with the highest correlations in the occiput, jaw articulation, and palate. We thus demonstrate that highly diverse phenotypes, exemplified by lizards and snakes, can and do arise from differential selection acting on conserved patterns of phenotypic integration.

Proceedings of the National Academy of Sciences, Volume 116, Issue 29, June 2019, pages 14688-14697

Copyright © 2019 the Author(s). Published by PNAS.

PDF

Text