Developmental dynamics of ecomorphological convergence in a transcontinental lizard radiation

Area of Science:

• Evolutionary Biology
• Developmental Biology
• Comparative Morphology

Background:

• Phenotypic convergence is a long-standing puzzle in evolutionary biology.
• Explanations include adaptation to similar environments or limitations in developmental pathways.
• Lizards (Lacertidae) exhibit significant cranial homoplasy linked to ecological niches.

Purpose of the Study:

• To investigate the roles of adaptation versus developmental constraint in convergent cranial evolution in Lacertidae.
• To quantify cranial shape variation related to ontogeny, allometry, and ecology across diverse lacertid lineages.

Main Methods:

• Utilized 3D X-ray computed tomography for cranial morphology analysis.
• Employed landmark-based geometric morphometrics.
• Covered all lacertid genera and a significant portion of species diversity.

Main Results:

• Cranial shape significantly varied across different biomes, with notable convergence in arid-dwelling species.
• Allometric postdisplacement during ontogeny was identified as the primary driver of convergent paedomorphic skull shapes in independent arid-dwelling lineages.
• Allometry, previously viewed as a constraint, demonstrates flexibility during early development.

Conclusions:

• Developmental allometry, rather than solely adaptive pressures, generates convergent ecomorphologies in lizards.
• Allometric flexibility during early ontogeny can produce convergent phenotypes across large spatial and temporal scales.
• This process can obscure underlying phylogenetic signals in evolutionary studies.