Morphological disparity opposes latitudinal diversity gradient in lacertid lizards

Area of Science:

• Evolutionary Biology
• Zoology
• Ecology

Background:

• Global species diversity often correlates with latitude, but the relationship between morphological disparity and geography is less understood.
• The Old World lizard family Lacertidae exhibits an inverse latitudinal diversity gradient, with fewer species in tropical regions.

Purpose of the Study:

• To investigate lineage diversification, morphological disparity, and phenotypic evolution rates in Lacertidae lizards.
• To determine if morphological disparity follows geographical gradients in parallel with species diversity.

Main Methods:

• Analysis of lineage diversification patterns.
• Estimation of morphological disparity and rates of phenotypic evolution.
• Comparison of evolutionary rates across different geographic regions and habitats.

Main Results:

• Lacertidae lizards show consistent lineage accumulation rates over time.
• Most morphological variation arose from recent divergence events, leading to greater disparity within subclades.
• Tropical arboreal lacertids displayed the fastest rates of shape change, while temperate European taxa showed the slowest.

Conclusions:

• An inverse relationship exists between latitudinal diversity and phenotypic evolution rates in Lacertidae.
• This pattern provides a counterexample to the ecological opportunity theory of diversification.
• Species diversity and morphological differentiation may be uncoupled across spatial scales.