Environmental colour pattern variation in Mediterranean Podarcis

Area of Science:

• Zoology
• Evolutionary Biology
• Ecology

Background:

• The genus Podarcis encompasses widespread Mediterranean lizards, typically exhibiting green-brown coloration.
• Some Podarcis populations display unusual blue or uniformly black colorations, prompting investigation into their origins.

Purpose of the Study:

• To investigate the factors driving chromatic variation in Podarcis lizards.
• To determine the influence of environmental factors (climate, island conditions) and evolutionary factors (phylogenetic trait conservatism) on lizard coloration.

Main Methods:

• Analysis of coloration in the CIELAB color space for 1400 individuals across 27 Podarcis species.
• Assessment of phylogenetic trait conservatism using Pagel's λ.

Main Results:

• Coloration showed weak conservation within phylogenetic lineages (Pagel's λ).
• Island surface area significantly impacts chromatic variability, while geographic isolation and climate have lesser effects.
• Small island populations often exhibit uniform, dark coloration, possibly linked to intraspecific competition and reduced predation.

Conclusions:

• Island populations are crucial for understanding the evolution of extreme phenotypes in small ectothermic vertebrates.
• Environmental factors, particularly island size, play a significant role in shaping lizard coloration diversity.