Brain evolution across the Puerto Rican anole radiation

Area of Science:

• Comparative neuroanatomy
• Evolutionary biology
• Vertebrate paleontology

Background:

• Brain evolution studies often focus on mammals and birds.
• Habitat complexity typically correlates with divergent neuroanatomy in these groups.
• Anolis lizards offer a model for studying brain evolution across distinct ecological niches.

Purpose of the Study:

• To investigate allometric scaling patterns in the Anolis lizard brain.
• To determine if brain structure size converges among Anolis lizards of the same ecomorph type.
• To explore the roles of concerted and mosaic brain evolution in Anolis lizards.

Main Methods:

• Examined allometric scaling of brain regions (telencephalon, cortex, cerebellum, etc.) in six Puerto Rican Anolis lizard species.
• Grouped species into three distinct ecomorphs based on habitat preference.
• Analyzed variance in brain region volumes relative to overall brain volume.

Main Results:

• Overall brain volume explained a high percentage of variance in individual brain region volumes (92.5–99.8%).
• This pattern suggests concerted brain evolution, where brain components scale together.
• Cerebellum volume showed a trend consistent with mosaic evolution, indicating differential scaling.

Conclusions:

• Anolis lizard brains exhibit a combination of concerted and mosaic brain evolution, with concerted evolution being predominant.
• Findings challenge the expected trend of habitat-driven neuroanatomical divergence.
• The presence of concerted brain evolution in Anolis lizards supports its potential role as a conserved developmental mechanism across vertebrates.