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The Evolution of Complex Brains in Animals
Context:
An assistant professor at the University of Detroit is investigating the relationship between brain structure and behaviour in reptiles, specifically lizards, to address gaps in understanding how brain function relates to behaviour.
More on News:
- Traditionally, the link between behaviour and brain function has been associated with brain size and the brain-to-body size ratio.
- The research involves analysing anoles from Puerto Rico, a region known for its rich biodiversity. Their research indicates that the complexity of an animal’s habitat may affect brain structure.
Anoles, a specific type of lizard known for their ability to change colour, possess a dewlap (throat fan), and have adhesive toe pads, are widespread in the Americas, particularly in tropical and subtropical regions.
- The team collected 64 anoles during the summers of 2019 and 2021, focusing on six species within the same ecomorph class that share many physical traits despite being different species.
- Anolis evermanni, Anolis stratulus, Anolis cristatellus, Anolis gundlachi, Anolis krugi, and Anolis pulchellus.
Key Highlights:
- The study found that lizards from more complex habitats (e.g., tree canopies) had higher neuron densities in certain brain regions compared to those from simpler habitats (e.g., tree trunks and grass).
- This suggests that cognitive demands in complex environments may lead to increased brain complexity.
- Brain processing capacity is influenced by neuron number, neural plasticity, signal processing speed, synapse density, and cell type diversity.
- Neuron density in the telencephalon and other brain regions increased with habitat complexity, while neuron density in the cerebellum did not show significant variation.
- Similar patterns have been observed in other vertebrates.
- For instance, Aegean wall lizards, three-spined sticklebacks, and zebrafish living in more complex habitats have shown better performance in spatial learning tasks and similar neuroanatomical findings.
Brain Regions Studied:
- Telencephalon: Involved in sensory integration and higher cognition.
- Cerebellum: Responsible for motor coordination and learning.
- Rest of the Brain: Handles sensory inputs and motor outputs.
Implications:
- The study suggests that differences in neuroanatomy among the anoles, despite their similar social structures, diets, and sensory systems, are likely due to the complexity of their habitats.
- It emphasises the importance of studying these differences to gain a deeper understanding of evolution and the functional diversity of brains across species.
