Accelerated evolution and diversifying selection drove the adaptation of cetacean bone microstructure.

Area of Science:

• Evolutionary biology
• Molecular genetics
• Comparative anatomy

Background:

• Cetaceans (whales, dolphins, porpoises) evolved from terrestrial mammals approximately 50 million years ago.
• This transition involved significant adaptations in morphology, physiology, and behavior, including changes in bone microstructure.
• The genetic underpinnings of cetacean bone microstructure evolution remain largely unexplored.

Purpose of the Study:

• To investigate the genetic basis of bone microstructure evolution in cetaceans.
• To identify genes and molecular pathways involved in adapting cetacean bone structure to aquatic environments.

Main Methods:

• Correlating bone microstructure with gene substitution rates in terrestrial and aquatic species.
• Detecting genes under positive selection along ancestral cetacean lineages.
• Analyzing genes involved in osteoclast function, Wnt signaling, and collagen synthesis.

Main Results:

• Genes regulating osteoclast activity show accelerated evolution in cetaceans, indicating a role in bone remodeling for aquatic adaptation.
• Genes within the Wnt pathway, crucial for bone development, exhibit divergent evolution in cetaceans.
• Several genes encoding bone collagens are under selective pressure, suggesting adaptation in bone composition.

Conclusions:

• Evolutionary pressures have significantly modified cetacean bone microstructure.
• Genetic changes in bone remodeling, development, and composition facilitate adaptation to diverse aquatic habitats.