Comparative Genomics Supports Ecologically Induced Selection as a Putative Driver of Banded Penguin Diversification

Area of Science:

• Evolutionary Biology
• Genomics
• Marine Biology

Background:

• Speciation drivers like genetic drift and local adaptation are debated, especially in highly mobile seabirds with potential gene flow.
• Seabirds, such as banded penguins, inhabit diverse environments, presenting opportunities for adaptation and divergence.
• Understanding the genomic basis of adaptation is key to explaining speciation in these marine species.

Purpose of the Study:

• To investigate the genomic underpinnings of adaptation and speciation in four banded penguin species.
• To identify molecular mechanisms and adaptive traits responsible for penguin diversification.
• To explore the roles of environmental factors and gene flow in lineage divergence.

Main Methods:

• Analysis of 114 genomes from 16 breeding colonies of Galápagos, Humboldt, Magellanic, and African penguins.
• Utilized positive selection and gene family expansion analyses to detect adaptive evolution.
• Examined genomic regions associated with reproductive isolation and ecological niche divergence.

Main Results:

• Identified candidate genes linked to reproductive isolation, potentially mediated by thermal niche divergence.
• Detected positive selection signals on genes related to spermatogenesis, particularly in the Galápagos penguin divergence.
• Found evidence for genome-wide selection on genes involved in thermoregulation, osmoregulation, hypoxia, and social behavior.

Conclusions:

• Local adaptation, driven by selection on genes for thermoregulation and spermatogenesis, plays a significant role in banded penguin speciation.
• Abiotic factors, alongside dispersal capabilities, promote lineage divergence in marine species, even amidst gene flow.
• The study highlights the complex interplay of environmental pressures and genetic mechanisms in shaping avian evolutionary trajectories.