Convergent evolution of noncoding elements associated with short tarsus length in birds

Area of Science:

• Evolutionary Biology
• Genomics
• Comparative Anatomy

Background:

• Convergent evolution describes similar traits evolving independently in unrelated species.
• Genomic signatures, like altered substitution rates, can reveal molecular-level convergence.
• This study investigates convergent evolution of bird tarsus length using genomic and population data.

Purpose of the Study:

• To identify independent shifts in avian tarsus length.
• To detect convergent evolutionary changes at the molecular level in birds with shorter tarsi.
• To link genomic changes to the evolution of skeletal traits.

Main Methods:

• Analyzed tarsus measurements from ~5400 bird species.
• Utilized a dataset of 932,467 avian conserved non-exonic elements (CNEEs) and whole-genome alignment of 79 birds.
• Performed comparative genomic and population genetic analyses.

Main Results:

• Found strong evidence for convergent acceleration in 14,422 CNEEs within short-tarsus bird clades.
• Observed no convergent positive selection patterns in 9854 protein-coding genes.
• Accelerated elements were concentrated near genes involved in skeletal system development, indicating regulatory element involvement.

Conclusions:

• Regulatory elements show convergent acceleration, playing a key role in convergent skeletal traits.
• Findings support the importance of regulatory elements in the evolution of skeletal phenotypes.
• Convergent changes in limb development gene regulation were identified.