Genes underlying the evolution of tetrapod testes size

Area of Science:

• Evolutionary Biology
• Genetics
• Comparative Genomics

Background:

• Testis size variation across species is significant, yet the underlying genetic factors remain largely unknown.
• Previous studies on gene-phenotype associations were limited to single species or directional selection.
• Comparative phylogenetic methods offer a macro-evolutionary perspective on genetic contributions to phenotypic diversity.

Purpose of the Study:

• To introduce a novel approach for detecting genotype-phenotype associations across species, irrespective of selection directionality.
• To investigate the role of twelve candidate genes in driving testis size evolution across tetrapod vertebrates.
• To explore the relationship between rates of genetic and phenotypic evolution.

Main Methods:

• Utilized contemporary comparative phylogenetic methods to analyze evolutionary rates.
• Sought relationships between rates of genetic (protein-coding substitutions) and phenotypic (testis size) evolution.
• Applied the method to twelve candidate genes across tetrapod vertebrates.

Main Results:

• Identified five genes (Alkbh5, Dmrtb1, Pld6, Nlrp3, Sp4) associated with testis size evolution.
• Found significant associations between protein-coding substitution rates and testis size evolution for these five genes.
• Demonstrated a novel method for testing genotype-phenotype associations across macro-evolutionary scales.

Conclusions:

• The developed approach successfully identifies genes influencing phenotypic diversity across species.
• Five specific genes have played unique and complex roles in shaping tetrapod testis size diversity.
• This work provides a framework for understanding how natural selection sculpts phenotypic change through genetic mechanisms over millions of years.