Y chromosome introgression between deeply divergent primate species

Area of Science:

• Evolutionary biology
• Genetics
• Primate research

Background:

• Hybridization and introgression are common in nature, influencing adaptation and speciation.
• Haldane's rule states heterogametic hybrids often have lower fitness, limiting introgression of sex-linked genes.

Purpose of the Study:

• To investigate Y-chromosomal introgression in guenons, African primates with a history of hybridization.
• To understand the mechanisms and evolutionary implications of Y chromosome introgression in the context of Haldane's rule.

Main Methods:

• Phylogenetic analysis of guenon Y chromosomes.
• Simulations to model introgression dynamics.
• Identification of genetic variations on the introgressed Y chromosome.

Main Results:

• A rare Y chromosome introgression event was identified between two guenon species.
• Haldane's rule generally applied, but Y chromosome introgression occurred approximately six million years after divergence.
• Selection likely drove the introgressed Y chromosome to fixation from a low frequency.
• Non-synonymous substitutions on the Y chromosome were identified as potential targets of selection.

Conclusions:

• This study presents a rare case of Y chromosome introgression in guenons.
• The findings suggest that the capacity for fertile heterogametic hybridization persisted for six million years in this primate lineage.
• Selection and potentially meiotic drive are explored as mechanisms facilitating Y chromosome introgression against Haldane's rule.