Mating ecology explains patterns of genome elimination

Area of Science:

• Evolutionary biology
• Genetics
• Animal reproduction

Background:

• Genome elimination, the discarding of parental chromosomes, is observed in numerous animal species.
• This phenomenon is frequently linked to inbreeding, male-biased occurrence, and paternal genome elimination, particularly under male heterogamety.
• The underlying evolutionary drivers for these observed patterns remain largely unexplained.

Purpose of the Study:

• To investigate the evolutionary dynamics of genome elimination using a mathematical model.
• To elucidate how factors such as inbreeding, sex determination systems, and parental origin influence the persistence of genome-elimination alleles.
• To explain the widespread pattern of paternal genome elimination in the heterogametic sex.

Main Methods:

• Development of a mathematical model analyzing the interactions between inbreeding, sex determination (male vs. female heterogamety), genomic location, gene expression, and parental origin of eliminated genomes.
• Simulation of allele frequency changes for genome-elimination alleles under varying ecological and genetic conditions.
• Analysis of population-level consequences, including extinction risk and sex-ratio dynamics.

Main Results:

• Inbreeding significantly promotes paternal genome elimination, especially in the heterogametic sex.
• Under female heterogamety, this can lead to population extinction due to the eradication of males.
• Extinction is averted under male heterogamety, as sex-ratio selection counteracts the effects of genome elimination.
• The model successfully explains the observed prevalence of paternal genome elimination.

Conclusions:

• The study provides a theoretical framework explaining the prevalence of paternal genome elimination in the heterogametic sex across animal species.
• It highlights the critical interplay between mating systems (inbreeding), sex determination mechanisms, and intragenomic conflict in shaping evolutionary trajectories.
• The findings underscore the potential for genome elimination to drive population-level dynamics, including extinction, depending on the mode of sex determination.