RT Journal Article
SR Electronic
T1 Gene-rich X chromosomes implicate intragenomic conflict in the evolution of bizarre genetic systems
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2020.10.04.325340
DO 10.1101/2020.10.04.325340
A1 Noelle Anderson
A1 Kamil S. Jaron
A1 Christina N. Hodson
A1 Matthew B. Couger
A1 Jan Ševčík
A1 Stacy Pirro
A1 Laura Ross
A1 Scott William Roy
YR 2020
UL http://biorxiv.org/content/early/2020/10/07/2020.10.04.325340.abstract
AB Haplodiploidy and paternal genome elimination (HD/PGE) are common in animals, having evolved at least two dozen times. HD/PGE typically evolves from male heterogamety (i.e., systems with X chromosomes), however why X chromosomes are important for the evolution of HD/PGE remains debated. The Haploid Viability Hypothesis argues that X chromosomes promote the evolution of male haploidy by facilitating purging recessive deleterious mutations. The Intragenomic Conflict Hypothesis instead argues that X chromosomes promote the evolution of male haploidy due to conflicts with autosomes over sex ratios and transmission. To test these hypotheses, we studied lineages that combine germline PGE with XX/X0 sex determination (gPGE+X systems). Because the evolution of such systems involves changes in genetic transmission but not increases in male hemizygosity, a high degree of X linkage in these systems is predicted by the Intragenomic Conflict Hypothesis but not the Haploid Viability Hypothesis. Through de novo genome sequence, we compared the genomes of 7 species with gPGE+X systems and 10 related species with typical XX/XY or XX/X0 genetic systems. We find highly increased X-linkage in modern and ancestral genomes of gPGE+X species, with an estimated 30 times more X-linked genes than in non-gPGE+X relatives. These results suggest a general role for intragenomic conflict in the origins of PGE/HD. These findings are among the first empirical results supporting a role for intragenomic conflict in the evolution of novel genetic systems.Competing Interest StatementThe authors have declared no competing interest.