Y recombination arrest and degeneration in the absence of sexual dimorphism

Lenormand, T.; Roze, D.

doi:10.1101/2021.05.18.444606

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bioRxiv · 10.1101/2021.05.18.444606

Y recombination arrest and degeneration in the absence of sexual dimorphism

Lenormand, T.·Roze, D.

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Abstract

Current theory proposes degenerated sex chromosomes evolve via three successive steps: recombination arrest, which links male-beneficial alleles to the Y chromosome; degeneration of these regions due to the inefficacy of natural selection in the absence of recombination; and lastly, the evolution of dosage compensation to correct the resulting low expression of X-linked genes in males. Here we investigate new models of sex chromosome evolution incorporating the coevolution of cis- and trans-regulators of gene expression. We show that the early emergence of dosage compensation favors the maintenance of Y-linked inversions by creating sex-antagonistic regulatory effects. This is followed by inversion degeneration caused by regulatory divergence between the X and Y chromosomes. In stark contrast to the current theory, the whole process occurs without any selective pressure related to sexual dimorphism. One Sentence SummaryTurning sex chromosome theory on its head: early evolution of dosage compensation can maintain successively forming Y chromosome strata that undergo genetic degeneration.

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Lenormand, T., Roze, D.. 2021-05-18. Y recombination arrest and degeneration in the absence of sexual dimorphism. https://doi.org/10.1101/2021.05.18.444606

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