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Abstract Sex chromosomes often differ between closely related species and can even be polymorphic within populations. Species with multifactorial sex determination segregate for multiple different sex-determining loci within populations, making them uniquely informative of the selection pressures that drive the evolution of sex chromosomes. The house fly (Musca domestica) is a model species for studying multifactorial sex determination because male-determining genes have been identified on all six of the chromosomes, which means that any chromosome can be a “proto-Y.” Natural populations of house flies also segregate for a recently derived female-determining locus, meaning house flies also have a proto-W chromosome. The different proto-Y chromosomes are distributed along latitudinal clines on multiple continents, their distributions can be explained by seasonality in temperature, and they have temperature-dependent effects on physiological and behavioral traits. It is not clear, however, how the clinal distributions interact with the effect of seasonality on the frequencies of house fly proto-Y and proto-W chromosomes across populations. To address this question, we measured the frequencies of house fly proto-Y and proto-W chromosomes across nine populations in the United States of America. We confirmed the clinal distribution along the eastern coast of North America, but it is limited to the eastern coast. In contrast, the annual mean daily temperature range predicts proto-Y chromosome frequencies across the entire continent. Our results therefore suggest that temperature heterogeneity can explain the distributions of house fly proto-Y chromosomes in a way that does not depend on the cline.
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Autosomal suppression of sex-ratio meiotic drive influences the dynamics of X and Y chromosome coevolution
Sex-ratio meiotic drivers are selfish genes or gene complexes that bias the transmission of sex chromosomes resulting in skewed sex ratios. Existing theoretical models have suggested the maintenance of a four-chromosome equilibrium (with driving and standard X and suppressing and susceptible Y) in a cyclic dynamic, but studies of natural populations have failed to capture this pattern. Although there are several plausible explanations for this lack of cycling, interference from autosomal suppressors has not been studied using a theoretical population genetic framework even though autosomal suppressors and Y-linked suppressors coexist in natural populations of some species. In this study, we use a simulation-based approach to investigate the influence of autosomal suppressors on the cycling of sex chromosomes. Our findings demonstrate that the presence of an autosomal suppressor can hinder the invasion of a Y-linked suppressor under some parameter space, thereby impeding the cyclic dynamics, or even the invasion of Y-linked suppression. Even when a Y-linked suppressor invades, the presence of an autosomal suppressor can prevent cycling. Our study demonstrates the potential role of autosomal suppressors in preventing sex chromosome cycling and provides insights into the conditions and consequences of maintaining both Y-linked and autosomal suppressors.
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- Award ID(s):
- 2047052
- PAR ID:
- 10569571
- Editor(s):
- Fishman, Lila
- Publisher / Repository:
- BioRxiv
- Date Published:
- Journal Name:
- Journal of Heredity
- Volume:
- 115
- Issue:
- 6
- ISSN:
- 0022-1503
- Page Range / eLocation ID:
- 660 to 671
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1093/jhered/esae048
