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How did the guppy Y chromosome evolve?
Deborah Charlesworth1, Roberta Bergero1, Chay Graham2
1Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom.
Plos Genetics
|August 9, 2021
Summary
Sexually antagonistic mutations in guppies drive the evolution of new Y chromosomes, explaining why they still recombine. This contrasts with genetic degeneration seen in related species.
Area of Science:
- Evolutionary genetics
- Sex chromosome evolution
- Population genetics
Background:
- Many species exhibit suppressed genetic recombination between sex chromosomes, unlike autosomes.
- This suppression is hypothesized to result from natural selection favoring linkage of sex-determining genes with sexually antagonistic mutations.
Purpose of the Study:
- To investigate the evolutionary dynamics of sex chromosomes in guppies, particularly regarding suppressed recombination and sexually antagonistic mutations.
- To explain the unique recombination patterns observed in the guppy Y chromosome despite the presence of sexually antagonistic traits.
Main Methods:
- Comparative analysis of guppy sex chromosomes with related species.
- Investigation of genetic degeneration patterns in Y chromosomes.
- Examination of recombination frequencies in the guppy sex chromosome pair.
Main Results:
- Guppies exhibit sexually antagonistic mutations affecting male coloration.
- Unlike related species with degenerated Y chromosomes, guppy Y chromosomes show occasional recombination with X chromosomes.
- Evidence suggests a recent evolution of a new Y chromosome in guppies, replacing an older, degenerated Y.
Conclusions:
- The evolution of a new Y chromosome in guppies explains their retained recombination capacity.
- Sexually antagonistic mutations likely played a role in the evolution of the guppy Y chromosome.
- The evolution of male-specific gene expression provides an alternative mechanism to resolve sexual conflict, distinct from recombination suppression.
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