@article{e34f327543f144c2a6ffece36e72b0d6,
title = "Extreme heterogeneity in sex chromosome differentiation and dosage compensation in livebearers",
abstract = "Once recombination is halted between the X and Y chromosomes, sex chromosomes begin to differentiate and transition to heteromorphism. While there is a remarkable variation across clades in the degree of sex chromosome divergence, far less is known about the variation in sex chromosome differentiation within clades. Here, we combined whole-genome and transcriptome sequencing data to characterize the structure and conservation of sex chromosome systems across Poeciliidae, the livebearing clade that includes guppies. We found that the Poecilia reticulata XY system is much older than previously thought, being shared not only with its sister species, Poecilia wingei, but also with Poecilia picta, which diverged roughly 20 million years ago. Despite the shared ancestry, we uncovered an extreme heterogeneity across these species in the proportion of the sex chromosome with suppressed recombination, and the degree of Y chromosome decay. The sex chromosomes in P. reticulata and P. wingei are largely homomorphic, with recombination in the former persisting over a substantial fraction. However, the sex chromosomes in P. picta are completely nonrecombining and strikingly heteromorphic. Remarkably, the profound degradation of the ancestral Y chromosome in P. picta is counterbalanced by the evolution of functional chromosome-wide dosage compensation in this species, which has not been previously observed in teleost fish. Our results offer important insight into the initial stages of sex chromosome evolution and dosage compensation.",
keywords = "Dosage compensation, Poeciliids, Recombination, Y degeneration",
author = "Iulia Darolti and Wright, {Alison E.} and Sandkam, {Benjamin A.} and Jake Morris and Bloch, {Natasha I.} and Marta Farr{\'e} and Fuller, {Rebecca C.} and Bourne, {Godfrey R.} and Larkin, {Denis M.} and Felix Breden and Mank, {Judith E.}",
note = "Funding Information: comments and suggestions on the manuscript, and K. Hughes and J. Travis for assistance in field collections. We acknowledge the use of the University College London Legion High Performance Computing Facility in the completion of this work. This work was supported by the European Research Funding Information: Council (Grants 260233 and 680951 to J.E.M.), the Biotechnology and Biological Sciences Research Council (PhD Grant BB/M009513/1 to I.D.), and a Canada 150 Research Chair (to J.E.M.). The CEIBA Biological Center partially subsidized our expenses during field collection in Guyana. Funding Information: We thank P. Almeida, A. Corral-Lopez, B. Furman, D. Metzger, J. Shu, W. van der Bijl, and two anonymous reviewers for helpful comments and suggestions on the manuscript, and K. Hughes and J. Travis for assistance in field collections. We acknowledge the use of the University College London Legion High Performance Computing Facility in the completion of this work. This work was supported by the European Research Council (Grants 260233 and 680951 to J.E.M.), the Biotechnology and Biological Sciences Research Council (PhD Grant BB/M009513/1 to I.D.), and a Canada 150 Research Chair (to J.E.M.). The CEIBA Biological Center partially subsidized our expenses during field collection in Guyana. Publisher Copyright: {\textcopyright} 2019 National Academy of Sciences. All rights reserved.",
year = "2019",
month = sep,
day = "17",
doi = "10.1073/pnas.1905298116",
language = "English (US)",
volume = "116",
pages = "19031--19036",
journal = "Proceedings of the National Academy of Sciences of the United States of America",
issn = "0027-8424",
publisher = "National Academy of Sciences",
number = "38",
}