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What was the ancestral sex-determining mechanism in amniote vertebrates?
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SYSNO ASEP 0461264 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title What was the ancestral sex-determining mechanism in amniote vertebrates? Author(s) Johnson Pokorná, Martina (UZFG-Y) ORCID
Kratochvíl, L. (CZ)Source Title Biological Reviews. - : Wiley - ISSN 1464-7931
Roč. 91, č. 1 (2016), s. 1-12Number of pages 12 s. Publication form Print - P Language eng - English Country GB - United Kingdom Keywords environmental sex determination ; phylogeny ; polyphenism Subject RIV EG - Zoology R&D Projects GAP506/10/0718 GA ČR - Czech Science Foundation (CSF) Institutional support UZFG-Y - RVO:67985904 UT WOS 000367985200001 EID SCOPUS 84953735051 DOI 10.1111/brv.12156 Annotation Amniote vertebrates, the group consisting of mammals and reptiles including birds, possess various mechanisms of sex determination. Under environmental sex determination (ESD), the sex of individuals depends on the environmental conditions occurring during their development and therefore there are no sexual differences present in their genotypes. Alternatively, through the mode of genotypic sex determination (GSD), sex is determined by a sex-specific genotype, i.e. by the combination of sex chromosomes at various stages of differentiation at conception. As well as influencing sex determination, sex-specific parts of genomes may, and often do, develop specific reproductive or ecological roles in their bearers. Accordingly, an individual with a mismatch between phenotypic (gonadal) and genotypic sex, for example an individual sex-reversed by environmental effects, should have a lower fitness due to the lack of specialized, sex-specific parts of their genome. In this case, evolutionary transitions from GSD to ESD should be less likely than transitions in the opposite direction. This prediction contrasts with the view that GSD was the ancestral sex-determining mechanism for amniote vertebrates. Ancestral GSD would require several transitions from GSD to ESD associated with an independent dedifferentiation of sex chromosomes, at least in the ancestors of crocodiles, turtles, and lepidosaurs (tuataras and squamate reptiles). In this review, we argue that the alternative theory postulating ESD as ancestral in amniotes is more parsimonious and is largely concordant with the theoretical expectations and current knowledge of the phylogenetic distribution and homology of sex-determining mechanisms. Workplace Institute of Animal Physiology and Genetics Contact Jana Zásmětová, knihovna@iapg.cas.cz, Tel.: 315 639 554 Year of Publishing 2017
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