Evolutionary dynamics of Anolis sex chromosomes revealed by sequencing of flow sorting-derived microchromosome-specific DNA
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Squamate reptiles show a striking diversity in modes of sex determination, including both genetic (XY or ZW) and temperature-dependent sex determination systems. The genomes of only a handful of species have been sequenced, analyzed and assembled including the genome of Anolis carolinensis. Despite a high genome coverage, only macrochromosomes of A. carolinensis were assembled whereas the content of most microchromosomes remained unclear. Most of the Anolis species have homomorphic XY sex chromosome system. However, some species have large heteromorphic XY chromosomes (e.g., A. sagrei) and even multiple sex chromosomes systems (e.g. A. pogus), that were shown to be derived from fusions of the ancestral XY with microautosomes. We applied next generation sequencing of flow sorting-derived chromosome-specific DNA pools to characterize the content and composition of microchromosomes in A. carolinensis and A. sagrei. Comparative analysis of sequenced chromosome-specific DNA pools revealed that the A. sagrei XY sex chromosomes contain regions homologous to several microautosomes of A. carolinensis. We suggest that the sex chromosomes of A. sagrei are derived by fusions of the ancestral sex chromosome with three microautosomes and subsequent loss of some genetic content on the Y chromosome.
KeywordsXY sex chromosomes Sex determining (SD) genes Squamata Reptilia
Compliance with ethical standards
The work was supported by the Budget Projects 0310-2014-0003, 0310-2014-0008, 0310-2014-0009 provided to Vladimir A. Trifonov, partly by RSF Grant No. 16-14-10009 provided to A. Graphodatsky, and by the funds provided by Ministry of Education, University and Research (Italy) (“Ricerche di citogenetica molecolare sui sistemi di determinazione del sesso nei rettili squamati, sottordine Sauria”; Grant number: PRIN2009/20093HYH97) to Vincenzo Caputo Barucchi.
Conflict of interest
The authors declare they have no competing interests.
This article does not contain any studies with human participants or animals performed by any of the authors.
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