RT Journal Article SR Electronic T1 Evolution of sex chromosomes is prior to speciation in the dioecious Phoenix species JF bioRxiv FD Cold Spring Harbor Laboratory SP 033365 DO 10.1101/033365 A1 Emira Cherif A1 Salwa Zehdi-Azouzi A1 Amandine Crabos A1 Karina Castillo A1 Nathalie Chabrillange A1 Jean-Christophe Pintaud A1 Amel Salhi-Hannachi A1 Sylvain Glémin A1 Frédérique Aberlenc-Bertossi YR 2015 UL http://biorxiv.org/content/early/2015/12/01/033365.abstract AB Understanding the driving forces and molecular processes underlying dioecy and sex chromosome evolution, leading from hermaphroditism to the occurrence of male and female individuals, is of considerable interest in fundamental and applied research. The genus Phoenix, belonging to the family Arecaceae, consists of only dioecious species. Phylogenetic data suggests that the genus Phoenix diverged from a hermaphroditic ancestor shared with its closest relatives. Here we investigated the evolution of suppressed recombination within the genus Phoenix as a whole by extending the analysis of P. dactylifera sex-related loci to eight other species within the genus. We also performed a phylogenetic analysis of a date palm sex-linked PdMYB1 gene in these species. We found that X and Y sex-linked alleles clustered in a species-independent fashion. Our data show that sex chromosomes evolved before the diversification of the extant dioecious species. Furthermore, the distribution of Y haplotypes revealed two male ancestral paternal lineages which may have emerged prior to speciation.