Evolutionary patterns of sex chromosome systems in crickets: an integrated analysis using cytogenetics and genomics

Abstract

The analysis of experimental models for knowledge of sex chromosomes evolution progressively advance and currently the molecular cytogenetic and genomic data has been explored for this proposes. In crickets, although few species have been studied at chromosomal point to view the group presents a wide diversity of sex determination chromosomal systems, occurring X0/XX, neo-XY/XX, neo-X1X2Y/X1X1X2X2 and X1X20/X1X1X2X2, originated by distinct chromosomal rearrangements between autosomes and sex chromosomes. Due the occurrence of distinct mechanisms, in distinct stage of differentiation, the crickets could be good experimental model to the understanding of origin/diversification of sex chromosomes. Thus, the objective of this work is to analyze the structure and evolutionary patterns of distinct sex chromosome systems based in the analysis of distinct repetitive DNAs, such multigene families, satellite DNAs, microsatellites, transposable elements, microdissection and chromosome painting, besides the use of genomic data obtained by sequencing. The model species are Gryllus assimilis (X0), Cicloptyloides americanus (X1X20), Neometrypus badius (neo-XY) and Eneoptera surinamensis (neo-X1X2Y), being E. surinamensis the main biological model. The possibility of the integration of genomic (such as, for example, whole sequenced genomes and isolation of sequences specifically from sex chromosomes) and chromosomal data (obtained from classical cytogenetics and physical chromosome mapping) became real with the advent of new technologies. The possibility of association of these data in crickets, mainly in E. surinamensis will permit a deeper knowledge related to the structure, molecular composition and evolution of sex systems in Orthoptera. These data will permit the proposition of new hypothesis that raise the origin/evolution of derived sex chromosomes and the test of them.