What drives sex chromosome turnover? However, we have not yet confirmed that spine length is a sexually antagonistic trait or identified any genes with sexually antagonistic alleles on the ancestral autosome chromosome 9 of the Pacific Ocean population. While the female-specific Sxl message encodes a protein of amino acids, the male-specific Sxl transcript contains a translation termination codon UGA after amino acid
However, only in rare cases in some fishes and amphibians do individuals with phenotypi-cally redetermined sex produce gametes opposite to their genoty-pic sex. Received Dec 1; Accepted May 8. In the highest group of plants, the seed-bearing plants, the female organ is the pistil pistilone of the four basic parts of a flower, the central structure around which are arranged the stamens, the petals, and the sepals.
J Fish Biol. Biol J Linn Soc.
Similarly, two overlapping sub-species of Eigenmannia have non-homologous sex chromosomes; E. Genomic degradation of a young Y chromosome in Drosophila miranda. Alves et al. Sex chromosomes and sexual selection in Poeciliid fishes.
Summary An excellent candidate for the master sex-determining gene on the Y chromosome of the medaka fish is not related to the mammalian SRY gene. If a homogametic parent is heterozygotic for a lethal gene that is borne by one of the homologous sex chromosomes X or Z , half of the heterogametic offspring will die, having received a lethal gene whose destructive effect in the genotype will not be opposed by the normal allele.
Arrows represent activation, while a block at the end of a line indicates suppression.