How genotype specify sex phenotype

Sex determination results in the development of individuals with characteristics that allow them to be identified as males, females, or in some cases, hermaphrodites. In certain species, like the solid nematode C. elegans, differences in sexual characteristics can be very small; in fact, in C. elegans, the only distinguishing sexual characteristic is the presence of a testis versus an ovotestis. In other species, the phenotypic differences between the sexes can be quite significant. Consider, for example, the remarkable plumage and display of a tom turkey versus the rather plain features of a female turkey. Female and male mammals are also readily distinguished by many differences in their internal and external phenotypes, behavior, and metabolism. The first major breakthrough in understanding sex determination was the discovery of sex chromosomes in the early 1900s. From meticulous analyses of male and female insect chromosomes, scientists discovered that, although most chromosomes were present in equal numbers in both males and females, there were one or two additional chromosomes that were unequally represented in the two sexes. Analyses of additional species over the years has revealed that chromosomal differences are primarily responsible for sex determination in most animals. #sexDetermination #GenderDetermination #genetics #XChromosome #SexChromsomes