Gonadal dysgenesis If a single or combination of these genes are mutated or deleted, downstream signalling is disrupted, leading to malformation of male external genitalia. SRY acts on gene SOX9 which drives Sertoli cell formation and testis differentiation. An absence in SRY causes SOX9 to not be expressed at the appropriate time or concentration, leading to a deficiency in testosterone and Anti-Müllerian hormone production. Inadequate levels of testosterone and Anti-Müllerian hormone disrupts the development of Wolffian ducts and internal genitalia that are key to male reproductive tract development. The lack of the male associated steroid hormones drives Müllerian duct development and perusal
Sexual conflict selection, continuous sexual conflict creates an environment in which mating frequency and male secondary sexual trait development are somewhat in step with the female's degree of resistance. It has primarily been studied in animals, though it can in principle apply to any sexually reproducing organism, such as plants and fungi. There is some evidence for sexual conflict in plants. Sexual conflict takes two major forms: Sexual conflict may lead to antagonistic co-evolution, in which one sex (usually male) evolves a favorable trait that is offset by a countering trait in the other sex. Similarly, interlocus sexual conflict can be the