Explain male heterogamety.

Explanation

Heterogamtic Males : In this method of sex determination the males are heterogametic producing dissimilar gametes while females are homogametic producing similar gametes. It is of kinds XX-XO type and XX-XY type.
(i) XX-XO Type: Eg. Cockroaches and grasshoppers.
(a) The female with two X chromosomes are homogametic (XX) while the males with only one X chromosome are heterogametic (XO).
(b) The presence of an unpaired X chromosomes determines the male sex. The males with unpaired 'X' chromosome produce two types of sperms, one half with X chromosome and other half without X chromosome.
(c) The sex of the offspring depends upon the sperm that fertilizers the egg.

(ii) XX-XY type (Lygaeus Type) : This method of sex determination is seen in huma beings and in Drosophila.
(a) The females are homogametic with XX chromosomes, while the males are heterogametic with X and Y chromosome.
(b) Homogametic females produce only one kind of egg, each with one X chromosome, while the heterogametic males produce two kinds of sperms some with X chromosome and some with Y chromosome.
(c) The sex of the embryo depends on the fertilizing sperm. An egg fertilized by an 'X' bearing sperm produces a female, if fertilized by a 'Y' bearing sperm, a male is produced.