Sexual dimorphism

condition where the two sexes of the same species exhibit different characteristics beyond the differences in their sexual organs

sex chromosome in the XY sex-determination system

sex chromosome present in both sexes, of species in which the male is the heterogametic sex

species of bird

thumb|Gynandromorph of Athyma inara inara thumb|Gynandromorph of the common blue butterfly (Polyommatus icarus)

Virilization or masculinization is the biological development of adult male characteristics in young males or females. Most of the changes of virilization are produced by androgens.

difference between males and females

biological rule in allometrics, concerning the relationship between the extent of sexual size dimorphism and which sex is larger

Sexing or gender identification is the process of determining the sex of an individual animal. Through sexing, biologists and agricultural workers determine the sex of livestock and other animals they work with. The specialized trade of chick sexing has a particular importance in the poultry industry.

results of sexual differentiation that are intermediate between male and female poles

thumb|Danaus chrysippus showing hair-pencil at the end of the abdomen Hair-pencils and coremata are pheromone signaling structures present in lepidopteran males. Males use hair-pencils in courtship behaviors with females. The pheromones they excrete serve as both aphrodisiacs and tranquilizers to females as well as repellents to conspecific males. Hair-pencil glands are stored inside the male until courtship begins, at which point they are forced out of the body by sclerotized levers present on the abdomen. Coremata (the singular form being corema) are very similar structures. Their exact defi