Sexual dimorphism describes differences in the physical characteristics of the two sexes (beyond sex organs)
- These differences may be subtle or exaggerated, and include size, colours, markings and behaviours
Sexual dimorphism has evolved as a result of differential mate selection in males and females of a species
- Exaggerated traits (ornaments) are more likely to attract female attention, despite increasing exposure to predators
- Over many generations, these traits have become more pronounced, leading to marked differences between sexes
Examples of sexual dimorphism can be seen in a number of animals:
- Many species of birds show clear differences between males and females of the species (e.g. peacock and peahen)
- Male and female deer can be differentiated by the presence of large antlers on the male stags
- Even humans demonstrate clear sexual dimorphism (e.g. facial hair and other secondary sex characteristics)
Sexual Dimorphism in Birds
