Sexual Dimorphism: The physical differences between males and females of a species. For example, in peacocks, males have vibrant feathers while females have more muted colors.
Intrasexual Competition: Competition among individuals of the same sex for access to mates. This can involve direct confrontation or indirect strategies like displaying attractive traits.
Parental Investment: The effort and resources an individual invests in raising offspring. It varies between genders and can influence mate preferences.