Sexual Selection

1. Sexual Selection By: James Schadenberg, MJ Pinheiro, Chad Gopauland Amy Van Asseldonk

2. What is Sexual Selection? • Sexual Selection is the favouring of any trait that specifically enhances the mating success of an individual. • This often leads to female and male species displaying behaviours and appearances that are unique to each other.

3. Two Forms of Sexual Selection • Intrasexual Selection: When members of the same species compete with each other for mating opportunities. Intrasexual selection often involves fighting, so the members of the species that are more physically developed will have the advantage. • Intersexual Selection: When females of a species choose the male based on their genetic makeup. They generally chose the more attractive male so that the positive traits are passed onto their offspring.

4. Intrasexual Selection • When members of the same gender (and same species) compete with each other in order to mate with the female they both want • Intrasexual selection often involves fighting, so species will adapt and develop better defensivetactics to try to beat out their competition • Sometimes intrasexualselection occurs after mating because the male wants to make sure the babies are laid safely

5. Intrasexual Examples • Elephants: Fighting over who gets to mate with the female • Dragonflies protecting their mate after intercourse to ensure that the female does not re-mate before laying her clutch of eggs Video: Elephants fighting over a mate

6. Intersexual Selection • Also known as female choice • Female chooses a male based on certain ornaments, example; peacocks colourful tail, colourful birds, etc. • Ornament often does not benefit the male (colour attracts predators) • Females prefers larger, brighter ornaments because those traits will be passed onto their offspring

7. Intersexual Example • Male peacocks have bright colours to attract females • Big horned sheep have big horns to attract females. They are also used to fight other males Video: Male peacock showing off bright feathers

8. In Summary… • Sexual selection is the favouring of any trait that helps an animal mate with another animal • Intrasexual selection: When members of the same gender and species compete with one another in order to mate with the female they both wantexample: elephants, dragonflies • Intersexual selection: Females choose a male based on certain ornaments, i.e. Colourful feathers, large horns, etc.example: peacocks, big horned sheep