Sexual SelectionBy: James Schadenberg, MJ Pinheiro, Chad Gopaul and Amy Van Asseldonk

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.

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.

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 defensive tactics to try to beat out their competition

Sometimes intrasexualselection occurs after mating because the male wants to make sure the babies are laid safely

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

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

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 malesVideo: Male peacock showing off bright feathers

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