Sexual Selection & Communication - 19 Flashcards
What is sexual selection?
The process by which secondary sexual traits become elaborated because they increase the ability to gain mates. First coined by Darwin. Arises from struggle for possession of mate.
What are the two processes of sexual selection?
- Intra-sexual competition: competition between members of the same sex over mates
- Inter-sexual choice: choies by members of one sex for particular mating partners of the opposite sex.
What are key forms of intra-sexual competition?
Direct combat: males with large body size and weaponry selected. Sperm competition: males whose sperm successful in fertilising eggs selected.
What are key parameters in inter-sexual choice?
Usually female choice. Good genes: females choose males with characteristics that indicate high genetic quality & give offspring genes that confer high viability (survive better). Attractive sons (through process of Fisherian selection) - females choose highly attractive males, and have sons who are chosen by females in next gen.
What are results in sexual dimorphism?
Sex with higher potential reproductive rate competes for the sex with the lower potential reproductive mate. Causes sexual displays (intra-sexual competition and inter-sexual choice). info transferred via signals.
What is involved in intra-sexual competition?
Resource holding potential (RHP). Where fighting is costly, individuals should monitor RHP of their oppontent and not fight if likely to lose. Assessed through e.g. roaring rate (indicator of fitness), voice pitch.
What is involved in inter-sexual choice?
Displays function to attract mating partners of the opposite sex & provide means to choose a mate that is the best of those available. Can choose males that sing more song types, degrees of symmetry.
