BOHA - 12 Flashcards
what are the 5 types of mating systems?
1) monogamy
2) polygamy
3) polyandry
4) polygyny
5) polygynandry
2 explanations for monogamy in birds?
- 2 parents can double the feeding rate of their offspring
- Males are forced into this situation by lack of opportunity
describe a situation where polygyny is more likely to occur?
if food is spatially clumped, females will also be clumped and hence monopolisable by males
what 2 evolutionary constraints mean most mammals are polygynous?
1) only females lactate so hard for males to rear offspring
2) internal fertilisation so male can abandon female
what are the 3 main types of polygyny?
1) female defence e.g lion with 9 lionesses
2) resource defence e.g. gains every females that enters their territory
3) lekking - skewed male reproductive success
what is lekking?
a traditional place where males assemble during the mating season and engage in competitive displays that attract females
what are the 4 hypotheses for why lekking occurs?
1) hotspot hypothesis: leks are where females pass/congregate
2) hotshot hypothesis: poor males congregate around higher quality males
3) female preference hypothesis: females select more quickly from congregated males
4) kin selection hypothesis: related males congregate (indirect benefits)
what is polyandry and an example of a species where this occurs?
where one female pairs with several males - Jacana - reversed sexual dimorphism
what is double clutching?
females lay eggs in multiple locations and leave males to sit/look after them
what is polygynandry and an example of a species that practices this?
2 + males and 2+ females = Dunnocks have very variable mating systems
in humans why would it every pay for a female to pair with an already paired male?
the polygyny threshold model - The model shows how females may gain a higher level of biological fitness by mating with a male who already has a mate. The female makes this choice despite other surrounding males because the choice male’s territory, food supply, or other important characteristics are better than those of his competitors, even with two females on the territory
describe the difference between mating systems in the san bushman tribe and the Ache Indians
san bushman = very low extra pair maternity
Ache Indians = women have primary, secondary and tertiary husbands
