Mating Systems Flashcards
(29 cards)
what is a mating system?
ensemble of behaviours and physical adaptations specific to mating
-ways in which animal societies are structured in relation to sexual behaviour
Batemans gradient
difference between male and female - males usually higher
what are the two major factors of mating systems?
- male parental care
2. distribution of resources in time and space
females are a ____ ____ to males.
why?
scarce resource
F with eggs, gestation, lactation.
M only sperm
Why is there a difference in parental care between sexes?
F = definite biological parent M = not definite
Female distribution theory
males respond spatially to what females are doing.
What are the 2 kinds of sexual selection?
Define each
Intersexual selection
-female choice of traits to increase attractiveness to opposite sex
Intra selection
-male male comp. through fighting, territory defence, dominance hierarchies
Why are males usually larger?
intrasexual selection
why care about sexual selection?
sexual selection can favour traits which otherwise would be disadvantageous to the males
ex. really large antlers
Define runaway selection
traits that actually negatively impacts the species
handicap hypothesis
male’s handicap must be honest and linked to overall genetic fitness
The intensity of sexual selection depends on what?
operational sex ratio
- M:F mating ratio
- Extent to which individuals can defend or monopolize matings with females
List and describe 2 types of Monogamy
- social - observable pairing
- genetic = offspring fathered by mate
* rare, primates, carnivora, rodentia
example of monogamy in mammals?
why?
prairie voles
increased vasopressin in brain triggered by copulation.
Extra DNA on the ViaR gene
Has to be in that exact location
WHY are prairie voles monogamous?
All of the noted factors contribute!!
- vasopressin
- extra DNA on V1aR gene
- males with more offspring if they stick to mate and prevent others
- ancestors benefited from monogamy
Polygyny
individual male mates with multiple males
Polygamy
more than one mate, either way
What are two examples of defence polygyny
- resource
- males defend resources that females need - hippos - female
- males defend females that are clumped. -elephant seals
Non-defence polygyny
- dominance hierarchy
- males compete for dominance - most dominant gets F - scramble competition
- males with best ability to find males are successful
Describe leke polygyny
males compete for small territories in preferred locations “arenas” where F come for copulations
Polyandy
Females with more than one mate
- wild dogs
- male care is crucial
- F have more offspring survive
Two mating types that are characterized by promiscuity
polygynandry
polyandrogyny
2 types of post-copulatory sexual selection?
- cryptic female choice
2. sperm competition
How to reduce sperm competition?
order effect macho sperm mate guard copulatory plugs infanticide
