Lecture 10 - mating systems Flashcards
what does mating system classification encompass?
Copulation behaviour
Social organisation
Parental care system
Competition for mates
what is monogamy and what animals is it seen in?
1 male and 1 female
- most birds a few mammals and fish
how many socially monogamous birds and also genetically monogamous?
<25%
- splendid fairy wren has about 70% of chick in its nest fathered by males not caring for them
what is polygyny and what animals is it seen in?
1 male and >1 female
- few birds, most mammals
what is simultaneous polygyny?
e.g. red winged blackbird- has a large territory with lots of females and breeds with them all at the same time
what is successive/sequential polygyny?
e.g orangutan - meets breifly with a female and then moves on - this is the most pro-dominant mating system in mammals
what is polyandry and what animals is it seen in?
1 female and >1 male
few birds, fish and mammals
examples of successive and simultaneous polyandry?
successive - spotted sandpiper - flies to many males nests lays eggs and moves on
simultaneous - painted snipe - sex role reversal - females have impressive secondary sexual characteristics
what is polygynandry and what animals is it seen in?
> 1 female and >1 male Few birds, few mammals, many fish, reptiles and amphibians
can species how more than one mating system?
yes e.g. dunnocks show monogamous, polyandrous and polygynandrous systems
describe the reproductive potential of males and females
male reproductive potential > females reproductive potential
- males are limited by access to females
- females are limited by access to resources
what is the general model for the evolution of mating systems?
ecology e.g. resource distribution -> female dispersion -> male dispersion
resource defence effects male dispersion
the interaction between female and male dispersion affects the mating system
what is resource defence polygyny and an example
- males defend key resources wanted by females
- tent making bats - Males construct and defend roosting tents which house harems of females
what does female monopolisation by males and hence mating systems depend on?
- female group size
- female range size
what mating systems occur if females live solitarily but have a defendable range size?
- if there range is small polygyny often occurs where one male had a large range with more than one female in it
- if the females range is larger monogamy often occurs where the male defends a range the same size as one female
what mating system occurs females live solitarily but their range is not defendable?
scramble competition polygyny occurs e.g. like the orangutan - males only come into contact with females for a short period of time
what mating systems occur if females live socially and have a defendable range size?
- in small groups you get uni-male polygyny - one male dominates many females
- in large groups you get multi-male polygyny - many males and many females
what mating systems occur if females live socially but have a large range size not defendable?
Males may aggregate in leks when competition for females is intense - males produce no resources -> extreme sexual selection occurs
what does the lek formation show under the general model?
male dispersion relies heavily on female dispersion
describe the mating system experiment on blue headed wrasse to provide evidence that resources determine female dispersion which in turn determines male dispersion
Females- Forage over large overlapping ranges
Spawn daily at predictable, favoured sites
Males- Can’t defend females
Compete for and defend spawning sites
experiment - Removed males, replaced with new males
=22/24 sites still used, no new sites
- Removed females, replaced with new females
= 11 sites lost, 10 new ones
results showed that if females stayed in the same place males continue to defend them but if the females move so do the males
spawning sites -> female dispersion -> male dispersion
describe the grey sided vole experiment
1) - added food and females range changed - showed that females range/ dispersion was affected by food distribution - males also converged on food
2) captive females and radio tracked males - showed that female dispersion determines male dispersion
3) captive males and radio- tracked females - proved the only thing affecting male dispersion was the female dispersion
how does the reproductive potential of male and females vary?
- males have a lot more variance in reproductive success than females e.g. elephant seal - one beach master but other males done get many copulations
what can effect the general model of mating systems?
if males provide alot of parental care less can be invested into mating - for females these males are a very important resource - affects the female behaviour as they try and monopolise the care the males can offer
explain sexual conflict over mating systems
- Males ‘prefer’ polygyny
- Females may ‘prefer’ polyandry if they get more/better resources (e.g. paternal care)
- In many species, monogamy occurs as a compromise between conflicting interests of the sexes
what did the yellow bellied marmot experiment show about sexual conflict over mating systems?
Females raise more offspring in small groups
Males raise more offspring in large groups
- in large groups the females have to share the males resources
describe female enforced monogamy in burying beetles
- Female and male make a nest containing a corpse, and then care for offspring.
- Males attempt to attract additional females, females try to prevent them doing so
