Lecture 10: mating strategies Flashcards
mating systems classification encompasses:
- copulation behaviour
- social organisation
- parental care systems
- competition for mates
monogamy
1M and 1F
most birds, a few mammals and fish
__% of socially monogamous birds are also genetically monogamous
<25%
polygyny =
1 m and >1 F
-few birds, most mammals
2 forms of polygyny
- simultaneous (red-winged blackbird)
- successive/sequential (orangutan)
polyandry;
1 female and >1 male
-few birds, fish and mammals
2 forms of polyandry
- successive/sequential (spotted sandpiper)
- simultaneous (painted snipe)
promiscuity
polygynandry
- > 1 females and 1> male
- few birds, few mammals, many fish, reptiles and amphibians
do mating systems vary within a species?
YES,
dunnocks and extra pair paternity in monogamous species (adelies penguins)
humans
who has a greater reproductive potential M/F?>
MALES
reproductive potential: Males are limited by
access to females
reproductive potential: females are limited by
access to resources
General model of mating systems
ecology –> female dispersion –> male dispersion
resource defence links ecology and male dispersion
resource defence polygyny =
males defend key resources wanted by females
-e.g. tent making bats
–> males construct and defend roosting test which house harems of females
sex ration: 1M:1-37F
Clutton-Brock 1989
- supports general model, leks?
- in mammals, male parental care is rare
- female monopolisation by males and hence mating system depends on :
- -female groups size
- -female range size
female solitary: range defendable
- 60% of mammal species
- small range –> polygyny
- large range –> monogamy
female solitary: range not defendable
scramble competition polygyny
female social: range defendable:
- small groups = uni-male polygyny
- large groups = multi-male polygyny
female social: large range not defendable
large unstable groups, males may aggregate in leks when competition for females is intense
lek polygyny
ecological basis for lek formation applies across taxa
experimental evidence that resources determines female dispersion which, in turn, determines male dispersion?
- Blue-headed wrasse (Thalassoma bifasciatum) Warner 1990
- Grey-sided vole
Warner 1990 blue-headed wrasse
females = forage over large overlapping ranges, spawn daily at predictable, favoured sites
Males = can’t defend females, compete for and defend spawning sites
-spawning sites –> female dispersion –> male dispersion
Grey sided vole experiment
1) female range encompassed by male range, food added in 2 separate sites, 2 new female ranges, males also converge to these sites
2) captive females, radio tracked males, so female dispersion determines male dispersion
3) revers exp. 2, captive males, radio tracked females, no effect of M dispersion on F dispersion
reproductive potential of males is not always
realised
when M provide parental care we see a ____ in reproductive potential
reduction
males ‘___’ polygyny
prefer
females may ‘prefer’ polyandry if they get
better/more resources (e.g. parental care)
in many species, monogamy occurs as a
compromise between coflidting interests of the sexes
sexual conflict over mating system: yellow-bellied marmot
females raise more offspring in small groups
- males raise more offspring in large groups
- compromise
sexual conflict over mating system: Female enforced monogamy in burying beetles
female & male make a nest containing a corpse, and then care for offspring
-males attempt to attract additional F, F try to prevent them doing so
potential reproductive rates of sexes drives
variation
