Chapter 13 Mating Systems
Terms in this set (31)
Polygyny: what conditions does it occur in?
One males and many females. Occurs when resources are clumped (resource or female defense) or uniform (male dominance). Female biased care is favoured.
What is male dominance polygyny?
Males with advertise to females in an area, and females decide who to mate with. This occurs when resource defence is not possible (uniform)
multiple males providing care to a female's offspring. Seen in clumped environmental and male biased parental care.
Both male and female biased care. No pairs, both males and females have multiple partners. Occurs in a indefensible (uniform) environment, that does not allow for social living.
What is the different between polygynandry and promiscuity?
Polygynandry had stable social bonds or associations, so the individuals will remain in a group for a period of time. This does not happen in promiscuity.
Study: mating systems of reed warblers
Q1: how does habitat quality (food resources) correlate with mating system?
Q2: how are habitat quality and mating system related?
M: rubric to measure habitat quality (poor, medium good)
looked at species, habitat quality, mating system, and male parental care and created phylogeny
R: found 3 mating systems (monogamy, polygyny, promiscuity) and varying amount of parental care.
Poor habitat quality favoured monogamy and high male parental care. M/G quality favoured polygyny and promiscuity and reduced male parental care.
Study: mating system of European badgers
Q: what is the mating system of European badgers?
M: observed over many generations, collected info about social associations and blood samples
R: mostly multiple males and females matin with each other (varying number of males and females per group) = polygynandry
What is scramble competition?
The indirect competition of individuals to find and secure copulations with multiple mate (little decision making, tends to exist in promiscuous systems).
STUDY: scramble competition and red squirrels
Q: what is the mating system of red squirrels?
M: marked individuals and collected blood samples, recorded mating chases and copulations
R: females copulated with high numbers or males and most litters were sired by multiple males
C: promiscuous mating systems with scramble competition
Social mating system
Based on observations of social associations among the sexes
Genetic mating system
based on the actual number of sexual partners that contribute to a set of offspring (DNA)
copulations that occur outside established social associations
Genetic quality hypothesis
females that engage in multi-male matings can improve fitness of offspring via genetic mechanisms (e.g. mating with a male that is not her partner that is more genetically fit)
STUDY: extra-pair mating in juncos
P: extra-pair offspring will be more fit
M: measured # number of children that offspring had (F2 generation)
R: for both males and females, extra-pair offspring had more offspring themselves (more fit)
Supports genetic quality hypothesis
STUDY: marmot extra-pair mating
P: extra-pair offspring will be more fit
M: measured survival probability and probability of being dominant in young
R: probabilities higher in EPY
VIDEO: Why sexual reproduction?
Sexual reproduction provides genetic diversity, so if there is a challenge in the environment, it is advantageous. Have evolve to make sex enjoyable because it's advantageous. Males provide genetic diversity. If environment is stable, asexual reproduction will do well.
STUDY: california mouse monogamy
Q: how male parental care affects reproductive success
M: male absent and male present condition, by removing male after birth, measured young born to female
R: more young survived in male present condition
C: male parenting is beneficial (provide warmth and protection)
STUDY: monogamy and biparental care in poison frogs
2 types of frogs R. imitator (monogamous) and R. variabilis (promiscuous)
Why different mating systems?
H: resources limited, monogamy evoles
M: small and large pools of tadpoles, with or without feeding
R: high survivorship in large pools
high survivorship in small pool with care
C: need for this care favours monogamy
territorial cooperation hypothesis
two individuals (one of each sex) can better defend a critical resource needed for reproduction
mate guarding hypothesis
selection favours males that mate with and guard one female over one or more reproductive cycles by remaining in close association with her
STUDY: Monogamy without biparental care in snapping shrimp
One done with single or pair residents and female or male intruders. Found that females in pairs won more than single females. Second, single male intruder put in when a female is close to sexually receptivity or not. Found males with high value female won more than low value female.
C: monogamy favoured, supports both the territorial cooperation hypothesis and the mate guarding hypothesis.
STUDY: resource or female defense polygyny
STUDY: Female defence polygyny in horses
studied bands of horses over 3 years and found they all use the same area at different times. Therefore: female defence not resource defence.
Polygyny threshold model
A model that predicts the occurrence of polygyny based on the amount of resources available to females in male territories. So, females will mate polygynously when benefits of access to resources out weigh the cost of sharing them with other females
STUDY: Polygyny threshold model in black birds
High and low quality territories for males to defend. 12 out of 14 females nested in HQ area.
C: benefit outweighs cost. female mating success varies less than male mate success in polygyny.
STUDY: Resource defence polygyny in carrion beetles
looking to see if variation in aggression in sexes indicates resource defence. Had 2 males and females of different sizes. Females had equal mating success, but large male had more children than small male.
C: resource defence.
all males can benefit by aggregating in a location where they are likely to encounter many females. Removal of some males from a hotspot will not affect attractiveness of hotspot.
males can increase their encounter rate with females by aggregating near an attractive male. The removal of a hotspot will decreased the attractiveness of a lek to both males and females. The removal of lower quality males will effect only males.
STUDY: Lekking behaviour in great snipe (bird). Which hypothesis is right, hotspot or hotshot?
Studied leks, removed individuals and observed other males. When dominate male removed, territory was unoccupied. When subdominant or subordinate males were removed, spaces were filled.
C: hotshot hypothesis
STUDY: peafowl leks
Studying which hypothesis is right looking at BOTH male and female behaviour. Found that when males removed, floaters took their spots and began displaying. Females found new males just as attractive.
C: hotspot hypothesis
What is the 3 phase hypothesis for role-reversed species in polyandry?
1. Male parental care is biased (females need to spend more time feeding if poor resources or spend time in defence or aggression).
2. Development of polyandry is the evolution of high females fecundity (females can lay more eggs than a single male can parent, therefore fitness depends on number of mates).
3. Increased competition for mates among females (males become limiting resource and competition favours fight ability and aggression).