Mating Systems

What is a mating system?

How individuals obtain mates, the number of mates, characteristics of pair bond, and extent of parental care.

Why did the views on mating systems change?

DNA fingerprinting.

What is the classical approach to classification of mating systems?

This takes into account dispersion of females and parental care (males essential).

Resource dispersion, predation, and benefits/costs of social living lead to female dispersion which leads to make dispersion.

What is polygyny and what animals practice it?

Males pair with 2 or more females, and provide little to no parental care.

Most mammals exhibit this, like elephant seals.

When should females choose polygyny?

If they can gain more resources in a polygynous mating situation.

What are the predictions of the Polygyny Threshold Model and who developed it?

1. Settle high quality territories first.

2. Secondary females on high quality territories do better than monogamous on poor territories.

Orion developed this.

What is an example of the Polygyny Threshold Model?

Female lark buntings choose polygyny over monogamy to gain high quality nest sites.

Secondary females had equal reproductive success to monogamous females with less shade.

What is an experiment testing polygyny?

Adding nest boxes to floodplain territories increased territory quality and induced polygyny in Prothonotary Warblers.

Polygynous females were as successful as monogamous females.

What is female defense polygyny?

This happens in stable groups with undefendable ranges where the males are short-lived so there is high competition.

Seasonal harems are formed.

What are some examples of groups that display female defense polygyny?

Elk, deer, and elephant seals.

What are some characteristics of female defense polygyny?

Females live in groups for protection, in larger groups females produce fewer young, and male reproductive success increases with group size.

What are characteristics scramble competition polygyny?

Females and resources needed are widely dispersed.

It is not economical to defend.

Females are only receptive for a few days or hours.

What is an example of scramble competition polygyny?

In wood frogs, breeding is limited to a few nights each year.

What are characteristics of lek polygyny?

There are no resources or pair bonds so females are choosy.

Females have large ranges or high population densities.

What are models that explain how leks form?

1. Hot spot model

2. Female preference model

3. Hotshot model

What is the hot spot model and what are predictions?

Males cluster because females travel along certain paths.

1. Males aggregate where they are most likely to encounter females.

2. If you remove attractive males, someone will fill the spot.

What is an example of the hot spot model?

Sage Grouse leks occur near highest densities of nesting females.

What is the female preference model and what are its predictions?

Males cluster because females want to shop around.

1. Larger leks attract more females.

What is an example of the female preference model?

Uganda kob female attendance at leks is proportional to number of males displaying there.

What is the hotshot model and what are its predictions?

Subordinates cluster around attractive males to improve chances of getting a mate.

1. Females are attracted by males not location.

2. Removal of hotshot causes subordinates to desert.

3. Removal of subordinates causes vacant spots to be filled.

What is an example of the hotshot model?

Black Grouse territories with the biggest number of copulations shift each year.

What is an experiment that tests the hotshot model?

Researchers covered dominant male Fallow Deer territories with plastic, but the dominant males still attracted more females.

What is monogamy and what animals display it?

Males and females cooperate to rear young and the life bonds are seasonal or life long.

Its common in birds.

What are some hypotheses as to why animals choose monogamy?

1. Male assistance hypothesis

2. Mate-guarding hypothesis

3. Female enforced hypothesis

4. Infanticide hypothesis

What are some characteristics of the Mate Assistance Hypothesis and what animals display this?

Male help greatly increases offspring survival.

Displayed by seabirds and birds of prey.

What is an example of the MAH?

Seahorse males can only carry one female’s eggs at a time, and there is no benefit to multiple matings or mate switches.

What is an experiment testing the MAH?

Researches widowed females causing them to produce one less chick pre brood.

What are characteristics of the Mate-guarding hypothesis?

Females left unguarded may be fertilized by another male.

This happens when females are receptive after mating, and they are scattered and difficult to locate.

What is an example of the MGH?

Receptive female clown shrimp are hard to find and only for a narrow amount of time.

What are characteristics of the Female Enforced hypothesis?

Females drive off other females or prevent males from advertising.

There is female-female aggression.

What is an example of the FEH?

Burying Beetles bury carcasses which the young will feed on, males attempt to attract other females, and females attack mates to prevent competition.

What is an experiment testing FEH?

Male burying beetles that are mates of tethered females emitted more pheromones.

What is an example of dual enforced monogamy?

Cleaner Wrass males and females are territorial and keep same-sex members away from their partners.

What are characteristics of the Infanticide hypothesis?

Males drive other males away to prevent infanticide.

What is an example of the IH?

Prairie Vole males drive away potential infanticidal males.

What is polyandry and who performs it?

Females mate with more than one male, or when they have extra-pair copulations.

Birds.

What are the different types of polyandry?

Cooperative polyandry and sequential polyandry?

What are characteristics of cooperative polyandry and what are examples?

Happens in harsh environments, and 2 or more males help females raise young.

Galapagos Hawks display this.

What are characteristics of sequential polyandry?

There is sex role reversal where females lay clutches with different males, several males nest on one female territory, and females commit infanticide.

What are hypotheses that explain why animals choose polyandry?

1. Good Genes

2. Genetic compatibility

3. Fertility insurance

4. More resources

5. More care

6. Better protection

7. Infanticide reduction

What is the good genes hypothesis?

Female mates with 2+ males because her partner is lower quality genetically.

What are experiments that tested the GGH?

Female Blue Tits uninfected with malaria are more likely to seek EPCs when mated to an infected male.

Female Cavys produced fewer surviving pups when restricted to a single mate.

What is the genetic compatibility hypothesis?

Mating several males increases genetic variety, which boosts chance that some sperm is unusually compatible.

What is an example of GCH?

Female pseudoscorpions prefer to mate with different males as it increases number of nymphs.

Which genders benefit most from which mating system?

Females benefit most from polyandry, males benefit most from polygyny.