Lectures 7, 8, and 9 Flashcards
Define socially monogomous
they pair with one mate, but might be genetically polyandrous
Define genetically polyandrous
when females “sneak” copulations outside their social pairing
What is the genetic mating system?
- may not be the same as the social mating system
- it is who you actually end up donating genetic material to (e.g., blue tits are a socially monogamous species, but 40% of the offspring come from “another man” )
Define promiscuity
the lack of any kind of social mating system, no social pair bonds.
Define monogamy
one male paired with one female. Socially, this means exclusive pair bonds. Genetically, this means that a pair exclusively reproduces with each other.
Define polygyny
males have multiple female partners, socially or genetically
Define polyandry
females have multiple male partners, socially or genetically
Promiscuity is the absence of a social mating system, which means…
- there are no ‘pair bonds’
- the individuals have multiple genetic partners. Socially promiscuous systems are often genetically polygynous
- since there are no male investment, the bulk of investment is carried by females
How does promiscuity evolve?
When the male benefits by leaving, rather than guard his mate and help with the offspring
What is an example of a promiscuous animal? What do they participate in?
Horseshoe crabs - participate in explosive breeding (meet in one spot, breed, and return to water)
What is the ecological driver of explosive breeding?
Predator satiation - predators can’t get them all if they all breed at the same time.
When can promiscuous systems arise?
Only when there is little reason for the pair to stick around each other
What is a lek?
a traditional location where multiple males display for females, waiting to be selected by a female.
What is an explosive lek?
A lek, but when lekking locations are dispersed a little more.
What is involved in lekking?
- genetic polygyny (some males mate with more than one female)
- extreme mating variance
-minority males get the majority of mating opportunities - ## female choice
What kinds of populations does lekking evolve in?
- populations whose females are widely dispersed enough that males cannot control a group of females
- populations whose offspring does not benefit from male parental investment
What is shown by the sage grouse example?
mating success in males has high variance. A few males mate with many females, while quite a few males have little to no copulation
-typical of lekking species
What are the three hypotheses for the questions: Why do leks form? Why don’t males display on their own?
- hotspots
- hotshots
- female preference
What is the hotspots hypothesis?
the males simply go where the females are.
- there isn’t great support because lek locations tend to wander a bit, which doesn’t support the idea that females congregate at a location for reasons other than lekking.
What is the hotshots hypothesis?
The idea that the hottest guys attract the most attention, so less superior males will congregate around them to get peripheral attention. An extension of satellite behaviour.
- E.g., Crickets —— satellite males (who do not call to females) hang out around calling males, they intercept the females as they respond to the calling male.
- has some evidence to support it (in snipes, if you remove the sexiest male, then the lek will center around somebody else)
What is the female preference hypothesis?
Females prefer to visit large groups of males (girls don’t want to go to a party if it’s not bumpin).
- If true: see positive relationship between the number of males and the number of responding females
- BUT: 1 to 1 ratio is not advantageous to either sex. In order for this to attract females, there needs to be an accelerating relationship, a curvilinear relationship.
True in Ruff’s graph
Not supported in Kobs graph
What does monogamy mean in both socially and genetically?
Socially: when one male is bonded to one female (fairly uncommon)
Genetically: pairs are exclusive sex partners
Define serial monogamy
moving from one monogamous relationship to another, but only being paired to one individual at a time.
In what type of animals is monogamy the main system for?
birds, some primates (humans are fairly monogamous), and termites
Define mutual mate choice
both males and females are choosy to some degree
What is an important feature to monogamous systems?
Compatibility - if you’re sticking with one individual, behavioural and genetic compatibility is key
What happened in the Oldfield mice experiement?
- a male is given two young females, and given the opportunity to choose one.
- when they were allowed to be with the female of choice, they had more reproductive success
- a new male, presented to those two females again, did not choose the previously preferred female significantly more than the other, suggesting mate choice is more about compatibility than simply choosing the superior mate (what is compatible for one male does not necessarily mean his mate would be preferred for all males)