Mating Systems Flashcards
Social Monogamy
Pair bonded species but there is extra
pair copulation preventing genetic monogamy.
Genetic Monogamy
True monogomy with only one reproductive partner. Birds have been found to be socially monogomous but not genetically.
Mate guarding
One reason for monogamy to ensure paternity
Lek Polygyny
communal area where 2 or more males perform courtship displays for females to evaluate. Females can go to a single lek and find a mate, but there is usually not long term bond between mated pairs.
Polygyny
male has more than one female mate
Polyandry
female has more than one male mate
Polygynandry
multiple males and females with parental
investment
Mammals (generally)
Notable for female parental investment sicne males can’t give birth or provide milk (except bats). Polygyny most common (mutliple females)
California Monogomous Mice. Why are they monogomous?
Increased offspring survival when polygynandry happens. Protect agaisnt infanticide, mate gaurd against competiiton prarie voles.
Rock Hunting Possum are spread far apart
They are monogomous (discrete range hypothesis) and can easily monit ofemales from afar.
When does monogomay make sense?
when defensible territory is possible and
mates are spread out
When does Polygamy make sense?
when mates or resources are clumped
and mates are easy to find
Give 3 theories on lek formation and the most likely evolutionary cause
- Lekking evolved likely in response to female feeding ecology.
- Hotspots hypothesis- males cluster in places where the routes to receptive females intersect
- Hotshots hypothesis- subordinate males cluster around highly attractive males in order to have a chance to interact with females and possibly to learn skills
- Female Preference hypothesis- males cluster because females prefer sites with large groups of males so they can quickly and safely compare quality
- Kin Selection Leks- in some species the leks are formed by males that are closely related brothers and half brothers. So even if only 1 or 2 males are chosen all males gain fitness though indirect selections.
(Peacocks ang Grouse)
6.Predation Protection Leks- animals join in groups- many eyes to protect against predators. Might explain why sometimes you find mixed species of leks- manakins and grouse
Explosive breeding assemblage
species highly compressed breeding season in which females are receptive only during a short window and need similar environmental conditions. Males and females respond to similar environmental variables.
Why Polyandry? (multiple males) Give 3 possible reasons.
Fertility Insurance: By mating with more then one male, if her partner is infertile she can still have offspring.
Good genes: Female may have a low quality
partner, so she mates secretly with a high quality male, but she gets parental support from the low quality male.
Genetic compatibility: The female is not interested in finding a dominant male but rather interested in finding a male whose genes arre compatible with her own.
More Resources: By mating with more than one male, she will get access to their territory and resources.
More care: By confusing paternity, more than one male will help with rearing the offspring.
Infanticide reduction: By confusing paternity, males will leave her offspring alone and not harass them.
Parental Favoritism
in many animals, parents do not necessarily treat each offspring the same sometimes parents help one offspring at the expense of the other
Siblicide
Can start as Intrauterine cannibalism (sharks). Great egret siblings fight to the death (parent doesn’t step in). Dependent on parental intervention or facilitation.
Parent-offspring conflict
Parent has to decide how much resources to offer one offspring vs. withholding those resources and using them to make more
offspring at a later date –
* when is it the right time to wean an offspring or extreme like refusing to
care for an offspring.
Reproductive Value
measure of potential of individuals to leave descendants (can be different males and females)
Reproductive Insurance hypothesis, Why allow siblicide? why not lay less eggs?
Paretns invest in ‘backup egg’
Paternity Assurance hypothesis
Male are more likely to provide parental care when they are certain of paternity
Cost Benefit analysis of Parental Care
The amount of parental care should maximizes the individuals own evolutionary fitness.
* Depends on the longevity of the animal and how many times they will get to reproduce over their lifetime.
Why do South American Birds lay smaller clutches than North American Birds.
South American birds have a longer lifespan becuase there are more howks in North America that shorten the birds life and make larger clutches mroe favorable.
Parental Investment
Time and energy and risk taken by parents to help offspring grow, reproduce
3 reasons why females typically put in more parental investment
1.Expensive to make eggs and so the female is more inclined to make sure their gametic investment is not wasted
2. Maternity is usually know for the females
3. Male on average have greater fitness the more females they mate with; therefore the cost of paternal care is usually greater
for males
External vs. Internal Fertilization
Internal - feamle more likely to provide paretnal care
external - male care is more common because the male can hold territory and attract more mates
bonus polynandry most common in monogomous pairs
Stickleback fish are paternal
A good nest attracts mor emates to the male. Also true for harvestman.
How can Mexican Free Tail Bats tell their pups appart from the other 4000?
By vocal and olfactory signals she find her pup 80% of the time. Discriminating parental care. (common in colonial animals)
Paternity Dilution
first seen in golden snub-nosed
monkeys. Females mate with mutliple males to confuse praternity and prevent infanticide. (also lions)
Alloparent Care
parental care directed toward non -
descendent young. (often becuase they cannot discern from their own young)
Signal of quality hypothesis vs. Signal of need. When is each best?
Signal of need: When times were good, mothers would feed the chicks that beg
the most
Signals of quality: But in poor quality environments, mothers responded to chicks that were the biggest
