Reproductive Behavior Flashcards
Sex Role Reversal
where the males are choosy and the
females are competing for mates
Important factors is choosiness:
* operational sex ratio (less sexually active males vs. females)
* nuptial gifts (e.g., spermatophore)
* population density (ease of finding mates)
* parental investment
Sexual Dimorphism
as opposed to monomorphism any difference between males and females of
the same species
Fundamental asymmetry of sex
Nuptial gift
ex. spermatophore
Operational sex ratio
Usually there are many fewer sexually active females than males at any given moment
Sex Role Reversal
The sex that invests most is a limiting resource for the sex that invests the least. This means if the operational sex ratio flips (more females than males) than females will take on male roles.
Alternative Mating Tactics
Conditional strategies: the ability of a subordinate individual to switch to an alternative tactic to secure a higher fitness payoff than they would if they behaved like the dominant individuals.
examples:
sneaky male
satellite male
polymorphism
May be an adaptable conditional strategy or a genetic polymorphic alternate strategy
Satellite Male
uses an alternative tactic to the dominant male to secure a mate.
Genetic Polymorphism
refers to different phenotypes determined by genes, with a lack of flexibility in behavior. morphs must occupy the same habitat at the same time and belong to a mating population
Run away selection give an example of when it went too far
creates a positive feedback loop, selecting for attractive features. Can become out of control: Irish Elk developed horns so large they couldn’t hold up their head
Chase away selection
akin to an arms race, where males and females try to gain the upper hand.
Conditional Strategy
Competition for mates can lead to alternative tactics where individuals make the best of the situation.
Secondary sexual characters (SS)
any physical characteristic developing at puberty which distinguishes between the sexes but is not directly involved in reproduction.
Satin Bower Bird
Decorates its nest blue. Females inspect while males are away and then return to a few of their favorites. She will watch part of the dance and leave to build her nest then return a third time to watch the whole dance copulate and leave.
Sexual Differences Theory
Males commonly try to mate with many females
Females mating with only a few males
Why? Eggs are expensive, and the limiting resource.
Gobie
Dynamic sex roles. Early in the season more males and fewer females: Male gobies compete to defend nest sites to attract females
late in the season the ratio swaps: females actively court males who are no longer
abundant
Empid fly
sexual role reversal: goes hunting,and when he returns with his nuptial gift, he has a dozen females to choose from. Females will not mate unless he offers a nuptial gift.
Brood Pouch
Sexual role refersal: Females compete to fill their eggs in the male pouches
Intraspecific competition
leads to armorment. Dominant males generally get to mate more often than
submissive males
Male Toad hanging around a dominant toad signaling for a mate to ambush female
satellite male
Scorpion Fly 3 strategies
1) defend nuptial gift 6x mates2) secrete saliva 2x 3) Omega male forces copulation 1x Depends on social order (largest gets best strategy)
Splotched Lizards 3 colors 3 strategies
a. A territorial male guards a nest to attract a female
b. Little sneaker males wait for opportunity to get close to egg
mass release their sperm at the same time as the territory
holder
c. A slightly larger satellite male with a body coloration of female
hovers above a nest before slipping between the territorial
male and his mate when the female spawns
Mate Gaurding
Why stay with a female after mating with her?
What is the cost?
What is the benefit?
1) To prevent her from mating again
2) Lost opportunity to find new female mates
3)Ensure that no one else mates with your “partner”
Seychelles warbler lay one egg does mate guarding make sense?
Yes, they mate gaurd.
Reproductive control male vs. female
Females:
*Mate choice
*Time of fertilization
*Investment in offspring
Male:
*Mate Guarding
*Sexual coercion
*Investment in offspring
The theory of mate choice
Many different theories are not mutually exclusive. healthy mates, good genes, runaway selection, and chase-away selection, good parent theory
Blue tits, males are the foragers. What might females look for?
Bright colors indicate carotenoids.
Sexual Conflict when does it happen?
common and arises between males and females who have different sexual motivations
Topi sexual conflict
Females hit males when they refuse to mate again
Cane Toad rejection
females reject males by inflating
Hermaphrodite conflict
between flatworms whoever is touched first become the ‘female’. Which takes more energy so it is less favorable.
