final Flashcards
Define intrasexual and intersexual
intrasexual = aggressive competition within a sex for mate access
intersexual = competition by charm to attract the opposite sex
What is anisogamy?
differences in gamete size (i.e female eggs > male sperm), which can affect parental involvement
What is Bateman’s principle?
male reproductive success is limited by mate access while female reproductive success is limited by resources
Define what an operational sex ratio is
the number of fertilizable females in a population to the number of sexually active males
What sexual competition occurs when gametes are small, and why?
intrasexual
small gametes = low parental involvement = high reproductive rate = fitness increases with more mates
What do females gain by being choosy?
- access to resources (nuptial gifts, territory, protection, male parental care)
- access to good genes (handicap hypothesis, runaway selection/sexy sons hypothesis)
What is the handicap hypothesis?
males presenting extreme sexual traits are honestly signalling their good genes/health to females
handicap because traits make males more vulnerable to predation and lower survival
What is the runaway selection/sexy sons hypothesis?
females develop a preference for a male trait and seek out mates with said trait, and daughters will inherit the preference while males inherit the traits
does not work when male trait is selected against in natural selection (costs > benefits)
What are some exceptions to female mate choice?
- mutual mate choice when male and female parental involvement are both high
- role reversal systems (i.e male seahorses bear offspring)
- low male OSR systems (causes female/female competition)
- changes in resource availability
Why do females reproduce with multiple mates in a single season?
- complying costs less energy than resisting
- may recieve multiple nuptial gifts
- insures her embryos get fertilized
- can be choosy with best sperm options
How do males guard their mating rights? How do females counter these?
- aggression/enforcement during copulation (females try to resist and seek extra pair copulations)
- intromittant organs (female reproductive traits form complex paths)
- grasping appendages (resistance)
- copulatory plugs and scoops (sperm ejection and choice)
- anti-aphrodisiac scent marking (chemical defense)
If probability of survival is low, which brood should parents prioritize?
current brood (minimize risk to offspring)
What is asynchrony?
delayed hatching of eggs creating an age/size divide within a clutch
What are parents’ ideal reproductive strategies?
maximize lifetime reproductive success
If siblings A and B are born at the same time, how should A react?
siblicide due to high risk to A (both A and B are equal in size)
If sibling A is born slightly before sibling B, how should A react?
mostly dominate B, and maybe siblicide due to moderate risk to A (slight size advantage)
If sibling A is born several days before sibling B, how should A react?
let B starve due to low risk to A (large size advantage)
In which conditions does synchrony and asynchrony do best?
synchronous = abundant conditions
asynchonous = limited conditions
What is polygyny?
one male + multiple females
What is polyandry?
one female + multiple males
What is a lek?
a gathering of males at a mating ground not motivated by resources
What is the difference between a tactic and a strategy?
tactics = phenotypes expressed from strategies, can be categorized
strategies = fixed or plastic genotypes
What are the three types of strategies?
- sequential (A –> B –> C)
- simultaneous (A –> B and C)
- reversible (A –> B –> C –> B)
What is disruptive selection and what is an example?
selection favouring both extremes (i.e both hooknoses and jacks)
