Lecture 3 (2ab) - Parental Strategies and Ensuring Paternity Flashcards
1
Q
LRO is about
A
F1
2
Q
LRS is about
A
F2
3
Q
What is LRO?
A
- number of offspring born to a parent in the F1 generation
- product of fecundity (fertility) x fertile lifespan
- fecundity proportional to success in
- locating
- courting
- retaining
a mate
- number of offspring you generate in a lifetime
- locating and courting assumes polygamy
- retaining assumes monogamy
4
Q
What determines LRS?
A
- LRO
- fecundity/fertility of F1
- probability that F1 survive to sexual maturity / achieve fertility
- highly dependent on parenting
5
Q
Difference between LRO and LRS
A
- LRO about finding mates
- LRS about parenting - surviving to produce children
6
Q
What would influence the probability of offspring surviving to sexual maturity?
A
- rate of development
- survival
- starvation
- predation
a parent can influence all of these
(development - ensuring nourished)
7
Q
What maximizes a species’ “reproductive success”?
A
reproduction
development
PARENTING
8
Q
Species can be
A
- r-selected
- K-selected
reproductive strategy is r- or K-
9
Q
r-selected
A
- reproduce and develop rapidly
- highly prolific
- little/no parental investment
- eg most insects
10
Q
K-selected
A
- reproduce and develop slowly
- eg monotocus
-
high level of parental investment
- eg humans and higher mammals
- at carrying capacity
11
Q
How can males maximize LRS?
A
- maximize LRO output
- maximize number of mates
- strong drive to polygyny (not picky)
- must be incentive for a male to be monogamous
- stay and contribute to parenting rather than finding a new mate
12
Q
How can females maximize LRS?
A
- maximize survival of offspring to sexual maturity
- PARENTING
- select “fittest” partner - sexual selection
- males visually extravagant
- maximize number of mates
- strong drive to polyandry (picky)
- can be pick after the fact
- SPERM COMPETITION
- impregnate vs inseminate
(invest in egg and yolk/uterine nutrition)
13
Q
What are the parental priorities?
A
- maximize the number of offspring
- keep offspring alive
14
Q
Parental priority:
maximize the number of offspring
A
- as dictated by resources - trade off against parental role
- even in K-selected species still want maximum number of offspring
- want more than 2 (the replacement number)
15
Q
Parental priority:
keeping offspring alive
A
- ensure infants avoid starvation
- ensure infants avoid predation
- ensure infants aren’t born into an overly competitive environment
- K-selected - making sure when at carrying capacity that they aren’t born into competition
- ensure infants **don’t **die by misadventure
- ensure infants aren’t killed
- different from predation - kill for eg fun, not eating
16
Q
How can parents ensure infants avoid starvation?
A
- ensure that there is sufficient food in the (immediate) environment
- before laying eggs / giving birth
-
before conceiving
- don’t reproduce if not enough food
- stressed → won’t reproduce
- may not have sex if not much food around
- food insufficiency renders animals sub/infertile and can terminate pregnancies
17
Q
How can parents sensure infants avoid predation?
A
- ensure offspring are cryptic
- (hidden)
- genetically selected to be cryptic
- eg grayscale = can’t see in grass if predator color blind (hidden)
- guard offspring
- put offspring in a “creche”
- leave with other adults when leave so still protected
18
Q
How can parents ensure infants avoid predation?
A
- don’t produce offspring in the vicinity of predators
- actively guard/protect infants
19
Q
How can parents ensure infants avoid competition?
A
- don’t produce offspring in an overcrowded/competitive environment
- natural selection against runts
- eg not enough teets for all piglets
- deliberately produce too many kids so pick (genetically) weakest
20
Q
How can parents ensure infants avoid death by “misadventure”?
A
- supervised play
- training
- train offspring to be safe
- looks like play but training for adulthood
21
Q
How can parents ensure infants avoid being killed?
A
- ensure infant is cryptic/guarded
-
social bonding with group members that might pose a threat
- mother might engratiate self with male
- complex societies
- eg baboons - biggest danger is other baboons
22
Q
How long are parents “useful” to their offspring?
A
- until offspring achieve sexual maturity and can give rise to F2 generation
- then become redundant
- until parents achieve “reproductive senescence”
- should basically die when can’t reproduce
- not contributing to gene pool, becomes competitor
- concept of extended family in matriarchal species - “aunt behavior”
- tolerate elders who don’t reproduce because form creche while F1 parents feed (babysit F2)
- grandparents in elephants
23
Q
Which parental roles CAN’T be assumed by males?
A
males can’t
-
nourish the embryo
- yolk or female tract secretions
-
lactate (mammals)
- pathology, not normal physiology
24
Q
Which roles CAN be assumed by males?
A
males CAN
-
carry the embryo
- “pregnant males”
- guard the embryo (egg)
- carry and guard the neonates (infants)
dad is normally (biologically) finding another mate
25
Q
“Pregnant males”
(Sygnathidae)
A
- eg pipe fish
- white underbelly = pregnancy belt
- male sea horse giving birth
- female deposits egg
- female still nourishes with egg yolk
- no placenta
- homones involved in giving birth
26
Q
Incubating males
A
- male guarding embryo
- embryo nourished by egg sac
- mom goes off to feed
- hungry because invested all her energy in producing the egg
- eg penguins, flightless bird in new zealand
27
Q
Carrying neonates
(Callithricidae)
A
- 2 babies on dad’s back
- twins to trap males into parenting
28
Q
Strategies for ensuring paternity
A
- sperm competition
29
Q
Sperm competition
A
- if a female is inseminated by 2 or more males, creates the opportunity for sperm competition within the female
- compete to fertilize the egg
- certain he’ll win (see another slide)
- guard female (before mating)
- more gametes/volume
- more volume
- volume several times
30
Q
How can a male win the “sperm competition”?
A
- fast sperm (long sperm)
- doesn’t always hold up - longest doesn’t always win
- Drosophila sperm 10x longer than fly
- high sperm number
- ejaculate volume or sperm density
- repeated insemination of same female
- drives toward monogamy
- amphibians release at righ time (time eggs come out) and when just about to ovulate
- exclude other sperm
- break penis off
- biochemical plug in female
31
Q
Highest sperm competition
→
A
largest amount of ejaculate or sperm density
32
Q
Harem
A
- single reproductively active male
- all offspring sired by harem-holder
- only males tolerated are “followers”
- usually offspring of the harem-holder, inherit harem
- followers tolerated as long as subordinate
- 2 choices - wait your turn for harem to die, take on harem-holder
- extreme case of mate guarding
- example - Hamadryas baboon
33
Q
Types of harem
A
- patriarchal harem - male holds it together
- another male comes along → fight
- canine teeth lethal in hamadryas baboons
- mate-guarding, sexual selection
- another male comes along → fight
- matriarchal harem - females choose harem
lions - take on harem with fight, espically if against harem with brother
34
Q
Infanticide
A
- eg lions
- ensure that a male isn’t wasting resources on offspring that he didn’t sire
- female then mates with new harem
- new harem better/more fit → better offspring
35
Q
Mate guarding
A
- pre-copulatory mate guarding
- has she already been inseminated?
- post-copulatory mate guarding
- has she been fertilized yet?
- could she still be fertilized by another male?
- block female tract
36
Q
Mate guarding
Gerris gracilicornis
A
- paint pair, but back
- don’t match = guarding male replaced
- high turnover
37
Q
Mating (copulatory) plugs
A
- widespread - invertebrates, reptines, metatheria, eutheria
- keep semen inside and other semen out
- plug may remain until impregnated, then sometimes comes out
38
Q
Mating (copulatory) plugs
complex composition
A
- fatty acids
- seminal proteins
- **anti-reproductive **molecules
- eg cycloprolylproline in invertebrates
- suppress her mating drive
- kil any other sperm before new male deposits
- can also be produced by females (polyandrous)
- when mated by desirable male
39
Q
Argiope bruennichi
A
- male leaves reproductive structure inside female
- can only do this twice (only 2 reproductive structures)
- male then dies
40
Q
A
