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Reproductive and Developmental Biology > Lecture 3 (2ab) - Parental Strategies and Ensuring Paternity > Flashcards

Lecture 3 (2ab) - Parental Strategies and Ensuring Paternity Flashcards

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1
Q

LRO is about

A

F1

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2
Q

LRS is about

A

F2

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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
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4
Q

What determines LRS?

A
  • LRO
  • fecundity/fertility of F1
  • probability that F1 survive to sexual maturity / achieve fertility
  • highly dependent on parenting
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5
Q

Difference between LRO and LRS

A
  • LRO about finding mates
  • LRS about parenting - surviving to produce children
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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)

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7
Q

What maximizes a species’ “reproductive success”?

A

reproduction

development

PARENTING

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8
Q

Species can be

A
  • r-selected
  • K-selected

reproductive strategy is r- or K-

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9
Q

r-selected

A
  • reproduce and develop rapidly
  • highly prolific
  • little/no parental investment
  • eg most insects
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10
Q

K-selected

A
  • reproduce and develop slowly
    • eg monotocus
  • high level of parental investment
    • eg humans and higher mammals
  • at carrying capacity
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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
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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)

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13
Q

What are the parental priorities?

A
  • maximize the number of offspring
  • keep offspring alive
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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)
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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
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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
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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
  • 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

Reproductive and Developmental Biology (8 decks)

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