Evolution of PC

post-fertilization benefit:

increased parental fitness and offspring lifetime RS

guarding:

extreme care

suicidal maternal matriphagy (ex. spiders):

offsprings get fed by mother and once they develop, they kill and eat the mother

cost of predominant care (1 parent, most likely female):

death of offspring due to predation + death of parents

benefit of predominant care (1 parent, most likely female):

increased offspring survival

when cost>benefit …

there is no PC

life history (ecology) includes:

life cycle, age of list reproduction, max # of offspring, lifespan, sex ratio, size of maturity

in life history, N.S favors …

evolution of behavior that will maximize an individual’s lifetime R.S

a parent’s energy allotment goes into …

one’s growth and maintenance

an offspring’s energy allotment goes into ..

reproducing and PC

parental cost (reproduction):

effort allocated towards reproduction reduces effort allocated towards an individual’s own growth and survival

parental cost (offspring):

effort allocated towards current offspring reduces effort allocated towards future offspring 

there is a large ______ of how life history traits are favored by N.S

range

one side of the life history traits continuum says N.S favors individuals that produce …

many small offsprings + no PC

the other side of the life history traits continuum says that N.S favors evolution of individuals that produce …

few but larger offspring who receive PC

North American Robin:

short lived (2 years), high parent mortality due to predation, collision

Argentinian Thrush:

long lives (25-30 years), low parent mortality due to poisoning, disease

study between Robin and Thrush involved predator music played by both of their nests and they found that …

the thrush comes back faster (since they have a longer-life span and aren’t worried about the predator), while the robin comes back longer (since they don’t want predators to find the eggs)

predator for thrush:

raptor

predator for robin:

hawk

ray-finned fish: a larger body size indicates …

higher fecundity, later maturity, fewer reproductive events/yr

the ancestral state of the ‘ray-finned fish’ included no care and external fertilization which …

shows benefit>cost (PC<5%)

‘ray-finned fish’: internal fertilization has …

PC = 90%, maternal care

‘ray-finned fish’: biparental care …

evolved but was not a stepping stone in evolutionary history

why did so many species evolve PC?

male prevents another male from spewing sperm

fish have indeterminate growth (keeps growing), while humans have determinate growth

female fish have …

no PC, allot all of their energy to their own personal growth (b/c bigger fish = more eggs)

cost > benefit in F to provide PC

male fish have …

to guard eggs to make sure they’re his

cost < benefit to provide PC, extra growth + more sperm

Gobi fish live in …

low flow, low current stream in quiet pools 

male Gobi fish …

build nests in rock crevice and goes to the middle of the stream in a fast current, and swims up and down

female Gobi fish have …

female mate choice

male gobi fish takes care of eggs and …

seals himself + his eggs in the nest crevice for 2 weeks (no eating, constantly fans eggs for O2)

a bad male Gobi fish would …

eat the eggs

Giant Water Bug:

female inseminated internally and lays eggs on males

cheaters have …

no PC + lay eggs on diff species nest (brood parasitism)

2 species of birds that are brood parasites:

cuckoos, cowbirds

host birds have …

the cuckoo egg in them

cuckoo cost:

possibility that host rejects the egg

wren (host bird) cost:

may lose all of its offspring to the cuckoo

cuckoo benefit:

no PC, no brooding, no nest, no feeding offspring

wren benefit:

none

the wren have no benefit and …

a huge cost (must feed other offspring and has no RD)

Arm’s Race:

ID strange egg in nest

cuckoo makes egg …

resemble the host

cuckoo behavior: 1).

already have eggs inside early in season before host lays

cuckoo behavior: 2).

lays 1 egg/1 host nest and steals/eats egg to replace it with their own

cuckoo behavior: 3).

fly around and spot ALL wren’s nest

cuckoo behavior: 4).

waits for wren to lay eggs —> cuckoo looks for an increase number of eggs day to day

female wren sings a song while brooding eggs and …

won’t feed unless they sing her song back

cuckoos evolved feather to look …

like hawks (predators)

the innate behavior of a cuckoo chick (who’s blind):

has notch for wren egg to push/kill the egg

the benefit for a cuckoo chick is that they are …

all alone in the nest

menopause …

no more reproduction (6 species)

grandmother hypothesis:

benefit of keeping old females around —> food resources (migration), grandmother care

prudent-mother hypothesis (done by Jane Goodall):

mother has offsprings until eldest daughter has an offspring, lessens risk of late-life reproduction (higher evo. benefit to stop reproducing and instead invest energy in caring for existing children and grandchildren)

if grandmothers don’t stop reproducing …

daughters and grandchildren will compete for food