Life history Flashcards
life history
the adaptations of an organism that influence aspects of its biology, such as the number of offspring it produces, its survival, and its size/age at sexual maturity
Principle of allocation
if an organism allocates energy towards one function, such as growth/reproduction, it reduces the amount of energy it can spend on other things, like defense mechanisms
What do costly traits signify
a high quality individual
Coho salmon reproductive trade offs
redder salmon have easier access to fertilize eggs because red is hard to produce and it makes them look better.
less red salmon invest in faster sperm
David Lack’s hypothesis
Selection favors clutch size with maximum surviving offspring. Accounts for trade offs b/t
- clutch size
- probability of individual survival
- how many survive
Why didn’t Lack’s hypothesis prove to be true?
- maximum clutch sizes reduced future reproductive fitness in the mother
- Maximum clutch sizes reduced (reproductive) fitness in offspring
- an individual’s maximum is not necessarily equal to that of the population
What experiment did lack do?
He added an extra egg to a clutch and it reduced both the mother’s future reproductive fitness and that of the offspring
Kiwi trade off
Giant egg
few offspring
invested in heavily
European kestrals
trade off between survival and paternal care
plant investment in seed size
Few large seeds = bigger, taller, stronger seedlings with increased recruitment
Many small seeds = advantage in areas of high disturbance
r selection (and example)
- high population growth rate (reproduce quickly)
- unpredictable environments
- better colonizers
- quickly harvest resources and reproduce, even if its inefficient
- e.g. tailless tenrec has 32 pups
K selection
- efficient resource use
- predictable environments
- better competitors
- slow growth and slow to reproductive maturity
- high investment in offspring to yield big size
- use resources efficiently –> good for scarce resources
Humpback whale
-loses 70% of blubber while feeding baby
3 key components to life history
- How many offspring per reproductive episode?
- How often does organism reproduce?
- What is the age of sexual maturity?
semelparity vs iteoparity
semelparity = reproduce once then die (r selection)
iteoparity = reproduces multiple times (K selection)
chambered nautilus
only iteoparous cephalopod spawner
synchronous semelparity
cicadas that only come out once every 13 or 17 years
- all emerge, reproduce, and die in same year
- all individuals in population are the same age
Salmon as a spawner
semelparous
- leave for ocean as a small fry
- return to natal ground to reproduce
- invest in MANY gametes
Advantage of iteoparity
- Cole found that r was greater in iteoparous organisms whether 40 or 50 offspring were produced
- greatest value when survival of offspring is uncertain
- tend to be iteoparous when adult survivorship is high
- also, shorter pre-reproductive time increased r
Reznick and Endler’s guppy experiment
- if predators focus on the young or there are no predators, then K selected syndrome
- if predators focus on adults, then r selected syndrome and faster reproduction
Pumpkinseed fish
when adult survival was lower than juvenile, there was greater body mass put towards gonads (GSI)
Opossums
-Mainland ones had higher predation, so their offspring aged and reproduced at quicker rates than the island ones
snakes + lizards
higher survival rate lead to later maturity
Lions
- males are evicted at 2 yrs old to go take over another pride
- females are therefore sexually mature by age 2
Prime reproductive age
stags are the ones with the prime reproductive age as opposed to the female hinds
Types of parental care
- none
- uni-parent
- bi-parent
No parental care
sea turtles, megapodes, praying mantis
uni parent care
seahorses (male), seals, spiders, humpbacks
bi-parental care
dung beetles, titi monkeys, birds
Grimes Triangle
- Ruderals (high disturbed habitat)
- grow fast, makes seeds quick, r-select - Stress-tollerant (high stress, no disturbance)
- grow fast, K select - competitice (low disturbance, low stress)
- grow well, but eventually compete for resources
