life histories Flashcards
3 goals of every individual in life
- consumer resources and grow to maturity
- avoid being killed
- reproduce (successful offspring)
fecundity
the number of offspring produced by an organism per reproductive episode
parity
the number of reproductive episodes an organism experiences
parental investment
the time and energy given to an offspring by its parents
longevity (life expectancy)
the life span of an organism
“slow” life history
-long time to sexual maturity
-long life spans
-low numbers of offspring
-high parental investment
(elephants, oak trees)
“fast” life history
-short time to sexual maturity
-short life spans
-high numbers of offspring
-little parental investment
(fruit flies, weeds)
stress tolerators
typically small herbs with a long life span, slow growth, and a long time to sexual maturity
competitors
grow fast, achieve early sexual maturity, and devote little energy to seed production
ruderals
grow fast and devote a high proportion of their energy to reproduction
principle of allocation
the observation that when resources are devoted to one body structure, physiological function, or behavior, they cannot be allotted to another
-natural selection will favor individuals that allocate resources optimally (maximum fitness)
as the number of offspring increases
the amount of parental care per offspring will decrease
-reduces chance of offspring survival
having more offspring makes parents work hard to feed more young which results in
decreased parental survival
determinate growth
a growth pattern in which an individual does not grow any more once it initiates reproduction
-occurs in many species of birds and mammals
indeterminate growth
a growth pattern in which an individual continues to grow after it initiates reproduction
-occurs in many species of plants, invertebrates, fish, reptiles, and amphibians
organisms with a long life span favor
determinate growth
-allows them to grow first and reproduce later
organisms with a short life span favor
indeterminate growth
-allows them to quickly reproduce before death
low predation
-higher adult size
-higher embryo weight
-fewer offspring
high predation
-lower adult size
-lower embryo weight
-more offspring
semelparous
-breed once in lifetime
-store resources for one reproduction
-programmed death after reproduction
-arises when there is a massive amount of energy required for reproduction
-common in insects and plants
iteroparous
-breed multiple times
-more common
-common among birds, reptiles, mammals, and amphibians
annual
an organism that has a life span of one year
perennial
an organism that has a life span of more than one year
senescence
a gradual decrease in fecundity and an increase in the probability of mortality
-inevitable consequence of natural wear and tear