life history Flashcards
what are life history strategies
various strategies that organisms have evolved in order to sustain their populations
stages of life history
birth
immaturity (cannot produce offspring)
maturity (start to breed)
post-reproductive stage
death
what are the names for the number of reproductive events
semelparous
- breed once in their lifetime
iteroparous
- individuals can potentially breed multiple times in their life
generation production per years name
several generations per year
one generation per year (annuals), usually lifespans only is 1 year
one generation over several years (perennials)
semelparous annuals
strongly seasonal temperature latitudes most annuals germinate, then reproduce and due before the end of summer
only reproduce once
iteroparous annuals
reproduce more than once in a season and then dies
lifespan is typically one year but will reproduce many times
killed by change in seasons
Perrenials
one generation over several years
birds, primates and mammals
can be reproductive spouts between years of no reproduction
reproductive phase can span many years
long juvenile phase followed by very high reproductive output phase
what is fecundity
an organisms reproductive capacity (number of offspring it can produce)
parental investment
the energetic investment into each offspring
early reproduction strategies
short lives, small body size
geared towards early energy towards reproduction rather than growth
reduces the risk of not reproducing at all
late reproductive strategy
longer lived and larger bodies
energy into growth and then reproduction later in life
strategy carries high risk of not reproducig at all or to maximum capacity if death occurs early
K selected species
operate in populations living at a density near the limit imposed by their resources
competition among individuals is stronger
traits that are good for high density populatiosn in reproduction
cyclic fluctuations of populations (iteroparous organisms)
large organisms with multiple reproductive cycles and slower population growth
fluctuations can occur for biotic and abiotic reasons
usually more stable populations
R selected speceis
maximise the r, the intrinsic rate of increase, and occurs in environments in which population densities are well below carrying capacity
invidiuals face limited competition
traits that are good for low density reproduction/where density isnt an issue
undergo booms and busts
