ecology Flashcards
(18 cards)
what are vital rates
they are the measure of life history traits and population dynamics such as mortality rates and birth rates.
they determine the abundance of a species
what are life history traits
adaptations affecting vital rates
type I survival and example
mortality accelerates over lifespan.
whales and elephants have fewer young and invest energy into parental care
how to calculate birth rates and death rates
type II survival and example
mortality remains unchanged over the lifespan
small mice: predation remains relatively constant, just as likely to be eaten early in the lifespan as later in the lifespan
type III survival and example
mortality decelerates over the lifespan
turtles: parents produce lots of offspring but dont invest energy into parental care. therefore, many offspring die initially, the ones who survive survive and this slows mortality rate
k & r strategies
K strategies:
few offspring, higher survival rates, larger size of offspring, less competition for resources
R strategists:
many offspring, lower survival rates, smaller size of offspring, more competition for resources
what is rmax and carrying capacity
rmax is the theoretical largest population growth a species is capable of
rmax reflects the fundamental niche
carrying capacity is the limitation posed by the availability of resources in an environment
what are the different outputs of dN/dt = rmax * N * (K-N)/K
N «_space;K, growth is indistinguishable from exponential
N = K, growth stops
N > K, growth is negative
NOT a -ve rmax causing negative growth: what is it instead
that a population has exceeded the carrying capacity
what happens togrowth when the size of the population reaches half of the carrying capacity
an inflection point: the rate of growth increases until the inflection point, then it decreases and slows after the inflection point
if rmax is large
goes into exponential growth quicker than if rmax is small
example: isle of royale
the land froze creating a bridge to an island
–> moose came over and were able to eat all of this vegetation
–> wolves came over and ate the moose
–> moose and thus wolf population declined
–> would have gone extinct twice based on population predictions if not for continued migration by the land bridge freezing again
populations cannot increase without limit but are expected to converge on a carrying capacity
exponential and logistic growth
K
primary productivity
ecological efficiency
understanding population regulation requires recognition of both intrinsic and extrinsic factors
rmax and r
fundamental niche and realised niche
life histories and ecological interactions
what determines K
interactions with the environment and other species
what determines rmax
intrinsic factors such as vital rates
1200 koalas were living on an island off Victoria on 1 January 2025. Ecologists have been studying the population for some time and are confident that the koala population’s intrinsic rate of increase equals 0.1 per individual per year. They know that the population exhibits logistic growth, and the carrying capacity of the island is 1800 koalas. How much will the population have increased by 1 January 2026? Show the formula you used to derive this answer.
40
