Apes unit 2 Flashcards
Sea otter
key stone species bc keep sea urchins n kelp eating animals from eating all the kelps forest which provided a home for other animals
population dynamics
study of how and why population change in
distribution
numbers
age structure
density
based on changes in envir
population distribution
clumping
uniform
random-rare
clumping distribution
most of living things are dispersed this way. why?
- resources a species needs vary greatly in availability
- provide protection from predators
- better chance of hunting
- group for mating and caring for child
population size
mostly made up of ppl in reproductive stage=population will increase
mostly made up off postreproductive age=decrease
stable when all ages are equal
limits of pop growth
biotic potential
envir resistance
biotic potential
capacity for population growth.
intrinsic rate of increase
r
rate a population would grow if it had unlimited resources
high r
reproduce early and have short generation times
have long reprodictive life
many offspring each birth
limiting factors
things/organisms that limit population growth
envir resistance
all factors that limit groeth of population
carrying capacity
K. not fixed
max population of a species a habitat can sustain indefinetly w/o degradation. determined by biotic potential and envir resistance.
growth rate decreases as the size is near K
exponential/geometric growth
starts slwoly then accelerates J curved. bottom part grows bc of r/biotic potential then converts to logistic growth.
logistic growth
rapid exponential then growth rate steady decreases population then stabilizes near K bc envir resistance. S shaped. population fluctuates around K. if exceeds then decline.
overshoot
exceed K when transitioning from exponential to logistoc. occurs bc of reproductive time lag. population suffers a dieback/crash unless animal switch resources or move
reproductive time lag
perioid needed for birth rate to fall n death rate to rise. reesponse to overconsumption of resource. during transition from exponential to logistic and causes an overshoot. after overshoot then dieback/crash
How to increase carrying capacity
developing adaptive traits-natural selection.
reduce envir resistance
K increases/decreases seasonally bc weather
migrating to other areas
population density
number of individ in population found in a particular area/volume
density dependent population controls
factors that limit pop growth when pop density increases. competition, predation,parasitism, disease
density independent
abiotic factors that can kill population. not affected by denisty. floods, hurricanes, fire, pollution
patterns of variation in population size
stable, irruptive, cyclic, irregular.
stable population size
pop size fluctuates around K
irrupt pop size
pop growth may irrupt to a high peak then crash. short lived, rapidly reproducing. insects link to seasonal changes
cyclic fluation/ boom n bust cycles pop size
regular fluctuation. ex. lemmings, lynx, snowshoe hare
top down population regulation
predation
bottomup population regulation
resource
irregular pop size
irrgular changes in pop size w/o recurring pattern
sexual reproduction disadvantages
- males dont five birth, females have to produce twice as many offspring asexual organisms does
- increase chance of genetic defects during chromosome splitting
- courtship/mating ritual consume time/energy
advantages of sexual reproduction
genetic diversity
male can gather food, protect, train young
r selected reproductive patern
high rate of pop increase. small offspring, little parental care, opportunist. reproduced rapidly when conditions are favorable. succesful during envir changes begining. iregular or unstable boomnbust cycle. exponential
K selected species
competitor. reproduce later in life, small # of offsprings, long life spans. do good in competition. logistic
reproductive pattern give temp. advantage but
availabilitu of suitable habitat determines ultimate pop size
survivorship curve
represent age structure of a population. shows percentage of members of pop surviving at different ages. late loss (live longer) early loss constant loss (die of all ages)
life table
shows projected life expectancy/probability of death of members at each stage of survivorship curve
