Population Dynamics over Space and Time Flashcards
fluctuations
random and cyclic changes through time due to factors such as availability of resources, predation, competition, disease, parasites, and climate
smaller organisms reproduce
faster so their populations often respond faster to favorable and unfavorable conditions
larger organisms
have a lower surface-area-to-volume ration, which allows them to maintain homeostasis when faced with unfavorable environmental change
overshoot
when a population grows beyond its carrying capacity; often occurs when the carrying capacity of a habitat decreases from one year to next (because less resources are produced)
die-off
a substantial decline in density that typically goes well below the carrying capacity
-occur when a population overshoots its carrying capacity
population cycles
regular oscillation of a population over a longer period of time
-some populations can exhibit highly regular fluctuations in size
cyclic populations
can occur among related species and across large geographic areas
delayed density dependence
when a density dependence occurs based on a population density at some time in the past
damped oscillations
a pattern of population growth in which the population initially oscillates but the magnitude of the oscillations declines over time
stable limit cycle
a pattern of population growth in which the population continues to exhibit large oscillations over time
deterministic model
designed to predict a result without accounting for random variation in population growth rate
stochastic model
a model that incorporates random variation in population growth rate; assumes that variation in birth and death rates is due to random chance
demographic stochasticity
variation in birth rates and death rates due to random differences among individuals
environmental stochasticity
variation in birth rates and death rates due to random changes in the environmental conditions (weather)
metapopulation
a set of local populations linked by dispersal
-exist with a balance of colonization and extinction
each subpopulation has its own independent
- birth rate
- death rate
habitat fragmentation
the process of breaking up large habitats into a number of smaller habitats
(can happen from clearing forests, road construction, etc.)
basic metapopulation model
assumes that all habitat patches are in equal in quality and that the matrix between patches is inhospitable
source-sink model
assumes quality differences between patches
sources
high quality patches that produce a large number of individuals that disperse to other patches
sinks
low quality patches that produce few individuals and rely on dispersers to keep the sink population from going extinct
landscape model
considers that the quality of habitat patch can be affected by the nature of the surrounding matrix and some matrix habitat are more easily traversed than others
rescue effect
when dispersers supplement a declining subpopulation and thereby prevent it from going extinct
