Lecture 9 Flashcards
Population Dynamics
the ways in which populations change abundance over time
Processes that change population size:
birth
death
immigration
emigration
Nt+1 =
Nt + B - D +1 - E
Extinction chance events
genetic
demographic
environmental
Genetic Drift
chance events influence which alleles are passed onto the next generation
Demographic stochasticity
chance events affect the survival and reproduction of individuals
Environmental stochasticity
change in the average birth or death rates from year to year because of random changes in environmental conditions
Allele effects
the finding that for some populations, there is a positive correlation between population size and growth rate
Metapopulation
a set of spatially isolated populations linked by dispersal of individuals or gametes
Habitat fragmentation
large tracts of habitat are converted to isolated patches, resulting in a metapopulation structure
Two important features of metapopulations
isolation by distance
patch size
Isolation by distance
when patches are too far apart, individuals cannot disperse easily, so they cannot spread their genes across the distance
Rescue effect
high rates of immigration that protect a population from extinction
Bottom-up control
increased nutrient inputs caused eutrophication (water is overriched with nutrients) and increased phytoplankton biomass, decreasing oxygen, fish die-offs
Top-down control
top predators control the abundance of populations
