EE Lecture 33: Conservation Biology and Biodiversity Flashcards
what 3 problems do small populations face?
- demographic stochasticity
- environmental stochasticity
- genetic problems
what is demographic stochasticity
the variability in population growth rates arising from random differences among individuals in survival and reproduction within a season
RANDOM COMPONENT TO BIRTHS AND DEATHS.
what is the population growth rate equation
Nt+1=Nt + (Bt -Dt +It-Et)
what is environmental stochasticity
variation in birth and death rates from one season to the next in response to weather, disease, competition, predation, or other factors external to the population
define stochasticity
randomness
what is the equation involving r that predicts whether extinction is likely or not
r > (2 x mean r) erxtinction is likely
give an example of a species threatened by environmental stochasticity
Rodrigues fruit bat - restricted to Mauritius
Down to
give an example of a species threated by demographic stochasticity
the Po’ouli bird - only discovered in1973
last seen 2003
why is genetic problems a threat for small populations
small populations lose genetic variation by drift and inbreeding - mutational meltdown
what is the extinction vortex
random genetic drift and inbreeding = loss genetic variability = decrease individual fitness and popn adaptability = decrease reproduction = increase mortality = even small pop
give the population model for exponential growth
dN/dt = rN
what is an alternative view to the extinction vortex
the declining popn paradigm
describe the declining popn paradigm
what eqtn does the declining popn paradigm propose
ongoing negative pop growth will wipe out any popn
Nt = N0 *exp(rt)
what does deterministic decline cause
extinction
