Conservation Bio Exam 2: Population Viability Analysis

population viability analysis

method for organizing and enhancing our understanding of factors that shape a population’s likelihood of persistence

first common feature of population viability analyses

often incorporate variability in vital rates, not just mean values; often stochastic models

second common feature of population viability analyses

focus on demographic threats rather than gentic threats

third common feature of population viability analyses

model must be tailored to the biology of the species being studied

first example of how the biology of a species should dictate the type of population growth model used in pva

the species is gregarious (live in clusters); need to incorporate allee effects

second example of how the biology of a species should dictate the type of population growth model used in pva

the species is long-lived and iterparous (reproduced multiple times); less important to incorporate demographic stochasticity related to sex ratio

third example of how the biology of a species should dictate the type of population growth model used in pva

the species has a broad geographic distribution; less important to incorporate small scale environmental stochasticity

fourth example of how the biology of a species should dictate the type of population growth model used in pva

the species forms shifting-mosaic metapopulations; need to incorporate rate of founding of new sub-pops

example of shifting mosaic meta pops

furbish’s lousewort

menges et al; furbish’s lousewort

in each iteration of the model there is a change that a new population will be added to the metapopulation

minimum viable population size

the smallest number of individuals that can be in a population and still
have an acceptably high probability of that the population will survive for a set number of years in the future

first caution concerning use of pva for prediction

poor quality data often used to estimate model parameters

second caution concerning use of pva for prediction

difficult to valitate or confirm model predictions

third caution concerning use of pva for prediction

even most complex models are crude approximations of exceedingly complicated natural processes

first suggestion for appropriate use of pva

compare relative extinction probabilities under different management regimes

second suggestion for appropriate use of pva

make predictions only over short time intervals (10-50yrs)

third suggestion for appropriate use of pva

construct simple models that data can support; deterministic models

fourth suggestion for appropriate use of pva

apply a variety of different pva models to each problem to observe the range of outcomes

overexploitation

human use of populations of organisms to an extent that threatens the viability of populations or alters the community

what are the 3 forms of wildlife harvesting

commercial exploitation, subsistence exploitation, incidental exploitation (by-catch)

what is the most damaging form of wildlife harvesting and why

commercial exploitation; insatiable demand

commercial extinction

population size below which it is no longer economically viable to pursue a species

convention on international trade in endangered species of fauna and flora (CITES)

international treaty that regulates international trade in endangered species of plants and animals