Small Population Dynamics Flashcards
species characteristics of higher extinction
- lower abundance
- restricted range/endemism
- higher specialization
- larger body size
- longer generation time
- shorter dispersal rate
- human higher need/greed/fear
it is good for species to be…
- small
- fertile
- abundant
- adaptable
what to consider first when trying to reverse a declining population trend?
- reverse the human-caused stressor(s) that led to decline in the first place
- deterministic stressors
stochastic factors
small population also become particularly vulnerable to these
3 types of stochasticity
- demographic
- environmental
- genetic
demographic stochasticity
mean vital rates are probabilistic
environmental stochasticity
drives random changes in vital rates
genetic stochasticity
arises from genetic drift
extinction vortex
- human caused deterministic stressors & stochastic stressors interact
- make small populations smaller, eventually leading to their collapse
how to assess risk of extinction?
- super coarse rules of thumb
- detailed, population ecology-based rules of thumb
- Quantitative Population Viability Analysis (PVA)
The Minimum Viable Population (MVP) Concept
- 50-500 rule
- expressed in terns of the effective population size (Ne)
short term MVP
Ne > 50 to minimize short-term loss of fitness (and heterozygosity) due to inbreeding
long term MVP
Ne > 500 to ensure long-term maintenance of genetic variation/preservation of evolutionary potential
Population Viability Analysis
the application of data and models to estimate probabilities of a population crossing specified thresholds of abundance or persistence within specified time spans, and to give insights into factors that constitute the biggest threats
