Small Population Dynamics

Question 1

species characteristics of higher extinction

Answer 1

• lower abundance
• restricted range/endemism
• higher specialization
• larger body size
• longer generation time
• shorter dispersal rate
• human higher need/greed/fear

Question 2

it is good for species to be…

Answer 2

• small
• fertile
• abundant
• adaptable

Question 3

what to consider first when trying to reverse a declining population trend?

Answer 3

• reverse the human-caused stressor(s) that led to decline in the first place
• deterministic stressors

Question 4

stochastic factors

Answer 4

small population also become particularly vulnerable to these

Question 5

3 types of stochasticity

Answer 5

• demographic
• environmental
• genetic

Question 6

demographic stochasticity

Answer 6

mean vital rates are probabilistic

Question 7

environmental stochasticity

Answer 7

drives random changes in vital rates

Question 8

genetic stochasticity

Answer 8

arises from genetic drift

Question 9

extinction vortex

Answer 9

• human caused deterministic stressors & stochastic stressors interact
• make small populations smaller, eventually leading to their collapse

Question 10

how to assess risk of extinction?

Answer 10

• super coarse rules of thumb
• detailed, population ecology-based rules of thumb
• Quantitative Population Viability Analysis (PVA)

Question 11

The Minimum Viable Population (MVP) Concept

Answer 11

• 50-500 rule
• expressed in terns of the effective population size (Ne)

Question 12

short term MVP

Answer 12

Ne > 50 to minimize short-term loss of fitness (and heterozygosity) due to inbreeding

Question 13

long term MVP

Answer 13

Ne > 500 to ensure long-term maintenance of genetic variation/preservation of evolutionary potential

Question 14

Population Viability Analysis

Answer 14

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