Captive Management

Question 1

Zoos

Answer 1

Currently give over5-10% of their space for endangered species. Global cooperation between zoos and integration with in situ conservation programmes began in 1980’s.

Question 2

Captive populations assist conservation by:

Answer 2

1) Establishing secure ex situ populations.
2) Acting as a tool to raise public awareness.
3) Providing a focus for fund raising events.
4) Providing individuals for reintroduction.

Question 3

Stages of captive breeding and reintroduction

Answer 3

1) Decline of wild population
2) Founding of captive population
3) Growth of captive population to secure size
4) Management of captive population over generation
5) Selection of individuals for reintroduction
6) Management of reintroduced population

Question 4

Stage one. Foundation

Answer 4

Number of founders is often an economic trade-off: Number of individuals collectable from the wild, Cost of stating a captive breeding programme and population size required to maintain 90% genetic diversity for 100 years. To avoid a bottleneck, founding populations require at least 20-30 genetically effective individuals, to reduce inbreeding to an acceptiable level. In reality most captive populations are too small.

Question 5

Stage two. Growth

Answer 5

First priority is to grow the population as fast as possible to Ne size pre-determined by the genetic target.
Next is to genetically manage it during the growth period is de-emphasised, but all founders encouraged to breed.
During growth period, there is a trade off between equalization of founder representation and growth rate.
Example, the Mauritius parakeet captive programme, skewed productivity by a single sibling pair.

Question 6

Stage 3. Management

Answer 6

Once target Ne size is reached, focus shifts towards intensive genetic management:

1) Maintain demographic stability
2) Counteract previous effects of inbreeding depression
3) Slow loss of heterozygosity
4) Reduce effects of accumulation of new deleterious mutations (long term concern)
5) Minimise genetic adaptation to captivity

Question 7

Stage 3. Management objectives

Answer 7

1) Maximise Ne/N ratio of captive population
2) Maximise avoidance of inbreeding
3) Equalise founder representation

Question 8

Minimising Kinship

Answer 8

Most effective strategy for retaining genetic diversity. Kinship of any 2 individuals = F of their potential offspring. A mean kinship value is derived for each individual. Those with lowest mean kinship values are bred first.

Question 9

Stage 4. Reintroduction

Answer 9

Biggest concern is genetic adaptation to captivity. Adaptation is more efficient in larger than smaller populations. Hence, problems of GAC are expected to be more severe in larger populations. Upon capture, the selective forces acting on an individual change:
-Selection for increased tameness, reduced predator avoidance and reduced disease resistance.

Question 10

Effects of GAC

Answer 10

Effects of GAC are only felt among reintroduction into the wild. GAC has only recently been recognised as a true problem. GAC can be expected in any captive population. GAC is essentially a process of domestication.

Question 11

Reintroduction conundrum

Answer 11

Large captive populations: Retain genetic diversity better, rate of inbreeding is lover but they suffer high GAC. Small populations suffer higher loss of diversity. Suffer high levels of inbreeding depression and experience less GAC.
One solution to reduce GAC is to maintain a large population amongst fragmented, captive sub populations.