Captive breeding programs

Peter de Sève

Saving species

Assuming a decline is already well under way: what to do?

- remove threats (harvest regulation, development, etc.)(what if threat is exotic species?)

- enhance natural reproduction; improve habitat(conspecific attraction; food supplementation, etc.)

- translocate individuals to increase variation, N

- captive breed for short term to produce stock for translocation

- captive breed for long term to have stock ready for periodic use

- captive breed indefinitely

Purposes of captive breeding programs:

• conservation of threatened species– objective to restore wild popns (no wild individuals left)

– objective to supplement wild populations that have

declined or are threatened

Purposes of captive breeding programs:

• captive maintenance of threatened species – habitat is completely lost

– threats to extinction cannot be overcome

– duration of captivity has irrevocably altered species

consequences of genetic mismanagement

minor major

maintain in permanent captivity

re-establish wild population

supplement wild population

Stages in a captive breeding program

• decline of wild population, genetic consequences

• choice of founder population

• growing captive population

• maintaining captive population

• reintroducing individuals

• managing reintroduced population

in captivity

Issues for captive propagation

• source of founder population(s)

• space requirements in captivity/space availability in zoos

• courtship/mating behaviors

• intrinsic rate of increase

• isolation of sub-populations

• availability of wild populations as sources of new variation

Rules for captive propagation

Founding the population - minimize genetic and phenotypic change

– collect random sample of founders

– collect data on locality, habitat of origin

– collect genetic data from founders– keep sub-populations isolated

Rules for captive propagation

Maintaining the population • maximize N and Ne (maximize sex ratio)• maintain equal family sizes

Rules for captive propagation

Maintaining the population • maximize N and Ne (maximize sex ratio)• maintain equal family sizes

Lion: average family size 1.65variance in family size 32.7reduces effective popn. size to 8%

Rules for captive propagation

Maintaining the population

• maximize N and Ne (maximize sex ratio)• maintain equal family sizes

golden lion tamarin - founder population 242 individuals- 48 contributed to subsequent gene pool- most of offspring (2/3) from single pair

Rules for captive propagation

• minimize loss of genetic variation – maximize N and Ne (maximize sex ratio)– maintain equal family sizes– periodically check variability, compare with wild populations

• minimize behavioral changes– minimize duration of captivity (maximize generation time)

• minimize inbreeding– conduct pedigree analysis/management– outcross population with new individuals

Rules for captive propagation

• manage demographics

– determine reasonable carrying capacity (note effect on other taxa)

– achieve carrying capacity rapidly

– stabilize population at carrying capacity• maintain representation of age classes

• what to do with excess animals?

Rules for captive propagation

Species Survival Plans (SSPs) for zoo species

goal: preserve genetic variation – 90% of H over 100 years

Rules for captive propagation

Species Survival Plans (SSPs) for zoo speciesgoal: preserve genetic variation – 90% of H over 100 years

– list each individual in a studbook – sex, sire and dam, likely alternatives if uncertain parentage

– acquire data: age-specific fecundity, mortality, lifetime reproductive success, inbreeding

– equalize reproductive contributions of each individual

– pair individuals of lowest mean kinship

– work with other zoos to share genetic material

Limits to zoo taxa….

Problems with captive propagation

http://www.cbsnews.com/video/watch/?id=7396832n&tag=segementExtraScroller;housing

African wildlife in Texas ranches

Problems with captive propagation

Deliberate (artificial) selection

• for increased productivity – fecundity, growth, or both

• for ‘better’ type or traits (color, size)

• for tractability (handling, breeding season)

– problems with linkage of undesirable traits

Problems with captive propagation

Problems with linkage of undesirable traits (white tiger):

• strabismus (crossed eyes)

• weakened immune system

• shortened tendons of the forelegs, club foot, kidney problems, arched or crooked backbone and twisted neck, reduced fertility and miscarriages

• unwanted (normal) kittens discarded…

Ron Kimball

Problems with captive propagation

Accidental selection• for increased productivity – fecundity, growth, or both

• domestication – select for fitness under captive conditions– tends to homogenize differences among sub-populations

Problems with captive propagation

Absence of selection…

General post-release problems

• lower fitness in wild – domestication – genetic and/or behavioral– loss of variation

• increased fitness in wild– loss of wild populations through competition for mates,

habitat – captive-bred may be healthier– different development stages

General post-release problems

• lower fitness in wild – domestication – genetic and/or behavioral– loss of variation

• increased fitness in wild– loss of wild populations through competition for mates,

habitat – captive-bred may be healthier– different development stages

lake trout (Foster 1984)• rapid early growth in hatchery• young age at sexual maturity• premature reproductive senescence

General post-release problems

• captive individuals may hybridize with wild indivs.– pollution of wild genome

– loss of variation if lowered variance in captive stock

Additional methods:

Cross-fostering“head-start” programs – minimize duration of captivityArtificial inseminationEmbryo transfer

Association of Zoos and Aquariums

Guidelines for Reintroduction of Animals Born or Held in Captivity

http://www.aza.org/reintroduction/