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Captive breeding programs

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... variability with that of founder/wild population(s) ... loss of wild populations through competition for mates, habitat captive-bred may be healthier ... – PowerPoint PPT presentation

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Title: Captive breeding programs


1
Captive breeding programs
(Conservation vs. preservation revisited.)
2
Purposes of captive breeding programs
  • protection of threatened species (captive
    maintenance)
  • habitat is completely lost
  • threats to extinction cannot be overcome
  • duration of captivity has irrevocably altered
    species

3
Purposes of captive breeding programs
  • conservation of threatened species
  • objective to restore wild populations (no wild
    individuals
  • left)
  • objective to supplement wild populations that
    have
  • declined or are threatened

4
maintain in permanent captivity
re-establish wild population
supplement wild population
minor major
consequences of genetic mismanagement
5
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

6
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

7
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

8
Rules for captive propagation
  • Maintenance of the population
  • maximize N and Ne (maximize sex ratio)
  • maximize generation time (minimize generations in
    captivity)
  • maintain equal family sizes

Lion average family size 1.65 variance in family
size 32.7 reduces effective popn. size to 8
9
Rules for captive propagation
  • Maintenance of the population
  • golden lion tamarin - founder population 242
    individuals
  • 48 contributed to subsequent gene pool
  • most of offspring (2/3) from single pair

10
Rules for captive propagation
  • minimize loss of genetic variation
  • maximize N and Ne (maximize sex ratio)
  • maximize generation time
  • maintain equal family sizes
  • minimize behavioral changes
  • minimize duration of captivity
  • minimize inbreeding
  • conduct pedigree analysis/management
  • outcross population with new individuals

11
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?

12
Rules for captive propagation
  • Species Survival Plans (SSPs) for zoo species
  • goal 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.

13
Rules for captive propagation
  • Use 50/500 rule
  • 50 parents for single generation
  • Ne of 500 for long-term maintenance
  • Conduct periodic genetic checking
  • compare present population variability with that
    of founder/wild population(s)

14
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

15
Problems with captive propagation
  • Deliberate (artificial) selection
  • to remove genetic diseases
  • Chondrodystrophy in California condor
  • - lethal recessive trait hatchlings die
  • - gene could be removed in one generation by
    removing 77 of 146 condors
  • - careful breeding program was implemented
    instead

16
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

17
Problems with captive propagation
  • Absence of selection

18
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

19
General post-release problems
  • lower fitness in wild
  • increased fitness in wild
  • Lake trout (Foster 1984)
  • rapid early growth in hatchery
  • young age at sexual maturity
  • premature reproductive senescence

20
General post-release problems
  • captive individuals may hybridize with wild
    indivs.
  • pollution of wild genome
  • loss of variation if lowered variance in captive
    stock
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