1 / 20

Captive breeding programs

Captive breeding programs. (Conservation vs. preservation revisited….). 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.

niveditha
Télécharger la présentation

Captive breeding programs

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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

More Related