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