Managed Breeding for Conservation: Sustainability of Ex Situ Populations

1. Managed Breeding for Conservation:Sustainability of Ex Situ Populations Kevin Zippel - CBSG/WAZA Amphibian Program Officer Materials produced by: R. Andrew Odum, Curator Department of Herpetology Toledo Zoological Society

2. Why do we maintain records?

3. Records are kept… To manage a collection To manage multiple collections in coordination (population management) To learn about the animals in our charges (Do Science)

4. Records are kept… To communicate Records are kept as part of our responsibilities for the animals in our charges

5. Data for Collection Management Identifiers Sex Parentage Where are they Who are they with What they did while they were here Husbandry Medical

6. Data for population management Genetic parentage Demographic Sex Location Immigration Emigration Births Deaths

7. Genetic Data Demographic Data Records for Population Management You guys sound like a bunch of treefrogs! They are both important! Genetic data is most important! No! Demographic data is most important!

8. Minimal Data Set How Obtained (demographic) Arrival Data (demographic) Sex (demographic) Birth Date (demographic) Parents (genetic)

9. Minimal Data Set Death date (demographic) Departure data (demographic) Specimen Identification (acc. #, pit tag, photograph, etc.)

10. Why do we cooperatively manage populations? For preservation of genetic diversity (GD) for the future(The Ark) For future reintroduction To efficiently utilize captive resources

11. Preserve Gene Diversity Maintain a specific amount of Gene Diversity (GD) for a specific amount of time e.g. 90% for 100 years THE ARK

12. SPARKS

13. PM-2000

14. Arabian oryx N = 13 in 1965 10 founders N = 416 in 1995 Stable 92% gene diversity Ne/N = 0.30 Mean Inbreeding=0.07 Markhor N = 35 in 1965 11 founders N = 81 in 1995 Unstable 86% gene diversity Ne/N = 0.07 Mean Inbreeding=0.19 Managed vs. Unmanaged

15. All populations fluctuate:stable populations fluctuate little. 100 @ 10% 100 @ 50% x 0.90 = 90 x 0.50 = 50 x 1.10 = 99 x 1.50 = 75 x 0.90 = 89 x 0.50 = 38 x 1.10 = 98 x 1.50 = 56 x 0.90 = 88 x 0.50 = 28 x 1.10 = 97 x 1.50 = 42 Good years don’t cancel bad years

18. Projection of dolphin population: Initial N = 100; K = 200

19. Projection of dolphin population: Initial N = 10; K = 20

20. Carrying Capacity (N) Founders Time Expansion Phase Maintenance Phase N

21. Factors that effect N from one census to the next • Nt = Nt‑1 + (B – D) + (I – E) Tomorrow Today

22. AB CD B D D A BD AD Loss of Gene Diversity by DriftThe problem with small populations Unrelated Animals Allele C is lost

23. Loss of gene diversity due to drift 1000 500 250 % Gene Diversity 100 N 50 10 Generation

24. Inbreeding Mating between relatives Reduces gene diversity (GD) Greatly increases probability of expressing deleterious alleles Reversible I love my cousin

25. Unrelated Animals 1 2 Non-inbred offspring 3 4 Inbred offspring 5 6 Inbreeding

26. AB CX B X X A Unrelated Animals BX AX X B X X Non-inbred offspring XX XB Inbred offspring Inbreeding Depression Expressed by XX Following deleterious allele X through a pedigree Inbreeding Depression X is a rare deleterious allele

27. Inbreeding reduces fitness Look What I Made Now!

28. Inbred vs. Non-Inbred Crested Wood Partridges at MN Zoo • 8% reduction in egg volume • 10% reduction in egg weight • 20% reduction in hatch rate • 51% reduction in 30 day survival • Inbred birds have 41% more medical notes than do their non-inbred counterparts!

29. Inbreeding is Reversible If an inbred animal is bred with an unrelated animal, the resulting offspring are not inbred Outbreeding

30. Outbreeding Unrelated Animals Unrelated Female Non-inbred offspring 1 2 3 4 Inbred #5 & #6 5 6 7 Non-Inbred Offspring 8 8 is not inbred, but GD is lost

31. Small populations Few breeders Isolationist, possessive management Little or no genetic management Poor records Larger populations More breeders Cooperative management Careful genetic management Good records The Bad vs. The Good

32. Population Management Goals • Maintain 90% gene diversity for 100 years • Defined target population size • Founders vs. offspring • Stable numbers • Stable age distribution • Avoid inbreeding, drift • Maximize Ne/N

33. How is managed breeding achieved? • data collected • compiled at institution - ARKS IV • compiled internationally - ISIS (future = ZIMS) • polished by studbook keeper - SPARKS • management recommendations - PM2000 • population modeling - VORTEX

34. Data to collect • Provenance • Genetic • Parentage • Demographic • Gender • Birth/capture date • Immigration • Emigration • Births/Breeding behavior/Development • Deaths

36. Studbooks • 300 Population Management Plans (PMPs) • Designated Population Manager keeps studbook and makes management recommendations • 90 Species Survival Plans (SSPs) • Species Coordinator & Management Group • elected committee, outside advisors • Established genetic goals for 50-100 years • Participation required of AZA member zoos • Field Conservation integral to program

37. How to Make Breeding Recommendations? 1. Quantify InbreedingThe Inbreeding Coefficient (F) F = probability that homologous alleles at a random locus are “identical by descent”

38. AB CX F=0 F= 0 AX BX F = 0.25 XB XX Inbreeding Coefficients of a Simple Pedigree Inbreeding Coefficient

39. How to Make Breeding Recommendations? 2. Select breeding pairs using the principle of inbreeding coefficient to determine relatedness Kinship

40. 1 2 3 4 5 6 H H Kinship Coefficients of a Simple Pedigree k= 0 between #1 and #2 F=0 F= 0 k= 0.25 between #3 and #4 k= 0.375 between #5 and #6 F = 0.25 Hypothetical cross of #5 & #6 F = 0.375 How related are we?Kinship

41. How to Make Breeding Recommendations? 3. Calculate Mean Kinship:the average of all the kinships of an animal to the rest of the population

42. 1 2 3 4 5 6 7 8 MK of PedigreeALL ANIMALS LIVING MK=0.225 MK=0.4125 MK=0.3375 MK=0.05 MK=0.3875 MK=0.2275 #7 is the most important animal

43. Mean Kinship • Determines Best Pairings • Determines Animals to Surplus

47. Incomplete data • May remove animals from analysis process • May create errors in analysis • May prevent analysis

48. Incorrect data • May create significant errors in analysis • Usually hurts captive population

49. The Future: Applying Our Knowledge • Cooperation among institutions • Larger populations, backup • More breeders • Careful genetic management • Population planning • Group management • Good records

50. Population Management is Balanced on Good Records Demography Genetics GOOD RECORDS Husbandry