Managed Breeding for Conservation: Sustainability of Ex Situ Populations

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Managed Breeding for ConservationSustainability
of Ex Situ Populations

• Kevin Zippel - CBSG/WAZA
• Amphibian Program Officer

Materials produced by
R. Andrew Odum, Curator Department of
Herpetology Toledo Zoological Society
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Why do we maintain records?
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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)

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Records are kept

• To communicate

Records are kept as part of our
responsibilities for the animals in our charges
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Data for Collection Management

• Identifiers
• Sex
• Parentage
• Where are they
• Who are they with
• What they did while they were here
• Husbandry
• Medical

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Data for population management

• Genetic
• parentage
• Demographic
• Sex
• Location
• Immigration
• Emigration
• Births
• Deaths

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Records for Population Management
You guys sound like a bunch of treefrogs! They
are both important!
Genetic data is most important!

• Genetic Data
• Demographic Data

No! Demographic data is most important!
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Minimal Data Set

• How Obtained (demographic)
• Arrival Data (demographic)
• Sex (demographic)
• Birth Date (demographic)
• Parents (genetic)

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Minimal Data Set

• Death date (demographic)
• Departure data (demographic)
• Specimen Identification (acc. , pit tag,
  photograph, etc.)

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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

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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
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SPARKS
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PM-2000
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Managed vs. Unmanaged

• Arabian oryx
• N 13 in 1965
• 10 founders
• N 416 in 1995
• Stable
• 92 gene diversity
• Ne/N 0.30
• Mean Inbreeding0.07

• Markhor
• N 35 in 1965
• 11 founders
• N 81 in 1995
• Unstable
• 86 gene diversity
• Ne/N 0.07
• Mean Inbreeding0.19

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All populations fluctuatestable populations
fluctuate little.

• 100 _at_ 10 100 _at_ 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 dont cancel bad years
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Projection of dolphin population Initial N
100 K 200
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Projection of dolphin population Initial N 10
K 20
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Carrying Capacity (N)
Founders
Time
Expansion Phase
Maintenance Phase
N
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Factors that effect N from one census to the next

• Nt Nt-1 (B D) (I E)

Tomorrow
Today
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Loss of Gene Diversity by DriftThe problem with
small populations
Unrelated Animals
Allele C is lost
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Loss of gene diversity due to drift
1000
500
250
Gene Diversity
100
N
50
10
Generation
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Inbreeding
I love my cousin

• Mating between relatives
• Reduces gene diversity (GD)
• Greatly increases probability of expressing
  deleterious alleles
• Reversible

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Inbreeding
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Inbreeding Depression
X is a rare deleterious allele
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Inbreeding reduces fitness
Look What I Made Now!
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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!

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Inbreeding is Reversible

• If an inbred animal is bred with an unrelated
  animal, the resulting offspring are not inbred

Outbreeding
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Outbreeding
8 is not inbred, but GD is lost
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The Bad vs. The Good

• 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

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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

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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

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Data to collect

• Provenance
• Genetic
• Parentage
• Demographic
• Gender
• Birth/capture date
• Immigration
• Emigration
• Births/Breeding behavior/Development
• Deaths

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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

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1. Quantify InbreedingThe Inbreeding Coefficient
(F)
How to Make Breeding Recommendations?

• F probability that homologous alleles at a
  random locus are identical by descent

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

• Kinship

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How related are we?Kinship
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3. Calculate Mean Kinship the average of all
the kinships of an animal to the rest of the
population
How to Make Breeding Recommendations?
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MK of PedigreeALL ANIMALS LIVING
MK0.225
MK0.4125
MK0.3375
MK0.05
MK0.3875
MK0.2275
7 is the most important animal
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Mean Kinship

• Determines Best Pairings
• Determines Animals to Surplus

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Incomplete data

• May remove animals from analysis process
• May create errors in analysis
• May prevent analysis

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Incorrect data

• May create significant errors in analysis
• Usually hurts captive population

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The Future Applying Our Knowledge

• Cooperation among institutions
• Larger populations, backup
• More breeders
• Careful genetic management
• Population planning
• Group management
• Good records

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