Transcript Captive propagation

Captive breeding programs
Peter de Sève
Saving species
Assuming a decline is already well under way: what to do?
- remove threats (harvest regulation, development, etc.)
(what if threat is exotic species?)
- enhance natural reproduction; improve habitat
(conspecific attraction; food supplementation, etc.)
- translocate individuals to increase variation, N
- captive breed for short term to produce stock for translocation
- captive breed for long term to have stock ready for periodic use
- captive breed indefinitely
Purposes of captive breeding programs:
• conservation of threatened species
– objective to restore wild popns (no wild individuals left)
– objective to supplement wild populations that have
declined or are threatened
Purposes of captive breeding programs:
• captive maintenance of threatened species
– habitat is completely lost
– threats to extinction cannot be overcome
– duration of captivity has irrevocably altered species
maintain in permanent captivity
re-establish wild population
supplement wild population
minor
major
consequences of genetic mismanagement
Stages in a captive breeding program
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decline of wild population, genetic consequences
choice of founder population
growing captive population
in captivity
maintaining captive population
reintroducing individuals
managing reintroduced population
Issues for captive propagation
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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
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
– keep sub-populations isolated
Rules for captive propagation
Maintaining the population
• maximize N and Ne (maximize sex ratio)
• maintain equal family sizes
Rules for captive propagation
Maintaining the population
• maximize N and Ne (maximize sex ratio)
• maintain equal family sizes
Lion: average family size 1.65
variance in family size 32.7
reduces effective popn. size to 8%
Rules for captive propagation
Maintaining the population
• maximize N and Ne (maximize sex ratio)
• maintain equal family sizes
golden lion tamarin
- founder population 242 individuals
- 48 contributed to subsequent gene pool
- most of offspring (2/3) from single pair
Rules for captive propagation
• minimize loss of genetic variation
– maximize N and Ne (maximize sex ratio)
– maintain equal family sizes
– periodically check variability, compare with wild populations
• minimize behavioral changes
– minimize duration of captivity (maximize generation time)
• minimize inbreeding
– conduct pedigree analysis/management
– outcross population with new individuals
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?
Rules for captive propagation
Species Survival Plans (SSPs) for zoo species
goal: preserve genetic variation – 90% of H over 100 years
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….
Problems with captive propagation
African wildlife in Texas ranches
http://www.cbsnews.com/video/watch/?id=7396832n&tag=segementExtraScroller;housing
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
Problems with captive propagation
Problems with linkage of
undesirable traits (white tiger):
• strabismus (crossed eyes)
• weakened immune system
• shortened tendons of the forelegs, club
foot, kidney problems, arched or crooked
backbone and twisted neck, reduced
fertility and miscarriages
• unwanted (normal) kittens discarded…
Ron Kimball
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
Problems with captive propagation
Absence of selection…
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
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
lake trout (Foster 1984)
• rapid early growth in hatchery
• young age at sexual maturity
• premature reproductive senescence
General post-release problems
• captive individuals may hybridize with wild indivs.
– pollution of wild genome
– loss of variation if lowered variance in captive stock
Additional methods:
Cross-fostering
“head-start” programs – minimize duration of captivity
Artificial insemination
Embryo transfer
Association of Zoos and Aquariums
Guidelines for Reintroduction of Animals Born
or Held in Captivity
http://www.aza.org/reintroduction/