7842

• UCREFRP Catalog Number: 7842
• Author: Knopf, F. L.
• Title: Biological Diversity in Wildlife Management.
• USFW Year: 1992.
• USFW - Doc Type: 1992.
• Copyright Material: NO

accurate pedigree data are essential. The captive individuals must be housed in such
a way that the parentage of all offspring is known with certainty and detailed records
on all individuals born in captivity, including their sire, dam, birth date and death
date, must be maintained (Glatston 1986). A number of computer software systems
have been developed for this purpose (ISIS 1991, Odum 1990).
Even when descriptive genetic data of the type shown in Table 1 do exist for a
specific captive population, as for example, the rail (Haig et al. 1990), management
to maintain genetic variation is still based on the population's pedigree rather than
the actual alleles known to be present at a few loci in each individual. The reason
is that heterozygosity measured by electrophoresis is a poor estimator of the overall
level of genetic diversity of the individual (Hedrick et al. 1986). Managing to preserve
diversity in a small part of an individual's genome based on descriptive genetic data
(such as the results of electrophoretic surveys) results in greater over-all loss of
diversity than managing on the basis of pedigree analyses (Haig et al. 1990, Hedrick
et al. 1986, Lande and Barrowelough 1987). Thus, management to preserve genetic
diversity revealed by electrophoresis is generally not advisable.
A specific form of management based on descriptive genetic data rather than
pedigree analysis was advocated by Hughes (1991). He recommended management
to maintain allelic diversity (as indicated by the use of DNA probes and antibody
reagents) at the major histocompatibility complex (MHC), because the MHC is known
to play an important role in pathogen recognition (Klein 1986, Miller and Hedrick
1991). However, this approach has not been adopted by those responsible for the
management of captive populations. The arguments against it, including the fact that
it would result in greater over-all loss of genetic variation than management based
on pedigrees, have been presented by Gilpin and Wills (1991), Miller and Hedrick
(1991), and Vrijenhoek and Leberg (1991).
Phases of a Captive Breeding Program
Ideally, the first step in the development of a captive breeding program is consensus
among all concerned parties (agency personnel, outside scientific advisors, non-
governmental conservation groups) that such a program likely would benefit a specific
taxon. This step may be difficult to achieve as value systems differ and there are no
precise scientific guidelines for the optimal point at which to begin capturing animals
for a captive breeding program. However, the IUCN Policy Statement on Captive
Breeding recommends starting a captive population well before the wild population
reaches a critical state: "Management to best reduce the risk of extinction requires
the establishment of captive populations much earlier, preferably when the wild
population is still in the thousands. Vertebrate taxa with a current census below one
thousand individuals in the wild population require close and swift cooperation
between field conservationists and captive breeding specialists to make their efforts
complementary and minimize the likelihood of extinction...." (IUCN 1987). This
recommendation does not imply that a full-fledged captive breeding and reintrod-
uction program is needed for all wild taxa with populations in the thousands but
rather than it often is prudent to develop and maintain the capacity to implement
such a program (captive animals, proven husbandry and reintroduction techniques)
as a safety measure. Although probably not appropriate for all taxa, the "below one
thousand individuals in the wild" criterion from this IUCN statement is being tried
266 ? Trans. 57`h N. A. Wildl. & Nat. Res. Conf. (1992)