Characterising microsatellite loci in the blue crane (Grus paradisea)
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Date
2007
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Abstract
The blue crane (Grus paradisea) is endemic to southern Africa and has the smallest
geographical range of the 15 crane species occurring world-wide. Although this species is still
found throughout most of its historic range, it has experienced a significant and rapid decline in
numbers over the last 20 years. One factor causing this decline is the illegal removal of chicks
from the wild. Permits are required to keep, trade in and breed cranes in captivity. However,
birds must be captive bred in order to obtain a permit. Therefore, chicks taken illegally from the
wild are fraudulently incorporated into an existing captive population under the pretence that
they offspring of a legal captive pair. This study describes the development of a set of
microsatellite markers to assist the identification of illegal trade in the blue crane. These
markers can ultimately be used to verify the relationship between the offspring and its claimed
parents by performing parentage analyses. Forty microsatellite loci were obtained from
genomic libraries previously developed in two other crane species and tested for cross-species
utility in the blue crane. In addition, 42 loci were developed for this study from a blue crane
species-specific genomic microsatellite library, of which 19 were tested for polymorphism in
this species. The microsatellite markers characterised here were also tested for their utility in
two other crane species: wattled crane (G. carunculatus) and grey-crowned crane (Balearica
regulorum). One locus, Gamu007, was found to be sex-linked and therefore excluded from the
set of markers. A total of 28 polymorphic loci were tested for the suitability in parentage
analysis in the blue crane. Of these, a set of 16 loci were determined to be as suitable for this
purpose. These loci were shown to be inherited in a Mendelian fashion in a single blue crane
family. In addition, statistical analysis of the loci were identified as exhibiting linkage
equilibrium, this was supported by their distant association on a predicted Grus microsatellite
map based on the chicken genome. The selected loci were also identified as having a low
frequency of null alleles as well as a total first and second parent exclusion power of 0.9999
and 1.0000, respectively. These loci provide a valuable tool for parentage testing in blue crane,
and may also be valuable in population genetic studies to assist conservation strategies. In
addition, this set may be used to assist legal cases involving the illegal trade in blue cranes
upon completion of additional microsatellite marker validation procedures. Twenty-seven loci
were polymorphic in the wattled and grey-crowned crane. These could provide a valuable
source of micro satellite loci in these species, and could potentially eliminate the need for the
development of a species-specific microsatellite library.
Description
Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.
Keywords
Cranes (Birds)--Africa, Southern., Microsatellites (Genetics), Cranes (Birds)--Conservation., Captive cranes., Genetic markers., Population genetics., Parents., Theses--Zoology.