Genetic Diversity
When working with a very small captive population, the first priority is preserving what genetic diversity is available for as long as possible. In the past, zoos merely bred whatever two animals they happened to have. This led to some pairs having lots of offspring, and others none. This is the way genes are lost from the population. In the 1970s the zoos established the International Species Inventory System (ISIS) to be a central repository of information about the animals in zoos. ISIS stores parentage/pedigree and ownership change data in an easily accessible form, giving zoos a better way to plan the reproduction of endangered species. The New Guinea Singing Dog Conservation Society (NGSDCS) has a stud book for NGSDs with known pedigrees begun with Dr. I. Lehr Brisbin’s former ISIS account. Now the stud book includes some individuals without ISIS pedigrees who passed an expert inspection, or when bred to a known purebred NGSD produced no anomalous offspring, or that tested genetically pure based on the Embark test.
The NGSDCS’s breeding plan was developed on the principles of population genetics. These principles include maximizing genetic diversity by: (1) including at least two offspring of every pair in the program; (2) not letting any one pairs’ offspring become over-represented in the breeding population; (3) choosing the least-related breeding pairs. Genetic diversity is important because it increases the chance that not all the members of the population would be affected by any one health problem or illness.
Such over-representation of one pair’s genes in a small population can result in loss of the rarer genes because specimens with some additional genetic ancestors are not used for breeding and this actually works against the long-term good of the NGSD.
The North American NGSD captive population had two littermate original founders, which came from the Taronga Zoo to the San Diego Zoo in ~1957. USA Zoos only had offspring of this pair to breed until the 1980s, when a female, Olga, was imported from Germany by the Sedgwick County Zoo in Kansas. The German NGSDs came from a different area of the island, and so were unrelated to the Taronga Zoo line. Adding Olga increased the captive North American NGSD genetic diversity by at least 33%. Dinkum, Olga’s mate, and a male named Dingo were the last known original Taronga line breeding males.
One other male and female were imported from Taronga in the late 1980s but the male sired only one litter of which only one offspring went on to produce pups, and the female had one litter with no offspring being used for breeding. So essentially all NGSDs in zoos (there were none in pet homes then) were as closely related as littermates. In the 1990s a male, Darkie, was imported from New Guinea (through the Taronga Zoo) first to Canada, where he reportedly did not reproduce, and then to the USA by Dr. I. Lehr Brisbin. Darkie reportedly had a Taronga Zoo sire and an unrelated wild-caught dam. At Dr. Brisbin’s facility in North Carolina, Darkie sired several litters out of Scratchley, who was an offspring of Dinkum and Olga. These puppies had 25% of genes unrelated to other NGSDs in North America.
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The above pair, Marlin and Samber, was donated to the San Diego Zoo by NGSDCS members for the breeding program. They were a mix of all available genetic lines in North America. They produced two litters.
The NGSDCS program was started with the offspring of Darkie and Scratchley. These were bred to the least-related (for at least two generations) Dinkum & Olga descendents. Subsequent generations have been judiciously bred together. An unrelated male, one of the last of two breeding-capable males in Europe, was imported by the NGSDCS in 2005 from Germany to increase genetic diversity. This male, Benji, was from the same lineage as Olga, but there is only a small chance his great-grandparents were the same specimens as Olga’s parents. Unfortunately, Benji proved to be infertile.
We believe this pedigree or genetic testing based plan is the best way to preserve what we have in the captive population until additional stock can be obtained from the wild. Unfortunately, breeding NGSDs is not as simple as it is for domestic dogs. Most people cannot keep two or three breeding pairs as some members did in the past.
Either sperm has to be collected from sedated males or males being neutered and stored frozen until a suitable female is available, or a pair must be kept together for an extended time to develop a bond. Even females in season may attack unfamiliar males if they are too bold upon meeting, and males are hesitant to court unfamiliar females. Today most NGSD owners want them as pets and desex them, or are not equipped for or capable of raising a litter. So the NGSDCS now sanctions only a litter every few years.
The NGSDCS’s intention has never been to breed NGSDs just for the sake of making more of them. The breedings we approve or sponsor are intended to maintain the captive population in good health. Those individuals that cannot go into the program, whether placed in zoos or private homes, are spayed and neutered to eliminate the chance of accidental litters and hybrids being produced.