by Meredith Hanel, Guest writer
Habitat loss, human-wildlife conflict and poaching have brought today’s cheetah population down to a mere 7100 individuals. As the cheetah races towards extinction, wild cheetah conservation efforts and captive breeding programs race together to save them. Research on captive cheetahs gives insights for protecting wild cheetahs. Boosting wild populations with captive bread cheetahs reintroduced to the wild is possible. Only 20% of cheetahs breed successfully in captivity, partly due to reduced genetic diversity but also because we are still learning what they need.
Cheetahs endured two major events which reduced their numbers and their genetic diversity. The first was when the modern cheetah’s ancestors migrated from North America to Asia, Europe and Africa, at the beginning of the last ice age. The second was when the ice age ended, around 12,000 years ago when a small fraction of cheetahs survived a large mammalian extinction. Lack of breeding partners lead to inbreeding which further reduced genetic diversity.
Certain disadvantageous gene variants, affecting their reproductive health, became common. Cheetahs have poor sperm motility and increased infant mortality. Knowing the genetic background of cheetahs allows zoos and sanctuaries to choose mating pairs that increase genetic diversity in their cheetahs. Getting them to mate and produce offspring is harder, but research is helping.
Unlike house cats, female cheetahs do not make it obvious when they are ready to mate and they may not go into heat for several months. The Smithsonian Conservation Biology Institute (SCBI) enlists male cheetahs to sniff the yards of a female. If she is ready the male will respond with a telltale barking sound attempting to call the female over. Still, when mating fails to produce offspring it is hard to tell if things went wrong at conception or if fetuses were lost. That’s why researchers there are looking for molecular markers in cheetah scat that could confirm pregnancy.
Males produce better quality sperm when they are away from the public eye or have fewer care-givers, and also when they are grouped with other males. The later research finding was informed by observations in the wild, of male cheetahs often living with their brothers. On the other hand, female cheetahs are more successful at breeding when they have been transferred away from the facility where they were born, mimicking what would happen for them in the wild.
Sometimes two cheetahs that are a good match genetically, just don’t like each other. Artificial insemination is one way to get around finicky cheetahs or to avoid transporting them. Unfortunately, cheetah sperm is finicky to preserve. Compared with human and bull sperm, the structure of cheetah sperm is more prone to damage from freezing and defrosting. To overcome this Cheetah Conservation Fund (CCF) and SCBI researchers are collaborating to find methods to better preserve sperm quality in cheetah samples. Artificial insemination using laparoscopy has proved successful because it gets the sperm closer to the eggs so they don’t have as far to swim. CCF and SCBI researchers have also successfully produced cheetah embryos by In vitrofertilization (IVF). CCF houses the only cheetah genetics laboratory in Africa and maintains a genome resource bank with sperm, eggs and very early stage embryos produced by IVF which may be used to boost genetic diversity in both captive and wild cheetahs. CCF holds the world’s largest wild cheetah database of biological material.
Despite hardships, the cheetah population bounced back to hundreds of thousands in the nineteenth century. While humans are to blame for their low numbers today maybe humans can help these resilient creatures bounce back again.
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