I feel that humankind is gradually approaching the time when we could argue that the inbreeding of some wild cat species might effectively extinguish them in the wild. Through human activity we have brought many wild cat species to their knees. The classic causes are habitat loss and direct persecution such as poaching for body parts. There must come a time when the population size of a particular wild cat species becomes unviable. And I really am not sure that the IUCN Red List of Threatened Species™ (Red List) have a handle on this. It may be because the mathematical models used to calculate survivability are inaccurate and/or are based on inadequate data collection.
Indeed, one of the biggest obstacles to assessing the status of a wild cat in the wild is knowing enough about it! There are several examples of cat species about which we know precious little even today. These are the Chinese Mountain Cat, Andean Cat and indeed pretty much all the small wild cats. And even in respect of the most famous of all cats, the most popular animal in the world, the tiger, we had inaccurate information as to population size until fairly recently and it probably is still inaccurate only, we don’t know it. How can you accurately classify the threat of extinction under these conditions?
What prompted me to believe that inbreeding of wild cats is a major problem are four stories (as at around 2009):
- The recent story of the reintroduction of cheetah into India, where it was extirpated many years ago.
- The ongoing story of the Florida panther, which suffers from inbreeding.
- The recent story of the threat of extinction of the Siberian tiger due to inbreeding
- The old but ongoing stories of inbreeding in captivity of Siberian tigers who are breed at least in part for tiger bone and body parts.
There are bound to be other examples of the inbreeding of wild cats but these come to mind, at the moment. Below I look at some examples as this is a very big topic.
People don’t often think about the wild cats, particularly the small ones. But when and if we do, we notice real problems with survivability despite what the Red List sometimes says. One issue, by the way about survivability in the wild is the time span over which it is being measured. The longer the time span the more uncertain survival becomes. Nearly every living creature will survive the next second! And everything in the Universe will one day be nothing more than protons in blackness.
If we bring together the four stories above and measure them against the concept of minimum viable population (MVP), I become very sceptical and pessimistic about the reintroduction of the cheetah to India.
Inbreeding of wild cats – reintroduction of cheetah into India
This concerns the plans being drawn up by Indian government to reintroduce the cheetah to India. Experts are meeting in Rajasthan in September to draw up plans and agree what seems will be a large budget in the millions of pounds to import cheetah from Africa to form a “foundation nucleus” of breeding cheetahs from which they will, once bred, be dispersed over the rest of India.
One factor behind the plan is to encourage better management of existing suitable habitats that “are being managed terribly” (quoting the chairman of the Wildlife Trust of India). How many are going to be introduced? And will this end up as another example of the inbreeding of wildcats? Read below, please.
Jumping forward to 2022, I am updating this page and notice that the Indian newspaper The Hindu reports on January 7 that 50 cheetahs are to be introduced into India over the next five years according to the environment minister. What happened to the original plan that was mapped out many years ago?
The newspaper reports that the cheetah became extinct in India in 1952. The plan stalled during the Covid pandemic. The plan is to import around 10-12 young cheetahs from Namibia or South Africa. Namibia is really the home of the cheetah in the wild. There are more there than anywhere else.
On the issue of inbreeding and genetic diversity, the lineage of the cheetahs to be imported into India will be checked in the host country to make sure that they are not inbred or inbreeding is at a minimum level. My understanding is that the cheetah is already inbred due to bottlenecks in its past.
They plan to introduce the cheetah into five central Indian states which have been carefully selected. One of the parks is the Kuno Palpur National Park (KNP) in Madhya Pradesh, which is rated highly for this task.
It seems to me that if you spread 50 cheetahs across five different national parks in India you are going to have 10 cheetahs in each park which is going to be arguably below the minimum viable population for that group of cheetahs. So, is this plan going to work? Will there be forced inbreeding of these imported cheetahs? Will that result in sterility and a crash in their numbers? I don’t know because I’m just a layperson discussing the matter.
The track record of Indian conservationists in respect of another species, the tiger, is not good. On one occasion they transferred three tigers from one reserve to another to introduce tigers to a reserve where they had been all destroyed by poaching. The trouble was that the three tigers were brothers and sisters 😢 – cast iron certainty of inbreeding to come. See: The Bengal Tiger is Mismanaged.
Minimum Viable Population (MVP)
MVP was originally defined as the smallest number of individuals required for an isolated population to persist (at some predefined ‘high’ probability) for some ‘long’ time into the future. I cannot find out what the minimum viable population size should be for anyone species are wild cat. Perhaps the experts don’t know. However, when you discuss MVP, you got to discuss fragmentation of distribution of any species of wild cat. So, if you have 500 individual breeding animals of one species but they are dispersed and fragmented into five groups of 100 each and there is no corridor between these groups, each group is more vulnerable to extinction. The fragmentation of habitat is a major conservation problem. And habitats become fragmented because of human activities such as the building of settlements, factories and the destruction of habitat to make way for plantations, as some examples.
Below is some more on MVP that I wrote in 2009:
[I use extracts from both eoearth.org (new window) – directly below under a Attribution-Share Alike 2.5 Generic creative commons license and Wikipedia under their license to explain this concept]
A minimum viable population (MVP) size is an estimate of the number of individuals required for a high probability of survival of a population over a given period of time. MVPs can be estimated using a number of mathematical techniques. Most commonly, population viability analyses (PVA) are used. Time periods {
for the period the animal survives] for PVAs are typically 20, 50, 100, 200, or sometimes 1000 years.
MVP estimates may also be derived from population censuses or genetic analyses. Genetic analyses typically involve the estimation of loss of genetic diversity and fitness and projection to extinction. Some studies indicate that inbreeding depression alone can lead to extinction, even among wild populations. Thus, when considering the viability of a given population, one should consider whether the population is large enough to avoid inbreeding depression, if there is sufficient genetic diversity for adaptive change to occur, and if the population is large enough to avoid accumulating new deleterious mutations.
Estimates of the population numbers required to overcome these effects (effective population or Ne) are 50 to avoid inbreeding depression, 500-5000 to retain evolutionary potential, and 12 to 1000 to avoid the accumulation of deleterious mutations…. An Ne of 50 is required to prevent an unacceptable rate of inbreeding, while a long-term Ne of 500 is required to ensure overall genetic variability. Given that the average Ne /N ratio is roughly 0.10 these rules of thumb translate to census sizes of 500 to 50,000 individuals. Where conservationists lack funds to obtain the essential information needed for population-specific MVP size estimates, a broad range of MVP from 100 – 10000 individuals may be cautiously used.
Minimum Viable Population is usually estimated as the population size necessary to ensure between 90 and 95 percent probability of survival between 100 to 1000 years into the future…..An MVP of 500 to 1000 has often been given as an average for terrestrial vertebrates when inbreeding or genetic variability is ignored. When inbreeding effects are included, estimates of MVP for many species are in the 1000s. Based on a meta-analysis of reported values in the literature for many species, Traill et al. reported a median MVP of 4169 individuals.
Florida Panther
We know that the Florida panther is inbred and that the population was under 100 (2009). Their story is the classic case of the inbreeding of wild cats. In the 1990s it was estimated that there were fewer than 30 Florida Panthers in the wild. Inbreeding was inevitable which brought the usual health problems due to inbreeding depression. These include heart failure, undescended testicles, pathogenic diseases and parasites. The Science Daily website tells us that, in order to improve the genetic diversity of the inbred Florida panther, conservationists introduced eight female Texas mountain lions into South Florida. The Science Daily report is dated October 3, 2019. They were therefore able to look back and see what happened after the introduction of these Texas pumas.
RELATED: Catastrophe: Florida panther species stricken with ataxia. Deliberate poisoning?
They found that genetic diversity tripled. Five of the pumas introduced produced at least 20 offspring. As at 2021 upwards of 230 individual mountain lions live in southern Florida thanks to the introduction of these five.
Of course, there was a time when people thought that the Florida panther was a subspecies or a distinct species from all other pumas but that can’t be the case now because of introduced fresh genes from outside that original group. Accordingly, there is an argument that we should no longer describe this species of mountain lion as the Florida panther.
RELATED: Economic expansion in Florida trumps Florida panther conservation
Thanks to conservation efforts to improve genetic diversity they have found that whereas in the past 60% of male Florida Panthers had undescended testicles, in recent years, just 3% had this health condition. It appears, too, that inbreeding results in a reduction in sense of smell and acuity of vision.
Wildcat hybrids
We know that a number of domestic purebred cats are inbred and that the Bengal cat foundation cats are numbered in single figures. The Bengal cat has some genetic health problems the most notable of which is (see Genetic Diseases in Purebred Cats and Bengal cats and HCM – new windows).
Siberian tiger
We also know that the Siberian tiger with an estimated world population of about 400-500 has an effective population, in terms of breeding of “a few”. The species is behaving as if the population is about 27-30 individuals.
RELATED: Three Siberian Tiger Cubs Infested with Maggots Found in Tiny Crate at Beirut Airport
“Although about 500 animals live in the wild, only a few are capable of reproducing their species”
(src:index.hu).
This is probably due to poor sperm quality that has come about as a result of inbreeding, which in turn is due to an initial small population compounded by fragmented “island” populations. Even a large overall population can act like an unviable one of it is badly fragmented. The story of the Siberian tiger is another example of the inbreeding of wild cats.
Captive breeding
Then there is captive breeding – more inbreeding of wild cats. We know that the true story behind the glamorous white tigers in Chinese zoos is that they are heavily inbred causing horrible genetic defects which are kept away from the public. And in respect of the Chinese Siberian tiger (photo above) breeding program in captivity:
“We’ve discovered genetic degeneration among our bred Siberian tigers,” said Liu Dan, the breeding center’s general engineer.
The degeneration symptoms included slow body development, blurry stripes, deformity and organ underdevelopment, Liu said.
[src: . The inbreeding of wildcats takes place routinely at the hands of humankind. We kill them off in the wild and then can’t get it right in captivity either. Mind you, they only breed them in China for their bones and they have been persecuted mercilessly in the wild (see also Siberian Tiger Habitat). The White Siberian tiger suffers the same fate.
Inbreeding of the wild cats – conclusion
A substantial percentage of the wild cat species are at or heading towards the tipping point where their population sizes are so small in the wild that it becomes unviable to maintain genetic health and when the inbreeding of wild cats finishes off the job that we started: their extinction.
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