Why low genetic diversity a problem and the affects it has on Cheetahs.
The Cheetah, a member of the cat family but is a bit of an outcast because will choose to run rather than fight If attacked which means it cannot fight to protect its food or it’s young. This is probably because of its weak jaw and small teeth so would be no match for a bigger heavier lion but also what the Cheetahs lack in weight the make up for with speed because of its long thin body and it incredible elasticated spine meaning it can reach speeds of around 110k/h and is capable of 0-60 in roughly the same speed as a sports car but can only keep this up for about a minute before the build up of lactic acid shuts down the muscle leaving the Cheetah exhausted defenceless and hungry, therefore the Cheetah has to catch its prey very quickly or stop and watch it run away (4).
When the climate change took place 10,000 years ago causing a genetic bottleneck, meaning only the Acinonyx jubatus was left which has recently been reduced to 12,000 in the wild meaning it is now endangered and because of it low genetic diversity risk extinction eventually.
The reason the Cheetah has a low genetic diversity is because its reduced numbers have forced it to inbreed with other closely related Cheetahs and quite often there are not any other more distantly related Cheetahs for many miles and the population density of Cheetahs in the Serengeti per 100 square kilometres can vary between 0.8-1 and 40 depending on the season (5). Other factors affecting genetic diversity and number of Cheetahs includes a loss of habitat to farming and development, farmers killing them for attacking their livestock (often in metal cage traps where they are shot or left to starve), poaching or the illegal taking of Cheetahs (as pets or for their fur) and competition for food with more aggressive predators such as lions and Hyenas.
Image3 Cheetah eating its kill Image4 Hyena stealing kill from Cheetah
My solution to the problem.
To start my idea is to put a ban on expansion and development in area with a high number of Cheetahs so that they are not forced in to a small area. Also farmers need to be banned from killing Cheetahs but in return a fund should be started to teach them about Cheetahs and also to help them protect the live stock with safe fences that Cheetahs can’t get stuck in or get through. But this will not help the genetic diversity by much to this all the male Cheetahs need to logged in a book and tagged (need to use male Cheetahs because they are easier to split up and move because they often travel on their own and don’t look after the cubs also the females release and egg every time it has sex so can get pregnant more than once at a time so a few males can be put with a female) then they need to be transferred to different locations after each mating season to try and stop inbreeding but this would only work on a short term. To really get the most out of this the Cheetahs would need to be split between different groups that only mix within that group then after they have each paired up mover them to a different group.
Also Cheetah in captivity need to be used in the same breading program moving from zoo to zoo as well as being used to study the Cheetahs characteristics and try to genetically modify the cells or selectively bread them to try and bread out the imperfections and then mix them with the weaker genes.
Evaluation.
However this method of transporting the Cheetahs to their mate might not be successful although it seems that it should give them the best chance of a successful pregnancy after fertilisation because there is no stress or threats to the mother but it could be difficult for the fertilisation because the female may not accept the male as a suitable mating partner as well as the males sperm abnormalities and a sperm count 10 times lower than a domestic cat due to inbreeding, making it hard for the sperm to reach the egg(4) also it is know that Cheetahs don’t breed well in captivity. Also it is not ethical to keep large numbers of Cheetahs in captivity for a breading program that could be Image5 why a mating program would work
risky because it is not fair on the Cheetahs and make their quality of life poor which would be unfair on the animal also when they are transported it would be very stressful for them(6). Yet on the other hand these beautiful creatures would have a positive effect on humans and would probably bring in large crowds to visit them so could be a good idea to only have a small breeding program and then rely on the public visiting zoo’s to fund the work in Africa but there is also a risk to being in captivity because these are wild animal in the presents of humans (zoo keepers and vets) which they could easily kill.
On an economic basis the work in Africa would cost a large amount with no return so would need sponsorship or big donations to get it going where as the captive breeding programs which would cost a lot because of travailing, veterinary bill and food cost. But would be covered by the return from the zoo visitors taking everything into account this idea would work to an extent but is not sustainable because of funding and a possible chance of failing.
Alternative solution.
Artificial Insemination.
Due to the high abnormalities of male Cheetah sperm an alternative solution to mating the Cheetahs in (captivity and in the wild) is to artificially inseminate the males sperm into the female. This would involve collecting sperm from the selected male Cheetah (which there can be choice to find the best one) then freezing it so it can be transported to the female Cheetah and placed in the uterus of the female where fertilisation can then take place.
This sperm have less distance to swim before reaching the eggs, therefore a higher chance of fertilisation. This method has been used to impregnate many Cheetahs and in zoos across North America it has had a 45% success rate.
Scientists are also currently working on ways to use wild or fresh sperm to improve the chance of getting pregnant and to bring a better quality of sperm in.(7).
Evaluation.
Although the success rate is still not that high it is still a lot higher than the success rate of mating and also means fertilisation can happen without having to transport the Cheetah therefore reducing costs which is cheaper and means that the Cheetah will not stressed and scared in travelling. Artificial insemination also allows semen to be taken from wild male Cheetahs and used in the captive breeding program and in 2004 two Cheetah litters were successfully born to captive mothers using the sperm of wild Namibian Cheetahs.(7)
Solution to low genetic diversity in Cheetahs.
I Feel the best way to improve the low genetic diversity is to use Artificial insemination because despite the fact Cheetahs raised in captivity are never going to be able to be re-introduced into the wild because they have not learnt to hunt and survive in the wild. As well as the wild cheetahs eventually being unable to find an unrelated mates which would lead to mass inbreeding. To solve this AI should be used to impregnate wild female Cheetahs living in controlled environment (for the time being so they can be watched) using sperm samples from wild or captive males. Then when they give birth they shall teach their cubs how to hunt and survive in the wild so they will all grow up as wild Cheetahs. Then creating a new generations of Cheetahs mixed with captive and wild genes yet are fully wild and I also believe that this solution is completely sustainable and can be used for any other species in a similar position.
Image(6) Performing the Artificial insemination
Resources
References
- http://www.biology-online.org/dictionary/Genetic_variation
- http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1288178/
- http://en.wikipedia.org/wiki/Inbreeding
- Life on earth (book by David Attenborough)
- http://nationalzoo.si.edu/publications/zoogoer/2005/5/futureforcheetahs.cfm
Images
- Google images (source unknown)
- http://www.corbisimages.com/stock-photo/rights-managed/42-15358554/artificial-insemination-for-kruger-royal-cheetahs-?popup=1&caller=enlargement
By Maxwell Taylor 26/10/2011
