Cloning - Part 1
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| Baby Elizabeth Ann, the cloned black footed ferret |
Recently, I have read a couple stories of animal cloning in the name of genetic diversity. I think these are interesting topics and relevant to the class. In August of 2020, a critically endangered animal called Przewalski’s horse was cloned from the DNA that had been collected in 1980 and preserved in the San Diego Zoo Global. With conservation efforts, the species was brought back from the brink of extinction and re-introduced to its native grasslands in China and Mongolia. What I think a key point to consider is that almost all of the the horses can be traced back to only 12 predecessors. Conservationists were only able to work with the genetic diversity of 12 horses - that is how critically endangered they were. The new baby that has been cloned using old DNA is meant to contribute genetic diversity into the dwindling species.
In December of 2020, a black-footed ferret was cloned for the same purposes as the Przewalski’s horse. The San Diego Zoo Global was again involved. Again, they nearly went extinct, but were brought back due to conservational efforts, and, again, there are only a few predecessors to whom all current black-footed ferrets can trace their lineages back to - just seven ancestors in fact. Not much in way of genetic diversity. According to the press release, a lack of genetic diversity could result in a higher susceptibly to diseases, genetic abnormalities, a decreased ability to adapt to natural environments, and lower fertility rates within a species.
After the sexual recombination that has taken place over generations of species, introducing a clone from decades ago would be safe and much more effective than continuing to try different combinations from the genome of current animals. Conservationists can likely control and develop genetic variation to a degree, but nature/randomness ultimately dictates which traits are passed on from which parent. Given that decades have passed, the cloned genome would likely not exist in its entirety in an individual in the population. This is what allows the clone to potentially introduce more diversity. Combining this clone genome with current genomes, aka genomes different than genomes in the past from the time of the original animal, means different combinations and diversity will result compared to the genomes that were created during the time of the original animal. Genetic diversity allows for greater variation and the ability for new mutations and/or adaptability to arise, thus potentially contributing to evolution within the population. Nature can select for (or against) the new genetic combinations.
Sources
Phys.org - "Black-footed ferret cloned to help preserve endangered species"
I really enjoyed your blog post. I thought it was so interesting how the black-footed ferrets lineages were traced back to only seven ancestors, and how they lack genetic diversity. This topic is something I would like to further look into. Until this class, I never would have see cloning working so effectively.
ReplyDeleteI didn't realize that only seven of the original population of black-footed ferrets was able to breed. While adding Elizabeth Ann's genes to the current population will surely help with diversity do you think they should continue cloning ferrets to introduce genetic diversity? At what point should we decide that the genetic diversity achieved from cloning is enough and hope that the population can survive on its own?
ReplyDeleteWow, that's a good question. I hadn't thought of that. I think it is a good idea for the zoo to keep tissues/DNA samples of all black-footed ferrets that they can for cloning purposes, just in case. If they had the ability to clone any ferrets from the past, I would think they would select traits they knew were different and had a more rare frequency in the population. I'm not sure if they have that ability now...I would think they do. Anyway, I imagine there must be a certain threshold of genetic diversity and population number that conservationists would want to hit before completely calling it quits on cloning. They have to keep in mind factors like genetic drift that reduce genetic variation in the wild. That is why it is important to keep DNA samples and the possibility for cloning on the back burner. Genetic drift is random, so only time will tell what will happen and what will be needed. The conservationists will also have to adapt.
DeleteErin, this is an awesome blog post! Thank you for sharing!
ReplyDeleteThis is a really interesting post! It's fascinating to see the possible applications of cloning technology today! Where do you stand on this issue of cloning? Do you think there are ethical dilemmas that could arise? What about if this was applied to humans instead of ferrets or other animals?
ReplyDeleteThank you! I believe that there are enough humans on earth and enough genetic diversity in humans that cloning is not necessary.
DeleteI invite you to read my second post: Cloning - Part 2.