Image from Wikimedia Commons
Narwhals are (in my opinion) are one of the most interesting marine species there is. Male narwhals have an enlarged tooth that appears to be a tusk on front of their head making them look as if they are the unicorns of the sea making them a very unique organism. They may be unique compared to other organisms but comparing them among themselves tells a different story.
Recently, researches in Denmark have analyzed the genome of Narwhals and found that they have a very low amount of genetic diversity. They have one of the lowest genetic diversity among the many mammals that have been studied. This characteristic of low genetic diversity is a unique one to the narwhal species compared to the many other arctic species, among which is the beluga whale which narwhals are very closely related to. This surprises many who read it as narwhals have a relatively large population size of over 80,000. The number of narwhals over time also has drastically increased since the lowering of genetic diversity. There is an idea that is pretty well known that in order to have a high population size there must also be a high level of genetic diversity. Narwhals show that this is not the case for all organisms and neutral theory of molecular evolution. The cause of low genetic diversity is usually caused by inbreeding within a population of a species, however when investigation narwhals there was no evidence to suggest inbreeding within the population. Low genetic diversity is also usually caused by bottlenecking of the species, meaning that a large amount of the species died off leading to a smaller population to rebuild the population, but there is no evidence to suggest that even such as this took place to affect the narwhal population. The researchers however suggest that an ideal location was created by the last glacial period, roughly 115,000 years ago, that the narwhals used to reproduce rapidly and at the time had a much smaller population size. With the smaller population size, there is less genetic diversity, and a ideal location to reproduce led to a drastic increase and population size with a very small amount of genetic diversity. The large population of narwhals have been able to survive for the past hundreds of thousands of years with low genetic diversity, but could be in harm in the future.
Narwhals depend heavily on the sea ice in the arctic to survive as it keeps humans and outside pressure out of their environment. With climate change becoming more of an issue, so is the threat on narwhals and their environment. As the ice caps melt, there will be an increase in hunters in the habitat of narwhals. Narwhals also play a crucial role in the environment of the arctic. They are in the top of the food chain, thus without narwhals the population of the organisms that it eats will begin increase at a very high rate.
The information from previous units has shown that high genetic variation is a good thing for the survival of a population, but it is interesting to see an exception to this rule and idea. Most likely however, the population of narwhals will not decrease due to the lack of genetic diversity, but instead due to climate change. Climate change is something that me, you, and humans can general can have an impact on climate change and help insure the survival of species such as narwhals.