Unnatural Selection: Tusklessness in Elephants

This is part three of a series of blog posts, click here to see the first post. This post is on the unnatural selection pressures of poachers on African elephants and how more and more elephants are now tuskless.

It’s World Elephant Day! To be honest I had no idea this existed until today, but I’m glad it does. Why not sign the pledge to help protect elephants at the World Elephant Day website by clicking here?

Anyway!

I had always planned on writing this post on tusklessness in elephants, but what better day to publish than today? Hopefully, although obviously a very sad topic, it’s not all doom and gloom.

A few months ago I read a paper titled Tusklessness in African Elephants: A Future Trend by H. Jachmann, P.S. Berry and H.Imae. In it they show that the decline of the African elephant due to poaching is not quite as straightforward as is usually presumed. That is, that it’s not just one huge downward arrow on every graph showing the number of elephants. They also present that tusklessness in these animals has an upside…

The Number of African Elephants

So… it may be an upside but it’s certainly not great. Below is a graph showing the number of African elephants in the Luangwa Valley in Zambia:

Number of Elephants FLAT2.png

As  you can see, the numbers are definitely not good. Although the numbers do appear to be on the rise and this is for two reasons. Firstly is the great work of the National Parks and Wildlife Service with the support of the Save the Rhino (SRT) Foundation, who have dramatically improved the security of the area. Secondly, may be the response to unnatural selection pressures from poachers.

Unnatural Selection

Poachers have been hunting these elephants for their ivory for many years and the result is an increased population of tuskless elephants. A certain amount of elephants are naturally tuskless, initially a very small amount (around 3-4%) but this amount has increased for two reasons. Firstly, the ones with tusks have been hunted increasing the proportion of tuskless elephant in the population, while those without tusks will often pass on their tusklessness gene to their offspring.

Tuskless Elephants FLAT2

So, according to this paper, the number of tuskless female elephants is now predicted to stabilise at around 20-30%, meaning around 20-30% of the species is unlikely to be hunted by poachers. Which is…good? Elephants do actually need their tusks for social dominance as well as other various tasks, but ultimately these tuskless elephants are now ‘well adapted’ to a world with humans in search of ivory.

This is of course not an ideal situation, but is definitely an interesting example of unnatural selection.

Overall Then

This is just another example of human’s influence on the world and the dramatic effects of unnatural selection. Although in regards to the elephants, things are looking a little better, with the net influx of elephants into the Luangwa valley stabilising, as well as the sex-ratio and the number of tuskless elephants.

References:

Jachmann, H., Berry, P. and Imae, H. (1995). Tusklessness in African elephants: a future trend. African Journal of Ecology, 33(3), pp.230-235.

Leader-Williams, N. and Milner-Gulland, E. (1993). Policies for the Enforcement of Wildlife Laws: The Balance between Detection and Penalties in Luangwa Valley, Zambia. Conservation Biology, 7(3), pp.611-617.

One thought on “Unnatural Selection: Tusklessness in Elephants

Comments are closed.