Oct 22, 2021 23:00:00

Elephants are evolving to prevent their fangs from developing due to poaching

The elephant population has declined significantly as the tusks used by elephants to bark and dig water have been targeted by many poachers due to their rarity. And in Mozambique, where the population has decreased by 90%, it has been reported that the proportion of 'elephants without fangs' is increasing.

Ivory poaching and the rapid evolution of tusklessness in African elephants

https://doi.org/10.1126/science.abe7389

Poaching drove the evolution of tusk-free elephants | Ars Technica
https://arstechnica.com/science/2021/10/poaching-drove-the-evolution-of-tusk-free-elephants/

Ivory hunting drives evolution of tuskless elephants
https://www.nature.com/articles/d41586-021-02867-y

Ivory poaching has led to evolution of tuskless elephants, study finds | Wildlife | The Guardian
https://www.theguardian.com/environment/2021/oct/21/ivory-poaching-evolution-tuskless-elephants-study

During the Mozambican Civil War between 1977 and 1992, many elephants were killed to raise funds, reducing the number of elephants in Mozambique Gorongoza National Park from 2542 to 242. A common feature of surviving elephants was 'no tusks', with the proportion of elephants without tusks increasing from one-fifth to one-half before the war. In addition, the proportion of elephants born after the war that have the characteristic of not growing tusks has also increased.

Elephants have tusks in both males and females, but a research team led by Shane Campbell of the University of California, Los Angeles found out that 'the characteristic of having no tusks is almost found only in females,' and 'mutated to the X chromosome.' Isn't there something wrong with this? '

Therefore, Campbell et al. Collected blood samples from 18 female elephants and performed whole-genome sequencing analysis. When investigating the difference between elephants with tusks and elephants without tusks, mutations were found in the

amelogenin gene involved in the formation of tooth enamel in elephants without tusks. Furthermore, it has been clarified that this gene is a recessive lethal gene, and individuals who have acquired the gene by homozygosity die without being born.

Due to the characteristics of X-linked inheritance, half of the males given to a fangless mother inherit this gene and die, so the final birth of males is half that of females. Due to these characteristics, the research team wrote that 'a herd of elephants with frequent poaching tends to increase the number of elephants without tusks and decrease the number of males.'

Elephant populations have been on the rise over the next 20 years after the war, so Campbell et al. 'If nature maintenance remains as good as it is today, this problem can be undone over time.' Said.