Investigating Craniofacial Abnormalities in Tuskless African Elephants: A Geometric Morphometric Approach

Abstract

Human activities have long influenced the evolution of wild species. This is the case with African elephants Loxodonta africana, whose populations have been affected by poaching, hunting, human-wildlife conflicts, habitat loss, and fragmentation. As a result of ivory exploitation, congenital tusklessness among female elephants is becoming more prevalent across the continent. In the elephant population of Gorongosa National Park (GNP), tusklessness is associated with mutations in the AMELX gene. While analogous mutations in this gene reduce tooth development in humans, they also have syndromic effects on craniofacial development and structure. It remains to be seen whether tuskless elephants exhibit similar syndromic effects and what implications this may have for their health. This project uses geometric morphometrics to investigate this question in the elephant population of South Africa's Addo Elephant National Park (AENP). Comparing the results from a Procrustes General Analysis of three craniofacial datasets reveals consistent, significant differences in craniofacial vertical and horizontal relationships based on tusk phenotype with potential functional implications. By elucidating the syndromic effects of tusklessness in elephants, this study sheds light on the broader health implications of human-induced adaptations in wild populations, informing conservation strategies in a changing environment.