African elephants are members of the genus Loxodonta comprising two living elephant species, the African bush elephant (L. africana) and the smaller African forest elephant (L. cyclotis). Both are social herbivores with grey skin, but differ in the size and colour of their tusks and in the shape and size of their ears and skulls.
Both species are considered at heavy risk of extinction on the IUCN Red List; as of 2021, the bush elephant is considered endangered and the forest elephant is considered critically endangered. They are threatened by habitat loss and fragmentation, and poaching for the illegal ivory trade is a threat in several range countries as well.
Loxodonta is one of two extant genera of the family Elephantidae. The name refers to the lozenge-shaped enamel of their molar teeth. Fossil remains of Loxodonta species have been excavated in Africa, dating to the Middle Pliocene.
Taxonomy
The first scientific description of the African elephant was written in 1797 by Johann Friedrich Blumenbach, who proposed the scientific name Elephas africanus. Loxodonte was proposed as a generic name for the African elephant by Frédéric Cuvier in 1825. This name refers to the lozenge-shaped enamel of the molar teeth, which differs significantly from the rounded shape of the Asian elephant's molar enamel. An anonymous author used the Latinized spelling Loxodonta in 1827. Anonymous was recognized as authority by the International Code of Zoological Nomenclature in 1999.
Elephas (Loxodonta) cyclotis was proposed by Paul Matschie in 1900, who described three African elephant zoological specimens from Cameroon whose skulls differed in shape from elephant skulls collected elsewhere in Africa. In 1936, Glover Morrill Allen considered this elephant to be a distinct species and called it 'forest elephant'; later authors considered it to be a subspecies. Morphological and genetic analyses have since provided evidence for species-level differences between the African bush elephant and the African forest elephant.
In 1907, Richard Lydekker proposed six African elephant subspecies based on the different sizes and shapes of their ears. They are all considered synonymous with the African bush elephant.
A third species, the West African elephant, has also been proposed but it needs confirmation. It is thought that this lineage has been isolated from the others for 2.4 million years.
Extinct African elephants
Between the late 18th and 21st centuries, the following extinct African elephants were described on the basis of fossil remains: North African elephant ( Loxodonta africana pharaohensis) proposed by Paulus Edward Pieris Deraniyagala in 1948 was a specimen from Fayum in Egypt. Loxodonta atlantica was proposed as Elephas atlanticus by Auguste Pomel in 1879 based on a skull and bones found in Ternifine, Algeria. Loxodonta exoptata proposed by Wilhelm Otto Dietrich in 1941 was based on teeth found in Laetoli, Tanzania. Loxodonta adaurora proposed by Vincent Maglio in 1970 was a complete skeleton found in Kanapoi, Kenya. Loxodonta cookei proposed by William J. Sanders in 2007 based on teeth found in the Varswater Formation at Langebaanweg, South Africa.
Phylogeny
Analysis of nuclear DNA sequences indicates that the genetic divergence between African bush and forest elephants dates 2.6 – 5.6 million years ago. The divergence between the Asian elephant and the woolly mammoths is estimated 2.5 – 5.4 million years ago, which strongly supports their status as distinct species. The African forest elephant was found to have a high degree of genetic diversity, perhaps reflecting periodic fragmentation of their habitat during the climatic changes in the Pleistocene.
Gene flow between the two African elephant species was examined at 21 locations. The analysis revealed that several African bush elephants carried mitochondrial DNA of African forest elephants, indicating they hybridised in the savanna-forest transition zone in ancient times.
DNA from the European straight-tusked elephant (Palaeoloxodon antiquus) indicates that the extinct elephant genus Palaeoloxodon is closely related to African elephants, and also hybridised with them, with the mitochondrial genome and over 30% of the nuclear genome of P. antiquus deriving from African forest elephants, with this ancestry being closer to modern west African populations than to central African populations of forest elephants.