A genomic investigation of the effects of declining population connectivity in African elephant species.
Figure 1: A depiction of growing numbers of orphaned elephants quenching their thirst and losing major sources of food supply.
African elephants were separated by habitat several million years ago into two species: Forrest and Savanna. Forrest elephants have higher heterozygosity and population size; however, savanna elephants have higher rates of inbreeding and genetic load. As their habitats have increasingly declined due to human expansion, limited mobility and genetic drift has become a reality for many populations. The savanna elephant is endangered, while the forrest elephant is critically endangered.
In the first content-wide genomic dataset treating forrest and savanna as distinct species, 232 genomes were studied across 12 different countries in Africa. This study found that these elephants are known for traveling long distances, maintaining high connectivity between species and genetic diversity. In recent years, these elephant populations have become isolated from one another due to human activity, including poaching, expanding infrastructure and declining agriculture to create habitat fragmentation. Smaller, isolated populations are more susceptible to harmful disease and decline from environmental change. As a major African keystone species, elephants shape ecosystems and support entire food webs. By protecting the genetic diversity of these mammalian megaherbivores, entire ecosystems can be protected for cascade and collapse.
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