image: This is a cose up of tibial cross section from permafrost preserved Woolly Mammoth. view more
Credit: Image courtesy of JD Howell (McMaster University, Hamilton, Ontario).
Analysis of high-quality genome sequences of living and extinct members of the elephant family reveals evolutionary insights with implications for conservation. The evolutionary history of elephants remains largely undeciphered. Eleftheria Palkopoulou and colleagues sequenced 14 genomes from living and extinct elephant family members, including a high-quality reference sequence for the African savanna elephant, a 120,000-year-old straight-tusked elephant, and the Columbian mammoth, as well as the extinct American mastodon. Phylogenetic analysis confirmed that African savanna elephants are a distinct species from African forest elephants, with little evidence of recent genetic exchange. Though hybridization between savanna and forest elephants occurs in regions of range overlap and results in fertile offspring, the species appear to have diverged around 5-2 million years ago, and their ancestors remained largely isolated for the past 500,000 years, reinforcing their distinct identities and the need for separate conservation measures. The genomes of Columbian and North American woolly mammoths revealed signs of admixture, bolstering previous accounts of interbreeding that were based on mitochondrial DNA analysis. Contrary to previous accounts, straight-tusked elephants were found to be of tripartite descent: from a lineage that gave rise to forest and savanna elephants, a lineage related to woolly mammoths, and a lineage related to living forest elephants. Analysis of the American mastodon genome revealed that mastodons diverged from elephant family members around 28-10 million years ago. In contrast to previous accounts of an evolutionary history marked by a series of diverging populations, the study uncovers signs of genetic commingling among elephant family members, replete with recurring periods of isolation and interbreeding.
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Article #17-20554: "A comprehensive genomic history of extinct and living elephants," by Eleftheria Palkopoulou et al.
MEDIA CONTACT: Eleftheria Palkopoulou, Harvard Medical School, Boston, MA; tel: 44-78-0452-5147; e-mail: elle.palkopoulou@gmail.com; David Reich, Harvard Medical School, Boston, MA; tel: 1-617-852-5240; email: reich@genetics.med.harvard.edu
Journal
Proceedings of the National Academy of Sciences