A team of researchers from Yale University, the University of Oviedo in Spain, the Galapagos Conservancy, and the Galapagos National Park Service has sequenced and analyzed the genomes of Lonesome George — the iconic last member of the Pinta Island tortoise (Chelonoidis abingdonii) — and the Aldabra giant tortoise (Aldabrachelys gigantea), and identified new candidate genes and pathways that may underlie the extraordinary characteristics of these iconic species, including their development, gigantism and longevity.
Giant tortoises are among the longest-lived vertebrate animals and, as such, provide an excellent model to study traits like longevity and age-related diseases.
However, genomic and molecular evolutionary information on these tortoises is scarce.
To obtain such data, Yale University researcher Adalgisa ‘Gisella’ Caccone and co-authors conducted genetic analysis of DNA from two long-lived giant tortoises: Lonesome George — the last representative of Chelonoidis abingdonii, endemic to the island of Pinta (Galapagos islands, Ecuador) — and an individual of Aldabrachelys gigantea, endemic to the Aldabra Atoll and the only extant species of giant tortoises in the Indian Ocean.
“Lonesome George is still teaching us lessons,” Dr. Caccone said.
“In 2010, I began sequencing the whole genome of Lonesome George to study evolution of the tortoise population on the Galapagos.”
“University of Oviedo’s Dr. Carlos Lopez-Otin analyzed these data and other species of tortoises to look for gene variants associated with longevity.”
The researchers found that the giant tortoises possessed a number of gene variants linked to DNA repair, immune response, and cancer suppression not possessed by shorter-lived vertebrates.
“We had previously described nine hallmarks of aging, and after studying 500 genes on the basis of this classification, we found interesting variants potentially affecting six of those hallmarks in giant tortoises, opening new lines for aging research,” Dr. Lopez-Otin said.
The findings appear in the journal Nature Ecology Evolution.
Víctor Quesada et al. Giant tortoise genomes provide insights into longevity and age-related disease. Nature Ecology Evolution, published online December 3, 2018; doi: 10.1038/s41559-018-0733-x