Seeking Lonesome George’s secrets
When Lonesome George, the only survivor of the Pinta Island tortoises of the Galápagos, died in 2012, the news landed with a blow. He had lived for a century or more, a common life expectancy for giant tortoises, and all attempts to mate him were unsuccessful.
Recently, a team of scientists researching longevity turned to George, mining his genetic code for clues to his life span. In a paper published in Nature Ecology & Evolution, the researchers reported preliminary findings of gene variants in George linked with a robust immune system, efficient DNA repair and resistance to cancer. The study also sets the stage for understanding giant tortoises’ evolutionary past.
The scientists sequenced the entire genome of Lonesome George, plus that of an Aldabra giant tortoise from the Seychelles, another extraordinarily long-lived species.
The researchers then compared the tortoise genomes with those of mammals, fish, birds and other reptiles. They found evidence that a mutation in a gene called IGF1R, which has been linked with longevity in humans and mice, might contribute to the tortoises’ exceptional life span. They also discovered that the tortoises had more copies of genes related to energy regulation, DNA repair, tumor suppression and immune defense compared with other creatures.
Little plant survives inside a duck
Duckweeds are humble-looking plants whose tiny, brilliant green globules spangle ponds all over the world. Some duckweeds are the smallest flowering plants in nature.
Scientists working in Brazil discovered that one duckweed, Wolffia columbiana, has a surprising talent. In Biology Letters, the authors reported that this duckweed can likely hop entirely intact from wetland to wetland by hitching a ride in the feces of birds.
Duckweeds can reproduce by copying themselves, so if one duckweed lands where a duck relieves itself, it is capable of eventually creating a dense mat of duckweeds where there were none before.
No thumbs but able to hitch a ride
A spring-green aphid clambers over a clot of soil, making its way to the shelter of a forest of plants in the distance. The insect’s long legs help it lever itself over the uneven ground at surprising speed, but if you look closely at its back, you’ll see that it has a passenger: A tiny juvenile aphid, or nymph.
This behavior, which scientists described for the first time in Frontiers in Zoology, results in the young one reaching the safety of a host plant much faster than it could on its own small legs. But the tactic is unpopular with the adults, who do not appreciate carrying a hitchhiker.