Subterranean snack attackFEELING PECKISH? A plant species in Brazil has an interesting strategy for getting food: it snares worms underground with its sticky leaves. The carnivorous plant, Philcoxia minensis, grows in the white sands of the Brazilian Cerrado, and keeps many of its tiny leaves underground.
Stalked glands on the surface of the leaves produce sticky substances, and it appears that strategy can trap nematode roundworms.
To get a handle on whether the plant can actually digest and absorb nutrients from such prey, an international team of researchers grew P minensis in a greenhouse and then introduced the roundworm Caenorhabditis elegans to the plant’s leaves.
Some of the roundworms contained a labelled isotope, and the experiment was able to track how the isotope moved from the nematode into the leaves.
Within 24 hours, around five per cent of the prey isotope was found in the leaves, and by 48 hours that had jumped up to 15 per cent. This strongly suggests that the nematodes were digested, rather than naturally decomposing, and were quickly absorbed by P minensis leaves, the researchers note in the Proceedings of the National Academy of Sciences. Meanwhile, their study of enzyme activity suggests the plants digest the worms directly, rather than microbes breaking down the prey.
Carnivory is relatively rare in the plant kingdom, and even here P Minensis stands out: “. . . to our knowledge, no other carnivorous species with adhesive traps has been described with subterranean leaves,” write the researchers.
Tortoise may not be extinct, just absent
A TORTOISE species on the Galápagos Islands that was thought to have been wiped out, may not be extinct after all, according to a new study. Its findings suggest that Chelonoidis elephantopus, which was considered hunted to extinction 150 years ago on Floreana island, could still be going strong on another island. The clues were found by a team at Yale University, who visited Isabela Island in 2008 and took blood samples from more than 1,600 tortoises there. And when they looked at the genetic information, they worked out that 84 tortoise individuals had a pure-bred C elephantopus as a parent.
Given that some breeding took place relatively recently – 30 of the 84 tortoises were less than 15 years old – the researchers figure that some purebreds could still be around.
“Given the documented lifespan of Galápagos tortoises of more than 100 years, there is a good chance that purebred C elephantopus tortoises are still alive,” write the researchers in Current Biology.
“The minimum number of equally contributing C elephantopus founders needed to produce the same genetic diversity observed in the 84 hybrids was 38.” The authors offer a suggestion about how the “missing” tortoises could have been relocated.
“Movement of tortoises between islands by pirate and whaling ships was not uncommon during the 1800s, representing a likely mechanism by which individuals from Floreana were translocated to northern Isabela, despite being presumed extinct soon after Charles Darwin’s historic voyage to the Galápagos Islands in 1835,” they write, adding that the new discovery offers hope for an attempt at species recovery through captive breeding.
“If found, these purebred individuals could constitute core founders of a captive breeding program directed towards resurrecting this species.”
