Nature Podcast: Discovering a new species of parasitoid wasp in a tropical fruit fly (Drosophila melanogaster)

The population of the island was not as large as it would have been if it had not been for the arrival of a founder group. But after that, the island’s population seemed to grow steadily until the nineteenth century.

Despite being a hugely studied model organism, it seems that there’s still more to find out about the fruit fly Drosophila melanogaster, as researchers have discovered a new species of parasitoid wasp that infects the species. Unlike other wasps, this one lays its eggs in flies and then eats its host from the inside. The minuscule wasp was discovered by chance in an infected fruit fly collected in a Mississippi backyard and analysis suggests that despite having never been previously identified, it is widespread across parts of North America.

How a bright color can change mouse tissues to be transparent, and an effective way to engage with climate-science skeptics.

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The final nail in the coffin of this collapse narrative: The case of Rapa Nui, an island of islands built between 1670 and 1950

The latest analysis, published on 11 September in Nature1, “serves as the final nail in the coffin of this collapse narrative”, says Kathrin Nägele, an archaeogeneticist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. “It’s correcting the image of Indigenous people.”

Human remains from the 19th and 20th century were found in the National Museum of Natural History. Genome sequences from the teeth or inner-ear bones of 15 individuals, and comparisons with other ancient and modern populations, suggested they were Rapanui, and radiocarbon dating showed that they lived between 1670 and 1950.

After settling Rapa Nui by around ad 1200, ancient Polynesian people developed a flourishing culture famous for its hundreds of colossal stone statues, called moai.

When Europeans first reached the island in 1722, they estimated that it had a population of between 1,500 and 3,000 people and found a landscape denuded of the palm-tree forests that would have once covered the island. By the late 19th century, the Rapanui were made up of 110 people, due to an outbreak of smallpox and the kidnapping of one-third of the inhabitants.

The theory that a pre-contact population of 15,000 or more plundered the once-pristine island’s resources has been challenged by researchers who have questioned humans’ role in deforestation and its effects on food production.

Anna-Sapfo Malaspinas, a geneticist at the University of Lausanne, Switzerland, and Vctor Moreno-Mayar, an evolutionary genetics professor at the University of Danes were both hopeful that ancient Rapanui genes could address the ecocide theory.

Information on how a population’s size has changed over time can be found in both ancient and modern genomes. When the population is small, segments of DNA shared between individuals — which are inherited from a common ancestor — tend to be longer and more abundant, compared with DNA segments from periods when numbers are higher.

The amount of people dropped from 15,000 to 3000 before the eighteenth century is not consistent with the genetic data. Malaspinas says there is no strong collapse. “We’re quite confident that it did not happen.”

Keolu Fox, a genome scientist at the University of California, San Diego, says the finding that Rapanui reached the Americas will come as no surprise to Polynesian people. “We’re confirming something we already knew,” he says. Do you think that people who find things like Hawaii would miss a whole country?

The researchers received a similar reaction when presenting their initial findings in Rapa Nui. Malaspinas recalls being told that ‘of course we went to the Americas’. She traveled to the island many times to meet with officials and residents of the island.

The researchers did a good job in engaging with the people in Rapa Nui. She adds that scientists should do more to get Indigenous remains returned to their place of origin.