Mass extinction on islands of snail diversity: An invasive predatory snail has wiped out more than 50 tree snail species on Tahiti and its neighboring islands over the past few decades. Using sophisticated technology, researchers have now solved the mystery of why a certain species was able to escape this fate. Therefore the dominant Partula hyalina snail can tolerate more sunlight than its dark enemy due to the “cool” white color of its home. Therefore, the native snail was able to survive in sunny forest-edge areas, report the biologist.
Humans were and are a catastrophe to many ecosystems in the world: the arrival of our species has had a particularly devastating effect on islands on which animal and plant species have long been able to develop unhindered. Partula snails in particular were able to outnumber several species, with their center Tahiti on the South Pacific Society Islands: hence they were also known as “Darwin’s wings of the snail world”. But this treasure trove of snail diversity was lost to evolutionary biologists due to human influence.
The sad story begins with the deliberate introduction of the giant African land snail to the Society Islands. It was supposed to serve as a human source of food, but then the gregarious mollusks started attacking the crops and became pests. In 1974, agronomists decided to import a snail again—but this time it was a predator: the pink wolf snail (Euglandina rosea) had to bring the African land snail under control. It was also successful – albeit with devastating collateral damage: the Society Islands’ native tree snails were also easy prey for predatory mollusks. “The endemic species had never encountered such a predator before, and so the wolf slug was able to very quickly drive the population to extinction,” says co-author Diermad A. Foighi from the University of Michigan.
Why did the white snail survive mass extinction?
Of the once 61 species, only five survive today and their future is uncertain. Shares of Partula Hylina have performed the best. This is a misfortune for the Polynesians, because in their culture this species plays a particularly important role as an ornamental item due to its shimmering white color. But why did this species survive? In their current study, Foighi and his colleagues examined the question of whether brilliant whites might play a role. Because perhaps this makes Partula hyalina more heat resistant than the wolf snail.
To test his suspicions, he asked P. decided to study the typical daylight exposure of hyalina and wolf slugs. The researchers adapted the “Michigan Micro Mot,” known as the world’s smallest computer, for their purposes: to be able to measure the intensity of light with the device, which is only a few millimeters in size, the researchers said. Harnessed data from energy production by small solar cells. The intensity of light can be continuously measured by scientists recording the speed at which the battery was charged. “Therefore, with computing systems that were small enough for a snail to stick to, we were able to generate the data,” says co-author David Blauw from the University of Michigan.
white makes you less hot
The team affixed the sensor directly to the wolf’s snails for data acquisition. Protected P. With the hyalina, however, they had to be more careful: with the help of magnets, the team placed the devices on both the upper and lower sides of the leaves on which the snails were living in their natural habitat. At the end of each day, the researchers could then wirelessly download the data from each small computer.
It was shown that the wolf snail usually only exposes itself to relatively low levels of radiation. In contrast, P. hyalina is exposed to an average of ten times more sunlight. There are peak values of up to 71,000 lux. Due to the reflective power of its white shell, it is distinctly P. What does not cause overheating in hyalina, explain scientists. However, high radiation values are potentially lethal to the wolf snail, as the light on its rather dark surface is intensely converted to heat. The researchers suspect that the predator was nocturnal P. does not venture to the edge of the forest to capture Hylina because there is a risk that she will not be able to escape into the shadows in time.
Thanks to a collaboration between biologists and engineers, it now seems clear why all people’s P. The hyalina was able to challenge the mad hunter snail: sunlight protects it in loosely overgrown forest edge habitats. “Sensor computers can thus show how we can protect endemic species on islands,” says co-author Cindy Bick from the University of Michigan. “If we are able to map their remaining habitats and protect them through appropriate measures, we may be able to ensure the survival of the species.”
Source: University of Michigan, Technical Articles: Communication Biology, DOI: 10.1038/s42003-021-02124-y
