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Darwin’s finches, considered to be icons of the theory of evolution, are now dying out because of a dangerous parasite, researchers have revealed in a recent study featured on December 18 in the Journal of Applied Ecology.
When Charles Darwin explored the Galapagos Islands back in the early 1830s, he identified various types of finches, which were extremely alike in appearance, with the exception of their beak, which tended to differ greatly from one region to another.
Given the fact that the archipelago is around 563 miles away from continental Ecuador, which is the nearest mainland, the naturalist came to the conclusion that all these avian creatures actually had a common ancestor, from which they had evolved gradually, due to environmental factors such as the supply of food they had access to.
Now it appears that some of Darwin’s finches, which played such a vital role in history, as one of the sources of inspiration for the theory of evolution, may soon become extinct.
Survival of the fittest may no longer work in their favor after all, given the fact that a new type of maggots has been severely depleting their population in recent years.
Experts led by Dale Clayton, professor of evolution at the University of Utah, analyzed a group of medium ground finches (Geospiza fortis), which were among the first that were proved to be evolving based on external changes.
Back in 1977, due to excessively low rainfall, this type of bird native to the Galapagos Islands no longer had access to tiny seeds, and had to turn to bigger sized ones instead, in order to survive, which led to a 10% increase in the dimensions of its beak, after just 2 generations had passed.
Now, researchers have discovered that the iconic species is threatened by Hilornis downsi, parasitic flies which were first reported in 1997, and probably reached the archipelago in the 1960’s.
These insects lay their eggs inside the birds’ nests, sometimes straight into the hatchling’s nostrils. As larvae emerge, they begin attacking the tiny chicks, piercing their beaks and causing severe injuries which are often fatal in less than a week.
By developing computer models in order to determine the impact of this parasitic species on the medium ground pinch population from Santa Cruz Island, scientists identified three possible scenarios.
The most alarming one, which is based on the fact that weather conditions will also be unfavorable, with excessive or grossly insufficient amounts of rainfall, is that the birds will become extinct in the next 50 years.
In fact, as study authors emphasize, the highest danger isn’t represented by low food supply as a result of climate changes, but by the Hilornis downsi flies, which are much more damaging to the avian species.
There is still a chance to curb this upsetting trend however, according to Dr. Jennifer Koop, assistant professor of evolution at the University of Massachusetts Dartmouth.
Prior research has shown that a similar species has managed to surpass an infestation of this kind when nestlings turned more clamorous in the presence of parasites, causing parents to bring them more food, which fortified them and boosted their resistance against pests.
While there may be no time left for such an evolutionary step, if humans took measures so as to lower the number of nests harboring these flies by approximately 40%, the medium ground finch will manage to survive for at least 100 more years.
For instance, this could be achieved by adding wasps to the mix, which would kill the harmful insects by depositing their own eggs inside the larvae.
Another solution would be to leave cotton balls soaked in insecticide within the birds’ reach: if tiny pieces of this kind were used so as to patch nests, then the flies would be annihilated.
Image Source: Flickr
