Darwin’s Finches Under Threat From New Parasite
Darwin and his finches are synonymous with biology lessons in secondary school. Millions of teenagers have sat and learnt about the variations in the finches beaks as a prime example of evolution. For those who need a brush up on their GCSE biology; Darwin observed differences in beaks amongst the Galapagos finches depending on which island they inhabited leading him to conclude that they all started as one original species but differing food sources had led them to evolve into different species.
Yet after becoming perfectly adapted to their individual islands, it appears that an invasive species may spell the end for these beloved pinnacles of evolution. Believed to have arrived in the 1960’s; the nest fly lays parasitic larvae in their nests which attack the young in a gruesome way. Some of their eggs are laid directly into the nostrils of the young so that when they hatch they immediately start eating at the bird.
If their repulsive method of survival wasn’t bad enough, scientists are now concerned that the nest fly has the potential to cause extinction within Darwin’s finches in just fifty years. Prof Dale Clayton from the University of Utah and his colleagues developed a mathematical model using five years of data to project the impact of fly damage on the reproduction rates. Two of the three modelled scenarios should the finches populations were at risk of extinction with the worst case scenario showing extinction in the next 50 years.
However the models also showed that if you can reduce the probability of infection, then you can remove the risk of extinction. The researchers have calculated that the number of infected nests must be reduced by 40% for this to occur.
Human intervention may be one way to stop the risk of extinction. Pesticides would be a simple option; treat cotton balls with the chemical which the finch would then use to line their nest. If the finch used just one gram of fumigated cotton it would kill 100% of the flies. Alternatively an introduction of wasps could be used as they lay their eggs in the fly larvae.
Finally it may just boil down once more to evolution. The stress caused by infestations may force Darwin’s finches to once again adapt and evolve to ensure their long-term survival. Obviously this is a lot to ask in a short space of time, but scientists have highlighted another related species where the nestlings would become more vocal when under attack from the pest, thus leading their parents to feed them more, creating higher rates of survival.
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