Introduced parasite changes host phenotype, mating signal and hybridization risk: Philornis downsi effects on Darwin's finch song

Parasite causes finches to sing a different tune

26 December 2019

A parasite that inhabits Darwin’s finches may be changing the evolutionary course of finishes.

Like many Galapagos birds, the small tree finch and the critically endangered medium tree finch are being decimated by an invasive parasitic fly. Its larvae live in the nares, or nostrils, of young birds and kill more than half of their hosts.

Now, three researchers at Flinders University in Australia and a colleague have found that survivors have impaired singing ability due to enlarged nares, which reduces their ability to attract a mate.

The reduced singing ability also diminishes the distinction between the songs of different species of finches. This might explain the recently documented hybridization between the two species of finches and suggests that parasites can alter the evolutionary trajectory of a species.

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References

1. Proceedings of the Royal Society. B. 286, 20190461 (2019). doi: 10.1098/rspb.2019.0461