The Galápagos-dwelling vampire finch might look small and unassuming but it has an unusual dietary habit that sets it apart from its closest relatives. As its namesake would suggest, it likes to feed on blood. Specifically, the blood of Nazca and blue-footed boobies.
In order to be able to digest blood, however, it has had to evolve specialized gut bacteria – an adaptation that was confirmed in a paper published last year. Now, researchers writing in the journal Philosophical Transactions of the Royal Society B have discovered certain similarities between the gut microbiota of vampire finches and those of vampire bats living in South and Central America.
Diet has a big effect on the composition and function of the gut microbiome. Studies have shown our human guts are influenced by the food we eat (and vice versa) – a diet high in fiber, for example, helps the good bacteria flourish. The reverse can be said for junk food.
A similar principle applies to animals. Those with extreme diets (like the vampire finch and the termite-munching aardvark) are of particular interest to scientists. The narrowness of these diets often require physiological adaptions to ensure the animal is ingesting sufficient nutrients – an evolutionary necessity that often results in a process called convergence.
Convergent evolution is the idea that entirely unrelated species develop similar traits simply because they share a similar environment, a similar diet, or another similar ecological niche. Sharks and dolphins are a good example. One is a fish and the other is a mammal. Yet, they both (independently) evolved to have a dorsal fin, a trait that helps them navigate their watery surroundings.
Watch the vampire finch in action. Luckily for the booby involved, these "attacks" are rarely fatal. YouTube/Natural History Museum
To find out whether the vampire finch and vampire bat display convergence – at least, so far as their microbiome is concerned – researchers led by Se Jin Song, a biologist at the University of California San Diego, analyzed bacterial gnomes in fecal samples from blood-feeding (vampire) and non-blood-feeding finches and blood-feeding (vampire) and non-blood-feeding bats.
The results were mixed. While the samples of vampire finches and vampire bats showed few similarities, there was at least one bacteria group they had in common: Peptostreptococcaceae.
Both species displayed high levels of Peptostreptococcaceae compared to the non-blood-feeding species. This type of bacteria tends to be quite useful if you need to process a lot of sodium and iron, as you would if your diet included a lot of blood. But how exactly this convergence happened is not yet clear.
As Song told The New York Times, the fact that the two species followed two extremely different paths to their blood-drinking diet, "it was still interesting that we were able to find something that they did share".
[H/T: The New York Times]
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