Researchers studying the population of finches on Daphne Major, a tiny Galapagos island, found that a population of birds here evolved into new species in a relatively short period of time.

Big Bird

In 1981, researchers noticed the arrival of a large cactus finch, a non-native species, on the island. The male then mated with a female belonging to one of the local species and this spawned around 30 offsprings.

The new birds, which took hold of unexploited food on the island, are bigger than other species on Daphne Major, so the researchers called them Big Bird. They followed and gathered blood samples from the new Big Bird lineage for six generations.

In a new study published in the journal Science, Peter Grant, from the Department of Ecology and Evolutionary Biology at Princeton University, and colleagues found that in just two generations, the Big Bird population was reproductively isolated from the native birds.

Their song, which is used to attract mates, is unusual, so they failed to attract the females of the local species. They also have distinct beak size and shape, so they mated exclusively with their own lineage over the years. Researchers found that these factors led to the birds to become genetically isolated.

"From the second generation onwards the lineage bred endogamously, and despite intense inbreeding, was ecologically successful and showed transgressive segregation of bill morphology," researchers wrote in their study.

This is the first time that scientists were able to directly observe Speciation, the formation of new and distinct species in the course of evolution in the field. It isn't just the finches though that go through a rapid evolution.

Here are other animals that are changing fast:

Mosquitoes

The London Underground was constructed in 1863. The mosquitoes that thrived here have since achieved reproductive isolation and evolved into a subspecies. Unlike its aboveground counterpart which only feeds on bird hosts and hibernates in the winter, the London Underground mosquito is cold intolerant, breeds all-year round, and also bites mice, rats, and humans.

Bumblebees

Two species of bumblebee that reside in the Rocky Mountains in the United States were found to have evolved shorter tongue likely because of climate change. Their tongue has shrunk by 25 percent in the past 40 years.

Great Tits

The British great tits evolved to have beaks that are longer than those of their European kin as a result of the widespread use of birdfeeders across the United Kingdom. Researchers found that the bird evolved the longer beak between the 1970's and today.