A McGill University-led research team used data from four species of Darwin's finches on the Galapagos Islands to test a long-standing theory that species diversity results from adaptations to a variety of resources. Evolutionary biologists have long believed that the process by which a single species transforms into many different species, known as "adaptive radiation," is the process by which each species adapts to its unique environment.
However, formally studying this theory has been a challenge because it is difficult to unequivocally determine the relationship between a species' traits and its evolutionary success, especially for a group of species that recently diverged from a common ancestor.
A global team of biologists led by McGill University compiled nearly two decades of field data representing more than 3,400 Darwin's finches on the Galapagos Islands to determine the relationship between beak characteristics and individual longevity in four different species.
The study used data from four species, all of which evolved from a common ancestor less than a million years ago. The researchers constructed a detailed "adaptive landscape" to predict an individual's likelihood of longevity in relation to its beak characteristics. They found that finches with beak characteristics typical of each species lived the longest, while those that deviated from typical characteristics had lower survival rates.
In short, the characteristics of each species correspond to peaks of fitness, which are like mountains on a topographic map, separated from other mountains by valleys of lower fitness.
Lead author Marc Olivier Beausoleil is a doctoral researcher at McGill University, and his supervisor is Professor Rowan Barrett. "The diversity of life is therefore a product of the radiation of species into different environments; in the case of Darwin's finches, these environments are different food types," he said.
Perhaps surprisingly, the researchers also found that the different species of finches studied did not reach the peak of their physical fitness, suggesting that each species was not fully adapted to their diet. Whether this "perfection" will eventually evolve remains to be seen.
Compiled source: ScitechDaily