In this study, Peter Grant and Rosemary Grant, two researchers who are known for their long-term studies of evolution, analyze data taken from 30 years of measuring body sizes, beak sizes, and beak shapes of two types of finches (G. fortis and G. scandens) on the Galapagos islands. They did this to show how evolution, brought on by changes in environmental and resource changes, showed natural selection at play, and why long-term studies can help the study of evolution as a whole.
G. fortis: https://ebird.org/species/megfin1/
G. scandens: https://ebird.org/species/cocfin3/
Oops! This image does not follow our content guidelines. To continue publishing, please remove it or upload a different image.
Because of how long their study was, Peter and Rosemary Grant witnessed adaptive radiation, (where organisms change to fit what they need to do in their lives), which was brought on by a change in food supply). G. fortis (medium ground finch) beak shape changed, and G. scandens (common cactus finch) body form and breeding with other species/races was shown to have an impact on introgression (introduction of a gene from one gene complex into another). This was carried out through adaptive radiation, because birds evolved to be able to consume what food source was available at the time.
This study analyzed patterns based on the theory of natural selection, the theory where species will survive in their environment based on how well they have adapted, or shifted, to survive. Then, through natural selection, birds who were well-adapted were able to survive longer and reproduce more. When they reproduced, they would pass their well-adapted genetics to their offspring and continue the cycle. Because the researchers had continued their studies for 30 years, they were able to get a more exact estimate of evolutionary events and were able to observe the evolutionary changes in finches due to natural selection that was in response to food supply.
They were able to witness evolution happening.
One of the conclusions in this study was that long-term studies (10+ years) can capture natural selection data compared to short-term studies (10 years or less). The unpredictability of evolution was captured in the study through consistent measurements over a long period of time, where it showed that if there were only data samples taken at the beginning and end of the experiment for a shorter period of time, there would not be as big of a fluctuation found in data that could trace how a species evolved and how natural selection was involved.
The importance of this study is to highlight how key geography and geographical location is to the adaptations acquired by species and how it affects a species' evolution. The study of biogeography is highlighted within this study and backs up Darwin's initial theories on the finches in the Galapagos.
Oops! This image does not follow our content guidelines. To continue publishing, please remove it or upload a different image.
