Epigenetics may explain how Darwin's finches respond to rapid environmental change

August 24, 2017
Darwin's finches. Credit: McNew et al., BMC Evolutionary Biology, 2017

Epigenetics may explain how Darwin's finches respond to rapid environmental changes, according to new research published in the open access journal BMC Evolutionary Biology.

By studying rural and urban populations of two species of Darwin's finches on the Galapagos Islands, researchers were able to show that while there was very little genetic variation, there were substantial epigenetic differences that could be related to environmental differences resulting from urbanization.

Sabrina McNew, PhD student at the University of Utah and lead author of the study said: "Urbanization of the Galapagos has happened relatively recently, so this is a good opportunity to study how animals respond to rapid environmental change."

Dr Michael Skinner, senior author from Washington State University, said: "In the finches that we studied, epigenetic alterations between the populations were dramatic, but minimal genetic changes where observed. We believe that the epigenetic differences may be a heritable component that might explain the rapid adaptation of Darwin's finches to an urban environment. These species of finch have distinct diets which could explain the differences in methylation patterns as diet is known to influence epigenetics. This is a novel mechanism which is not seriously considered in at this time".

Epigenetics, particularly a chemical modification to DNA known as methylation, has emerged as a heritable component linked to differences between members of a population and might play a role in the molecular basis of evolutionary change. DNA methylation can be induced by the environment and can impact gene expression, leading to changes in physical traits such as size.

Sabrina McNew explained: "We can't say for sure how these methylation differences affect the morphology or physiology of the finches; however, it's exciting to document epigenetic variation on a population-level. This project is a first step in understanding if epigenetic changes are involved in adaptation to changing environments."

In this study, the authors captured over 1,000 birds of two species of Darwin's finch, the medium ground finch (Geospiza fortis) and the small ground finch (G. fuliginosa), from a rural and an urban site located 10km apart on the Galapagos Islands. Morphological study of the birds revealed that G. fortis from the urban environment were larger in all measured traits than their rural counterparts. There were no size differences recorded between the urban and rural G. fuliginosa, which could be due to the fact that the two species have different diets and because G. fuliginosa are less variable in size than G fortis, according to the researchers.

Genetic analysis of the birds revealed very little differences in genetic make-up between the rural and urban populations of both species. Analysis of DNA methylation patterns revealed significant differences between urban and rural populations for both species.

This study compared just two populations of finches so it cannot be said with certainty that urbanization is the key influencer of epigenetics or morphology. However the results are consistent with a potential role of epigenetic variation in rapid adaptation to changing environments. Future studies are needed to determine what direct effects DNA methylation has on physical traits, and to what extent these may play a role in evolution.

Explore further: Our epigenome is influenced by our habitat and lifestyle

More information: Sabrina M. McNew et al, Epigenetic variation between urban and rural populations of Darwin's finches, BMC Evolutionary Biology (2017). DOI: 10.1186/s12862-017-1025-9

Related Stories

Our epigenome is influenced by our habitat and lifestyle

November 30, 2015

Research on the genomes of Pygmy hunter-gatherer populations and Bantu farmers in Central Africa, carried out by scientists from the Institut Pasteur and the CNRS in cooperation with French and international teams, has shown ...

Epigenetics could help diagnose different types of cleft

June 15, 2017

Cleft lip and/or palate are common birth defects and affect around 15 in every 10,000 births in Europe. New research by the University of Bristol from the largest study of cleft lip and/or palate in the world, the Cleft Collective, ...

Evolution in action detected in Darwin's finches

April 21, 2016

The most characteristic feature of Darwin's finches is the diversification of beak morphology that has allowed these species to expand their utilization of food resources in the Galápagos archipelago. A team of scientists ...

Darwin's finches may face extinction

December 17, 2015

Mathematical simulations at the University of Utah show parasitic flies may spell extinction for Darwin's finches in the Galapagos Islands, but that pest-control efforts might save the birds that helped inspire the theory ...

Recommended for you

New discovery challenges long-held evolutionary theory

October 19, 2017

Monash scientists involved in one of the world's longest evolution experiments have debunked an established theory with a study that provides a 'high-resolution' view of the molecular details of adaptation.

Gene editing in the brain gets a major upgrade

October 19, 2017

Genome editing technologies have revolutionized biomedical science, providing a fast and easy way to modify genes. However, the technique allowing scientists to carryout the most precise edits, doesn't work in cells that ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.