Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Darwin's finches have reached their limits on the Galápagos

23.06.2015

The evolution of birds on the Galápagos Islands, the cradle of Darwin's theory of evolution, is a two-speed process. Most bird species are still diversifying, while the famous Darwin's finches have already reached an equilibrium, in which new species can only appear when an existing one becomes extinct. This finding expands the classical theory on island evolution put forward in the 1960s. The study is published online on June 23 in Ecology Letters.

Islands are seen as natural laboratories for the study of evolution. They form isolated ecosystems with barriers to migration. Classical Island Theory predicts that a dynamic equilibrium will occur between immigration and extinction of species. Recent theory adds that as species diversity increases, ever more ecological niches become occupied, which has a negative effect on immigration (new immigrants from outside of the Galápagos cannot settle) and diversification (radiation into new species is blocked).


This is a small Galápagos ground finch (Geospiza fuliginosa), Pinta Island, Galápagos. There is no more room for new species on the Galápagos islands, unless one of the existing species becomes extinct.

Credit: Ruben Heleno

Evolutionary dynamics

'However, this has never been tested in detail, for lack of data and the right analytical tools', explains Rampal Etienne, Associate Professor of Theoretical and Evolutionary Community Ecology at the University of Groningen, the Netherlands. Together with Luis Valente (University of Potsdam, Germany) and Albert Phillimore (University of Edinburgh, UK), he developed DAISIE, a mathematical model that uses phylogenetic data on living species to reconstruct evolutionary dynamics. DAISIE stands for Dynamic Assembly of Islands by Speciation, Immigration and Extinction, and was named after famous radiations of daisy-like plants on Hawaii.

DAISIE was fed with the phylogenetic trees of existing bird species on the Galápagos Islands. These were constructed with genomic data that has become available in recent years. DAISIE then estimates diversity limits and rates of immigration, speciation and extinction per lineage.

'The analysis shows that for the finches, diversity does indeed have a negative effect. There is no more room for new species, unless one of the existing species becomes extinct, so the islands are saturated regarding finch-type species', Etienne explains. This does not mean the radiation is static. 'We found that the rates of both evolution and extinction are very high for Darwin's finches. That is probably why these birds have reached an equilibrium.'

Isolated ecosystems

Other species like mockingbirds have not yet reached equilibrium, which contrasts sharply with the current view that oceanic islands are at equilibrium. 'Our data shows that they are evolving more slowly and are still diversifying.' In a million years or so, more mockingbird species may have appeared - granted that conditions on the islands remain the same.

The study shows that the DAISIE model - which the authors have made available as a library* in the free and widely used R software environment - is a valuable tool for the study of evolutionary dynamics on islands. It includes speciation and thus extends existing island theory, which is based on immigration and extinction. Etienne: 'And of course, it works for all isolated ecosystems, not just islands but also lakes or mountain tops.'

Apart from explaining evolutionary history, DAISIE also predicts future diversity. 'This could be interesting from a conservation point of view: we are not just conserving existing species, but also future diversity.'

###

*Link to the DAISIE programme: http://cran.r-project.org/web/packages/DAISIE/index.html

Rene Fransen | EurekAlert!

Further reports about: Evolutionary Groningen ecosystems equilibrium isolated new species species

More articles from Ecology, The Environment and Conservation:

nachricht Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel

nachricht Removing fossil fuel subsidies will not reduce CO2 emissions as much as hoped
08.02.2018 | International Institute for Applied Systems Analysis (IIASA)

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

'Lipid asymmetry' plays key role in activating immune cells

20.02.2018 | Life Sciences

MRI technique differentiates benign breast lesions from malignancies

20.02.2018 | Medical Engineering

Major discovery in controlling quantum states of single atoms

20.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>