Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Biologist’s new experiment may vindicate Darwin

25.09.2002


Charles Darwin, the founder of the modern theory of evolution, was an avid proponent of sympatric speciation, the idea that a single species need not be geographically divided in order to evolve into two separate species. In the mid-20th century, however, certain vocal scientists convinced the scientific community that geographically isolating two halves of a population was a necessary factor in creating a new species. It wasn’t until the last few decades that modern biologists began to reexamine Darwin’s ideas to discover that he may have been quite right all along. Now the theory behind one such idea is undergoing its most exhaustive test yet at the University of Rochester.

James D. Fry, assistant professor of biology, is running fruit flies through a series of tests to see if a few, subtle changes in the flies’ environment could be enough to trigger the creation of a new species.

"For a long time there has been speculation that small differences in the environment coupled with small differences in the way organisms behave could lead to speciation without any other external factors," says Fry. "This is this first time this idea has been tested in the same way it might happen in nature. If we can get the flies to start exhibiting changes with these tests, then it’s very likely that it can happen easily in nature."



Similar trials tested speciation mechanisms that worked well in theory, but may not be very applicable to insects in the wild. Those experiments gave a choice of several of habitats, with only those flies choosing the most extreme habitats allowed to breed. This method imposes selection directly on the trait of habitat choice by weeding out those organisms that choose "incorrect" ones, whereas Fry’s experiment is designed specifically so that no fly’s habitat choice will automatically exclude it from breeding--a design he feels more closely approximates the natural world.

Fry lets the flies group together in a sort of lobby area before letting them out via two tunnels. One tunnel leads to a bright area and the other toward a darker area. Inevitably, some of the flies choose to go to the light and others to the darkness. Once in their new light or dark homes, Fry inspects the number of the bristles on each fly, acting like a sort of natural selection by removing sparsely bristled flies from the bright area and more densely bristled flies from the darker one. The bristles act as a marker that Fry can track over generations. The leftover flies in each habitat are then allowed to reproduce before being sent back to the lobby to make a habitat choice again.

Initially, Fry does not expect much correlation between bristle number and the individual’s preference for light or dark abodes, but after several dozen generations over the course of several months he expects to see that flies with fewer bristles tend toward the dark while multi-bristled ones head for the light. A fly that prefers the dark and happens to have few bristles will survive Fry’s "weeding out" process and will reproduce with another few-bristled dark-lover. Genetics being what they are, the couple is more likely to have offspring with fewer bristles and a hankering for a darker habitat. The couple may very well have some multi-bristlers or light-lovers, but those will never be able to reproduce because once everyone is sent back to the lobby, those offspring will head toward the habitat where their number of bristles will mark them for removal. The bristle number is being used as a sort of surrogate for a trait that might affect survival in nature, such as the camouflage coloring of a moth. This survivability variable was missing in previous studies since in them the only thing being selected for or against was the choice of habitat itself.

Eventually, after months of weeding and 50 to 60 generations, Fry hopes to see a correlation between brightness preference and bristle number. Already, a weak correlation is appearing after just 12 generations. If he finds that all the flies moving toward the light have few bristles, he’ll be fairly sure that they will never again mate with the dark-loving flies. If left in this artificial ecosystem, the flies will likely develop into completely separate species.

This kind of speciation mechanism relies on small differences in the environment that interact with the small differences in the behavior of individuals of a species. Individual preferences and small environmental differences are far more common than large geologic events such as floods or rising mountain ranges that are necessary for full geologic isolation so this model, if it is successful, could give biologists a new tool when piecing together the history of a species.

"Speciation without geologic isolation has been tested before, but the tests weren’t all that applicable to nature," says Fry. "If this test shows two separate populations of flies forming, it would add a new model of speciation to evolution--one that describes bugs, which account for a quarter of the species on earth."

Jonathan Sherwood | EurekAlert!
Further information:
http://www.rochester.edu/

More articles from Life Sciences:

nachricht Russian scientists show changes in the erythrocyte nanostructure under stress
22.02.2019 | Lobachevsky University

nachricht How the intestinal fungus Candida albicans shapes our immune system
22.02.2019 | Exzellenzcluster Präzisionsmedizin für chronische Entzündungserkrankungen

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: (Re)solving the jet/cocoon riddle of a gravitational wave event

An international research team including astronomers from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has combined radio telescopes from five continents to prove the existence of a narrow stream of material, a so-called jet, emerging from the only gravitational wave event involving two neutron stars observed so far. With its high sensitivity and excellent performance, the 100-m radio telescope in Effelsberg played an important role in the observations.

In August 2017, two neutron stars were observed colliding, producing gravitational waves that were detected by the American LIGO and European Virgo detectors....

Im Focus: Light from a roll – hybrid OLED creates innovative and functional luminous surfaces

Up to now, OLEDs have been used exclusively as a novel lighting technology for use in luminaires and lamps. However, flexible organic technology can offer much more: as an active lighting surface, it can be combined with a wide variety of materials, not just to modify but to revolutionize the functionality and design of countless existing products. To exemplify this, the Fraunhofer FEP together with the company EMDE development of light GmbH will be presenting hybrid flexible OLEDs integrated into textile designs within the EU-funded project PI-SCALE for the first time at LOPEC (March 19-21, 2019 in Munich, Germany) as examples of some of the many possible applications.

The Fraunhofer FEP, a provider of research and development services in the field of organic electronics, has long been involved in the development of...

Im Focus: Regensburg physicists watch electron transfer in a single molecule

For the first time, an international team of scientists based in Regensburg, Germany, has recorded the orbitals of single molecules in different charge states in a novel type of microscopy. The research findings are published under the title “Mapping orbital changes upon electron transfer with tunneling microscopy on insulators” in the prestigious journal “Nature”.

The building blocks of matter surrounding us are atoms and molecules. The properties of that matter, however, are often not set by these building blocks...

Im Focus: University of Konstanz gains new insights into the recent development of the human immune system

Scientists at the University of Konstanz identify fierce competition between the human immune system and bacterial pathogens

Cell biologists from the University of Konstanz shed light on a recent evolutionary process in the human immune system and publish their findings in the...

Im Focus: Transformation through Light

Laser physicists have taken snapshots of carbon molecules C₆₀ showing how they transform in intense infrared light

When carbon molecules C₆₀ are exposed to an intense infrared light, they change their ball-like structure to a more elongated version. This has now been...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Global Legal Hackathon at HAW Hamburg

11.02.2019 | Event News

The world of quantum chemistry meets in Heidelberg

30.01.2019 | Event News

Our digital society in 2040

16.01.2019 | Event News

 
Latest News

JILA researchers make coldest quantum gas of molecules

22.02.2019 | Physics and Astronomy

Understanding high efficiency of deep ultraviolet LEDs

22.02.2019 | Materials Sciences

Russian scientists show changes in the erythrocyte nanostructure under stress

22.02.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>