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 Programming cells with computer-like logic
27.07.2017 | Wyss Institute for Biologically Inspired Engineering at Harvard

nachricht Identified the component that allows a lethal bacteria to spread resistance to antibiotics
27.07.2017 | Institute for Research in Biomedicine (IRB Barcelona)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Physicists Design Ultrafocused Pulses

Physicists working with researcher Oriol Romero-Isart devised a new simple scheme to theoretically generate arbitrarily short and focused electromagnetic fields. This new tool could be used for precise sensing and in microscopy.

Microwaves, heat radiation, light and X-radiation are examples for electromagnetic waves. Many applications require to focus the electromagnetic fields to...

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

 
Latest News

Programming cells with computer-like logic

27.07.2017 | Life Sciences

Identified the component that allows a lethal bacteria to spread resistance to antibiotics

27.07.2017 | Life Sciences

Malaria Already Endemic in the Mediterranean by the Roman Period

27.07.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>