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 Protein linked to cancer acts as a viscous glue in cell division
08.07.2020 | Rensselaer Polytechnic Institute

nachricht Enzymes as double agents: new mechanism discovered in protein modification
08.07.2020 | Westfälische Wilhelms-Universität Münster

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Excitation of robust materials

Kiel physics team observed extremely fast electronic changes in real time in a special material class

In physics, they are currently the subject of intensive research; in electronics, they could enable completely new functions. So-called topological materials...

Im Focus: Electrons in the fast lane

Solar cells based on perovskite compounds could soon make electricity generation from sunlight even more efficient and cheaper. The laboratory efficiency of these perovskite solar cells already exceeds that of the well-known silicon solar cells. An international team led by Stefan Weber from the Max Planck Institute for Polymer Research (MPI-P) in Mainz has found microscopic structures in perovskite crystals that can guide the charge transport in the solar cell. Clever alignment of these "electron highways" could make perovskite solar cells even more powerful.

Solar cells convert sunlight into electricity. During this process, the electrons of the material inside the cell absorb the energy of the light....

Im Focus: The lightest electromagnetic shielding material in the world

Empa researchers have succeeded in applying aerogels to microelectronics: Aerogels based on cellulose nanofibers can effectively shield electromagnetic radiation over a wide frequency range – and they are unrivalled in terms of weight.

Electric motors and electronic devices generate electromagnetic fields that sometimes have to be shielded in order not to affect neighboring electronic...

Im Focus: Gentle wall contact – the right scenario for a fusion power plant

Quasi-continuous power exhaust developed as a wall-friendly method on ASDEX Upgrade

A promising operating mode for the plasma of a future power plant has been developed at the ASDEX Upgrade fusion device at Max Planck Institute for Plasma...

Im Focus: ILA Goes Digital – Automation & Production Technology for Adaptable Aircraft Production

Live event – July 1, 2020 - 11:00 to 11:45 (CET)
"Automation in Aerospace Industry @ Fraunhofer IFAM"

The Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM l Stade is presenting its forward-looking R&D portfolio for the first time at...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Contact Tracing Apps against COVID-19: German National Academy Leopoldina hosts international virtual panel discussion

07.07.2020 | Event News

International conference QuApps shows status quo of quantum technology

02.07.2020 | Event News

Dresden Nexus Conference 2020: Same Time, Virtual Format, Registration Opened

19.05.2020 | Event News

 
Latest News

On-chip spin-Hall nanograting for simultaneously detecting phase and polarization singularities

08.07.2020 | Physics and Astronomy

Engineers use electricity to clean up toxic water

08.07.2020 | Agricultural and Forestry Science

Atomic 'Swiss army knife' precisely measures materials for quantum computers

08.07.2020 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>