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 Modern genetic sequencing tools give clearer picture of how corals are related
17.08.2017 | University of Washington

nachricht The irresistible fragrance of dying vinegar flies
16.08.2017 | Max-Planck-Institut für chemische Ökologie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

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

26.07.2017 | Event News

 
Latest News

Gold shines through properties of nano biosensors

17.08.2017 | Physics and Astronomy

Greenland ice flow likely to speed up: New data assert glaciers move over sediment, which gets more slippery as it gets wetter

17.08.2017 | Earth Sciences

Mars 2020 mission to use smart methods to seek signs of past life

17.08.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>