Guppies are small fresh-water fish that biologists have studied for long.
Posted on 06/11/2009 11:19:01 AM PDT by Pharmboy
Guppies are small fresh-water fish that biologists have studied for long.
UC Riverside-led study shows wild Trinidadian guppies adapted in less than 30 generations to a new environment
RIVERSIDE, Calif. – How fast can evolution take place? In just a few years, according to a new study on guppies led by UC Riverside's Swanne Gordon, a graduate student in biology.
Gordon and her colleagues studied guppies — small fresh-water fish biologists have studied for long — from the Yarra River, Trinidad. They introduced the guppies into the nearby Damier River, in a section above a barrier waterfall that excluded all predators. The guppies and their descendents also colonized the lower portion of the stream, below the barrier waterfall, that contained natural predators.
Eight years later (less than 30 guppy generations), the researchers found that the guppies in the low-predation environment above the barrier waterfall had adapted to their new environment by producing larger and fewer offspring with each reproductive cycle. No such adaptation was seen in the guppies that colonized the high-predation environment below the barrier waterfall.
"High-predation females invest more resources into current reproduction because a high rate of mortality, driven by predators, means these females may not get another chance to reproduce," explained Gordon, who works in the lab of David Reznick, a professor of biology. "Low-predation females, on the other hand, produce larger embryos because the larger babies are more competitive in the resource-limited environments typical of low-predation sites. Moreover, low-predation females produce fewer embryos not only because they have larger embryos but also because they invest fewer resources in current reproduction."
Study results appear in the July issue of The American Naturalist.
Natural guppy populations can be divided into two basic types. High-predation populations are usually found in the downstream reaches of rivers, where they coexist with predatory fishes that have strong effects on guppy demographics. Low-predation populations are typically found in upstream tributaries above barrier waterfalls, where strong predatory fishes are absent. Researchers have found that this broad contrast in predation regime has driven the evolution of many adaptive differences between the two guppy types in color, morphology, behavior, and life history.
Gordon's research team performed a second experiment to measure how well adapted to survival the new population of guppies were. To this end, they introduced two new sets of guppies, one from a portion of the Yarra River that contained predators and one from a predator-free tributary to the Yarra River into the high-and low-predation environments in the Damier River.
They found that the resident, locally adapted guppies were significantly more likely to survive a four-week time period than the guppies from the two sites on the Yarra River. This was especially true for juveniles. The adapted population of juveniles showed a 54-59 percent increase in survival rate compared to their counterparts from the newly introduced group.
"This shows that adaptive change can improve survival rates after fewer than ten years in a new environment," Gordon said. "It shows, too, that evolution might sometimes influence population dynamics in the face of environmental change."
###
She was joined in the study by Reznick and Michael Bryant of UCR; Michael Kinnison and Dylan Weese of the University of Maine, Orono; Katja Räsänen of the Swiss Federal Institute of Technology, Zurich, and the Swiss Federal Institute of Aquatic Science and Technology, Dübendorf; and Nathan Miller and Andrew Hendry of McGill University, Canada.
Financial support for the study was provided by the National Science Foundation, the Natural Sciences and Engineering Research Council of Canada, the Le Fonds Québécois de la Recherche sur la Nature et les Technologies, the Swedish Research Council, the Maine Agricultural and Forestry Experiment Station, and McGill University.
The University of California, Riverside is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California's diverse culture, UCR's enrollment of about 17,000 is expected to grow to 21,000 students by 2020. The campus is planning a medical school and has reached the heart of the Coachella Valley by way of the UCR Palm Desert Graduate Center. The campus has an annual statewide economic impact of more than $1 billion. To learn more, visit www.ucr.edu or call (951) UCR-NEWS.
Bigger guppies are not a new species.
Who even knows what the definition of Evolution is? Evolutionists say it means measurable/observable changes in species over time, yet they also say it is how all species came from one. That’s a huge difference! They act like thinking that way is no big deal. There is a scientific probability for the first, the second is the biggest joke in scientific history.
Evolution in Your FaceLake Victoria, Africa's largest lake, is home to more than 300 species of cichlids. These fish, which are popular in aquariums, are deep-bodied and have one nostril, rather than the usual two, on each side of the head. Seismic profiles and cores of the lake taken by a team headed by Thomas C. Johnson of the University of Minnesota, reveal that the lake dried up completely about 12,400 years ago. This means that the rate of speciation of cichlid fishes has been extremely rapid: something on average of one new species every 40 years!
by Patrick Huyghe
Omni
|
|
|||
Gods |
Thanks Pharmboy. |
||
|
· Discover · Nat Geographic · Texas AM Anthro News · Yahoo Anthro & Archaeo · Google · · The Archaeology Channel · Excerpt, or Link only? · cgk's list of ping lists · |
|||
It’s also not classic evolution.
Nothing changed....a guppy is still a guppy.
Not really that fast. I saw my ex-wife go from hot sexy babe to cold bitch in less than a year.
It took me years to understand that this was a permanent evolution of the organism and get out.
I call divorce survival of the fittest.
My family line has developed several new traits. We have only two wisdom teeth and an extra muscle in our hands. (Discovered that during carple tunnel surgery.) Evolution does go on.
“Women, you can’t live with ‘em, pass the beer nuts.” — Norm Peterson, “Cheers”
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.