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."
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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.
See post 40
They are both still guppies, even of the same species, correct?
This is adaptation, not evolution. Somebody call me when the guppies turn into dogs.
This is adaptation not evolution. Big difference.
Bummer, I thought they were going to change into a horse or cow or something interesting. They are still fish!!
I’m seeing that more and more often ... trying to pass adaptation off as macro-evolution. Can’t tell if it’s just an under-educated few or another example of the liberal attempt at word redefinition to suit political purpose.
Well, it could have been worse: it might have already been posted, THEN I would REALLY be in trouble...
...monkeys.
It is not evolution. There is no new species here no even anything that leads to a new species. it is ADAPTATION. Happens all the time.When you don’t have predators the basic herd adapts this isn’t even new
It's easy to say that evolution has happened when the definition or species or evolving is so flexible are to meaningless.
At that rate, there are uncounted billions of species on the planet with only a one member representation.
So many species of Homo Sapiens are there?
You missed a few. But still no fire....
...adapted in less than 30 generations ...
...guppies in the low-predation environment above the barrier waterfall had adapted to their new environment ...
...No such adaptation ...
...of many adaptive differences ...
...how well adapted to survival ...
...This shows that adaptive change ...
Gotta be the latter. Dontcha know that anyone who believes in evolution is a *real* scientist who got a *real* education?
Now if only they can change their underware fast enough when it all comes crashing down on them that this is not evolution. No change of species; just cousins that look different.
And did you ever notice how lawn grass that gets mowed produces seed heads on shorter stems?
Clearly this evidence could be supporting evidence for evolution theory, but it could also just be that larger babies are best and when females arent under predation threat they grow to full term.
Do they become anything other than a fish? There is a difference between speciation and evolution. I suspect that what is occurring is speciation.
So, in the low-predation area, did fewer of the offspring of the guppies that produced more offspring survive and reproduce than did the offspring of the guppies that produced fewer (but larger) offspring? If so, that would be natural selection, with the offspring of the guppies that were genetically predisposed to produce fewer, but larger, offspring more likely to survive and pass their genes on to the next generation. But the article didn’t say that-—it merely reported that in the low-predation area guppies did not see the need to have as many offspring. That’s a change in behavior, not a genetic change. It’s not natural selection or evolution.
It is fast, and it goes with what many of us Creationists believe to be true. It happens a lot quicker than what many think. Important note, these are still guppies and will forever be guppies.
Well said...the goalposts keep moving...by design ironically enough, so that merely defining evolution now is like nailing jello to a wall.
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