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.
Just look how much weight Rosie O’Donnell has gained in the last decade.
ping
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...but no sexual reproduction there, either. Ha!
From the standpoint of "the controversy" the biggest issue is: does one kind of animal give rise to another kind of animal? The adaptation seen in this population of guppies does not contribute to that debate.
Does anyone dispute “fast” change?
Guppies have frequently gone from the salubrious environment of a home fish tank with power pump, regular feeding, perfect temperature RIGHT INTO THE TOILET and down the sewer, and still survived.
That nothing!... The country evolved from Capitalist to Fascist in less that 5 months!
Evolution is defined as genetic change over time, sometimes leading to new species, sometimes sub-species, sometimes breeds or races.
correct. i’ve heard it described also as “microevoltion” or “macroevolution”. The former of course is observable...the latter is not. The former is change within a species or kind, and the latter—complete change of species or kind has not been demonstrated.
but they keep graspin’, don’t they? ;-)
‘They are equating Adaptation with Evolution.’
Exactly. Adaptation is not evolution. If the guppies turned into Great Danes, then we’d see an example of evolution. Back to the drawing board...
ping for ya...put another pin in their bubble...
No you would be seeing magic dust!!
So no predators and they grow larger since they eat more and grow... that is not evolution. After 10 years, they are still guppies.
Call me about “evolution happening” when the guppies start walking out onto land.
Mutations happen; some of them improve their host’s life, some might be passed on to future generations. and some might lead to creation of new species.
Steve Jones, on page 170 of “Darwin’s Ghost,” writes: “DNA’s inability to copy itself without mistakes — mutation — means that evolution is inevitable.”
Amen! The fact that one body of water now has more ‘high-predation’ females **MIGHT** be a reflection of changes in the prominence of certain members of the gene pool AND their more successful reproduction, BUT that is NOT evolution.
If this article is about “evolution” then we should conclude that Swedes (dare I say Aryans) — blonde, fair, blue eyes — represent more highly evolved members of the human race than those in geographies and [older] gene populations in equatorial zones.
That of course is preposterous. We are all Homo sapiens sapiens — just like these are all the same species of ‘guppy’.
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