For thousands of years, humans have been influencing evolution, through changes we have caused in the environment – and through artificial selection in the domestication of plants and animals. In many cases, scientists have carefully documented evolution through artificial selection in the lab. The spots on guppies can be manipulated through artificial selection. John Endler performed experiments in microevolution, allowing artificial selection to manipulate the spots guppies. Guppy spots are largely genetically controlled. Spots that help the guppy blend in with its surroundings protect it from predation – but spots that make it stand out help it attract mates. Endler set similar populations of guppies in artificial ponds in the laboratory. Ponds varied in the coarseness of grave the bottom and all ponds had predators. Below is a simplified representation of Endler's experiment. Initial set-up: course gravel, predator present fine gravel, predator present

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For thousands of years, humans have been influencing evolution, through changes we have caused in the
environment – and through artificial selection in the domestication of plants and animals. In many cases,
scientists have carefully documented evolution through artificial selection in the lab.
The spots on guppies can be manipulated
through artificial selection.
John Endler performed experiments in microevolution, allowing artificial selection to manipulate the spots on
guppies. Guppy spots are largely genetically controlled. Spots that help the guppy blend in with its
surroundings protect it from predation - but spots that make it stand out help it attract mates. Endler set up
similar populations of guppies in artificial ponds in the laboratory. Ponds varied in the coarseness of gravel on
the bottom and all ponds had predators. Below is a simplified representation of Endler's experiment.
Initial set-up:
course gravel, predator present
fine gravel, predator present
fewer than 15
generations of selection
fewer than 15
generations of selection
After fewer than 15 generations of selection, the markings of guppies in different ponds had substantially
diverged as a result of natural selection. In the presence of predators, guppies evolved to blend in with their
background.
Endler then performed another experiment, with the same pond set-ups but without predators.
Transcribed Image Text:For thousands of years, humans have been influencing evolution, through changes we have caused in the environment – and through artificial selection in the domestication of plants and animals. In many cases, scientists have carefully documented evolution through artificial selection in the lab. The spots on guppies can be manipulated through artificial selection. John Endler performed experiments in microevolution, allowing artificial selection to manipulate the spots on guppies. Guppy spots are largely genetically controlled. Spots that help the guppy blend in with its surroundings protect it from predation - but spots that make it stand out help it attract mates. Endler set up similar populations of guppies in artificial ponds in the laboratory. Ponds varied in the coarseness of gravel on the bottom and all ponds had predators. Below is a simplified representation of Endler's experiment. Initial set-up: course gravel, predator present fine gravel, predator present fewer than 15 generations of selection fewer than 15 generations of selection After fewer than 15 generations of selection, the markings of guppies in different ponds had substantially diverged as a result of natural selection. In the presence of predators, guppies evolved to blend in with their background. Endler then performed another experiment, with the same pond set-ups but without predators.
Initial set-up:
course gravel, no predator
fine gravel, no predator
fewer than 15
fewer than 15
generations of selection
generations of selection
Download the two graphics above from the Image library.
Without predators, there was sexual selection for male guppies that stood out from their background and
attracted the attention of the females.
View thie article opline at
Transcribed Image Text:Initial set-up: course gravel, no predator fine gravel, no predator fewer than 15 fewer than 15 generations of selection generations of selection Download the two graphics above from the Image library. Without predators, there was sexual selection for male guppies that stood out from their background and attracted the attention of the females. View thie article opline at
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