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
Genetic Variation
Genetic variation refers to the variation in the genome sequences between individual organisms of a species. Individual differences or population differences can both be referred to as genetic variations. It is primarily caused by mutation, but other factors such as genetic drift and sexual reproduction also play a major role.
Quantitative Genetics
Quantitative genetics is the part of genetics that deals with the continuous trait, where the expression of various genes influences the phenotypes. Thus genes are expressed together to produce a trait with continuous variability. This is unlike the classical traits or qualitative traits, where each trait is controlled by the expression of a single or very few genes to produce a discontinuous variation.
In each experiment, what was the variable that differed??
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