In nature, populations are usually evolving. The grass in an open meadow, the wolves in a forest, and even the bacteria in a person’s body are all natural populations. And all of these populations are likely to be evolving for at least some of their genes. Evolution is happening right here, right now!
To be clear, that doesn’t mean these populations are marching towards some final state of perfection. All evolution means is that a population is changing in its genetic makeup over generations. And the changes may be subtle—for instance, in a wolf population, there might be a shift in the frequency of a gene variant for black rather than gray fur. Sometimes, this type of change is due to natural selection. Other times, it comes from migration of new organisms into the population, or from random events—the evolutionary “luck of the draw.“
In this article, we’ll examine what it means for a population evolve, see the (rarely met) set of conditions required for a population not to evolve, and explore how failure to meet these conditions does in fact lead to evolution.
Problems:
Genetic variation _____.
A) must be present in a population before natural selection can act upon the population
B) is created by the direct action of natural selection
C) tends to be reduced by when diploid organisms produce gametes D) arises in response to changes in the environment
Whenever diploid populations are in Hardy-Weinberg equilibrium at a particular locus, _____.
A) two alleles are present in equal proportions
B) individuals within the population are evolving
C) the allele’s frequency should not change from one generation to the next
D) natural selection, gene flow, and genetic drift are acting equally to change an allele’s frequency
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