22. Evolution of Populations

Which of the following would seem to be an example of neutral variation?

No two people are genetically identical, except for identical twins. The main source of genetic variation among humans isa. new mutations that occurred in the preceding generation.b. genetic drift.c. the reshuffling of alleles in sexual reproduction.d. environmental effects.

The human genome consists of approximately 3 billion base pairs. If humans typically differ from one another by about 3 million base pairs, what is the nucleotide variability of Homo sapiens?

Stabilizing selection __________.

Which of the following mechanisms can form entirely new alleles?

Sexual recombination includes the shuffling of chromosomes in __________ and fertilization.

Which type of mutation plays the most important role in increasing the number of genes in the gene pool?

What is the importance of neutral variation in evolution?

__________ and __________ generate variation, whereas __________ results in an adaptation to the environment.

A population of 15 birds inhabits a fairly new island. Ten of the birds are dark brown, and five of them are light brown. By chance, two of the dark brown birds and three of the light brown birds die before producing any offspring. All of the birds in the next generation are dark brown. This change in phenotypic frequency can be attributed to __________.

An earthquake hits a small island. All but a small group of closely related lizards are eliminated, and the survivors spread out over the island. This is an instance of __________.