Exam 17: The Means of Evolution: Microevolution

A population of salamanders migrates from a sand beach to a pebble beach and evolves over many generations from a solid color to speckled coloration. This process is called stabilizing selection.

As world travel becomes easier and human populations intermix, the occurrence of what phenomenon will probably decrease?

There can be more than two varieties of alleles for a particular gene in a population.

You are studying leaf size in a natural population of plants. The second season is particularly dry, and the following year the average leaf size in the population is smaller than the year before. But the amount of overall variation is the same, and the population size hasn't changed. Also, you've done experiments that show that small leaves are better adapted to dry conditions than are large leaves. Which of the following has occurred?

A small minority of mutations is adaptive, providing an improvement to the gene pool of the population.

Without mutation, evolution would eventually cease, because mutations create the variation that evolution acts upon.

The original source of variation within a population comes from ________.

In order for migration to alter allele frequencies in another population:

Habitats set aside for endangered species are often sectioned into areas by roads, producing separate small populations. This causes problems in conservation because it reduces:

If a species of bird with an intermediate beak size evolves into two varieties, one with large beaks and one with small beaks, this could result from disruptive selection.

How have Caesarean sections and intensive neonatal (near-birth) medical care likely affected the average birth weight of American babies?

When a population decreases in number until a small remnant of the original population remains, a ________ has occurred.

Mutations:

Refer to the figure below, and then answer the question that follows. -The changes in cranial capacity over the course of human evolution are an example of:

Phenotypes that show a wide range of almost continuous variation, such as height or skin color in humans, are probably:

Male guppies are known for their bright colors. Having bright colors attracts mates, but it also attracts predators. So in an environment with a lot of predators, male guppies have more dull colors. In an experiment, guppies were removed from an area with predators to an area without predators. Over a period of 12 months the population became much more colorful. This is an example of a response to:

Genetic drift has a much more significant effect on small populations than on large populations.

If after several generations 30 percent of the males have antlers with 9 to 11 points, 40 percent have antlers with 15 to 17 points, and 20 percent have antlers with 12 to 14 points, this development will have been the result of:

A bottleneck may be dangerous to a population because:

The basic units that evolve are species.