BIO midterm #2-Chapter 13

gene pool

- all of the alleles of all the genes in a population.

genetic drift

A change in the gene pool due to chance events in small populations or as the result of disasters;

The human immune system cannot effectively suppress the HIV virus on its own. What key feature of HIV makes it so hard to beat?

The HIV virus has an extremely high rate of mutation.

founder effect

a few individuals from an existing population establish a new one

Natural selection is best described as _____.

a filtering process that fine-tunes the traits of populations by sorting among existing, randomly produced variations

A population is __________.

a group of individuals of the same species occupying a given area

Natural selection can be defined as ______.

a process in which organisms with certain inherited traits are more likely to survive and reproduce than individuals with other traits

Sickle-cell disease is caused by __________.

a recessive allele

microevolution

change at the genetic level (small picture). change in gene pool of populations

macroevolution

change at the species level (big picture)

evolution

genetic change through time

The evolution of populations due to chance is

genetic drift

the bottleneck effect and founder effect are part of

genetic drift

bottleneck effect

genetic drift due to a drastic reducion in population size

When Darwin wrote On the Origin of Species, he knew very little about the subject of _____, an essential component of evolutionary theory today.

genetics

population

group of individuals of the same species, living in the same place, and at the same time

nonrandom mating

Changes in the gene pool due to selective mating.

Which of the following is an example of natural selection?

Green beetles leave more offspring than brown beetles because they are better at finding food.

As proposed by Darwin, what sorts of traits are favored by natural selection?

Heritable traits that help individuals survive and reproduce more successfully than others in the same population.

Gene flow occurs when

individuals move into or out of a population, changing the allele frequencies in the population

___________ is a type of sexual selection in which individuals of one sex (usually male) compete directly for mates. this may involve ritualized displays or physical combat

intrasexual selection

darwin inferred that those organisms with traits best suited to the environment tend to

leave more offspring than other members of a population

When they were first sold, aerosol insecticides were highly effective in killing flies and mosquitoes. Today, some 30 years later, a much smaller proportion of these insects die when sprayed. The reason fewer insects are being killed is that __________.

many mosquitoes today are descendants of mosquitoes with insecticide-resistant characteristics

What does evolutionary fitness measure?

relative reproductive success

in sexual selection, individuals with certain inherited traits are more likely to obtain mates than other individuals. this often results in _____________, differences between the sexes in size, appearance, and behavior

sexual dimorphism

This crash in the population of bison and recent recovery is a good example of _____.

the bottleneck effect

Which of the following is an example of natural selection that has been seen in our lifetime?

the evolution of antibiotic-resistant bacteria

Imagine that a new population of humans is established on a new planet from ten randomly selected people in your biology class. Over thousands of years, the descendants of those ten people reproduce and prosper, but do not reflect well the diversity of humans on Earth. This change in the diversity of people on the new planet is an example of _____.

the founder effect

If color is an inherited trait in beetles, and birds are more likely to eat brown beetles than green beetles,

the frequency of the green allele will increase.

biogeography

the geographic distribution of species

all of life is related through common ancestry, accounting for the _____ of life

unity

Natural selection relies on

variation among individuals in a population

Which of the following is a requirement for natural selection?

variation in individuals

Genetic drift affects the evolution of ________ populations more than it affects the evolution of _______ populations.

small, large

_________ favors intermediate phenotypes, selecting against phenotypes at both ends of a range and reducing variation

stabilizing selection

Scientists have warned doctors of the danger of their increasing use of antibiotics (for instance, penicillin) for treating minor illnesses. They are concerned because _____.

strains of microorganisms that are resistant to these drugs will increase

The smallest unit that can evolve is a _____.

population

two key observations underlying natural selection are that

1. members of a population vary in their inherited traits 2. all species can produce more offspring than the environment can support

mechanisms of evolutionary change

1. mutation 2. natural selection 3. nonrandom mating 4. gene flow 5. genetic drift

sources of genetic variation

1. mutation 2. sexual reproduction

darwin spent _____ years on a ship, the ____________ as the ship's _______ and went to places like the

5, H.M.S. Beagle, naturalist, galapagos islands

Imagine that four people are infected with HIV from a common source (an infected blood sample). Initially, the patients' HIV populations are genetically identical. By the time they develop full-blown AIDS, how would the viral populations of the four patients compare?

Each patient's viral population would be unique, specifically adapted to deal with—and overcome—his or her unique immune system responses.

what is the founder effect?

The founder effect involves the colonization of a new habitat by a few individuals who do not represent all of the diversity of the parent population

unequal reproduction in a population leads to the gradual accumulation of ____________ to the environment

adaptations

Darwin proposed the theory of natural selection as the mechanism of evolution based on three observations about nature. Which of the following were part of Darwin's observations? a. Populations have the potential to produce more individuals than the environment can support. b. Individuals in some populations have varied characteristics. c. Variation in individuals appears to be inherited. d. All of the above are correct.

all of the above

At the base of the evolutionary tree of all life is ______________.

an organism that is a common ancestor to all living organisms.

the phrase darwin used to describe his broad theory of evolution is

descent with modification

____________ favors phenotypes at one end of a range and is common in periods of environmental change

directional selection

___________ favors phenotypes at both ends of a range over intermediate phenotypes. this type of selection may occur when the habitat is varied

disruptive selection

the _______ of life arises from the adaptation of species to different habitats over long spans of time

diversity

in a type of sexual selection often called ___________, individuals of one sex (usually females) are choosy in selecting mates. this choice is often based on the showy appearance or behavior of the male

mate choice

Generation-to-generation change in the allele frequencies in a population is _____.

microevolution

gene flow is the

migration of individuals or gametes.

"Differential success in reproduction" is just another way of saying _____.

natural selection

-Of all causes of microevolution, only _____________ promotes adaptation.

natural selection

darwin proposed a mechanism for how evolution occurs, which he called

natural selection

__ + ___ = ___

p+q=1

hardy-weinberg formula

p2 + 2pq + q2 = 1