Chapter 22

evolution and drug resistance

-not all evolution is slow -antibiotics- didn't induce mutations but killed the susceptible bacteria The population of HIV viruses has therefore developed resistance to 3TC

Darwin developed two main ideas:

1. Descent with modification explains life's unity and diversity 2. Natural selection is a cause of adaptive evolution

Analogy

A comparison of two different things that are similar in some way

natural selection

A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.

Given a population that contains genetic variation, what is the correct sequence of the following events under the influence of natural selection? ​1Well-adapted individuals leave more offspring than do poorly adapted individuals. 2. ​change occurs in the environment. 3. ​Genetic frequencies within the population change. 4. ​Poorly adapted individuals have decreased survivorship.

A) 2 → 4 → 1 → 3

inherited characteristics or organisms that enhance their survival and reproduction in specific environments.

Adaptations

Which of these conditions should completely prevent the occurrence of natural selection in a population over time?

All variation between individuals is due only to environmental factors.

artificial selection

Breeding organisms with specific traits in order to produce offspring with identical traits.

During a study session about evolution, one of your fellow students remarks, ʺThe giraffe stretched its neck while reaching for higher leaves; its offspring inherited longer necks as a result.ʺ Which statement is most likely to be helpful in correcting this studentʹs misconception?

Characteristics acquired during an organismʹs life are generally not passed on through genes.

Which of these conditions are always true of populations evolving due to natural selection? Condition 1: The population must vary in traits that are heritable. Condition 2: Some heritable traits must increase reproductive success. Condition 3: Individuals pass on most traits that they acquire during their lifetime.

Conditions 1 and 2

Homologous features

Current anatomical features - Embryonic anatomical features - Vestigial anatomical features

may be defined by Darwin's phrase descent with modificatio

Evolution

helped to lay the groundwork for Darwin's ideas

Fossils

What must be true of any organ described as vestigial?

It must be homologous to some feature in an ancestor.

interpreted organismal adaptations

Linnaeus

was the founder of taxonomy, the branch of biology concerned with classifying organisms

Linnaeus

Charles Darwin published

On the Origin of Species

To observe natural selectionʹs effects on a population, which of these must be true?

One must observe more than one generation of the population. B) The population must contain genetic variation.

Which of the following represents an idea that Darwin learned from the writings of Thomas Malthus?

Populations tend to increase at a faster rate than their food supply normally allows.

convergent evolution

Process by which unrelated organisms independently evolve similarities when adapting to similar environments

Currently, two extant elephant species (X and Y) are classified in the genus Loxodonta, and a third species (Z) is placed in the genus Elephas. Thus, which statement should be true?

Species X and Y share a greater number of homologies with each other than either does with species Z.

homologous structures

Structures in different species that are similar because of common ancestry.

Which of Darwinʹs ideas had the strongest connection to Darwin having read Malthusʹs essay on human population growth?

Struggle for existence

Darwin's book

The Origin of Species

Which of the following scientists argued that variation among individuals allows evolution to occur?

Wallace

Which of these naturalists synthesized a concept of natural selection independently of Darwin?

Wallace

Which statement about natural selection is most correct?

Well-adapted individuals leave more offspring, and thus contribute more to the next generationʹs gene pool, than do poorly adapted individuals.

population of organisms will not evolve if _

all individual variation is due only to environmental factors

Of the following anatomical structures, which is homologous to the bones in the wing of a bird?

bones in the flipper of a whale

The role that humans play in artificial selection is to ___

choose which organisms reproduce

The role that humans play in artificial selection is to _____.

choose which organisms reproduce

Darwin and Wallace's theory of evolution by natural selection was revolutionary because it _____.

dismissed the idea that species are constant and emphasized the importance of variation and change in populations

Which of the following must exist in a population before natural selection can act upon that population?

genetic variation among individuals

Structures as different as human arms, bat wings, and dolphin flippers contain many of the same bones, which develop from similar embryonic tissues. These structural similarities are an example of

homology

Fossils of Thrinaxodon, a species that lived during the Triassic period, have been found in both South Africa and Antarctica. Thrinaxodon had a reptile-like skeleton and laid eggs, but small depressions on the front of its skull suggest it had whiskers and, therefore, fur. Thrinaxodon may have been warm-blooded. The fossils of Thrinaxodon are consistent with the hypothesis that _____.

mammals evolved from a reptilian ancestor

Charles Darwin was the first person to propose

mechanism for evolution that was supported by evidence.

In Darwinʹs thinking, the more closely related two different organisms are, the

more recently they shared a common ancestor.

does not create new traits, but edits or selects for traits already present in the population

natural selection

Darwin and Wallace were the first to propose _____.

natural selection as the mechanism of evolution

Vestigial structures

remnant of a structure that may have had an important function in a species' ancestors, but has no clear function in the modern species.

Homology

similarity resulting from common ancestry

Which of Darwin's ideas had the strongest connection to his reading of Malthus's essay on human population growth?

struggle for existence

Which of the following evidence most strongly supports the common origin of all life on Earth? All organisms _____.

use essentially the same genetic code