Chapter 22: Evolution by natural selection
Which of the following is a correct restatement of Charles Darwin's phrase "descent with modification"?
"Descent with modification" means that the species that exist in the present descended from other, preexisting species and that species change over time.
Which conclusion can be drawn from the following graphs concerning different characteristics of medium ground finches over the time period shown?
Beak depth has decreased since 1980.
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
Over time, the lineage that led to modern whales shows a change from four-limbed land animals to aquatic animals with two limbs that function as flippers. This change is best explained by __________.
natural selection
Charles Darwin and Alfred Russel Wallace were the first to propose __________.
natural selection as the mechanism of evolution
Pseudogenes are __________.
nonfunctional, vestigial genes
Developmental homologies most likely occur because __________.
of genetic homologies
Two of the extant (living) elephant species (X and Y) are placed in the genus Loxodonta, and a third extant species (Z) is placed in the genus Elephas. Assuming this classification reflects evolutionary relatedness, which of the following is the most accurate phylogenetic tree?
see image
The modern definition of evolution is __________.
a change in allele frequencies in a population over time
Recent analyses of the fossil record suggest that more than ___ percent of all the species that have ever lived are now extinct.
99
The natural increase in red blood cells of individuals exposed to high altitude is an example of what biologists call _____, which is a change in an individual's phenotype that occurs in response to a change in natural environmental conditions.
Acclimatization
A group of boys work out, practice for long hours, and become very good at playing basketball. Which of the following statements is true about this observation?
All of their efforts will not influence evolution because they have not changed anything that is heritable.
Who proposed that organisms could be organized into a scale of nature?
Aristotle
During a study session about evolution, one of your fellow students remarks, "The giraffe stretched its neck while reaching for higher leaves; its offspring inherited longer necks as a result." Which of the following statements will most likely be helpful in correcting this student's misconception?
Characteristics acquired during an organism's life are generally not passed on through genes.
Which of the following scientists argued that variation among individuals, acted upon by the forces of natural selection, allows evolution to occur?
Charles Darwin
The horizontal axis of the cladogram depicted is a timeline that extends from 100,000 years ago to the present; the vertical axis represents nothing in particular. The labeled branch points on the tree (V-Z) represent various common ancestors. Let's say that only since 50,000 years ago has there been enough variation between the lineages depicted here to separate them into distinct species, and only the tips of the lineages on this tree represent distinct species. Which pair of scientists would probably have agreed with the process that is depicted by this tree?
Charles Darwin and Alfred Russel Wallace
Which of these conditions are always true of populations evolving via 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
What is considered Charles Darwin's greatest contribution to science?
Darwin described the process of natural selection.
How do the theories of Jean-Baptiste Lamarck and Charles Darwin differ?
Darwin proposed that populations change, whereas Lamarck proposed that individuals change.
What three major lines of evidence did Charles Darwin use to argue that species have changed over time?
Darwin's evidence was that (1) fossils frequently resemble present-day species found in the same area, (2) many species have gone extinct, and (3) vestigial traits are common.
During the drought of 1977, 84 percent of the medium ground finch population on Daphne Major disappeared. The individuals that survived had beaks that were deeper and larger than the beaks of individuals who did not survive. Given that natural selection favored large individuals with deeper and larger beaks, how can the presence of individuals with small, pointier beaks in 1983 be explained?
Even though the majority of birds after 1977 had deeper and larger beaks, there was still variation in beak size in the population. As seed type and seed availability changed, birds with beaks suited to exploit abundant seeds had higher reproductive success.
On Daphne Major, the medium ground finches did not reproduce, and 84 percent died during the drought of 1977. Did evolution occur during this time?
Even though there was no reproduction because mortality was not random, evolution occurred.
Which of the following must exist in a population before natural selection can act upon that population?
Genetic variation among individuals
Resistance to a wide variety of insecticides, fungicides, antibiotics, antiviral drugs, and herbicides has recently evolved in hundreds of insects, fungi, bacteria, viruses, and plants. Why do we observe this increased resistance?
Humans have altered the environments of these organisms and naturally resistant organisms have higher fitness in the altered environment.
If Charles Darwin had been aware of genes and their typical mode of transmission to subsequent generations, with which statement would he most likely have been in agreement?
If natural selection can change gene frequency in a population over generations, then given enough time and genetic diversity, natural selection can select for sufficient genetic change to produce new species from old ones.
Which of the following statements best depicts population thinking?
Individual giraffes within a population exhibit a range of different neck lengths.
Why is Aristotle's great chain of beings an incorrect theory?
It is incorrect because it considers species as "higher" or "lower" organisms, and it does not recognize that species change.
In the mid-1900s, Soviet geneticist Trofim Lysenko believed that his winter wheat plants, exposed to increasingly colder temperatures, would eventually give rise to more cold-tolerant winter wheat. Lysenko's attempts in this regard were most in agreement with the ideas of __________.
Jean-Baptiste Lamarck
Jean-Baptiste Lamarck proposed that evolution occurs through the inheritance of acquired characteristics. What is the main difference between Lamarck's view of evolution and Charles Darwin's view of evolution?
Lamarck's ideas correlate to a ladder of evolution. Lamarck proposed that organisms become more complex over time.
Which statement restates the fact that rifampin resistance in Myocobacterium tuberculosis is an adaptation?
Rifampin resistance is a heritable trait that increases the fitness of resistant individuals compared to susceptible individuals.
In a hypothetical environment, fishes called pike-cichlids are visual predators of large, adult, algae-eating fish (in other words, they locate their prey by sight). The population of algae-eaters experiences predatory pressure from pike-cichlids. Which of the following is least likely to occur in the algae-eater population in future generations?
Selection for larger female algae-eaters, bearing broods composed of more, and larger, young
The question refers to the following evolutionary tree, in which the horizontal axis represents time (present time is on the far right) and the vertical axis represents morphological change. Which species is most closely related to species W?
Species V is most closely related to species W.
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.
Which of the following statements describes the law of succession?
Species in the fossil record were succeeded in the same region by similar species.
A biologist studied a population of squirrels for 15 years. During that time, the population was never fewer than 30 squirrels and never more than 45. Her data showed that more than half of the squirrels born did not survive to reproduce because of both competition for food and predation. In a single generation, 90 percent of the squirrels that were born lived to reproduce, and the population increased to 80. Which inference(s) about this most recent surge in the population size might be true?
The amount of available food may have increased or the predators that prey on squirrels may have decreased.
How did the theory of special creation differ from Charles Darwin's theory of evolution by natural selection?
The theory of special creation proposed that species are independently created and immutable over time. Charles Darwin observed that species are related and change over time.
Evidence for the Earth's vast age began to become clear with James Hutton's proposal of the principle of _______, which is the idea that geological processes occurring today are similar to what occurred in the past.
Uniformitarianism
You are studying a group of fossils, and you notice that a particular trait is present in the older fossils, but that this trait disappears in the more recent species. What is the meaning of this observation?
This observation means that in more recent species, individuals without the trait may have had higher biological fitness.
HIV's genome of RNA includes the code for reverse transcriptase (RT), an enzyme that acts early in infection to synthesize a DNA genome from an RNA template. The HIV genome also codes for protease (PR), an enzyme that acts later in infection by cutting long viral polyproteins into smaller, functional proteins. Both RT and PR represent potential targets for antiretroviral drugs. Drugs called nucleoside analogs (NAs) act against RT, whereas drugs called protease inhibitors (PIs) act against PR. Which of the following represents the treatment option most likely to avoid the evolution of drug-resistant HIV (assuming no drug interactions or side effects)? Using a single PI, but slowly increasing the dosage over the course of a week Using high doses of NA and a PI at the same time for a period not to exceed one day Using a series of NAs, one at a time, and changed about once a week Using moderate doses of NA and two different PIs at the same time for several months
Using moderate doses of NA and two different PIs at the same time for several months
Refer to the following evolutionary tree, in which the horizontal axis represents time (present time is on the far right) and the vertical axis represents morphological change. Which of these is the extant (that is, living) species most closely related to species X?
V
What are vestigial traits? Do vestigial traits support the idea of special creation or descent with modification?
Vestigial traits are structures that are incompletely developed or reduced and have limited or no function. This indicates that species change over time and is an important pattern component of the theory of evolution. Vestigial traits are inconsistent with the theory of special creation.
Which of the following statements is an example of typological thinking?
Women are shorter than men, have longer hair, and like to shop.
The horizontal axis of the cladogram depicted is a timeline that extends from 100,000 years ago to the present; the vertical axis represents nothing in particular. The labeled branch points on the tree (V-Z) represent various common ancestors. Let's say that only since 50,000 years ago has there been enough variation between the lineages depicted here to separate them into distinct species, and only the tips of the lineages on this tree represent distinct species. Which of the five common ancestors, labeled V-Z, is the common ancestor of the greatest number of species, both living and extinct?
Y
Has evolution by natural selection recently occurred in populations of Mycobacterium tuberculosis?
Yes. The frequency of the adaptive allele for drug resistance in M. tuberculosis has increased over time.
Refer to the following evolutionary tree, in which the horizontal axis represents time (present time is on the far right) and the vertical axis represents morphological change. Which of these is (are) the extant (that is, living) species that are least related to species X?
Z and Y
Prior to the work of geologists and biologists (like Charles Darwin), the prevailing belief was that Earth is __________.
a few thousand years old and that populations are unchanging
Arctic toothfishes live in very cold water year-round. These fishes have genes that code for freeze-resistant proteins. The production of such proteins in these fish is an example of __________.
an adaptation
If two modern organisms last shared a common ancestor 50 million years ago, we expect that they __________.
have fewer homologous structures than two modern organisms that last shared a common ancestor one million years ago
To support his idea of _______, Cuvier focused on the fossils of large terrestrial animals such as mammoths, mastodons, and giant sloths.
extinction
The horizontal axis of the cladogram depicted is a timeline that extends from 100,000 years ago to the present; the vertical axis represents nothing in particular. The labeled branch points on the tree (V-Z) represent various common ancestors. Let's say that only since 50,000 years ago has there been enough variation between the lineages depicted here to separate them into distinct species, and only the tips of the lineages on this tree represent distinct species. Evolutionary trees such as this one are properly understood by scientists to be __________.
hypotheses
Organisms on islands are commonly different from, but closely related to, similar forms found on the nearest continent. This is taken as evidence that __________.
island forms are descended from mainland forms
The best definition of biological fitness is __________.
the ability of an individual to successfully reproduce relative to other individuals in the population
A _______ feature is a trait in a fossil species that is intermediate between those of ancestral (older) and derived (younger) species.
transitional
To help determine the geological age of the Earth, scientists study the rate of decomposition of _______________________.
uranium