The Whale and the Virus: How Scientists Study Evolution

Question 1

Define Biological Evolution

Answer 1

Biological Evolution is any change in the inherited traits of a population that occurs from one generation to the next (that is, over a time period longer than the lifetime of an individual in the population).

Question 2

Describe the relative roles of mutation and selection in evolution.

Answer 2

Mutation is the engine of evolution in that it generates the genetic variation on which the evolutionary process or mechanism of selection depends.

Question 3

Discuss the evolution of Cetaceans: mammals that went to sea.

Answer 3

The change of environment provided selective pressures that allowed the propagation of certain genes from one generation to the next resulting in a change in the inherited traits of the population. Remnants of divergence in functional use from ancestry can be seen in vestigial structures such as the hip bones in whales.

Question 4

Define Synapomorphy

Answer 4

A derived form of a trait that is shared by a group of related species (that is, one that evolved in the immediate common ancestor of the group and was inherited by all its descendants)

Question 5

Explain how viruses can evolve and how new viruses can emerge.

Answer 5

Viruses reproduce by infecting and using host genetic machinery to make copies of themselves. During replication, there are natural mutations that occur, some may be deleterious, yet others may be beneficial. The traits that give the virus a selective advantage and permit them a better chance of reproduction are more likely to be propagated through future generations. Further, viruses can “swap” genes, a process known as viral reassortment, which occurs when two viruses infect one cell at once, and their genetic material is shuffled together and becomes packaged into protein shells.

Question 6

Define Microevolution

Answer 6

Microevolution is evolution occurring within populations, including adaptive and neutral changes in allele frequencies from one generation to the next.

Question 7

Define Macroevolution

Answer 7

Macroevolution is evolution occurring above the species level, including the origination, diversification, and extinction of species over long periods of evolutionary time.

Question 8

Define Macroevolution

Question 9

The process of natural selection involves most accurately
A. individuals of a population able to reproduce.
B. differential survival.
C. successful reproduction among all members of a
population.
D. differential survival and reproduction among survivors.

Answer 9

D. Differential survival and reproduction among survivors.

Question 10

Natural Selection

Answer 10

Differential survival and reproduction of individuals cause some genetic types to replace (outcompete) others, leading to evolution (change in the genetic traits of a population from one generation to the next).

Question 11

Mutation

Answer 11

Any change to the genomic sequence of an organism.

Question 12

Cetaceans
A. all originated from a single common ancestor within the past 50
million years.
B. originated from several different ancestral forms that each
transitioned into aquatic forms over the past 50 million years.
C. originated as a distinct mammalian lineage at the same time that
other mammals evolved, more than 200 million years ago.
D. have evolved multiple times over the past 100 million years.

Answer 12

A. all originated from a single common ancestor within the past 50 million years.

Question 13

Dolphins have the same set of genes that regulate the development
of hindlimbs that land mammals have. Why don’t dolphins grow
hindlimbs?
A. Dolphins do grow hindlimbs, but other add-on genes turn them
into flippers.
B. Dolphins do not grow hindlimbs because they are not needed in
an aquatic environment.
C. Dolphin embryos do grow hindlimb buds, but their development
is terminated very early because of a mutation in a regulatory
gene.
D. The regulatory genes for limb development in dolphins have
been completely deactivated.

Answer 13

C. Dolphin embryos do grow hindlimb buds, but their development is terminated very early because of a mutation in a regulatory gene.

Question 14

Given how natural selection works by favoring certain traits and not favoring others; how could a lineage or group ever go extinct?
A. Natural selection is an inherently flawed process in that it allows
harmful mutations to remain in the gene pool of species.
B. The environment changes more quickly than natural selection
can act on populations to adapt.
C. Living things evolve to become better adapted to the
environment, so they can also go extinct to make way for new
species.
D. Prey species are often driven to extinction by predation.

Answer 14

B. The environment changes more quickly than natural selection

Question 15

Natural selection favors those viral particles with mutations that make them more effective at infecting cells. What does this mean for humans?
A. Other than modern medical advances, humans have no recourse against viral infections.
B. Only those humans who were not exposed to viruses in the past will survive.
C. Natural selection in humans should also favor those who can effectively withstand viral infections.
D. Viruses have only gained the ability to infect humans in the last century or so.

Answer 15

C. Natural selection in humans should also favor those who can effectively withstand viral infections.

Question 16

Viral reassortment takes place when
A. viral particles insert their genes into the genome of a host cell.
B. one type of viral particle outcompetes another type outside their host cell.
C. viral particles of different types trade genes with one another in the same host cell.
D. influenza DNA recombines with cellular DNA.

Answer 16

C. Viral particles of different types trade genes with one another in the same host cell.