Chapter 20 Quiz

. Microevolution involves _______, whereas macroevolution involves _______.

processes that occur within species; evolution above the species level (i.e., higher taxa)

molecules; organisms

genetic changes; phenotypic changes

evolution above the species level (i.e., higher taxa); processes that occur within species

organisms; ecosystems

. Almost all of the genes affecting the development of feathers are found in crocodilians. What can we conclude from this observation?

Ancient crocodilians had feathers.

Genes responsible for feather development were used for other functions in crocodilians, but were co-opted for feather development later.

We have not yet identified all of the genes responsible for feathers.

Crocodilians belong in the Aves taxonomic group.

Feathers evolved only once in the lineage leading to birds, but before complete reproductive isolation, feather genes introgressed into crocodilians.

. Critical characteristics that distinguish most mammals from their reptile-like ancestors do not include

the lower jaws of mammals is reduced to a single bone.

the inner ear bones of mammals are increased to three (hammer, anvil, stirrup).

mammal teeth are distinguished into multiple types with different arrangements of cusps.

mammals possess a large space (temporal fenestra) behind the eye socket.

mammals evolved smaller size, allowing a paedomorphic skull with relatively large eyes.

. Which scenario represents a case of a saltation resulting in a "hopeful monster"?

A small population that has been isolated from a widely distributed species has new mutations fixed rapidly by genetic drift. These "monsters" "hope" that they are not absorbed by the larger population.

After a long period of evolutionary stasis, a species undergoes relatively rapid morphological evolution. These "monsters" had "hoped" for a new adaptation to overcome a novel environmental challenge.

A systemic mutation disrupts the genetic system of an organism so much that it results in a "monstrous" mutation. The individuals "hope" to encounter an environment where the change is beneficial.

A predatory organism gradually grows larger over evolutionary time. These "monsters" are "hopeful" to encounter prey large enough to sustain their populations.

A "monstrous" population evolves following a driven trend; they "hope" to arrive at a new, high-fitness phenotype before their population goes extinct.

. Refer to the figure showing the evolutionary morphology of two different taxa.

The figure demonstrates

evolution of morphological differences between species by gradualism.

that morphology can evolve via saltations.

that the common ancestor of two different forms need not have morphology that is precisely intermediate.

Both a and c

All of the above

. In many reptiles, locomotor muscles insert on the ribs, limiting the ability of the organisms to breathe while running. However, in birds and mammals the muscle insertions have shifted to processes on the vertebrae. How does this change facilitate evolutionary novelty?

The features have been co-opted to new function.

The genes controlling muscle development have been recruited to new purpose.

It decouples the multiple functions of the ancestral trait, decreasing functional constraints.

It leaves the selective regime unchanged.

None of the above; evolutionary novelty will not be increased because the change involves the modification of existing structures, rather than the origination of a new structure.

. Creationist opponents of evolution cite the complexity of the eye as a feature that would be impossible to have been produced by evolution. Even Darwin wrote, "That the eye, with all of its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection seems, I freely confess, absurd in the highest possible degree." Why are creationists wrong and how has this been resolved?

It is still unresolved and is a major weakness of Darwin's evolutionary theory. Creationists call this "irreducible complexity."

Eyes are often lost through drift and natural selection, for example by cave fish and moles.

Complex eyes evolved via systemic mutations (by saltation, as predicted by Richard Goldschmidt).

Numerous examples of intermediate forms have been found, indicating that complex eyes can evolve via gradual change.

The fossil record indicates that complex eyes are ancestral and simple eyes are derived.

. The "genetic toolkit" consists of

highly expressed genes.

enzymes that maintain the structural integrity of the genome.

the set of all genes shared by all metazoans.

Taq polymerase, buffer, nucleotides, primers, template DNA, and a thermocycler.

highly conserved genes that encode transcription factors and regulatory genes that underlie development.

. Why might a species' "optimal" phenotype remain unchanged for long periods of time, resulting in apparent evolutionary stasis?

Gradual environmental change

Saltational evolution

Directional selection

Habitat tracking

Passive trends

. Cycadophyta is a group of plants with a small number of extant species, but are well known from fossils from the Mesozoic era. Living "cycads" are nearly identical to fossils. What best explains these "living fossils"?

Biological homology

Punctuated equilibria

Phylogenetic niche conservatism

Passive trends

Hopeful monsters

. The hypothesis of punctuated equilibrium is controversial because

it relies on data from the fossil record.

the hypothesis requires that morphological evolution be accompanied by speciation.

evolutionary stasis is rarely observed.

different characters evolve at different rates.

a combination of directional and balancing selection may be required for punctuated equilibrium to occur.

. How can speciation enhance the rate of adaptive evolution?

Speciation "punctuates" the "equilibrium" of evolutionary stasis.

Speciation can occur only when there is a very high mutation rate, increasing the likelihood of new, beneficial mutations.

High speciation rates lead to high diversity, and this progress is the goal of natural selection.

Without speciation, organisms that evolve new adaptations would go extinct.

Reproductive isolation allows new beneficial mutations to become fixed before they can be swamped by gene flow from the larger population.

. Cope's rule, that animals tend to increase in size over evolutionary time, is a(n)

driven trend, because natural selection always favors larger animals.

active trend, because there is a persistent bias against smaller animals.

passive trend, because there is a minimum size under which animals cannot function, but increased variance in size moves the mean and maximum upward.

case of saltation, because increases in size occur by great jumps.

example of phylogenetic niche conservatism, because ecological niches favor the large.

. Why are colonies of social insects, like termites, sometimes referred to as superorganisms?

They have overcome the influence of genetic drift and only evolve by natural selection.

They have achieved a level of hierarchical organization greater than the individual.

The amount of phenotypic similarity among individuals in the colony is exceptionally high.

They have greater levels of morphological complexity than other insects.

They represent the pinnacle of evolutionary progress, having maximized their efficiency and adaptedness.

. Stephen Jay Gould suggested that if we were to replay the "tape of life," the course of events that we know as "history" might play themselves out very differently. Which statement supports this idea?

Historical contingency suggests that small differences in random events can result in large downstream differences.

Many organisms have evolved similar phenotypes through the process of convergent evolution.

Organisms all experience the same physical constraints (e.g., gravity) and respond to them similarly.

There are finite numbers of solutions to certain engineering problems.

Organisms such as crows, parrots, and dolphins show intelligence, so it is likely that even in the absence of humans, complex cognition would have evolved in other lineages.

. How do evolutionary biologists view the notion of biological "progress"?

Evolution proceeds toward a goal (teleology).

Lasting evolutionary progress does not occur because of cyclical phenomena, such as iterative mass extinctions.

Progress can be measured by levels of hierarchical organization among individuals of the same species.

Objective definitions of progress are fraught with difficulty, as the processes that drive evolution have no mechanism for foresight.

Progress can be measured by how much a given species resembles Homo sapiens.

Chapter 20 Quiz

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