Bio 427 Exam 2

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

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

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

Habitat tracking

When asked what the study of evolution reveals about the mind of the Creator, J. B. S. Haldane famously replied "that he has an inordinate fondness for beetles." Why did he say this?

Haldane recognized beetles as the most diverse taxon, with over 350,000 described species.

Which statement offers the best explanation for why the only native land mammal to Hawaii is the Hawaiian hoary bat?

Hawaii formed and was isolated before the evolution of mammals in the Mesozoic era.

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.

Which term is defined as any consistent difference in fitness among phenotypically different classes of biological entities as a consequence of competition for mates?

Sexual selection

Observations of the biogeographic distributions of organisms provided both Darwin and Wallace with evidence for the occurrence of evolution. Which of the following was not part of the evidence used by Darwin to support his theory of descent with modification?

Species distributions are closely aligned with the movement of continents.

If we use molecular clocks to estimate that the most recent common ancestor of a species pair existed 5 million years ago in a specific region, what strata of fossil-bearing rock would be the best choice for finding a fossil most similar to that ancestor?

Strata slightly older than 5 million years old

Stickleback fish found in lakes rapidly evolve a low armor plate morphology when compared to marine populations. Analysis of the gene responsible shows that populations with low plating form one clade and marine populations form another. However, gene trees formed with other genes show that the low plating phenotype probably evolved independently multiple times. How have scientists resolved these contradictory gene trees?

A single origin of the low plating gene in the oceanic population that remained at a low frequency until lakes were colonized. Then the gene independently became fixed in each.

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

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.

Which scenario depicts adaptations incorrectly?

A trait evolves in anticipation of a future environmental change.

Which trait cannot describe an adaptation?

A trait that does not change the probability of survival or reproduction, like the color of cave-dwelling fish

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"?

Phylogenetic niche conservatism

Refer to the figure. Imagine you have a phylogeny that you are sure is correct that includes five species. You examine a gene sequence and discover that species A and E differ by 100 base pairs, species B and E differ by 101 base pairs, species C and E differ by 180 base pairs, and species D and E differ by 183 base pairs. What would you say is the most likely pattern of evolutionary rates among these species?

Rates of evolution increased for species C and D after they diverged from their common ancestor with species B.

Which of the following is not a well-documented example of adaptive evolution in response to human activities?

Reduced genetic diversity in elephant seal populations because of overhunting in the 1890s

How can speciation enhance the rate of adaptive evolution?

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

After the breakup of Gondwana, new species evolved in South America, Africa, and Australia. Which speciation model best fits this vicariance event?

Allopatric speciation

Which of these is an example of an evolutionary trade-off?

An oak tree must make decisions about whether to invest energy in growth or reproduction.

Which observation does not provide evidence that birds are theropod dinosaurs?

Both pterosaurs and birds evolved flight.

Historically, humans were placed into the taxonomic family Hominidae, and the great apes (orangutan, gorilla, bonobo, and chimpanzee) were placed into Pongidae. Modern taxonomists now place humans, along with the other great apes, into a single family, Hominidae. Use the phylogeny in the figure to identify the fact that led to this revision.

Chimps and bonobos are more closely related to humans than they are to the other great apes.

There are two likely explanations for the observation that the background extinction rate declined during the Phanerozoic. One is that a greater number of genera and species made higher taxa less likely to go extinct. What is the other explanation?

The extinction of "volatile" taxa left taxa with longer "life spans."

The Isthmus of Panama formed about 3 million years ago, isolating the Caribbean Sea from the Pacific Ocean. Which observation would provide evidence that sister species of angelfish found on either side are the result of a vicariance event cause by the formation of the landmass, rather than the dispersal of a founder population across the Isthmus?

The molecular clock dates the divergence time between the species to be 3 million years or greater.

Different models for species accumulation have been proposed to account for the difference in species richness between tropical and temperate regions. Which model best describes the greater diversity of treefrogs (Hylidae) in the tropics compared to the temperate zone?

Time and area hypothesis

A feature that reduces the fitness of an individual but benefits the population or species

cannot evolve by individual selection. can evolve by group selection. will decline in frequency among other nonaltruistic phenotypes.

Silvestre and colleagues found that diversity of the now extinct Canid subfamily Hesperocyoninae decreased as the diversity of the Caninae subfamily and Felidae family increased in North America. This is an example of _______.

competitive displacement.

Taxa that arose recently are more likely to still be extant, which has the effect of making diversity appear to increase as we draw closer to present day. This bias, called "the pull of the Recent," can be reduced by_______

counting only fossil occurrences of a taxon and not counting it between its last fossil occurrence and the Recent.

Paleobiologists have suggested that competition among species for resources may limit the possible number of species to some maximum number. The pattern that would best provide evidence for such diversity dependence would be higher diversity correlated with a(n) _______ in _______ rate.

decrease; origination

Refer to the graph. The data in the graph suggest that

different types of data are most informative at different timescales.

Wallace's line is a deep-water boundary that separates islands that differ greatly in their fauna, despite their close proximity and similar climate. Accordingly, these islands are assigned to two different biogeographic realms, each of which has a large number of species that are restricted to that location and found nowhere else in the world. These species are considered _______.

endemic.

Meiotic drive, or segregation distortion, is an example of

gametic selection.

The "genetic toolkit" consists of _______.

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

The major utility of the comparative method is that it ensures _______ in studies of adaptation in groups of species.

independence of data poin

The fitness of a biological entity is

its average per capita rate of increase in numbers.

Some groups of butterflies diversified rapidly after developing a tolerance to toxic alkaloids and the mechanical defenses of host plants. Such features represent a(n) _______.

key adaptation.

Alarm calls by ground squirrels alert other ground squirrels to danger, but they also draw attention to the caller and expose it to increased risk of predation. Such altruistic behavior is best explained by the phenomenon of

kin selection.

The Red Queen hypothesis proposes that the relationship between taxon age and extinction rate is

linear.

The figure shows relationships among major groups of vertebrates.

mammals are monophyletic for both phylogenies.

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

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

Charles Mitter and colleagues found evidence that herbivory promotes high diversification rates by comparing the diversity of groups of herbivorous insects with the diversity of _______.

nonherbivorous sister groups.

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

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

Many temperate plant taxa have not adapted to tropical environments, and many animal species shifted their ranges during the Pleistocene rather than adapting to climate change. These observations are consistent with _______.

phylogenetic niche conservatism.

An experiment shows (1) that the size of a population may decline as a result of natural selection, even as individual organisms become fitter, and (2) that selection for larger groups opposes the consequences of individual selection. These observations provide evidence for the

process of group selection. effects of individual selection.

Microevolution involves _______, whereas macroevolution involves _______.

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

The rate of change of diversity depends on the _______.

rate at which taxa originate. rate at which taxa become extinct.

Species selection occurs when there is a correlation between some trait and the rates of two processes: _______ and _______.

speciation; extinction

You examine four forested Caribbean islands. Each has four species of Anolis lizard that use four ecological niches (for a total of 16 species). On each island, one species exclusively occupies either the ground, tree trucks, limbs and branches, or the smallest twigs and leaves. Phylogenetic analysis shows that the species on each island form their own monophyletic groups. Which is the best explanation for this pattern?

Each island was founded by a colonizer, perhaps from a mainland, and divided up ecological niche space as they diversified into the four species present.

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

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

The hypothesis of punctuated equilibrium is controversial because _______.

the hypothesis requires that morphological evolution be accompanied by speciation.

You discover patterns of genetic divergence that are very similar among multiple unrelated species that share a region. This suggests that

the species experienced a similar history of subdivision, owing to geological and climatic processes.

Likelihood is preferable to parsimony to infer a phylogeny when _______.

there is a great deal of homoplasy. a researcher wishes to incorporate different models of molecular evolution into phylogenetic estimates. evolutionary rates vary greatly among the taxa of interest. a researcher wishes to include a measure of confidence in the nodes of the phylogeny.

Which of these is an example of an organism with a disjunct distribution?

European starlings are found in Europe and North America.

Which pattern best characterizes the history of extinctions on Earth?

Five major mass extinctions and several lesser episodes of heightened extinction rates

Which condition cannot cause the evolution of an adaptation?

Future extinction of a population

Which of these would be an advantage of using Bayesian inference instead of maximum likelihood to construct a phylogeny based on DNA sequence data?

Bayesian methods allow one to incorporate prior information to weight probabilities.

Which method would be the best way to test whether larger body size in amphipods is an adaptation to risk of predation?

Correlate body size with predation risk across a number of closely related species, taking into account phylogenetic relationships.

If a clade of organisms approaches the diversity equilibrium, K, which of the following might occur?

Diversification will approach zero. The number of taxa will stabilize. Speciation rate will decline. Extinction rate will increase.

The node that represents the most recent common ancestor of all archosaurs is _______, and the node that represents the most recent common ancestor of all dinosaurs is _______.

D; C

Which observation does not provide evidence that modern humans dispersed from Africa to the rest of the world (according to the "out of Africa" theory)?

Humans in specific regions have distinct adaptations to the environment in those regions.

Refer to the figure showing a phylogenetic tree of some snakes and lizards.

If we created a new taxon consisting of the venomous snakes (shown in figure as group V), it would be paraphyletic.

Which complication to phylogenetic inference is most likely to be widespread in a group of species that have undergone an evolutionary radiation?

Incomplete lineage sorting

Mammals, like humans and apes, have five digits on their fore and hind limbs. Modern horses have one. How might you reconstruct the ancestral state of mammal toe number?

Investigate the number of toes for other mammals and use parsimony to deduce the ancestral state. Investigate the number of toes for an outgroup that is closely related to mammals, for example reptiles or amphibians.

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?

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

Not all traits are adaptations. Which statement may also explain the evolution of a particular trait?

It may be a necessary consequence of physics or chemistry. It may have evolved by genetic drift, rather than by natural selection. It may have evolved because it was correlated with another trait that conferred an adaptive advantage. It may be a consequence of phylogenetic history.

Which trait can be thought of as a preadaptation for the corresponding function?

Kea's beak → piercing skin

Which factors that may increase extinction rates is most likely to be influenced by the activities of humans?

Major changes in the distribution or conditions of global climate

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?

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

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

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

Creationists criticize the idea of natural selection as a circular argument, or tautology, claiming "The fittest are those that survive, and survival is how fitness is defined." Why is our definition of natural selection not tautological?

Natural selection is measured by contribution to the next generation, not simply survival of an individual organism.

The phylogeographic analysis in the figure shows that the grasshopper Chorthippus parallelus expanded its range through northern and central Europe from the Balkans after the last glacial period, but it could not cross mountain ranges in southern Europe. In contrast, a similar analysis found that hedgehogs colonized northern Europe from all three areas. How might the pattern of mitochondrial DNA haplotypes across European hedgehog populations differ from grasshoppers?

Northern and central European populations would likely contain haplotypes from all three refugial regions.

Which condition would most likely lead to an increase in the frequency of an altruistic behavior in a population?

The beneficiaries of the behavior are related to the individual performing it.

Evolutionary biologists and geologists recognize the "big five" mass extinctions and are actively studying a potential sixth. Which of these describes that potential sixth mass extinction?

The current extinctions, caused primarily by human activities

The two main hypotheses for a taxon's distribution are dispersal and vicariance. Which of the following would be the poorest source of data for testing these hypotheses?

The current geographic distribution of the organism

If a population of kangaroos (known as a dominant mammal in Australia) was discovered living on island northwest of Wallace's line, which of these would be the most likely explanation?

The population was recently founded by kangaroos that dispersed there from Australia.

You examine long sequences from four genes in three closely related species, species A, B, and C. Genes 1-3 all suggest A and B are each other's closest relative, but gene 4 suggests that A and C are. Assuming that the "true" phylogeny is that A and B are sister species, which explanation is least likely to account for the different relationship shown by the fourth sequence?

The sequence similarity of the fourth gene between A and C is a result of homoplasy.

Which data would not affect maximum likelihood estimates of phylogenies when comparing different tree hypotheses?

The tree topology The lengths of the branches The branching order of the tree Nucleotide substitution rate

Refer to the graph showing a lineage-through-time plot for a clade. What does the exponential growth tell us about the diversification of the clade in question?

There is a constant diversification rate for the clade.

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

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

Refer to the figure showing a phylogeny of the cypresses. The phylogeny in the figure suggests that the distribution of cypress species is best explained as

a vicariant event, followed by several dispersal events to Africa.

Insectivorous bats and fruit-eating bats, which hunt at night, occupy two _______ that differ from those of diurnal insect- and fruit-eating birds.

adaptive zones