Chapter 25

3 & 4

In the accompanying phylogenetic trees, numbers represent species and the same species are shown in both trees. Which two species are represented as sister species in Tree 2 but are not shown as sister species in Tree 1?

Malaria is a tropical, mosquito-borne disease caused by a parasitic protist, Plasmodium. The species P. falciparum is particularly deadly, killing about 1 million people each year. There has been considerable debate over the origin of this species. Use this recent phylogenetic evidence to determine if P. falciparum originated from another strain of Plasmodium in humans, in chimpanzees, or in gorillas. Explain your reasoning.

P. falciparum originated from Plasmodium in gorillas because P. falciparum shares a most recent common ancestor with Plasmodium in gorillas.

The major evolutionary episode corresponding most closely in time with the formation of Pangaea was the _____.

Permian extinctions

inferring evolutionary relatedness from the number of sequence differences

Regarding these sequence homology data, the principle of maximum parsimony would be applicable in ________

Three students have drawn alternate versions of the reference tree. Which tree or trees show the same relationships as this reference tree?

Rotating the branches of this reference tree at the node representing the common ancestor of sorghum, corn, and asparagus does not change the relationships in the tree.

Which of the following statements best describes the rationale for applying the principle of parsimony in constructing phylogenetic trees?

Similarity due to common ancestry should be more common than similarity due to convergent evolution.

Which of the following statements about the evolution of Anolis lizards in the Caribbean islands is true? Hint 1. Think about how adaptive radiation occurs and can be studied.

The phylogeny of ecomorphs on a given island reveals that adaptive radiation has taken place. This statement is true; the historical evidence of adaptive radiation on an island is recorded in the evolutionary history of the ecomorphs currently living on the island.

True or false? Convergent evolution is said to have occurred if the mouse species on two islands with similar habitats are found to have similar characteristics even though they originated from different species that did not have these characteristics. Hint 1. What is convergent evolution?

True Convergent evolution occurs when selective pressures produced by similar conditions (such as habitat) favor the evolution of similar solutions.

Archaeopteryx and living birds share a more recent common ancestor than either does with Aurornis.

What is wrong with the statement: Archaeopteryx is more closely related to Aurornis than to living birds?

Which of the following would be LEAST likely in the fossil record?

desert-dwelling species

Adaptive radiations can be a direct consequence of four of the following five factors. What is the exception?

genetic drift

Which of the following is an example of homoplasy?

streamlined bodies in dolphins and ichthyosaurs

Feathers either play a role, or may have played a role, in _____.

-gliding -extended hops -flight courtship All of these are, or may have been, functions of feathers

Identify whether each statement about this phylogenetic tree is true or false.

1. Corn is more closely related to Sorghum than to Asparagus. True 2. Asparagus is more closely related to Papaya than to Orange. False 3. Peach is more closely related to Orange than to Papaya. False 4. Papaya is more closely related to Asparagus than Peach is to Sorghum. False

_____ is rapid speciation under conditions in which there is little competition.

Adaptive radiation Adaptive radiation is rapid speciation under conditions in which there is little competition.

E B C D A

Based on the tabular data, and assuming that time advances vertically, which phylogenetic tree is the most likely depiction of the evolutionary relationships among these five species?

Which of the following pieces of evidence supports the hypothesis that the adaptive radiation of many groups observed during the Cambrian explosion was due to morphological innovation? See Section 25.3 (Page) . Hint 1. What would cause the appearance of new body forms?

Duplication and then diversification of Hox genes occurs just prior to and during this time. The Hox genes are key players in determining body organization during development, and new versions of these genes would be associated with new morphologies.

Which is strong evidence supporting the impact hypothesis for the extinction of the dinosaurs? See Section 25.4 (Page) .

Extremely high quantities of iridium in rocks that formed around 65 million years ago Presence of an element abundant only in asteroids and meteorites supports the hypothesis that an asteroid impact occurred at the K-P boundary, around the time dinosaurs went extinct.

Trait 2

Given that phylogenies are based on shared derived characteristics, which of the following traits is useful in generating a phylogeny of species W, X, Y, and Z?

On the phylogenetic tree shown, where did SINEs 10, 12, and 13 first insert themselves into the genomes of artiodactyls? See Section 25.1 (Page). Which lineages possess these genes and which do not?

In the population that is ancestral to hippo, whale, deer, and cow

Spong

Indicate the outgroup.

A

Indicate which tree is most parsimonious.

Which statement about fossilization is correct? See Section 25.2 What are the conditions that are likely to produce fossils?

Rare, local, or ephemeral species leave a poor fossil record. Fossils are more likely to be found from species that have more abundant individuals, whether due to commonness, longevity of the species, or broad geographic range.

Living birds are more closely related to Enantiornithes than to Confuciusornis.

Referring to the tree on the left, select a statement that is true.

Which statement is correct? See Section 25.1 What is a synapomorphy?

Synapomorphies identify monophyletic clades. It is a trait shared by the members of the clade that is not present in other taxa outside the clade.

Given that phylogenies are based on shared derived characteristics, which of the following traits is useful in generating a phylogeny of species W, X, Y, and Z?

Trait 2

Which Anolis lizard ecomorph has long legs? Hint 1. Consider the habitat that favors lizards with long legs.

Trunk/ground These ecomorphs need long legs to jump from one broad perch to another

the presence or absence of a trait in a taxon In this character matrix, a 1 indicates the presence of a trait in a taxon. (The scoring system may vary depending on the type of characters used.)

What do the 1's and 0's represent in this data matrix?

Mass extinctions create conditions that promote _____.

adaptive radiation Mass extinctions reduce competition and allow for periods of rapid speciation.

The appearance of an evolutionary novelty promotes _____.

adaptive radiation The appearance of an evolutionary novelty may allow for the exploitation of previously unexploited niches.

The different finch species found on the Galápagos Islands probably arose as a result of _____.

adaptive radiation mass The finches that initially immigrated to the Galápagos Islands experienced little competition, the result of which was the promotion of speciation.

Choose the best definition of a fossil.

any trace of an organism that lived in the past

Which statement represents the best explanation for the observation that the nuclear DNA of wolves and domestic dogs has a very high degree of sequence homology? Dogs and wolves _____.

share a very recent common ancestor

How can mass extinction events be distinguished from background extinctions? See Section 25.4 (Page) . Hint 1. What is a mass extinction?

A mass extinction occurs when at least 60 percent of species are wiped out within 1 million years. Note that this time frame makes our modern extinction rate unprecedented in the history of our planet.

Which of the following statements about adaptive radiation is correct? Hint 1. What conditions favor adaptive radiation?

Adaptive radiation occurs within a single lineage. Adaptive radiation occurs when a single lineage produces many descendant species.

No, because theropods are a monophyletic group that includes extinct dinosaurs and birds but also living birds. Because birds are part of the monophyletic group called theropods and birds still live today, dinosaurs are not extinct. (The original definition of dinosaurs did not include birds and therefore was not a monophyletic group.)

Are all the theropod dinosaurs extinct?

True or false? The evolution of different ecomorphs on the Caribbean islands is an example of stabilizing selection. Hint 1. The characteristics of each new ecomorph prevented them from living in all habitats on the island.

False The evolution of different ecomorphs is an example of disruptive selection. Each new ecomorph had characteristics that were ideal for a particular habitat, but as these characteristics developed, the lizards lost the ability to survive effectively in the other habitats on the island.

Tree I branch lengths represent genetic distance between taxa, whereas tree II branch lengths represent time since divergence between the taxa.

How do the branch lengths in these two trees differ?

Researchers could compare the sequences of human and gorilla strains of Plasmodium, then look for a sequence change present in a human parasite that might be linked to lethality, see what the sequence codes for, and make a drug that targets its product.

Malaria is a tropical, mosquito-borne disease caused by a parasitic protist, Plasmodium. The species P. falciparum is particularly deadly, killing about 1 million people each year. How might this information be useful in developing medical treatments for malaria?

P. falciparum‎ ‎ originated from Plasmodium ‎ in gorillas because P. falciparum‎ shares a most recent common ancestor with Plasmodium ‎in gorillas.

Malaria is a tropical, mosquito-borne disease caused by a parasitic protist, Plasmodium. The species P. falciparum is particularly deadly, killing about 1 million people each year. Use this phylogenetic evidence to determine if P. falciparum originated from another strain of Plasmodium in humans, in chimpanzees, or in gorillas.

Which organisms are not examples of an adaptive radiation? Hint 1. Which organisms are not descended from a single lineage?

Mammals and reptiles in the post-dinosaur age Mammals and reptiles are not descended from a single lineage.

Which of the following student-drawn trees correctly highlights the nodes representing the "most recent common ancestors" (sometimes called the MRCAs)?

On a phylogenetic tree, the most recent common ancestor for two branches is found where the two branches come together; that location is called a node.

A "one-snip test" is recommended to identify monophyletic groups−−meaning that if you cut any branch on a tree, everything that "falls off" is a monophyletic group. Why is this valid?

One snip gets an ancestor and all of its descendants.

What is exceptional about the early animal faunas from the Ediacaran and Cambrian Periods? See Section 25.3 (Page) . Hint 1. Why are these three faunas so unusual?

Soft-bodied animals are well represented in these faunas. Correct. Soft-bodied fossil assemblages are rare.

What was the main selective pressure behind the evolution of different Anolis lizard species in the Caribbean? Hint 1. The same ecomorphs appeared on all Caribbean islands with similar habitat types.

Specific ecological niches Different species evolved in response to the selective pressures created by specific ecological niches on the islands.

P. falciparum originated from Plasmodium in gorillas because P. falciparum shares a most recent common ancestor with Plasmodium in gorillas. How might this information be useful?

This information could possibly be used to understand how P. falciparum is so lethal.

Archaeopteryx is assumed to be a sister group to the clade that includes living birds, not a direct ancestor.

What is wrong with the statement: Archaeopteryx is an ancestor of living birds?

T. rex and living birds share a common theropod ancestor, but T. rex is not a direct ancestor of birds.

What is wrong with the statement: Tyrannosaurus rex (Tyrannosauroidea) is an ancestor of living birds?

Paired hemipenes (paired penis-like structures) occur in lizards but not in lungfish, dogs, or humans. Show how you would indicate the origin of paired hemipenes on this tree.

When a trait occurs in only one taxon in a tree, you can indicate its origin with a bar and label on the branch that terminates only in that one taxon.

It codes for a polypeptide domain that has a crucial function.

Which of the following is the best explanation for the high degree of sequence homology observed in Exon I among these five species?

What kinds of characters can you use to create a data matrix for estimating phylogenetic trees?

any heritable trait Any heritable trait (whether morphological, molecular, physiological, behavioral, or developmental) can be used as a character in a data matrix to estimate a phylogeny. To be useful, however, the heritable trait must vary among the taxa included in the study

Your professor wants you to construct a phylogenetic tree of orchids. She gives you tissue from seven orchid species and one lily. What is the most likely reason she gave you the lily?

to serve as an outgroup