Week 6.2 - Pre-Class Questions

- a branch point and common ancestor

A node on the phylogenetic tree indicates: - a branch point in evolution - a common ancestor - a branch point and common ancestor

- wings in birds and bats

Based on Figure 23.7, which of the following are examples of convergent evolution? - the amniotic egg of crocodiles and mammals - lungs in lungfish and turtles - wings in birds and bats - jaws in sharks and lizards

- older; bonobo

Based on the diagram below, you predict that the earliest fossil gorilla (which may not resemble modern-day gorillas) would be _____ than the earliest fossil _____. - older; orangutan - younger; chimp - younger; bonobo - older; bonobo - None of the answer options is correct.

- fewer differences because mutation rates are usually relatively constant and recently diverging species have had less time to accumulate differences.

Compared with more distantly related taxa, the DNA sequences of two closely related taxa are expected to show: - more differences because mutation rates accelerate during speciation events, leading to more changes in DNA sequences. - fewer differences because mutation rates are usually relatively constant and recently diverging species have had less time to accumulate differences. - fewer differences because mutation rates slow down after speciation events so that recently diverging species have fewer mutations. - more differences because mutation rates are relatively constant and recently diverging species have had more time to accumulate differences. - fewer differences because mutation rates are highly variable and it is just by chance that recently diverging species accumulate fewer differences in DNA sequences.

- We can't decide from the information given as trees with species A, B, or D as sister to all other species are equally parsimonious.

Examine the following table of characters in four different species of flower. Based on the matrix, Derek concludes that species A is sister to the remaining three species. Wilma, in contrast, argues that species D is sister to all other species. Who is CORRECT? - We can't decide from the information given as trees with species A, B, or D as sister to all other species are equally parsimonious. - Neither, because the most parsimonious tree puts species B as sister to all others. - Wilma is correct, as the tree that puts D as sister to all other species is the most parsimonious. - Derek is correct, as the tree that puts A as sister to all other species is the most parsimonious.

- the root

In the phylogenetic tree above, A indicates: - a node - a branch point - the root

- B

In the phylogenetic tree above, which of the following could be considered a sister group? - A - B - C - D

- turtles and birds are equally related to bats

Of the taxa listed on the phylogeny, which is more closely related to bats? - turtles - birds - turtles and birds are equally related to bats

- class

Of the following taxonomic categories, which is the MOST inclusive? - genus - order - species - family - class

- phylogeny 2

Examine the following table of characters in four different species of flower. Based on the matrix, which tree represents the MOST parsimonious explanation of relatedness among these species? - phylogeny 1 - phylogeny 2 - phylogeny 3

- There are no equivalent sister-taxa shown between the two phylogenies.

Excluding the outgroup, taxon A, how many equivalent sister-group relationships are depicted between the two phylogenies given below? - one - three - There are no equivalent sister-taxa shown between the two phylogenies. - four - two

- If molecular sequence data show that bats and this new species share a common ancestor not shared by other mammals, the wings of these two species would be considered homologous.

Imagine that a scientist discovers a new, flying species of mammal that resembles a winged rabbit. What can the scientist say about this organism? - No data could support or disprove the hypothesis that the wings of bats and the new species are homologous. - If molecular sequence data show that bats and this new species share a common ancestor not shared by other mammals, the wings of these two species would be considered homologous. - If molecular sequence data show that bats and this new species share a common ancestor not shared by other mammals, the wings of these two species would be considered analogous. - Without any further information, the scientist can say that bat wings and the wings of this new species are homologous. - If molecular sequence data show that bats and this new species do not share a common ancestor not shared by other mammals, the wings of bats and this new species would be considered homologous.

- caecilians

Of the taxa listed on the phylogeny, which is more closely related to the frog? - lungfish - caecilians - turtles - coelacanths

- ceolacanths

Of the taxa listed on the phylogeny, which is more distantly related (least related) to the lungfish? - birds - ceolacanths - bats - caecilians

- paraphyletic

Refer to the phylogenetic tree above. The grouping that includes Salamanders and Caecilians is: - monophletic - paraphyletic - polyphyletic

- monophletic

Refer to the phylogenetic tree above. The grouping that includes Turtles, Lizards and snakes, Crocodiles and alligators, Birds, and Bats is: - monophletic - paraphyletic - polyphyletic

- paraphyletic

Refer to the phylogenetic tree provided. The grouping that includes Hagfish, Lampreys, Sharks and Rays is: - monophyletic - paraphyletic - polyphyletic

- convergent evolution.

Seals and penguins both have streamlined body forms that allow them to move through water efficiently. This similarity in body shape is MOST likely the result of: - cladistics - phylogeny - convergent evolution. - homology. - shared ancestry.

- Trees 1 and 2 are equivalent.

The diagram below depicts three phylogenetic trees. Which of the three show the same sister group relationships among groups A, B, and C? - Trees 2 and 3 are equivalent. - Trees 1 and 3 are equivalent. - Trees 1 and 2 are equivalent. - All three trees are different: no two are equivalent. - All three trees are equivalent.

- common ancestors.

The nodes on a phylogenetic tree represent: - homologies. - common ancestors. - descendant lineages. - present-day groups. - sister groups.

- humans and gorillas are more closely related than orangutans and gorillas.

The phylogeny below shows: - humans and gorillas are more closely related than orangutans and gorillas. - the orangutan is the most recent common ancestor of all great apes. - the gorilla is the most recent common ancestor to bonobos, chimps, and humans. - all great apes walk with an upright gait. - orangutans and gorillas are more closely related than humans and gorillas.

- True

Traditional levels of taxonomy are nested in categories from least to most inclusive. This same relationship is also represented on a phylogenetic tree by moving from the terminal (most recent) nodes to the earliest nodes. (T/F)

- homologous.

Traits that are similar in two species as a result of common ancestry are referred to as: - derived. - convergent. - ancestral. - homologous. - analogous.

-Phylogenetic trees could be considered physical representations of hypotheses that seek to establish the evolutionary relationships between different organisms.

Which of the following statements is TRUE regarding a phylogenetic tree? -Phylogenetic trees could be considered physical representations of hypotheses that seek to establish the evolutionary relationships between different organisms. - Given the sheer number of prokaryotic and eukaryotic species on Earth, it is impossible to create a phylogenetic tree encompassing all of these organisms. - Phylogenetic trees only depict the evolutionary relationships between different classes; relationships among different species within the same genus are not illustrated in such trees. - Phylogenetic trees are constructed based solely on the morphological characteristics of species; sequence similarities among different organisms are only evaluated by taxonomists. - Within a phylogenetic tree, the order of groups located at the tree tips, not the nodes within a tree, determines sister group relationships.

- Sister taxa always share a most recent common ancestor that is not shared with any other taxon on the phylogeny.

Which of the following statements is always TRUE about sister taxa on a phylogenetic tree? - Sister taxa are always the result of the most recent divergence event represented on a phylogeny. - Sister taxa are always the result of speciation events that result in two new genera. - Sister taxa are always defined by shared ancestral characteristics that have been modified in all other taxa in the phylogeny. - Sister taxa always share a most recent common ancestor that is not shared with any other taxon on the phylogeny.

- Gene sequence changes may not result in morphological changes. - Some highly conserved genetic sequences can result in unrelated species appearing closely related in a molecular phylogeny, and not reflect the same pattern as the morphologic phylogeny.

Why might a phylogeny based only on molecular data show a different pattern of relationships than a phylogeny of the same taxa that is based only on morphological traits? (Select all that apply.) - Morphological analyses always provide more data because each morphological trait is the result of the expression of many genes. - Gene sequences always provide more data than morphological traits. - Gene sequence changes may not result in morphological changes. - Some highly conserved genetic sequences can result in unrelated species appearing closely related in a molecular phylogeny, and not reflect the same pattern as the morphologic phylogeny. - The molecular data may be based on the analysis of introns, which aren't expressed and don't contribute to the evolutionary history of a group of taxa.

- I would branch the gorilla lineage and add the new species sister to gorillas.

You discover a new species of ape that is more closely related to gorillas than to any other species of ape, but walks upright. How would you change the phylogeny below? - I would not change the phylogeny at all because only molecular data are considered when studying evolutionary relationships. - I would group gorillas with humans based on the synapomorphy (shared trait) of upright stance. - I would branch the gorilla lineage and add the new species sister to gorillas. - I would not change the phylogeny at all until a fossil of the new species is found because fossil evidence is a required component of the data set.

- True

A phylogenetic tree is a hypothesis about the evolutionary relationships among organisms based on available anatomical and/or molecular data. (T/F)

- diagram K

A population of rodents, called population A, lived together in harmony on a large landmass until one group of the population dispersed to a nearby island. Two million years later, the island population is split into two smaller, equal-sized populations when a river formed across the middle of the island. Now two new species have evolved on the island, A1 and A2. They have replaced the population from which they were derived. Which represents the phylogeny of the three extant species discussed in this scenario? - diagram M - diagram H - diagram K

- monophyletic

A taxon that includes a single common ancestor and all its descendants is a _____ group. - paraphyletic - polyphyletic - monophyletic