Question 1

Traits that are similar in two species as a result of common ancestry are referred to as:

Accepted Answer

Traits that are similar due to common ancestry are referred to as homologous. Analogous traits are similar in function, but not in structure, and occur as a result of convergent evolution. Convergent evolution occurs when two unrelated species evolve similar traits due to similar selective pressures, rather than due to a common ancestor. Derived traits are traits that have evolved more recently in a species, while ancestral traits are traits that have been present in a lineage for a long time.

Question 2

When several possible phylogenetic trees can be produced from a data set, the MOST parsimonious tree is the one that shows the:

Accepted Answer

The principle of parsimony states that the tree that requires the fewest number of evolutionary changes is the most likely to be accurate. This is because it is generally believed that evolution strives for simplicity and efficiency, and therefore the simplest explanation is often the best. Therefore, the most parsimonious tree is the one that shows the smallest number of evolutionary changes.

Question 3

Imagine that a researcher has created two possible phylogenetic trees for a group of organisms-one that hypothesizes that five character changes occurred in a given group, and one that predicts only two character changes occurred in the same group. If the researcher wants to choose a phylogenetic tree based on parsimony, she will pick the phylogenetic tree with two character changes as her working hypothesis.

Accepted Answer

The principle of parsimony, often used in phylogenetic analysis, favors the simplest scientific explanation that fits the evidence. In this case, the tree predicting fewer character changes (two instead of five) is considered simpler and thus would be chosen based on parsimony.

Question 4

Both analogies and homologies are always used to create phylogenetic trees. In fact, analogies often provide more information regarding the evolutionary relationships between different species than do homologies.

Accepted Answer

Homologies provide more reliable information about evolutionary relationships because they indicate shared ancestry between species due to a common ancestor, while analogies can arise from convergent evolution or other reasons which do not necessarily indicate a close evolutionary relationship. However, both analogies and homologies can be used to create phylogenetic trees.

Question 5

In order to be useful for constructing a phylogeny, a character must:

Accepted Answer

Characters useful for constructing a phylogeny must have a genetic basis to reflect evolutionary relationships accurately.

Question 6

Phylogenetic trees can be used to infer character states of extinct organisms.

Accepted Answer

Phylogenetic trees can be used to study evolutionary relationships among organisms, including those that are extinct. By examining the characteristics and traits of related species across the tree, researchers can make inferences about the likely traits and characteristics of their common ancestors and extinct relatives. This can provide important clues about the evolutionary history and biology of extinct species.

Question 7

Which of the following character states would be MOST helpful in identifying sister groups?

Accepted Answer

Character states that are homologies found in some, but not all, members of a single group (synapomorphies) are useful for identifying sister groups as they indicate shared derived traits from a common ancestor.

Question 8

Traits that are shared by more than one member of a group because of common ancestry are known as:

Accepted Answer

Synapomorphies are traits that are shared by more than one member of a group because of common ancestry.

Question 9

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:

Accepted Answer

Seals and penguins are not closely related in terms of ancestry, so the similarity in body shape is not due to shared ancestry (B). While both animals have similar body shapes, they do not share any specific homologous structures (C), which are structures with a common evolutionary origin. Phylogeny (D) refers to the evolutionary history and relationships among groups of organisms, and while it is relevant to the topic, it is not the best answer in this case. Cladistics (E) is a method of analyzing evolutionary relationships based on shared derived traits, but is not directly relevant to the question. Thus, the best answer is convergent evolution (A), which refers to the process by which organisms independently evolve similar characteristics due to similar environmental pressures or niche requirements. In this case, the similar streamlined body shape of seals and penguins is likely due to the selection pressures of moving efficiently through water.

Question 10

Examine the following table of characters in four different species of flower. Based on the matrix, which character would be the least informative for resolving phylogenetic relationships between the species? $$\begin{array} { | l | c | c | c | c | } 
\hline & \text { Species A } & \text { Species B } & \text { Species C } & \text { Species D } \
\hline \begin{array} { l } 
\text { Presence of } \
\text { sepals }
\end{array} & \text { yes } & \text { yes } & \text { yes } & \text { no } \
\hline \begin{array} { l } 
\text { Number of } \
\text { petals }
\end{array} & \text { five } & \text { five } & \text { ten } & \text { ten } \
\hline \begin{array} { l } 
\text { Arrangement of } \
\text { petals }
\end{array} & \text { whorled } & \text { whorled } & \text { whorled } & \text { whorled } \
\hline \begin{array} { l } 
\text { Number of } \
\text { carpels }
\end{array} & \text { ten } & \text { ten } & \text { ten } & \text { five } \
\hline
\end{array}$$

Accepted Answer

The arrangement of petals is the least informative for resolving phylogenetic relationships because all four species share the same characteristic (whorled), providing no variation to distinguish among them.

Question 11

Examine the following table of characters in four different species of flower. $$\begin{array} { | l | c | c | c | c | } 
\hline & \text { Species A } & \text { Species B } & \text { Species C } & \text { Species D } \
\hline \begin{array} { l } 
\text { Presence of } \
\text { sepals }
\end{array} & \text { yes } & \text { yes } & \text { yes } & \text { no } \
\hline \begin{array} { l } 
\text { Number of } \
\text { petals }
\end{array} & \text { five } & \text { five } & \text { ten } & \text { ten } \
\hline \begin{array} { l } 
\text { Arrangement of } \
\text { petals }
\end{array} & \text { whorled } & \text { whorled } & \text { whorled } & \text { whorled } \
\hline \begin{array} { l } 
\text { Number of } \
\text { carpels }
\end{array} & \text { ten } & \text { ten } & \text { ten } & \text { five } \
\hline
\end{array}$$ Do the characters presence of sepals and number of petals together provide a unique solution to the question of phylogenetic relationships among species A, B, C, and D?

Accepted Answer

The characters "presence of sepals" and "number of petals" do not provide a unique solution for determining phylogenetic relationships among the species, as species A and B both have sepals and five petals, making it impossible to distinguish between them based solely on these two characters.

Question 12

To conduct a phylogenetic analysis, an outgroup is needed in order to:

Accepted Answer

The outgroup is needed to determine which character states are ancestral and which are derived. This is important in constructing a phylogenetic tree, as it allows for the determination of which traits evolved in the lineage leading to the group of interest. The other options may be important in conducting a phylogenetic analysis, but the primary purpose of the outgroup is to distinguish ancestral from derived characteristics.

Question 13

Phylogenetic reconstruction based on shared derived characters is called:

Accepted Answer

Phylogenetic reconstruction based on shared derived characters is called cladistics. This method focuses on grouping organisms based on their common ancestry and identifying synapomorphies, or shared derived characteristics, that define each clade. Monophyly is a term that refers to a group of organisms that includes an ancestor and all of its descendants, and taxonomy is the science of naming and classifying organisms.

Question 14

Only homologous characters are useful in constructing phylogenetic trees.

Accepted Answer

Homologous characters are those which are inherited from a common ancestor and are therefore useful in constructing phylogenetic trees. Non-homologous characters may occur due to convergent evolution or other reasons and can lead to inaccurate or misleading phylogenies.

Question 15

Which of the following statements is TRUE regarding phylogenetic trees?

Accepted Answer

Both morphological and molecular synapomorphies can be used to construct phylogenetic trees. In fact, the use of molecular data has become increasingly common due to its ability to provide more precise and accurate information than morphological data alone. Some molecular sequences can provide synapomorphies that reflect evolutionary relationships that may not be evident from morphological features. Additionally, molecular data can be obtained from a wider range of species, including those that may not have fossil records, allowing for a more comprehensive understanding of evolutionary relationships.

Question 16

The specific types of homologies used to develop phylogenies are shared derived characters or:

Accepted Answer

Synapomorphies are unique derived traits shared by two or more taxa that are inherited from a common ancestor, and they are used to infer evolutionary relationships in phylogenetics. Shared derived traits that are not unique to the group being studied are not informative for evolutionary relationships, and convergent characteristics may lead to grouping of unrelated taxa. Sister groups and parsimonious branches are concepts used to describe the structure of a phylogenetic tree, but they are not specific types of homologies used for phylogenetic inference.

Question 17

Compared with more distantly related taxa, the DNA sequences of two closely related taxa are expected to show:

Accepted Answer

The correct answer is A because mutation rates are usually relatively constant, and recently diverging species have had less time to accumulate differences. As a result, we would expect the DNA sequences of closely related taxa to show fewer differences.

Question 18

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?

Accepted Answer

Molecular data can sometimes show different relationships due to highly conserved sequences that don't reflect morphological divergence, and gene sequence changes may not always lead to observable morphological changes.

Question 19

Imagine that a scientist discovers a new, flying species of mammal that resembles a winged rabbit. What can the scientist say about this organism?

Accepted Answer

The question is asking what the scientist can say about the organism based on its resemblance to a winged rabbit. Option A assumes that the wings are homologous without any evidence and is therefore incorrect. Option C does not make sense grammatically as it states that if molecular sequence data show that bats and the new species do not share a common ancestor, then their wings would be homologous, which is not correct. Option D is partially correct, as if molecular sequence data show that bats and the new species share a common ancestor not shared by other mammals, then their wings would be considered analogous (similar function, different structure). However, the question specifically asks about homology (similar structure, different function), so option B is the best choice. Option E is incorrect, as molecular sequence data could support or disprove the hypothesis that the wings of bats and the new species are homologous.

Question 20

Examine the following table of characters in four different species of flower. $$\begin{array} { | l | c | c | c | c | } 
\hline & \text { Species A } & \text { Species B } & \text { Species C } & \text { Species D } \
\hline \begin{array} { l } 
\text { Presence of } \
\text { sepals }
\end{array} & \text { yes } & \text { yes } & \text { yes } & \text { no } \
\hline \begin{array} { l } 
\text { Number of } \
\text { petals }
\end{array} & \text { five } & \text { five } & \text { ten } & \text { ten } \
\hline \begin{array} { l } 
\text { Arrangement of } \
\text { petals }
\end{array} & \text { whorled } & \text { whorled } & \text { whorled } & \text { whorled } \
\hline \begin{array} { l } 
\text { Number of } \
\text { carpels }
\end{array} & \text { ten } & \text { ten } & \text { ten } & \text { five } \
\hline
\end{array}$$ Which character would be MOST useful for identifying the sister group of species D?

Accepted Answer

The answer of Examine the following table of characters in...

Quiz 23: Evolutionary Patterns: Phylogeny and Fossils