Chapter 21

With regard to choosing the most likely cladogram, explain how the principle of parsimony is used

the tree that has the fewest number of evolutionary changes is chosen

New species can be formed by

Anagenesis Cladogenesis

Molecular systematics

Analysis of genetic data, such as DNA and amino acid sequences, to identify and study genetic homologies and propose phylogenetic trees DNA and amino acid sequences from closely related species are more similar to each other than to sequences from more distantly related species

Horizontal gene transfer

Any process in which an organism incorporates genetic material from another organism without being the offspring of that organism The transfer of genes between different species

Phylogenetic tree

Diagram that describes phylogeny A hypothesis of evolutionary relationships among various species Based on available information

Primate evolution

Evolutionary relationships derived from DNA sequences for cytochrome oxidase subunit II Tends to change fairly rapidly on an evolutionary timescale, so good for close relationships Three branch points to examine (A, D, E)

Morphological analysis

First systematic studies focused on morphological features of extinct and modern species

Binomial nomenclature

Genus name and species epithet ex: Homo sapiens Genus name always Capitalized Species epithet never capitalized Both names either italicized Rules for naming established and regulated by international associations

Monophyletic group or clade

Group of species - a taxon - consisting of the most recent common ancestor and all of its ancestors Smaller and more recent clades are nested within larger clades that have older common ancestors

Hierarchical system of taxonomy

Hierarchical system involving successive levels Each group at any level is called a taxon Highest level is domain All of life belongs to one of 3 domains Bacteria, Archaea, and Eukarya

Taxonomy

Science of describing, naming, and classifying living and extinct organisms

Shared derived character

Shared by two or more species or taxa and has originated in their most recent common ancestor Basis of the cladistic approach is to analyze many shared derived characters to deduce the pathway that gave rise to those species

Homology

Similarities among various species that occur because they are derived from a common ancestor ex: Bat wing, human arm and cat front leg Genes can also be homologous if they are derived from the same ancestral gene

Ancestor E

This ancestor diverged into two species of chimpanzees Two modern species of chimpanzees have fewer differences in their gene sequences

Ancestor D

This ancestor diverged into two species that eventually gave rise to humans and chimpanzees Differences in gene sequences between humans and chimpanzees are relatively moderate

Ancestor A

This ancestor diverged into two species that ultimately gave rise to siamangs and the other five species 23 million years for siamang genome to accumulate changes different from other 5 species

Convergent evolution

(traits arising independently due to adaptation to similar environments) can cause problems

Anagenesis

- single species evolves into a different species

Outgroup

- species or group of species that is assumed to have diverged before the species in the ingroup An outgroup will lack one or more shared derived characters that are found in the ingroup

Branch point

- two species differ in shared derived characters

Which of the following differences between prokaryotic cells and eukaryotic cells is not correct? a. Prokaryotic cells lack a nucleus. b. Prokaryotic cells have small ribosomes. c. Prokaryotic cells have membrane bound organelles. d. Prokaryotic cells have circular chromosomes. e. All of the above are correct.

1. C

Constructing a cladogram

1. Choose species 2. Choose characters 3. Determine polarity of character states 4.Analyze cladogram 5.Choose the most likely cladogram 6.Choose a noncontroversial outgroup (ROOT)

Which of the following complicates the construction of monophyletic groups? a. Analogous structures b. Incomplete fossil record c. Convergent evolution d. Neutral mutations e. All of the above can cause problems

10. E

Humans and rabbits share more synapomorphies than humans and toads. What does this indicate about the relationships between these species? a. Humans are more closely related to toads than rabbits b. Rabbits are more distantly related to humans than to toads c. Toads are closely related to rabbits d. Humans and rabbits are more closely related to each other than either is to a toad e. Humans evolved from rabbits

11. D

Which of the following would be a synapomorphy that would be used to separate a monkey and a rabbit from a lizard, frog, and shark? a. Lungs b. Tails c. Heart d. Teeth e. Mammary glands

12. E

Birds evolved from dinosaurs and are classified as Aves, but dinosaurs are classified as Reptilia. Using this model, the Reptilia is a monophyletic group. a. This is true b. This is false

13. B (False)

A hypothetical group of organisms is used to construct a phylogenetic tree based on sequence divergence of a particular gene. Which of the following phylogenetic trees would be the best reconstruction based on the principle of parsimony? a. Tree #1 requires 6 mutations b. Tree #2 requires 8 mutations c. Tree #3 requires 9 mutations d. Tree #4 requires 12 mutations e. Tree #5 requires 14 mutations

14. A

If the DNA divergence rate for a particular gene is 5 changes per million years and the gene sequences between two closely related species has 50 differences between them, approximately how long ago did these species share a common ancestor? a. 1,000 years ago b. 100,000 years ago c. 1,000,000 years ago d. 10,000,000 years ago e. 100,000,000 years ago

15. D

Vibrio cholerae is a bacterium that lives in water and is normally harmless to humans. If infected by a certain type of virus, it acquires the genes to produce the cholera toxin and can then cause disease in humans. This acquisition of genes is an example of __________. a. Vertical gene transfer b. Independent evolution c. Horizontal gene transfer d. Induced mutations e. Analogous gene transfer

16. C

Protista is a valid kingdom containing organisms that are more closely related to one another than other groups of organisms. a. This is true. b. This is false.

2. B

The study and reconstruction of evolutionary relationships is called __________. a. Speciation b. Systematics c. Evolution d. Natural selection

3. B

The scientific name of an organism denotes the __________. a. Class and order b. Family and Genus c. Kingdom and phylum d. Genus and species e. Class and Family

4. D

A Monophyletic group __________. a. Consists of a common ancestor and some of its descendants b. Does not contain the common ancestor of a group c. Is not an evolutionarily meaningful group d. Consists of only extant living species e. Contains a common ancestor and all of its descendants

5. E

Derived traits that are shared by all members of a clade are called __________. a. Symplesiomorphies b. Ancestral c. Synapomorphies d. Homoplasies e. Non-adaptive

6. C

A species that is related to the species being classified but is not included in the classification is __________. a. A common ancestor b. An outgroup c. A homoplasy d. An infidel e. A paraphyletic species

7. B

The principle of parsimony states that the hypothesis with the most assumptions is most likely to be the correct hypothesis. a. This is true. b. This is false.

8. B (False)

The direct exchange of genes between unrelated taxa is an example of vertical gene transfer. a. This is true. b. This is false.

9. B (False)

It has been suggested that horizontal gene transfer can complicate vertical evolution forming a "web of life" rather than a "tree of life". Which of the following statements is consistent with this idea? An ancestor will always be common to two or more related species. An ancestor will always have more than one descendent. An ancestor does not need to be common to two or more related species. An ancestor does not need to be older than a descendent.

An ancestor does not need to be common to two or more related species.

In what domain is horizontal gene transfer most common? Bacteria Eukarya Archaea Horizontal gene transfer is common to all domains Protista

Bacteria

Which of the following are at the classification level of domain in the taxonomic hierarchy? Bacteria Archaea Eukarya Animalia Amoebozoa

Bacteria Archaea Eukarya Animalia Amoebozoa

According to mitochondrial gene sequences encoding the protein cytochrome oxidase, the lineages of which of the following pairs of species diverged most recently? Gorillas and orangutans Common chimpanzees and humans Common chimpanzees and gorillas Gorillas and humans

Common chimpanzees and humans

What is the order of TAXA

Domain supergroup kingdom phylum class order family genus species

Taxonomic Hierarchy

Domain > Supergroup > Kingdom > Phylum > Class > Order > Family > Genus > Species

The three domains of life are?

Eukarya, prokaryotes, and viruses

Molecular Clocks

Favorable mutations are rare, detrimental mutations are quickly eliminated - so most mutations are neutral If neutral mutations occur at a constant rate they can be used to measure evolutionary time Not perfectly linear over long periods of time Not all organisms evolve at the same rate Differences in generation times

Of the morphological traits of the four extant species in the phylogenetic tree below, which are homologous among all four species? Select all that apply. Two eyes A dorsal fin Tail bone structure Forelimb bone structure Whiskers

Forelimb bone structure

To construct a phylogenetic tree, a researcher compares the DNA sequence of a gene that encodes the cytoskeleton protein called tubular among different species, this would be an example of using ?

Genetic homology

Which pair of species would be expected to have fewer genetic differences: orangutans and gorillas or gorillas and humans? Why?

Gorillas and humans because their common ancestor (C) is more recent than that of orangutans and gorillas (B).

Earlier in this chapter, we considered the taxonomy of the gray wolf. what taxa would have a common ancestor that is the oldest

Kingdom

Principle of parsimony

Preferred hypothesis is the one that is the simplest for all the characters and their states Challenge in a cladistic approach is to determine the correct polarity of events It may not always be obvious which traits are primitive (came earlier) and which are derived (came later in evolution) Fossils may be analyzed to help resolve

Genes on a plasmid are transferred through a population of microbes, sometimes of different species, through horizontal gene transfer. If a scientist sequenced a specific gene carried on the plasmid and compared the sequence of many different microbes, what is the most probable pattern of relationships that she would see? It is impossible to sequence genes on a plasmid because it is not part of the bacterial chromosome, so this study would not be possible. Microbes would appear related strictly through a pattern of ancestor-descendent relationships. Each species of microbes would be a separate lineage. Relationships between species could not be readily discerned among microbes. Different species in similar locations would appear more closely related than the same species that occurred in different locations.

Relationships between species could not be readily discerned among microbes. Different species in similar locations would appear more closely related than the same species that occurred in different locations.

Shared primitive character

Shared by two or more different taxa and inherited from ancestors older than their last common ancestor

In a cladogram, the branch points or nodes are determined by differences in?

Shared derived characters

Cladistics

Study and classification of species based on evolutionary relationships

Systematics

Study of diversity and evolutionary relationships among organisms, both extinct and modern

When the same homologous gene is compared between closely related species (for example the tiger) versus distantly related species (for example turtle and a lion)

The genes between the closely related species have fewer differences because their common ancestor occurred more recently

Cladogenesis

a species diverges into two or more species

vertical evolution

The traditional view of evolution Changes in groups due to descent from a common ancestor

What would be an example of horizontal gene transfer

The transfer of an antibiotic resistance gene from one bacterial species to a different species

According to this phylogenetic tree, when did cladogenesis of the following occur?

a.species D into species H and J about 6.5 million years ago b. species A into species F and I about 2.5 million years ago c. species A into species A and B about 11 million years ago d. species B into species B and D about 8 million years ago e. species B into species B and E about 6.5 million years ago

Based on what you know about cladistics, indicate which of the following statements are correct about the DNA sequences shown in the phylogenetic tree. The sequences of living species are labeled A, B, C, and D. Changes in nucleotide sequence are indicated for each branch in the tree. For example, T2 → A means that the second base, a T, was changed to an A. The first base (G) in sequences B, C, and D is a shared primitive character. The second base (A) in sequences B and D is a shared derived character. The third base (C) in sequences B, C, and D, is a shared derived character. The fourth base (A) for sequences B and C is a shared primitive character. The fifth base (G) for sequences B and D is a shared derived character.

all of the aboveq

A phylogenetic tree is? a. a hypothesis about the evolutionary relationships among different species b. diagram that depicts the evolutionary relationships among different species c. a diagram that should be organized according to the grouping of species into clades d. all of the above

d. all of the above

An analysis of the number of neutral genetic changes among different species can be used to estimate the dates of past evolutionary events , such as the divergence of one species into two species, for this to be valid, a. researchers must have a way to calibrate their clock, such as using information from the fossil record b. the rate of neutral mutations must be relatively constant over a given time period c. the gene sequences that are analyzed must be relatively short d. both a and b

d. both a and b

Cladistic approach

discriminates among possible trees by considering the various possible pathways of changes and then choosing the tree that requires the least complicated explanation compares homologous traits, also called characters, which may exist in two or more character states

Phylogeny

evolutionary history of a species or group of species To propose a phylogeny, biologists use the tools of systematics Trees are usually based on morphological or genetic data

Ingroup

group we are interested in

Horizontal gene transfer can occur between only individuals of the same species. only one bacteria and another. individuals of the same or closely related species. individuals that are closely or distantly related. only bacteria and virus.

individuals that are closely or distantly related.

Horizontal gene transfer is the transfer of DNA between different genomes. is the transfer of DNA by mutation. is the transfer of DNA by crossing over. is the transfer of DNA between tumor cells. is the transfer of DNA during normal cell division.

is the transfer of DNA between different genomes.

Vertical gene transfer is the transfer of DNA by mutation. is the transfer of DNA between different genomes. is the transfer of DNA during normal cell division. is the transfer of DNA between tumor cells. is the transfer of DNA by crossing over.

is the transfer of DNA during normal cell division.

Which of the following is a shared derived character of primates (i.e., lemurs, monkeys, apes, and humans)? four limbs backbone hair opposable thumb

opposable thumb

According to the phylogeny depicted here, check all of the following that are examples of cladogenesis.

species C into species G species D into species H and K

According to the phylogeny of various bird species depicted here, which species is the most recent common ancestor of species K and J? species B species E species D species H

species D