Chapter 16 Opener
In-Text Art, Ch. 16, p. 316 (1)
In-Text Art, Ch. 16, p. 316 (1)
In-Text Art, Ch. 16, p. 316 (2)
In-Text Art, Ch. 16, p. 316 (2)
In-Text Art, Ch. 16, p. 316 (3)
In-Text Art, Ch. 16, p. 316 (4)
In-Text Art, Ch. 16, p. 316 (4)
In-Text Art, Ch. 16, p. 317
Figure 16.1 Clades Represent All the Descendants of a Common Ancestor
Concept 16.1 All of Life Is Connected through Its Evolutionary History
Homologous features:
• Shared by two or more species
• Inherited from a common ancestor
They can be any heritable traits, including DNA sequences,
protein structures, anatomical structures, and behavior
patterns.
Concept 16.1 All of Life Is Connected through Its Evolutionary History
Each character of an organism evolves from one condition
(the ancestral trait) to another condition (the derived
trait).
Shared derived traits provide evidence of the common
ancestry of a group and are called synapomorphies.
The vertebral column is a synapomorphy of the
vertebrates. The ancestral trait was an undivided
supporting rod.
Concept 16.1 All of Life Is Connected through Its Evolutionary History
Similar traits can develop in unrelated groups:
Convergent evolution—when superficially similar traits
may evolve independently in different lineages
Concept 16.1 All of Life Is Connected through Its Evolutionary History
In an evolutionary reversal, a character may revert from a
derived state back to an ancestral state.
These two types of traits are called homoplastic traits, or
homoplasies.
Figure 16.2 The Bones Are Homologous, the Wings Are Not
Figure 16.2 The Bones Are Homologous, the Wings Are Not
Concept 16.1 All of Life Is Connected through Its Evolutionary History
In 2009 it was discovered by marine biologist Gary
Dickinson and colleagues that some amino acid
sequences in a species of barnacle (a marine
invertebrate) exactly matched sequences in a human
blood clotting protein.
Read the following description of their experiment and then
discuss the question that follows.
Concept 16.1 All of Life Is Connected through Its Evolutionary History
Although they have hard shells like mussels and snails, barnacles are actually
crustaceans—related to crabs and lobsters. A barnacle is “basically a shrimp
that is glued down to the ground with its head, and kicks food into its mouth
with its feet,” says marine biologist Gary Dickinson.
Prior to his co-authored study, published in 2009 in the Journal of Experimental
Biology, Dr. Dan Rittschof had been studying marine invertebrates for 30
years. He already knew that when you took certain chemical factors derived
from human blood they sometimes triggered specific reactions in their
ancient evolutionary cousins. For example, when he took factors C5A and
C3A—blood clotting chemicals that attract white blood cells in the human
body—and gave them to blue crabs that had eggs attached to their bodies, it
caused the eggs to be released.
So Rittschof proposed the seemingly far-fetched idea that perhaps barnacle
glue was related to blood clotting and scab formation in humans, and his
graduate student, Dickinson, set out to try to prove his professor wrong.
Funny thing was, he couldn’t. It turned out that despite a number of
independent analyses using atomic force microscopy, gel electrophoresis,
and mass spectrophotometry, all of Dickinson’s experiments indicated that in
fact barnacle glue was very similar, and in some respects identical, to the
chemical components of human blood clotting.
Concept 16.1 All of Life Is Connected through Its Evolutionary History
Dickinson started by figuring out how to use the barnacles as living glue
sticks, prodding and gently squeezing them to release the glue.
Using techniques called gel electrophoresis and mass spectrometry,
Dickinson separated out the glue’s components.
His first breakthrough was identifying a protease—an enzyme that cuts
human blood proteins apart in preparation for scab formation. Next
he found that the barnacle cement’s proteins had amino acid
sequences that, despite a billion years of evolution, exactly matched
factor XIII, a human blood clotting factor that cross-links scab fibers.
Dickinson’s team suggests that barnacle cement is an evolutionary
modification of wound healing, and suspects that this ancient
chemical pathway is used by many other marine invertebrates that
need to “get a grip.”
Concept 16.1 All of Life Is Connected through Its Evolutionary History
Based on the description of this study provided on the
previous slides, what do the researchers appear to be
interpreting from their study about evolutionary history of
barnacles and humans?
a. It’s just a coincidence, since barnacles and humans
are not evolutionarily related.
b. Humans and barnacles share a common ancestor.
c. The presence of this protein is likely an ancestral,
homologous trait.
d. Both b and c
e. None of the above
Concept 16.1 All of Life Is Connected through Its Evolutionary History
Many very distantly related species of birds (e.g., penguins,
ostriches, flightless ducks, and rails) share the trait of
flightlessness even though their ancient common
ancestors were able to fly. This independent evolution of
flightlessness in many distantly related taxa exemplifies
what type(s) of evolutionary/phylogenetic patterns?
a. Convergent evolution
b. Evolutionary reversal
c. A homoplastic trait
d. A synapomorphic trait
e. a, b, and c
Table 16.1 Eight Vertebrates and the Presence or Absence of Some Shared Derived Traits
Figure 16.3 Inferring a Phylogenetic Tree
Figure 16.3 Inferring a Phylogenetic Tree
Apply the concept p.320
Phylogeny can be reconstructed from traits of organisms
This matrix supplies data for seven land plants and an outgroup
(an aquatic plant known as a stonewort). Each trait is scored
as either present (+) or absent (-) in each of the plants. Use
this data matrix to reconstruct the phylogeny of land plants
and answer the questions.
1. Which two of these taxa are most closely related?
2. Plants that produce seeds are known as seed plants. What is
the sister group to the the seed plants among these taxa?
3. Which two traits evolved along the same branch of your
reconstructed phylogeny?
4. Are there any homplasies in your phylogeny?
Apply the Concept, Ch. 16, p. 320
Figure 16.4 The Chordate Connection
Figure 16.4 The Chordate Connection
Figure 16.4 The Chordate Connection (Part 1)
Figure 16.4 The Chordate Connection (Part 2)
Figure 16.4 The Chordate Connection (Part 3)
Figure 16.4 The Chordate Connection (Part 4)
Figure 16.5 The Accuracy of Phylogenetic Analysis
Figure 16.5 The Accuracy of Phylogenetic Analysis
Figure 16.5 The Accuracy of Phylogenetic Analysis (Part 1)
Figure 16.5 The Accuracy of Phylogenetic Analysis (Part 2)
Concept 16.2 Phylogeny Can Be Reconstructed from Traits of Organisms
In a hypothetical study, physical fitness was measured in
humans from seven European countries. Physical fitness
levels were classified according to a scale from 1
(lowest) to 10 (highest).
Do you think it would be problematic to infer phylogenetic
relationships (i.e., create a phylogeny) from such data?
Why or why not?
Concept 16.2 Phylogeny Can Be Reconstructed from Traits of Organisms
In a hypothetical study, physical fitness was measured in
humans from seven European countries. Physical fitness
levels were classified according to a scale from 1
(lowest) to 10 (highest). Inferring phylogenetic
relationships from such data would be problematic
because
a. it is difficult to find an outgroup for humans.
b. only molecular genetic data can be used to construct
phylogenies.
c. physical fitness is a morphological trait that is
predominantly environmental, and not heritable.
d. All of the above
e. None of the above
Concept 16.2 Phylogeny Can Be Reconstructed from Traits of Organisms
Using this hypothetical table of traits (left column) for these
imaginary taxa (top row), construct a phylogeny,
assuming that the Priltezon is the outgroup:
Concept 16.2 Phylogeny Can Be Reconstructed from Traits of Organisms
The constructed phylogeny would look like:
a.
b.
c.
Concept 16.2 Phylogeny Can Be Reconstructed from Traits of Organisms
Parsimony principle—the preferred explanation of
observed data is the simplest explanation
In phylogenies, this entails minimizing the number of
evolutionary changes that need to be assumed over all
characters in all groups.
The best hypothesis is one that requires the fewest
homoplasies.
Concept 16.2 Phylogeny Can Be Reconstructed from Traits of Organisms
Mathematical models are now used to describe DNA
changes over time.
Models can account for multiple changes at a given
sequence position, and different rates of change at
different positions.
Maximum likelihood methods identify the tree that most
likely produced the observed data. They incorporate
more information about evolutionary change than do
parsimony methods.
Figure 16.6 A Portion of the Leptosiphon Phylogeny
Figure 16.6 A Portion of the Leptosiphon Phylogeny
Figure 16.7 Phylogenetic Tree of Immunodeficiency Viruses
Figure 16.8 The Origin of a Sexually Selected Trait
Figure 16.8 The Origin of a Sexually Selected Trait
Figure 16.9 A Molecular Clock of the Protein Hemoglobin
Figure 16.9 A Molecular Clock of the Protein Hemoglobin
Figure 16.10 Dating the Origin of HIV-1 in Human Populations
Figure 16.10 Dating the Origin of HIV-1 in Human Populations
Figure 16.10 Dating the Origin of HIV-1 in Human Populations (Part 1)
Figure 16.10 Dating the Origin of HIV-1 in Human Populations (Part 2)
Concept 16.2 Phylogeny Can Be Reconstructed from Traits of Organisms and Concept 16.3
Phylogeny Makes Biology Comparative and Predictive
In flowering plants, self-compatibility (the ability to selfpollinate) independently evolved three times within the
genus Leptosiphon.
Discuss whether this pattern of evolution contradicts the
principle of parsimony.
Concept 16.2 Phylogeny Can Be Reconstructed from Traits of Organisms and Concept 16.3
Phylogeny Makes Biology Comparative and Predictive
In flowering plants, self-compatibility (the ability to selfpollinate) independently evolved three times within the
genus Leptosiphon.
Does this pattern of evolution contradict the principle of
parsimony?
a. Yes
b. No
c. Can’t be determined from the information given.
Concept 16.3 Phylogeny Makes Biology Comparative and Predictive
The amino acid sequence of cytochrome c has been analyzed in over
100 eukaryotic species, and the molecular data support the idea that
cytochrome c is an evolutionarily conservative protein.
Refer to the graph below showing the molecular clock for cytochrome c.
You are given a sample of this protein that has roughly 60 amino
acid changes per 100 sites, when compared to an ancestor. How
many millions of years ago would you predict that the species the
sample came from diverged from that ancestor?
Concept 16.3 Phylogeny Makes Biology Comparative and Predictive
How many millions of years ago would you predict that the species the
sample came from diverged from that ancestor?
a. 400
b. 600
c. 800
d. 1,000
e. 1,200
Figure 16.11 Monophyletic, Polyphyletic, and Paraphyletic Groups
Figure 16.11 Monophyletic, Polyphyletic, and Paraphyletic Groups
Concept 16.4 Phylogeny Is the Basis of Biological Classification
In the following figure, which of the following groups are
correctly described?
a. Chimpanzees, humans, and gorillas are polyphyletic.
b. Orangutans, gorillas, and humans are monophyletic.
c. Humans and gorillas are paraphyletic.
d. Chimpanzees, humans, and gorillas are paraphyletic.
e. None of the above
Figure 16.12 Same Common Name, Not the Same Species
Apply the concept p. 330
Phylogeny is the basis of biological classification
Consider this phylogeny and three possible classifications of the
living taxa.
1. Which of these classifications contains a paraphyletic group?
2. Which of these classifications contains a polyphyletic group?
3. Which of these classifications is consistent with the goal of
including only monophyletic groups in a biological
classification?
4. Starting with the classification you named in question 3, how
many additional group names would you need to include all
the clades shown in this phylogenetic tree?
Apply the Concept, Ch. 16, p. 330
Figure 16.13 Evolution of Fluorescent Proteins of Corals
Figure 16.13 Evolution of Fluorescent Proteins of Corals