1. Chapter 10 pt 1
Intro to Bio Sci
Assoc Prof Biology
2. Learning Goals
Life on earth
Species are the
originated from basic units of
trees help us
Macroevolution An overview of
the diversity of
diversity of life.
life on earth.
4. 10.1 Complex organic
molecules arise in non-living
5. Phase 1: The Formation of Small Molecules
Containing Carbon and Hydrogen
8. The Urey-Miller Experiments
The first demonstration that complex organic
molecules could have arisen in earth’s early
9. Why is it important that Urey and Miller’s
experiment produced amino acids?
1. Because they are the building blocks of
2. Because they are the building blocks of
3. Because they are the building blocks of
4. Because they are the building blocks of
10. Take-Home Message 10.1
Under conditions similar
to those on early earth,
small organic molecules
form which have some
chemical properties of life.
11. 10.2 Cells and self-replicating systems
evolved together to create the first
Life on earth most likely originated from
12. Phase 2: The Formation of Self-Replicating,
- RNA appears on the scene
- RNA can catalyze reactions necessary for
13. The “RNA World”
life and DNAbased life
15. Life Is Defined by Two Characteristics:
1) the ability to replicate
2) the ability to carry out some sort of
16. Phase 3: The Development of a
Membrane, Enabling Metabolism,
and Creating the First Cells
Membranes make numerous aspects of
17. How Did the First Cells
19. Take-Home Message 10.2
The earliest life on earth
appeared about 3.5 billion
years ago, not long after
earth was formed.
possibly RNA—may have
formed in earth’s early
environment and later
acquired or developed
Membranes enabled these
self-replicating molecules to
replicate and make
metabolism possible, the
two conditions that define
21. 10.3 What is a species?
22. Biological Species Concept
kinds of organisms
are natural populations of organisms
• interbreed with each other or could possibly
• cannot interbreed with organisms outside their
own group (reproductive isolation)
24. Two Key Features of the Biological
1) Actually interbreeding
or could possibly
2) “Natural” populations
25. The biological species concept is not easily applied to
bacteria and fossils. What other characteristics could we
use to decide whether two different bacteria are two
1. Observe asexual reproduction.
2. Measure the size of each bacteria.
3. Compare the sequences of specific
genes in the bacteria.
4. All of the above.
Make it impossible for
individuals to mate
with each other
Make it impossible for
reproductive cell to
fertilize the female’s
28. Examples of
29. Postzygotic Barriers
30. Which answer below is considered to be a
postzygotic barrier to reproduction?
1. Two species of frogs mate at different times in the
2. Birds about to mate need to go through specific
3. The male gamete (pollen) of one flower is not
compatible with the female organs of another
4. Fertilization occurs, but the embryo dies before it is
5. There is a mechanical isolation that prevents
31. Take-Home Message 10.3
Species are generally
defined as populations of
individuals that interbreed
with each other or could
Species cannot interbreed
with organisms outside
their own group.
This concept can be
applied easily to most
plants and animals, but for
many other organisms it
cannot be applied.
32. 10.4 How do we name species?
We need an organizational system!
33. Carolus Linnaeus and
A scientific name consists
of two parts:
2) Specific epithet
34. Hierarchical System
Inclusive categories at the
…leading to more and
more exclusive categories
35. Take-Home Message 10.4
Each species on earth is
given a unique name,
using a hierarchical
system of classification.
Every species on earth
falls into one of three
36. 10.5 Species
are not always
37. Difficulties in Classifying
involve fertilization or even two
involve any interbreeding
isolation is not meaningful
38. Chihuahuas and Great Danes
generally can’t mate.
Does that mean they are different
39. Difficulties in Classifying Ring Species
insect-eating songbirds called
to live at the higher elevations of the
Tibetan mountain range
in a ring around the mountain range
40. Difficulties in Classifying Ring Species
interbreed at southern end of ring.
population splits as the warblers move north
along either side of mountain.
the two “side” populations meet at
northern end of ring, they can’t interbreed.
41. Difficulties in Classifying Ring Species
variation in the warblers on each side
of the mountain range has accumulated…
two populations that meet have become
exact point at which one species stops
and the other begins
42. Difficulties in Classifying Hybridizing
• the interbreeding of closely related species
postzygotic barriers evolved?
43. Morphological Species Concept
on aspects of organisms other than
reproductive isolation as defining features
species based on physical
features such as body size and shape
be used effectively to classify asexual
44. Which answer below would require
the morphological species concept to
delineate between the two species?
Dog and cat
Salmonella and E. coli
Cow and goat
Donkey and horse
45. Take-Home Message 10.5
The biological species concept
is useful when describing most
plants and animals.
It falls short of representing a
universal and definitive way of
distinguishing many life forms.
Difficulties arise when trying to
classify asexual species, fossil
species, speciation events that
have occurred over long periods
of time, ring species, and
In these cases, alternative
approaches to defining species
can be used.
46. 10.6 How do new species arise?
species splits into two distinct species.
in two distinct phases
more than just evolutionary change in
48. Allopatric Speciation
with geographic isolation
51. Speciation without Geographic Isolation
cell division in plants
are duplicated but a cell does
doubling of the number of sets of
chromosomes is called polyploidy.
individual with four sets can no longer
interbreed with any individuals having only
two sets of chromosomes
or mating with other
individuals that have four sets can occur.
reproductive isolation, considered a
55. Take-Home Message 10.6
Speciation is the process
by which one species
splits into two distinct
species that are
It can occur by polyploidy
or by a combination of
and genetic divergence
57. 10.7 The history of life can be
imagined as a tree.
58. Systematics and Phylogeny
names and arranges species in a
manner that indicated:
• the common ancestors they share
• the points at which they diverged from each other
59. Systematics and Phylogeny
• evolutionary history, of organisms
• The common ancestor points at which species diverge
61. Take-Home Message 10.7
The history of life can be
visualized as a tree; tracing
from the branches back
toward the trunk follows the
pathway of descendant back
The tree reveals the
evolutionary history of
every species and the
sequence of speciation
events that gave rise to
62. 10.8 Evolutionary trees show
66. Monophyletic Groups
group in which all of the individuals are
more closely related to each other than to any
individuals outside of that group
by looking at the nodes of the
68. Which animals are represented in a
monophyletic group indicated by the red
1. Fish, bird, human,
rat, and mouse
2. Bird, human, rat
3. Human, rat, and
4. Rat and mouse
69. Constructing evolutionary trees
requires comparing similarities
and differences between
72. Below are genetic sequences for a gene found in
four different species. Which species are the
most closely related?
Species A and B
Species A and C
Species A and D
Species B and D
73. Take-Home Message 10.8
constructed by biologists are
hypotheses about the
relationships among species.
The trees represent an
attempt to tell us which
groups are most closely
related to which other groups
based on physical features,
usually DNA sequences.