Download the origin of species

Chapter 14
How Biological Diversity Evolves
PowerPoint® Lectures for
Campbell Essential Biology, Fifth Edition, and
Campbell Essential Biology with Physiology,
Fourth Edition
– Eric J. Simon, Jean L. Dickey, and Jane B. Reece
Lectures by Edward J. Zalisko
© 2013 Pearson Education, Inc.
Biology and Society:
The Sixth Mass Extinction
• Over the past 540 million years, the fossil record
reveals five periods of extinction when 50–90% of
living species suddenly died out.
• Our current rate of extinction, over the past 400
years, indicates that we may be living in, and
contributing to, the sixth mass extinction period.
• Mass extinctions pave the way for the evolution of
new and diverse forms, but it takes millions of
years for Earth to recover.
© 2013 Pearson Education, Inc.
THE ORIGIN OF SPECIES
• When Darwin visited the Galápagos Islands, he
realized that he was visiting a place of origins.
– Although the volcanic islands were geologically
young, they were home to many plants and
animals known nowhere else in the world.
– Darwin thought it unlikely that all of these species
could have been among the original colonists of
the islands.
Video: Galápagos Islands Overview
© 2013 Pearson Education, Inc.
THE ORIGIN OF SPECIES
• In the 150 years since the publication of Darwin’s
book On the Origin of Species by Means of Natural
Selection, new discoveries and technological
advances have given scientists a wealth of new
information about the evolution of life.
• The diversity of life evolved through speciation,
the process in which one species splits into two or
more species.
© 2013 Pearson Education, Inc.
What Is a Species?
• Species is a Latin word meaning
– “kind” or
– “appearance.”
• The biological species concept defines a
species as “A group of populations whose
members have the potential to interbreed with one
another in nature to produce fertile offspring.”
© 2013 Pearson Education, Inc.
Figure 14.2
Similarity between different species
Diversity within one species
What Is a Species?
• The biological species concept cannot be applied
in all situations, including
– fossils and
– asexual organisms.
• Some other definitions of species are based on
– measurable physical traits,
– the use of ecological resources, or
– unique adaptations to particular roles in a biological
community.
© 2013 Pearson Education, Inc.
Figure 14.3
INDIVIDUALS OF DIFFERENT SPECIES
Prezygotic Barriers
Temporal isolation
Habitat isolation
Behavioral isolation
MATING ATTEMPT
Mechanical isolation
Gametic isolation
FERTILIZATION (ZYGOTE FORMS)
Postzygotic Barriers
Reduced hybrid viability
Reduced hybrid fertility
Hybrid breakdown
VIABLE, FERTILE OFFSPRING
No Barriers
Figure 14.3a
INDIVIDUALS OF DIFFERENT SPECIES
Prezygotic Barriers
Temporal isolation
Habitat isolation
Behavioral isolation
MATING ATTEMPT
Mechanical isolation
Gametic isolation
Figure 14.3b
INDIVIDUALS OF DIFFERENT SPECIES
FERTILIZATION (ZYGOTE FORMS)
Postzygotic Barriers
Reduced hybrid viability
Reduced hybrid fertility
Hybrid breakdown
VIABLE, FERTILE OFFSPRING
No Barriers
Reproductive Barriers between Species
• Prezygotic barriers include
– temporal isolation,
– habitat isolation,
– behavioral isolation,
– mechanical isolation, and
– gametic isolation.
Video: Albatross Courtship Ritual
Video: Blue-footed Boobies Courtship Ritual
Video: Giraffe Courtship Ritual
© 2013 Pearson Education, Inc.
Reproductive Barriers between Species
• Postzygotic barriers operate if
– interspecies mating occurs and
– hybrid zygotes form.
• Postzygotic barriers include
– reduced hybrid viability,
– reduced hybrid fertility, and
– hybrid breakdown.
© 2013 Pearson Education, Inc.
Mechanisms of Speciation
• A key event in the potential origin of a species
occurs when a population is somehow cut off from
other populations of the parent species.
• Species can form by
– allopatric speciation, due to geographic
isolation, or
– sympatric speciation, without geographic
isolation.
© 2013 Pearson Education, Inc.
Allopatric Speciation
• Speciation occurs with the evolution of
reproductive barriers between
– the isolated population and
– its parent population.
• Even if the two populations should come back into
contact at some later time, the reproductive
barriers will keep them as separate species.
© 2013 Pearson Education, Inc.
Figure 14.8
Populations
become
allopatric
Populations
become
sympatric
Populations
interbreed
Gene pools merge:
No speciation
Geographic
barrier
Populations
cannot
interbreed
Reproductive
isolation:
Speciation has
occurred
Time
Sympatric Speciation
• Sympatric speciation occurs in populations that live
in the same geographic area.
• An accident during cell division that results in an
extra set of chromosomes is a common route to
sympatric speciation in plants.
• Many polyploid species arise from the hybridization
of two parent species.
© 2013 Pearson Education, Inc.
Sympatric Speciation
• Many domesticated plants are the result of
sympatric speciation, including
– oats,
– potatoes,
– bananas,
– peanuts,
– apples,
– coffee, and
– wheat.
© 2013 Pearson Education, Inc.
What Is the Pace of Speciation?
• There are two contrasting patterns for the pace of
evolution:
1. the gradual pattern, in which big changes
(speciations) occur by the steady accumulation of
many small changes, and
2. the punctuated equilibria pattern, in which there
are
– long periods of little apparent change (equilibria)
interrupted (punctuated) by
– relatively brief periods of rapid change.
© 2013 Pearson Education, Inc.
Figure 14.10
Punctuated
pattern
Time
Gradual
pattern
Figure 14.UN03
Bacteria
Earliest
organisms
Archaea
Eukarya
Chapter 15
The Evolution of Microbial Life
PowerPoint® Lectures for
Campbell Essential Biology, Fifth Edition, and
Campbell Essential Biology with Physiology,
Fourth Edition
– Eric J. Simon, Jean L. Dickey, and Jane B. Reece
Lectures by Edward J. Zalisko
© 2013 Pearson Education, Inc.
Biology and Society:
Has Life Been Created in the Lab?
• How did life first arise on Earth?
• To gain insight, scientists have
– synthesized from scratch the entire genome of a
small bacterium known as Mycoplasma mycoides
and
– transplanted the artificial genome into the cells of a
closely related species called Mycoplasma
capricolum.
© 2013 Pearson Education, Inc.
Biology and Society:
Has Life Been Created in the Lab?
• The newly installed genome
– took over the recipient cells,
– began cranking out M. mycoides proteins, and
– reproduced to make more cells containing the
synthetic M. mycoides genome.
© 2013 Pearson Education, Inc.
MAJOR EPISODES IN THE HISTORY OF
LIFE
• Earth was formed about 4.6 billion years ago.
• Prokaryotes
– evolved by about 3.5 billion years ago,
– began oxygen production about 2.7 billion years
ago,
– lived alone for more than a billion years, and
– continue in great abundance today.
© 2013 Pearson Education, Inc.
MAJOR EPISODES IN THE HISTORY OF
LIFE
• Single-celled eukaryotes first evolved about 2.1
billion years ago.
• Multicellular eukaryotes first evolved at least 1.2
billion years ago.
© 2013 Pearson Education, Inc.
Figure 15.1a
Precambrian
Ancestor to
all present-day life
Origin of
Earth
4,500
Earth’s crust
solidifies
4,000
Oldest
prokaryotic fossils
3,500
Millions of years ago
3,000
Atmospheric
oxygen begins
to appear
2,500
Figure 15.1b
Precambrian
Oldest eukaryotic
fossils
2,000
Origin of
multicellular
organisms
1,500
Millions of years ago
Oldest
animal
fossils
1,000
Figure 15.1c
Paleozoic Meso- Cenozoic
zoic
Bacteria
Archaea
Fungi
Animals
Cambrian explosion
Oldest animal
fossils
1,000
Extinction of
Plants
colonize land dinosaurs
First humans
500
Millions of years ago
0
Eukaryotes
Protists
Plants
Prokaryotes
Precambrian