Transcript APES chapter4 2013 Lewis

Chapter 4
Evolution and
Biodiversity
ORIGINS OF LIFE
• 1 billion years of chemical change to form the
first cells, followed by about 3.7 billion years
of biological change.
Figure 4-2
Biological
Evolution
• By natural
selection
involves the
change in a
population’s
genetic
makeup;
Leads to
biodiversity.
Figure 4-2
How Do We Know Which
Organisms Lived in the Past?
•
•
•
•
Fossils
Radiometric Dating
Ice Cores
DNA analysis.
Figure 4-4
EVOLUTION, NATURAL
SELECTION, AND ADAPTATION
• Macroevolution
• Microevolution - brought about by mutation,
natural selection, gene flow, & genetic drift
• Gene pool
• Differential reproduction
• Directional Selection
• Disruptional Selection
• Stabilizing Selection
EVOLUTION, NATURAL
SELECTION & ADAPTATION
• BIOLOGICAL EVOLUTION BY NATURAL
SELECTION INVOLVES THE CHANGES
IN A POPULATION’S GENETIC MAKEUP
• NOTE: POPULATIONS- NOT
INDIVIDUALS – EVOLVE BY BECOMING
GENETICALLY DIFFERENT. NATURAL
SELECTION ACTS ON INDIVIDUALS.
STEPS OF BIOLOGICAL
EVOLUTION
• 1. DEVELOPMENT OF GENETIC
VARIABILITY IN A POPULATION
OCCURRING THROUGH MUATIONS.
BENEFICIAL MUTATIONS RESULT IN
NEW GENETIC TRAITS THAT GIVE AN
INDIVIDUAL AND ITS OFFSPRING
BETTER CHANCES FOR SURVIVAL
AND REPRODUCTION IN THE
ENVIRONMENT.
STEP 2
• NATURAL SELECTION – OCCURS
WHEN SOME INDIVIDUALS OF A
POPULATION HAVE GENETICALLY
BASED TRAITS THAT INCREASE THEIR
CHANCES OF SURVIVAL AND ABILITY
TO REPRODUCE OFFSPRING WITH
THOSE TRAITS;
STEP 2
• NATURAL SELECTION EXPLAINS HOW
POPULATIONS ADAPT TO CHANGES IN
THE ENVIRONMENT.
Natural Selection and Adaptation:
• Three conditions necessary for biological
evolution of a population by natural selection:
– 1) Genetic variability
– 2) Heritable traits
– 3) Trait must lead to Differential reproduction –
enables individuals with trait to leave more
offspring than other members of a population
SUMMARY:
BIOLOGICAL EVOLUTION BY NATURAL
SELECTION
• GENES MUTATE – INDIVIDUALS ARE
SELECTED – POPULATIONS EVOLVE
THAT ARE BETTER ADAPTED TO
SURVIVE AND REPRODUCE UNDER
EXISTING ENVIRONMENTAL
CONDITIONS.
3 TYPES OF NATURAL
SELECTION
• Stabilizing Selection-- The extremes are
selected against. Example: height; most
beings tend to the average height- not too
many really short ones or really tall ones.
• Directional selection-- One extreme value
is selected for. Example: speed; faster is
always better so a population will tend to
get faster over time.
NATURAL SELECTION
• Disruptive selection-- The extremes are
both selected for. This type of selection is
not as common as the first two. Example:
Prey-type animal with distinctive markings
which the predators know will over time
move away from the norm in both
directions.
DISRUPTIVE SELECTION
Extreme phenotypes selected for
STABILIZING SELECTION
Increase in individuals with intermediate
phenotype
DIRECTIONAL SELECTION
Eliminates one extreme variation from an
array of possible phenotypes. Results in a
shift towards the other extreme.
Coevolution: A Biological Arms
Race
• Predator and prey species
• Batesian Mimicry (1 bad, 1 not)
• Mullerian Mimicry (many poisonous animals
are brightly colored)
Plate Tectonics – Also Responsible for
Changes in Species’ Distribution & Evolution
225 million years ago
65 million years ago
135 million years ago
Present
Fig. 4-5, p. 88
Climate Change and Natural
Selection
• Changes in climate – affects biodistribution &
evolution
Figure 4-6
ECOLOGICAL NICHES AND
ADAPTATION
– Fundamental niche: the
full potential range of
physical, chemical, and
biological conditions and
resources a species could
theoretically use.
– Realized niche: to survive
and avoid competition, a
species usually occupies
only part of its fundamental
niche.
Generalist and Specialist Species:
Broad and Narrow Niches
• Generalist tolerate a wide
range of
conditions.
• Specialist can only
tolerate a
narrow range of
conditions.
Figure 4-7
SPOTLIGHT
Cockroaches: Nature’s Ultimate
Survivors
• 350 million years old
• 3,500 different species
• Ultimate generalist
– Can eat almost anything.
– Can live and breed almost
anywhere.
– Can withstand massive
radiation.
Figure 4-A
Specialized Feeding Niches
• Resource partitioning- reduces
competition and allows sharing of limited
resources – “you take yours & I’ll take
Figure 4-8
mine”
Evolutionary Divergence
• Adaptive radiation
– through beak
shapes
Figure 4-9
SPECIATION AND
BIODIVERSITY
• Speciation: Allopatric & Sympatric
• Allopatric – Involves a geographical
barrier
• Sympatric –Does not involve a
geographical barrier
Allopatric Speciation
• Involves a geographic barrier that
physically isolates populations of a species
and blocks gene flow;
• Once isolated, allopatric populations living
in different places accumulate genetic
differences due to natural selection, genetic
drift and new mutations
Sympatric Speciation (common in
plants, rare in animals)
• Results from chromosomal changes and
nonrandom mating
• Sympatric populations become genetically
isolated even though their ranges overlap
• Mechanisms include,(Gametes are 2n, not n)
–
–
–
–
Polyploidy
Allopolyploidy
Autopolyploidy
Nonrandom mating
SPECIATION, EXTINCTION, AND
BIODIVERSITY
• Speciation: new species arise when
members of a population become isolated for
a long period of time.
– 3 Types of Reproductive isolation:
– 1) Temporal isolation
– 2) Behavioral isolation
– 3) Geographic isolation
Temporal Isolation
• Occurs because species mate at different
times
• Examples:
– Different species of plants flower at different
times
– Closely related species of fireflies mate at
different times of night
Behavioral Isolation
• Differences in:
– courtship behavior,
– chemical signals or vocalizations
– Color or morphology that allow individuals to
recognize their own species
Fireflies respond only to the light pattern
emitted by their own species
Geographic Isolation
• Leads to reproductive isolation, divergence of
gene pools and speciation.
Figure 4-10
Extinction: Lights Out
The
golden toad of Costa Rica’s
Monteverde cloud forest has
become extinct because of
changes in climate.
• Background
extinction
• Mass Extinction
• Adaptive
radiation
• Gradualism
• Punctuated
Equilibrium
• Fitness
Figure 4-11
Cenozoic
Era
Period
Millions of
years ago
Quaternary
Today
Tertiary
65
Mesozoic
Cretaceous
Jurassic
180
Triassic
Species and families
experiencing
mass extinction
Extinction Current extinction crisis caused
by human activities. Many species
are expected to become extinct
Extinction within the next 50–100 years.
Cretaceous: up to 80% of ruling
reptiles (dinosaurs); many marine
species including many
foraminiferans and mollusks.
Extinction
Triassic: 35% of animal families,
including many reptiles and marine
mollusks.
Bar width represents relative
number of living species
250
Extinction
345
Extinction
Permian
Paleozoic
Carboniferous
Devonian
Permian: 90% of animal families,
including over 95% of marine
species; many trees, amphibians,
most bryozoans and brachiopods,
all trilobites.
Devonian: 30% of animal
families, including agnathan and
placoderm fishes and many
trilobites.
Silurian
Ordovician
Cambrian
500
Extinction
Ordovician: 50% of animal
families, including many
trilobites.
Fig. 4-12, p. 93
SHAPING GENE FREQUENCIES
• 2 Types of Artificial selection:
1. Selective Breeding – get desired traits
2. Hybridization – get variety
Genetic engineering – used to
create transgenic organisms
Figure 4-15
Genetic Engineering:
Genetically Modified Organisms (GMO)
Figure 4-14