Download Chapter 13 - Biology Honors

Chapter 13
How Populations Evolve
Videos
As you watch the following videos, take not of
different events that occur during each. Once
all videos are watched – are there any things
that remain consistent throughout all of them?
Evolution in 1 minute
How did Homer Simpson evolve?
Guiness’ idea of evolution
Evolution with Emojis
Evolution with Emojis
Examples of Evolution
1. Write down 5 animals or plants that first
come to mind
2. Explain the environment the animal or
plant lives in.
3. Explain how each animal or plant is
adapted for the environment that it lives in.
History of Life on Earth
Evolutionary Timeline
Theorists that helped contribute to our modern day
theory of evolution from Charles Darwin:
• Charles Lyell –uniformintarianism (geologic
processes still changing Earth)
• Thomas Malthus – struggle for existence
(resources)
• James Hutton - Gradualism
• John Baptiste Lamarck – Inheritance of
acquired Characteristics and Law of Use and
Disuse
• Alfred Russel Wallace – organisms evolved
from common ancestors
Myths and Misconceptions of
Evolution
Darwin’s Voyage
Darwin’s Voyage
- 22 yo– traveled on the HMS Beagle from
England
- 5 year voyage around the world
- Collected samples of
plants/animals/fossils
- much of collections and
observations came from
the Galapagos islands
- wrote his ideas in a book
“On the Origin of Species”
Galapagos Islands
• Group of islands off coast of S. America
• Each island has different climates
• Animals on each island were unique
–Tortoises
–Iguanas
–Finches
• Organisms differ from
island to island and from
S. America
• Artificial selection – humans have modified
species by selecting and breeding individuals
that possess desired traits (selective breeding)
- Natural selection – process of selection in nature
observation #1 – members of a population vary in their
traits, and most traits are inherited from parent to
offspring
observation #2 – all species are capable of producing
more
offspring than the environment can support
inference #1 – individuals whose inherited traits give
them a
higher probability of surviving and reproducing
in a given environment tend to leave more offspring than
other
individuals
inference #2 – unequal production of offspring will
cause favorable traits to accumulate in a population
Natural Selection in Action
Natural
Selection in
Action
Natural Selection in Action
Before Industrial
Revolution
During Industrial
Revolution
What is Evolution?
Darwin Summary
1. Struggle for Existence
2. Survival of the Fittest
3. Descent with Modification
Struggle for Existence
Organisms compete for resources
Resources include….
Survival of the Fittest
•
Fitness
– Ability of an Individual To Survive &
Reproduce
•
Adaptation
– Inherited Characteristic That Increases an
Organisms Chance for Survival
– Physical
» Speed, Camouflage, Claws, Quills, etc.
– Behavioral
» Solitary, Herds, Packs, Activity, etc.
Descent with Modification
• Takes Place Over Long Periods of Time
• Natural Selection Can Be Observed As
Changes In
– Body Structures
– Ecological Niches
– Habitats
Darwin’s Theory of Evolution by
Natural Selection
1. All species have genetic variation.
2. Living things struggle to exist.
3. Individuals of species compete with one another to
survive.
4. Individuals that are better adapted to their
environment leave more offspring than those less
adapted.
5. Characteristics of individuals better adapted for their
environment increase in a population over time.
Strong Evidence of Evolution
1. Fossils – preserved remnant or impression or an
organism that lived in the past
- found in different sedimentary rock layers
called strata
- oldest fossils (prokaryotes) = 3.5 BYA
Strong Evidence of Evolution
2. Biogeogrpahy
- different animals on different continents but
similar adaptations to shared environments
- animals move to new area and eventually
become adapted to their new environment
Strong Evidence of Evolution
3. Comparative anatomy
- homology – similarity in characteristics that results
from common ancestry
- homologous structures – structures that have
different functions but are structurally similar
- vestigial organ – remnants of structures that served
important functions in the organisms ancestors but
serve no function today
- embryology – looking at embryos for similar
structures
Strong Evidence of Evolution
4. Molecular Biology
- all forms of life use the same genetic
language of DNA, RNA and genetic code
- looking at DNA sequences of organisms
- shows how closely related organisms are
Example of Evolution Camouflage
http://www.youtube.com/watch?v=EJGtNigCu8&safe=active
Mimicry
http://ngm.nationalgeographic.com/2009/08/mimicry/
mimicry-interactive
Macroevolution vs. Microevolution
Macroevolution – change on a grand scale;
events that create and destroy species
Microevolution – a change in a population’s gene
pool over time
- gene pool = alleles for genes in a
population
Hardy Weinberg Equilibrium
-
works when looking at microevolution of populations
(group of same organism)
Principle stating that the shuffling of genes occurring
during sexual reproduction is not the only thing changing
the genetic makeup of a population
- For a population to be in Hardy Weinberg equilibrium
it must satisfy 5 conditions:
1. Very large population
2. No gene migration
3. No mutations
4. Random mating
5. No natural selection
Hardy Weinberg Equilibrium
Hardy Weinberg Equilibrium
The following statements look at wildflower population.
After reading each statement, state which conditions
the population deviates from.
1. A windstorm blows in hundreds of seeds from a
nearby meadow, where nearly all the flowers are
yellow.
2. A pollutant molecule from the soil gets in the way just
as a developing egg cell in one of the red flowers is
replicating its DNA. Quite by chance, the red allele is
transformed into a yellow allele.
3. The flowers tend to grow in red and yellow patches. A
landslide buries and kills most of the red flowers.
Hardy Weinberg Equilibrium
4. The red pigment in the petals of the red flowers is
poisonous and protects them from beetles that eat the
developing seeds. The yellow flowers are not protected
in this way.
5. The bees that pollinate the f lowers tend to develop a
“search image.” Once they start visiting flowers of a
certain color, they stick to that color. So pollen from red
flowers is more likely to be delivered to other red
flowers, and pollen from yellow flowers is more likely
to fertilize other yellow flowers.
Evolutionary Tree
• Hypotheses reflecting current understanding of
patterns of evolutionary descent
Alterations in Allele Frequencies
1. Genetic drift – change in the
gene pool of a population due to
chance
tends to reduce genetic
variation
Bottleneck effect – drastic
reduction in population size
and change in allele
frequencies
- Due to earthquakes,floods,
fires, etc.
Founder effect – when a few
individuals become isolated
from a larger population
Alterations in Allele Frequencies
2. Natural selection
3. Gene Flow – when a population may gain/lose
alleles when fertile individuals move into/out of
a population or when gametes are transferred
between populations
Natural Selection on Polygenic Traits
1. Stabilizing selection
– favors intermediate
phenotypes
2. Directional
selection – acts
against a phenotype
at one extreme
3. Disruptive selection
– favors individuals
at both phenotypic
extremes
Sexual Selection
- natural selection in which individuals with
certain characteristics are more likely than other
individuals to obtain mates
- Sexual dimorphism – differences in
males/females in secondary sex characteristics
Sexual Selection
• Intrasexual selection (w/i same sex) – in some
species, secondary sex structures may be used to
compete with members of the same sex for
mates.
– Physical combat, ritualized displays
• Intersexual selection/mate choice – individuals of
one sex are choosy in selecting their mates
– Females choose males based on traits
Chapter 14
The Origin of Species
• Speciation – emergence of a new species
– Bridge between microevolution and macroevolution
– Taxonomy classifies and names these organisms
– Barriers keep species separate
Reproductive Barriers – keep species
separate
1. Prezygotic Barriers – prevent mating or
fertilization
a. temporal isolation – mating occurs at
different seasons/times of day
b. habitat isolation – populations live in
different habitats and do not meet
Reproductive Barriers – keep species
separate
c. behavioral isolation – little/no sexual attraction
between different species
d. mechanical isolation – structural differences
between organisms do not allow them to mate
e. gametic isolation – male/female gametes die
before uniting or fail to unite
Reproductive Barriers – keep species
separate
2. Postzygotic barriers – prevent the development of
fertile adults
a. reduced hybrid viability – hybrids fail to
develop or to reach sexual maturity
b. reduced hybrid fertility – hybrids fail to
produce functional gametes
c. hybrid breakdown – offspring of hybrids are
weak/infertile
Types of Speciation
1. Allopatric speciation – geographic barrier
isolates a population and causes new species
2. Sympatric speciation – formation of new
species of organisms in the same geographic
area
a.accidents during cell division (new species called
polyploid)
Speciation occurs rapidly or slowly
• Punctuated equilibrium – long periods of little
change
• Graduated equilibrium – long period with small
changes
Adaptive Radiation
- Evolution of diverse species from a common
ancestor
- Occurs when a few organisms colonize a new
area or when environmental changes cause
extinctions and provide opportunities for
survivors
Evolutionary Relationships
Look at the diagram above and answer the following:
1. What does this diagram depict?
2. Where does the information come to depict a diagram like this?
3. Which organisms are closely related? Which are not closely related? Give an
example for each.
4. Which organism is the most recently evolved? Which organism is the oldest,
evolutionarily speaking?