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Focus 12: Evolution & Natural Selection

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Nicole Martin

on 6 May 2018

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Transcript of Focus 12: Evolution & Natural Selection

3. Gymnosperms - Conifers
Evolution & Natural Selection
Focus 12
Natural Selection
Essential Question
What factors drive natural selection?
Charles Darwin
Theory of Natural Selection

Species that are better adapted to their environment will live longer and reproduce creating more offspring like them

survival of the fittest
How did Darwin get his Theory?
1831: naturalist on the H.M.S. Beagle for a 5 year voyage around the world

Galapagos Islands
Made observations
Darwin's Finches
13 species of finches

Beak size and shape varied, most likely due to their island locations and available food

Finches had adapted to best obtain food in their environment

The Struggle for Existence
There is a constant struggle for survival.
The faster or “smarter” the predator the more likely it is to capture food

The better camouflaged, protected, or cunning the prey the more likely it would not be eaten

Survival of the Fittest
How well an individual is able to survive and reproduce in a specific environment

An inherited trait which makes an individual more fit in its environment
How Natural Selection Works
All populations have genetic diversity (they are not 100% identical)

If an individual is born/produced that has trait which make it more fit it then is more likely to survive and reproduce

When it reproduces there is a higher chance that the beneficial traits will be passed on to its offspring

Natural Selection
Over very long periods of time this selection can lead to the entire population having the similar beneficial traits which then makes the entire population more fit

Differences between members of the same species

Variation is important to survival!

Imagine that you go to a corn field and sample beetles.
80% of the genes in the population are for green coloration
You go back the next year, repeat the procedure, and find a new ratio:
A change in gene frequency over time means that the population has evolved.
Natural Selection Story
20%of them are for brown coloration
60% are now green
40% are now brown
Exit Ticket
What does it mean biologically if I say you are very "fit"?
Natural Selection Activity
You are a bird.
Candy corn are the plants.
m&ms are the bugs.
Grab ONLY the m&ms, Not the candy corn1
Genetic Flow
Gene migration

The transfer of alleles of genes from one population to another

Gene Flow
Beetles with brown genes immigrated from another population, or some beetles carrying green genes emigrated.
What are the two main uses for DNA fingerprinting?
Evolution BY Natural Selection
Evidence for Evolution
Why is variation important within a population?
Essential Question
How does natural selection lead to evolution of species?
Natural Selection
Occurs when an organism with a favorable mutation is better adapted to an environment.

This better adapted organism will be able to pass on its GENES and these favorable traits become more common in the population.
In our example...
What was the favorable trait?
Why were these better adapted?
How did the population change?
REMINDER: Any change in the nucleotide sequence of DNA.
This changes the genetic makeup of certain organisms phenotype allowing for changes that can be harmful or beneficial

Green gene RANDOMLY mutated into brown gene!
Organisms DO NOT mutate because it benefits them!
of Natural Selection:

Environmental influence

Example #1
Treatments like Frontline are regularly used to kill fleas and ticks on family pets.
Today, many fleas are RESISTANT to Frontline.
Hypothesis A
Exposure to Frontline actually caused mutations for resistance to the medicine.
Hypothesis B
Resistant strains of fleas were always there—and are just more frequent now because all the non-resistant lice were killed by Frontline.
Which of these hypotheses is correct?
Hypothesis B
Variation is there already
Frontline killed the “weaker” fleas
Other fleas live and reproduce to make more resistant fleas

JEan-Baptiste Lamarck
Believed in "Acquired Characteristics"
Agreed with HYPOTHESIS A
He was WRONG!!!
Charles Darwin
He called these mutations or changes ADAPTATIONS

HYPOTHESIS B is what Darwin explained!!!

Process by which organisms pass on traits from generation to generation

Origin of new species
Diversity of living species
Common traits between species.
Exit Ticket
How do favorable adaptations lead to changes in gene frequency and thus evolution?

Evaluate this statement:
"When placed in a hostile environment organisms are more likely to develop mutations."
Essential Question
What pieces of evidence support evolution by natural selection?
6 Pieces of Evidence for EVOLUTION
1. Fossil Records
2. Homologous Structures
3. Analogous Structures
4. Vestigial Structures
5. Embryology
6. DNA / Amino Acid Homology

1. Fossil Record
Fossil- A piece of organism or imprint left behind.

Fossils show that species have changed over time.

2. Homologous structures
Any structure like a bone, that is shared by a group of different species because it is inherited from a common ancestor

3. Analogous Structures
Two structures that perform the same or similar function by a similar mechanism but evolved separately.

4. vestigial organs
Any “left over” structures from a common ancestor

5. Similarities in Embryology
In the early stages of development of animals with backbones are very similar

6. DNA/Amino Acid Homology
Similar nucleotide sequences on very different organisms.
What is a
These spiders are all the same species.
They look different because all species show VARIATION

Population of individuals that can interbreed and produce FERTILE offspring

The process in which new species are formed.

Geographic isolation
Physical separation of members of a population

Caused by...
exit ticket
Why are mules not considered a species?
What are the six pieces of evidence for evolution?
essential question
How are living organisms grouped by taxonomists?
There are over 13 billion known species on Earth.
This is only 5% of all organisms that ever lived
New organisms are still being found and identified

Arrangement of organisms into orderly groups based on their similarities

...also known an
are scientists that identify & name organisms

Benefits of classifying
1. Accurately & uniformly name organisms

2. Prevents misnomers such as starfish & jellyfish that aren't really fish

3. Uses same language (Latin or some Greek) for all names

Confusion in Using Different Languages for Names
Latin Names are Understood by all Taxonomists
Carolus Linnaeus
Swedish scientist 1707 – 1778
Classified organisms by their structure

Developed naming system still used today

binomial nomenclature
Developed by Linnaeus
Two word naming system for organisms.
Includes genus and species name.
Always written in italics.
Hierarchy-Taxonomic Groups
Broadest group
Most specific group
DOMAIN - Eukaryota, Prokayota or Archaea

is based on
Evolutionary Relationships
Diagram showing how organisms are related based on shared characteristics such as feathers, hair, or scales

In this cladogram the name of the taxonomic group is at the end of each branch.
Dichotomous Key
Used to identify organisms.
Characteristics given in pairs.

Choose one of the options based on the organism!
Dichotomous Key - Example
1a Tentacles present – Go to 2
1b Tentacles absent – Go to 3

2a Eight Tentacles – Octopus
2b More than 8 tentacles – 3

3a Tentacles hang down – go to 4
3b Tentacles upright–Sea Anemone

4a Balloon-shaped body–Jellyfish
4b Body NOT balloon-shaped -
Dichotomous Key
Using a...
Binomial Nomenclature
Word Sort
Phylogenetic Tree
A chart that shows the evolutionary
relationships between species.
aka "Evolutionary Tree"
Evolutionary Paths
Convergent evolution
divergent evolution
When two organisms that are not closely related develop similar traits.
Causes differences between groups of organisms... this is what leads to NEW SPECIES!
Isolating Mechanisms
Homologous Species
Example: Analogous Species
The ways in which species are prevented from mixing with each other genetically (interbreeding).
1. Geographic Isolation
2. Reproductive Isolation
3. Behavioral Isolation
4. Temporal Isolation
1. Geographic isolation
Physical separation of members of a population

2. reproductive Isolation
Being unable to successfully mate.
3. Behavioral Isolation
Differences in courtship rituals or reproductive strategies
4. Temporal Isolation
Populations reproduce or are active at different times.
Exit Ticket
Explain the difference between the beliefs of C. Linneaus and C. Darwin.
Kingdoms of life
List the naming convention technique in order from top to bottom, beginning with Domain.
Essential Question
What are the 6 kingdoms of life and which organisms can be found in each?
The grouping of organisms into KINGDOMS is based on
3 factors:

1. Cell Type (prokyotic or eukaryotic)

2. Cell Number (unicellular or multicellular)

3. Feeding Type (autotroph or heterotroph)

Cell Type
The presence or absence of cellular structures such as the nucleus, mitochondria, or a cell wall

Cell Number
Unicellular- single celled organism – protozoans, bacteria, some algae

Multicellular- many celled organism – cells start to specialize/differentiate

Feeding Type
Autotroph / Producer: Make their own food

Heterotroph / Consumer:
Must eat other organisms to survive
Includes decomposers – those that eat dead matter!

6 Kingdoms
1. Archaebacteria
2. Eubacteria
3. Protista
4. Fungi
5. Plantae
6. Animalia

Characteristics of Kingdoms
Table - Fill in what you know!
Ancient bacteria
Live in very harsh environments

Typical bacteria, they live in more neutral conditions.

Bacterial SHapes
Rod or Stick (bacilli)

Sphere (cocci)

Helical or spiral (borrelia)

BActerial Locomotion
Flagellum - Tail like projection
Cillia - Hair like projections
Include many widely ranging microbes, including slime molds, protozoa and primitive algae.

Protist Locomotion
3 Types:
1. Pseudopoda (false foot)

2. Flagella/cilia

3. Contractile vacuoles

Break down dead organic material, they continue the cycle of nutrients through ecosystems. >HETEROTROPHS

Fungi Nutrition
All are heterotophs!
Saprophytes-get their nutrients from dead organic matter

Mutualists – live symbiotically
Parasites – absorb from a host, eventually killing the host
Multicellular photosynthetic autotrophs.
4 Plant Groups
1. Bryophytes - Mosses
2. Pteridophytes - Ferns
4. Angiosperms - Flowering Plants
Muticelluar heterotrophs.
No cell wall.
Can only reproduce inside a living cell.
Exit Ticket
Differentiate between gymnosperms and angiosperms.
Greek philosopher 384 to322 BC
First to classify living things.
Divided into plants and animals.
Also divided by locomotion - walking, flying or swimming.
His system was used until the 1600s.
Divided into kingdoms and then genera.

Robert Whittaker
American ecologist 1920-1980
First to propose a five kingdom system.
The first to classify biomes by temperature and precipitation.
Whittaker's Five Kingdoms
Genetic Similarities!
Today the best way to classify organisms is by their GENETICS!
DNA Fingerprinting can help us to do this!
A similar chart that shows evolutionary relationships and common ancestors.
Common Ancestor
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