MicroEvolution

HS Bio Work SampleSpring 2013

Learning TargetI can explain the sources and

significance of genetic variation.

1.I can explain the sources of genetic variation.

2.I can explain the significance of genetic variation.

What is “Micro-Evolution”? Micro, meaning small Evolution, meaning change over time

So, microevolution has something to do with small changes over time?

What is “Micro-Evolution”?

Well, yes!

We tend to think of evolution as occurring at the organism level, but in order for this to happen, changes must occur at a much smaller level… the genetic level.

The Genetic Basis of Evolution

For evolution to occur, inherited genetic differences must at least partially account for phenotypic differences.

Genotype

Phenotype

What are the sources of Genetic Variation?

Mutations!

Mutations are the ultimate source of variation, and are thus the raw material of evolution.

If there were no variation, then there could be no evolution.

What causes mutations?Environmental Agents

DNA damage from environmental agents • UV light (sun)• nuclear radiation• chemicals agents

Mistakes in Duplication

Mistakes that occur when a cell copies its DNA in preparation for cell division.

Do we need to review the structure & function of DNA?

What purpose does DNA serve in the cell? (Why do our cells even need DNA?)

Information Storage What are the two main structural

components of DNA? Phosphate sugar backbone &

the nitrogenous bases What five letters are used to spell out

organismal genomes? Which letters relate to DNA, which relate to RNA?

DNA: A, C, G & T RNA: A, C, G, & U

Mutations by Environmental Agents

Change in DNA nucleotide

OR

Cutting of DNA sequence

Mutations during Duplication

You awake out there?

If you could have any super power what would it be?

Chin Dimples Lactose

intolerance Colorblindness Pattern Baldness Heart Disease Diabetes Stroke Sickle Cell

Anemia Etc…

Some common mutations

What do these all have in common?

• They are caused by a unique change in human gene sequence, or “genome”.

• They are inherited from ones parents.

• Generally, they do not negatively influence the afflicted individuals chance for reproduction.

Check for understanding… I’ve discussed two sources of mutation,

what was one?

I’ve discussed two sources of mutation, what was the other?

Which source of mutation do you think is more common?

Which source of mutation do you think is more deleterious (causing harm or damage)?

Why is genetic variation important?

Remember… mutations are the “raw materials” for evolution

AND… mutations lead to genetic variation

SO… without genetic variation there is not evolution!

But, what is genetic variation?

What is genetic variation? Genetic

• from Ancient Greek genetikos, "genitive" and from genesis, "origin”

• Of or related to genes, genetic makeup, and heredity in living organisms

Variation• In Biology: marked difference or deviation from

normal or recognized form, function, or structural characteristics

Genetic Variation• Varying characteristics in a the genetic makeup of

a species (as a result of genetic mutation)

But why was genetic variation important?

Let’s break it down…

Genetic Diversity: Total variety of genetic characteristics in a

species Species Diversity:

Diversity of within an ecological community Biodiversity: The variations of life forms in an ecosystem.

Ecosystem Diversity: Variety of species that inhabits the planet

WARNING: from this point forward I will being using the words “variation” and “diversity” as synonyms

(like they mean the same thing)

So what you’re saying is…Mutations lead to genetic diversity...

Genetic diversity leads to species diversity…

Species diversity leads to biodiversity…

Biodiversity leads to ecological diversity…

But, have I answered the question:Why is genetic variation important?

You’re all still awake aren’t you???

As a planet, we grow and eat a lot of corn and corn products (we’re talking 324 million ton in 2010 alone). Currently the majority of corn grown in the USA is one species, Zea mays. Say some nasty infectious disease decided to start eating our corn “monocrop”…

how would that affect your life?

Just a few examples of surprising places where you can find corn ingredients…

Toothpaste – sorbitol Salad Dressing – high fructose corn syrup

Gum – HFCS, sorbitol, or maltitol Make Up – starch (filler)

Milk – corn fed cows & Vit D Shampoo – ascorbic acid

Diapers – cornstarch Soda – HFCS & caramel color

Envelope Glue – nitrocellulose glue Perfume & Cologne – grain alcohol

Aspirin – cellulose microcrystalline

Check In- How does corn play a role in your life?

How would your life be affected if the corn crops in the US were to be infected?

Why is genetic variation (aka genetic diversity) important?

Why is genetic variation important?

How does this relate to our good friend C. sweetus? What evidence is there that variation

exists within the C. sweetus population?

Why are some variations inherited and others eliminated?

How do variation, selection, and time fuel the process of evolution?