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Biology 11. Unit 1: Evolution Lesson 1: Why Evolution??. By the end of the lesson you should be able to: Explain why DNA is so important to the theory of evolution State the men of evolution and what they contributed to the developing theory

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Biology 11

Biology 11

Unit 1: Evolution

Lesson 1: Why Evolution??


Objectives

By the end of the lesson you should be able to:

  • Explain why DNA is so important to the theory of evolution

  • State the men of evolution and what they contributed to the developing theory

  • Explain Darwin’s theories (Decent with Modification and Natural Selection) and his 2 problems

  • Use these examples to explain evolution: Peppered Moth, Giraffe necks, Finch beaks

Objectives:


Dna and evolution

Before we can truly understand evolution we need to understand DNA

DNA = deoxyribonucleic acid

DNA and Evolution


Characteristics of dna

Double helix understand DNA

Sugar phosphate backbone

4 nitrogenous bases (ATCG)

Complimentary base pairing

(A = T; C Ξ G)

Characteristics of DNA


Dna and evolution1

DNA is unique to each organism understand DNA

If DNA changes the organism changes

Evolution is the change of populations of organisms over time

THEREFORE the DNA must be changing over time if the organisms are changing!

DNA and Evolution


So what is evolution all about
So What is Evolution All About? understand DNA

  • Evolution:

    - the change through time

    - all living and non-living things change over time

  • We have lots of evidence that the earth is changing and has changed over time

This is a picture of what Alberta used

to look like. It was a Carboniferous Swamp that existed 300 mya…this is where our fossil fuels come from.


Why evolution
Why Evolution? understand DNA

  • As the earth changes life must adapt or die

  • Most life dies

  • But some adapts and survives – this is evolution!!


Evolution as a theory

Evolution is just a theory! understand DNA

It has a large body of evidence that is very widely accepted and has been scientifically tested for many years

Its more than just a hunch or guess

Evolution as a Theory


A theory emerges
A Theory Emerges understand DNA

  • Charles Darwin is credited with formulating our modern theory

  • He couldn’t have done so without all the scientists before him

  • Lets look at who was working before Darwin


Erasmus darwin
Erasmus Darwin understand DNA

  • Believed that organisms evolved over time, including man, but didn’t know how

  • Did not widely spread his ideas but profoundly influenced his grandson Charles


Jean baptiste lamarck

Proposed understand DNAInheritance of Acquired Characteristics

or “Theory of Use-Disuse”

First person to propose a mechanism for evolution, although wrong, he really challenged peoples long held ideas

Jean Baptiste Lamarck


Use disuse theory

If an organism uses a structure a lot and so do its ancestors, over time that structure develops better. Ex: Giraffes

Why is this wrong?

Use-Disuse Theory


Charles darwin
Charles Darwin ancestors, over time that structure develops better. Ex: Giraffes

  • As a young naturalist he sailed on a 5 year voyage around the globe on HMS Beagle

  • During this trip, especially to the Galapagos Islands, he put all the evolution puzzle pieces together


Darwin s ideas
Darwin’s ancestors, over time that structure develops better. Ex: GiraffesIdeas

  • Darwin was puzzled by the diversity of life on the Galapagos.

  • He knew these islands were young volcanic islands.

  • He observed 13 varieties of finches, all clearly related, but different from the one variety found on the mainland


Darwin’s 13 varieties of finches: ancestors, over time that structure develops better. Ex: Giraffes

  • note the variations in color and beak size


Darwin s main ideas

Darwin contributed two main ideas: ancestors, over time that structure develops better. Ex: Giraffes

1. Evolution, which he called “Descent with Modification.”

2. The mechanism of evolution: Natural Selection

Today we refer to Darwin’s theory as “Gradualism”

Darwin’s Main Ideas


Darwin s publication
Darwin’s Publication ancestors, over time that structure develops better. Ex: Giraffes

  • Although his voyage ended in 1836, he did not publish his theory until 1859

  • He published “The Origin Of The Species”

  • Although he was publicly ridiculed, the scientific community quickly became convinced


Darwin s theory descent with modification

In nature, more offspring are produced than can possibly survive

From this overabundance, there is a “struggle to survive” among the offspring

In every population, there are variations in all traits

Darwin’s Theory:Descent with Modification


Descent with modification

Those offspring with variations that make them better adapted to their environment are more likely to survive (Survival of the Fittest)

Those offspring who survive will mate with others who possess the favorable trait and this trait will be passed on to future generations (Natural Selection)

Descent with Modification


Two problems with the theory
Two Problems with the Theory adapted to their environment are more likely to survive (Survival of the Fittest)

  • Darwin couldn’t explain how variations could appear in a population.

    - The answer was in Gregor Mendel’s work on pea genetics


Problems with the theory
Problems with the Theory adapted to their environment are more likely to survive (Survival of the Fittest)

2. He could not show a single example of evolution occurring today, ie evolution in progress.

- He missed a good example right under his nose: the Peppered Moths of the Manchester Forest.


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