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Theory of Evolution  Just how do species change over time???? Theory of Evolution  Just how do species change over time????

Theory of Evolution Just how do species change over time???? - PowerPoint Presentation

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Theory of Evolution Just how do species change over time???? - PPT Presentation

Early atmosphere evidence natural selection and disease agents influence natural selection Introduction Evolution simple definition change over time Evolution helps us to understand the history of life ID: 912623

evolution selection natural species selection evolution species natural population gene organisms genetic similar genes pool populations evolve time change

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Slide1

Theory of Evolution

Just how do species change over time????

Early atmosphere, evidence, natural selection and disease agents influence natural selection.

Slide2

Slide3

Introduction

Evolution “ simple” definition: change over time

Evolution helps us to understand the history of life.

Slide4

The central idea of biological evolution is that all life on Earth shares a common ancestor, just as you and your cousins share a common grandmother

Central idea

Slide5

Adaptations

Fossil Record

Comparative Anatomy

Embryological Development

DNA Similarities

Evidence for Evolution

Slide6

All organisms have adaptations which help them survive in their particular environment

Adaptation

: a structure or behavior that helps an organism better survive in its environment

Examples: Mimicry, camouflage and physiological

Adaptations

Slide7

Slide8

Mimicry

Mimicry

: a structural adaptation that enables one species to resemble another species

E.g. A harmless species might mimic a poisonous one

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Camouflage

Camouflage

: a structural adaptation that allows a species to blend in with its surroundings

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Many bacteria have evolved resistance to antibiotics in the last 50 yearsPests have evolved resistance to pesticides

Physiological Adaptations

Slide18

Pathogens can influence natural selection by weeding out the weaker ones

Organisms

with stronger immune systems are more likely to survive pathogens.

Eventually

, the species that builds up antibodies for this particular pathogen will thrive

.        

 

Slide19

Bacteria are also affected by Natural Selection.

The

bacteria that build up a resistance the antibiotics

survive.

T

he

ones that do not also die, just like in animals and

plants

.

Pathogens a bacterium, virus, or other microorganism that can cause disease

Slide20

https://www.youtube.com/watch?feature=player_embedded&v=zjR6L38yReE

http://

www.pbs.org

/

wgbh/evolution/library/10/4/quicktime/l_104_03.html

Slide21

Variation in Populations

Evolution by natural selection happens in populations, not individuals. A single organism cannot evolve. Populations evolve.

Inheritable

characteristics are traits you are born with.

Populations evolve because there is variation

Variation causes some organisms to be better fit than others. These better fit organisms are more likely to survive and pass their genes to the next generation

Slide22

Slide23

Evolution

is the gradual change in a population over time

Darwin was the first scientist to realize that evolution can work by

natural

selection.Natural Selection – Organisms with traits well suited to an environment are more likely to survive and produce more offspring than organisms without these favorable traits

Survival of the fittest

E.g. Thicker fur is a favorable trait in cold environments

Evolution by Natural Selection

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English naturalist who proposed the theory of evolution by natural

selection

Charles Darwin (1809 – 1882)

Slide28

Darwin sailed around the world on the HMS Beagle and carefully studied thousands of different plants and animals

HMS Beagle Voyage

Slide29

On the Galapagos Islands Darwin found very strange plants and animals that don’t exist anywhere else in the world!

The Galapagos Islands

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Different islands have different types of finches not found on any other islands. This is where species all deriving from a common ancestor have over time successfully adapted to their environment via natural selection.

Darwin’s Finches

Slide32

Two Types of Evolution

Convergent evolution

: distantly related organisms evolve to become more similar

Happens when unrelated species adapt to

similar environments, possibly in different parts of the world

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Divergent evolution: species that once were similar become increasingly different

Happens when populations adapt to

different

environments

Two Types of Evolution

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Galapagos Giant Tortiose

Slide37

Blue-footed Booby

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Natural Selection

There are 3 basic types of natural selection

Directional Selection

Stabilizing Selection

Disruptive Selection

Slide41

Directional Selection

Directional selection

: favors one of the extreme variations of a trait

E.g. Male peacock tail feathers: Females favor larger tail feathers. Therefore males with larger feathers reproduced more often. Over many generations tail feathers grow larger and larger

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Stabilizing selection: favors average individuals in a population

E.g. Human infants: Too small = bad; too large = bad; average = good

Stabilizing Selection

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Disruptive Selection

Disruptive selection

: favors individuals with either extreme of a trait but intermediate individuals have a disadvantage

E.g.

Cuddlefish (a type of squid): Being large is an advantage because females prefer larger males. Being small is an advantage also. Small males impersonate females trick the females into mating.

Slide47

Slide48

Atmosphere contained all of the following gases:

Nitrogen

Ammonia

Methane

Carbon Dioxide

Water

Hydrogen

No oxygen….oxygen came

later

with photosynthesis.

Early Atmosphere conditions

Slide49

Slide50

Endosymbiotic Theory

https://www.youtube.com/watch?v=FGnS-Xk0ZqU

is an evolutionary theory of the origin of eukaryotic cells from

prokaryotic organisms

Remember the webquest you did!

Slide51

How did the first cells evolve?

Experiment conducted by

Miller and Urey

proposed simple- organic molecules could have been synthesized in the atmosphere of early Earth and rained down into the oceans.

Slide52

Fossil: Any trace of a dead organism

Fossils show the evolution of species over the past millions of years

Fossil evidence proves that modern species have evolved from ancient species

Fossil Evidence

Slide53

Puijila the walking seal

Slide54

Tiktaalik

Slide55

Archaeopteryx

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Comparative Anatomy

Homologous structures

: Body structures on different organisms that are

similar in structure

(same bones) and evolved from a common ancestor

Slide58

Homologous Structures

Slide59

Comparative Anatomy

Analogous structures

: Body structures on different organisms that are

similar in function

but did not evolve from the same ancestor (bird wing and butterfly wing)

Slide60

Analogous Wing Structures

Moth (insect)

Pterodactyl (reptile)

Bird

Bat (mammal)

Slide61

Comparative Anatomy

Vestigial structure

: body structure in an organism that no longer serves its original purpose but was useful to an ancestor (useless wings on the African ostrich)

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Embryological Development

Early in development, human embryos and embryos of all other vertebrates are very similar, which suggests that all vertebrates are related

Slide66

Slide67

DNA Similarities

Nearly all organisms have DNA, ATP, and many of the same proteins and enzymes

The DNA (genes) of closely related organisms looks very similar

Slide68

What Drives Evolution?

Mutations

Genetic Drift

Gene Flow

Natural Selection

Slide69

Gene Pool

Gene pool

: collectively, all of the alleles of the population’s genes

Allelic frequency

: the percentage of any specific allele in the gene poolGenes can enter and leave a population’s gene pool for many reasons

Populations in which the gene pool is not changing are said to be in

genetic equilibrium

Slide70

Genetic Drift

Genetic drift

: when gene frequencies are changed by random events in a isolated population

Example: diseases, natural disasters, mating habits

Slide71

Genetic drift can cause big losses of genetic variation for small populations.

population's

size is reduced for at least one

generation

Reduced genetic variation means that the population may not be able to adapt to new selection pressures, such as climatic change or a shift in available resources, because the genetic variation that selection would act on may have already drifted out of the population.

Bottleneck Effect

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Gene Flow

Gene flow

: the transport of genes by traveling individuals

When an individual leaves a population, its genes are lost from the gene pool

When an individual enters a population, its genes are added to the gene pool

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Mutations

New genes can be added to the population by errors in DNA copying called

mutations

Most mutations are neutral or bad!

Slide76

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Mutations

Very very rarely a mutation might come along that improves an organism’s chance at survival or reproduction

These mutant genes will be passed along to offspring and become more common in the gene pool over time

If the mutation offers a large advantage, eventually (after many generations) all members of the population will have the beneficial mutation

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Artificial Selection: Humans choose individuals with certain traits for breeding

After many generations of selection, dramatic evolutionary changes can result

Dogs

Fruits/Vegetables

Livestock

Evolution by Artificial Selection

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Slide83

Speciation-the evolution of a new species

A certain population may become isolated and evolve to fit new or different environmental conditions

The isolated population may change so much that it can no longer mate with the original population

Similar to the evolution of new languages

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How Fast Does Speciation Occur?

Gradualism

: idea that species originate through a gradual change of adaptations (longer than 10,000 years)

E.g. Fossil evidence shows that sea lilies evolved slowly and steadily over time

Punctuated equilibrium: idea that species originate in rapid bursts (10,000 years or less) with long periods of genetic equilibrium in between

Global ice age causes rapid adaptation of thick fur

Both gradualism and punctuated equilibrium are known to occur