Evolution

Evolution: organisms changing over time

Evolution explains how species in the past have changed into species of the present

Process of Natural Selection

• Those individuals with the best traits for survival in the environment will live and reproduce. They pass on the DNA for those advantageous traits to their offspring.

• Individuals with unsuitable traits will die. • For this to be true

– Variation: there are differences between organisms of the same species

– Overproduction: each species produce more offspring then will survive.

United streaming video: Evolution Video: Icons of

Science, Discovery Science1. Charles Darwin is famous for introducing The theory of Evolution and the mechanism (the

way) species change called Natural Selection.  2. On Darwin’s voyage to South America what did Darwin find what was unique about the plants and animals of the Galapagous Islands? There were animals and plants that don’t exist anywhere else. 3. What did Darwin conclude about the different kinds of finches with their differently shaped beaks? They evolved from the same original species 4. Different beaks allow them to survive on different food sources.  5. According to Darwin what are the requirements that must be present for natural selection to occur?

There must be a breeding population with Variation There must be a population that can make copies of them self The coping must be imperfect The copying errors must sometimes make the organisms better able to survive

• 6. Moth Example: What were the two variations in color of the “peppered moth” light color and dark color

• 7. When the birch forest had light colored tree trunks which variation was survived most often to reproduce and pass this “light colored” gene on? The light colored moths blended in, got eaten less, and survived more often to reproduce then the dark colored moth.

• 8. After the industrial revolution the tree bark was polluted turning a dark color. How did that change the population of peppered moth? Explain why. The dark colored moth was camouflaged and got eaten less, survived more to reproduce so over a short period of time more moths were dark then light.

• 9. Usually our genes are faithful copies from our parents. Half from mother and half from father. What do you call it when a gene is not copied correctly? Mutation

• 10. What happens to an organisms DNA when that organism has a mutation that improves the chances for survival. That organisms survives and passes the DNA with the beneficial mutation on to their offspring.

11. What is altruism? When an individual organism does something that might harm themselves but improves the survival of organism of the same species.  12. How would a peahen benefit from mating with a peacock with a big colorful tail? Peacocks with big tails are more healthy then peacocks with wimpy tails.  13. What is a species? A group of individuals that can interbreed.

14. What is a gene pool? The set of genes in a population at any given time.  15. Evolution is a change in a gene pool of a population over time.

16. Speciation is the process by which new species are created.

17. In convergent speciation unrelated species evolve in similar ways. Name three organisms that all have wings but have no common ancestor. Birds, insects and bats.18. Divergent evolution is what happens when a population splits off and becomes a new species. They become two species though closely relation will have new traits to better help them fit into their environments.  19. The process of evolution can be summarized in 7 words: Genes mutate, individuals are selected, populations evolve.

20. Earth was formed 4.6 billion years ago what do scientists think lightning provided the energy to spark the production of organic chemicals. In 1953 Stanley Miller passed an electrical current through a mixture of hydrogen nitrogen carbon water, ammonia and methane which produced __________ ___________ which make up the building blocks of protein was made.

21. Similarities in DNA can be used to determine how closely related two types of animals are. How does the DNA of a human, domestic dog, and mice compare. What does this suggest about the ancestory of these organisms? The human and dog have more similar DNA then the mice because the share a more recent common ancestor.

22. According to the principals of Natural Selection animals best adapted to survive in their environment are more likely to produce offspring causing the beneficial adaptation to spread throughout the population. • 23. Complex changes can occur through an accumulation of smaller changes that accrue over generations. There must be a possible sequence of many small steps.

24. Natural selection takes many tiny changes over millennia.

Lamarck He got it right species change. So, what is the problem with this explanation?

PROBLEMS:

Physical Traits can not be changed in the adult elephants .

Changes in the traits of the adult will not be passed to offspring. For example injury to a mother’s leg will not be passed to her baby.

DarwinWhy is this explanation better? And accepted by modern scientists as

THE PROCESS OF NATURAL SELECTION

There is variation in the trunk length of elephants due to slight differences in their DNA.

Because of these differences DNA of elephants with “good” trunks will be passed to offspring and they will have “good” trunks.

Evolution Vocabulary: Variation: differences in traits/DNA of organisms of the same species.

Evidence of Evolution• Evidence includes:

– The fossil record • Scientists examine fossils to study how ancient organisms

changed to become modern organisms, or they went extinct

– Homologous structures

» organisms with similar body structures have recent common ancestors

– Similarities in Embryology» Organisms with similar embryos have a

recent common ancestor (http://www.pbs.org/wgbh/evolution/library/04/2/l_042_02.html) run with internet explorer

Evidence of Evolution• Evidence includes (continued):

• Geographic distribution

• Similarities in Biochemistry– Organisms with similar DNA, have a

recent common ancestor.– http://www.youtube.com/watch?v=zi8FfMBYCkk Ken Miller human versus

Chimpanzee chromosome number 4:22 min

Charles Darwin

• Before Darwin most people believed species did not change ever.

• Darwin is famous for explaining why and how species change.

• Process of Natural Selection: In a population of one species there is variation. Those individuals with the best traits for survival in the environment will live and reproduce. They pass on the DNA for those advantageous traits to their offspring.

• Individuals with unsuitable traits will die.

• James Hutton: 1785 geologist proposed the theory that Earth is millions of years old – geologic processes work slowly over millions

of years• Charles Lyell: 1833 geologist provided

evidence that earth is millions of years old.– Processes that shaped the Earth for millions

of years continue in the present• Thomas Malthus: 1793 economist proposed

idea that continued human population growth would lead to insufficient living space and food for everyone

Evolution by Natural Selection

• Struggle for Existence –– Members of each species compete to obtain

food, living space, and other resources necessary for life

• Survival of the Fittest –– Individuals that are better suited to their

environment survive and reproduce most successfully.

– Adaptation any inherited characteristic that increases an organism’s chance at survival

The result of Natural selection . . .• New Species: a groups of organisms that

can reproduce and make fertile offspring– Species today look different from their

ancestors

• 2 main sources of genetic variation:– Mutations (random changes in DNA due to mistakes

in copying)– Gene shuffling during sexual reproduction\

• All eggs have different DNA from the mom• All sperm have different DNA from the dad• So no two offspring are alike

• Gene pool: all genes (and alleles) that are present in a population

• Relative frequency: # of times an allele occurs in a gene pool (given as a percentage)

• Evolution: is any change in the relative frequency of alleles in a population

How do genes found in a population change?

Hardy Weinberg

Darwin’s finches• Darwin collected birds from different

islands of the Galapagos Islands and brought them back to England to study.

• He noticed there differences in beak structure.

• He determined they were from 13 different species.

• Video You tube: A look at the finches of the Galapagos islands http://www.youtube.com/watch?v=l25MBq8T77w

• Different Beaks are different adaptations to their environment

• Adaptation: An inherited trait that gives an organism an advantage in its particular environment

What beak is adapted to which food source: grubs, insects, leaves,

buds/fruit, tool for getting insects

• Woodpecker finches were able to evolve into the same niche as the woodpeck ers because they have no competition for that particular niche. They have the ability to use and make tools that allow them to feed on insects in their environment. Had there been another bird in that niche the competition might have forced them into another lifestyle or they would have become extinct.

• Both birds are able to occupy the same role because they re in different environments

• If both birds were to somehow reside in the same environment they would compete for the same diet. Since the woodpecker is better able to geed with out the aid of a tool they would be able to feed faster. Survive easier and reproduce more offspring.

• The woodpecker finch would not find enough food to survive in the environment if the woodpecker finch could not change to another niche it would become extinct.

• There might be a lack of predators for one of the birds that would cause that species to overpopulate that area.

• The bird more accustomed to the insects and plant s in the environment would be the best fit and would survive.

• The bird new to the environment would be an invasive species and though it may become abundant by changing the environment. It could cause a reduction in the food for another species of animal destroying breeding places the overgrowth of another unwelcome species etc.

• 73. #3 both have grasping bills and eat insects

• 74. #2 grasping and probing would enable the birds to eat those prey

• 75. #4 parrot like bill of the vegetarian tree finch is suited to eating fruits.

Darwin reasoned that the ancestor was a bird from South America which over generations had changed to become adapted to the different environments of different Galapagos Islands.

website

• http://evolution.berkeley.edu/evolibrary/article/evo_14

Natural Selection and Genetic Change 3 different outcomes:

– Directional Selection– Stabilizing Selection– Disruptive Selection

– Good website to visit: http://wps.pearsoncustom.com/wps/media/objects/3014/3087289/Web_Tutorials/17_A02.swf

Directional Selection

Stabilizing Selection

Disruptive Selection

The Process of Speciation

• Formation of a new species (organisms that breed and produce fertile offspring)

• As new species evolve, populations become isolated from one another because of . . . . . – Reproductive isolation members of 2 populations

can no longer interbreed and produce fertile offspring– Behavioral Isolation differences in courtship or other

reproductive strategies that involve behavior– Geographic Isolation 2 populations are separated

by geographic barriers– Temporal Isolation 2 or more populations reproduce

at different times of the year

Rate of speciation might be . . .

• Gradual: gradualism• Rapid and then stay the same: Punctuated

Equilibrium

Gradualism

Punctuated Equilibrium

Cladogram

• http://evolution.berkeley.edu/evolibrary/article/evo_03

Interpreting a cladogram

Antibiotic resistance bacteria

• Why does evolution matter now TB in Russian prisons. http://www.pbs.org/wgbh/evolution/library/10/4/l_104_09.html (discusses “Sasha”)

• http://www.pbs.org/wgbh/evolution/library/11/2/quicktime/e_s_6.html (best clip uses term “natural selection”

• Human Skin colorhttp://www.ted.com/talks/nina_jablonski_breaks_the_illusion_of_skin_color.html

End of notes for 2012-13 (classification covered 1st

semester)

Yes, you too are a Homo sapiens

Common Names

• Names for organisms that are commonly used in a particular language– The name is different in different languages

• Dog (english)• Hund (german)

– The name can be different in the same language in different regions• Crayfish• Crawdad

Vocab word: Binomial nomenclature

• The two word naming system that makes up scientific names is called: binomial nomenclature

• Scientific names are:– Two words– 1st word is the Genus, 1st letter capital– 2nd word is the species, all lower case– Example: Homo sapiens

Who uses scientific names?• Scientists, of course • Farmers• anyone buying or selling seeds• Florists• Horticulturists, people who

own/work at a greenhouse or nursery

• Landscapers• Arborists (person who takes

care of trees, like pruning them, planting for a city, etc)

• Gardeners• Veterinarian• Doctor• fisherman

•

Commonly used taxonomic categories in today’s science

• DOMAIN• Kingdoms• Phylum• Class• Order• Family• Genus• Species

• DO• Keep• Pigs• Clean • Or• Fear• Great • Smell

3 DomainsDomains are groupings larger then Kingdoms

http://www.globalchange.umich.edu/globalchange1/current/lectures/complex_life/threedomains.gif

• Single celled• prokaryotic cells• Cell wall with

peptidoglycan • Single celled• prokaryotic cells• Cell wall without peptidoglycan

• Single and multi-celled• eukaryotic cells• Some have Cell walls some do

not

Cladogram• A cladogram is a diagram that shows how organisms are related to one another

by comparing body organs and parts.• Branching lines of a cladogram show how closely two organisms are related. • The intersection between lines is the point where there would have been a

common ancestor that evolved into the organisms at the end of the lines.• Time is shown on a cladogram the top is most recent and lower down towards

the bottom is the past.• Along the lines shared characteristics are shown. Any organism above that

mark has that characteristic.

http://evolution.berkeley.edu/evolibrary/article/0_0_0/phylogenetics_10

Time

Shared characteristics

humanMost recent

Distant past

Human Horse Tuna

Common ancestor of human and horse

placenta

backbone

Cladogram from textbook