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Evolution Part I

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Evolution

• Changes in a population over time

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Earths Position in the Universe

• 400 years ago the general public thought that the earth was the center of the universe– Sun revolves around

the earth

– The earth does not move

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Galileo and Corpernicus

• Demonstrated scientific evidence that the sun is at the center of our solar system and the earth moves around the sun

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Galileo and the Church

• Religious leaders felt the heliocentric theory (sun at the center) was a direct contradiction to the literal interpretation of the Bible

• Galileo found guilty of heresy

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Copernican System (Heliocentral Theory)

• Did not destroy peoples belief in God

• Public now accepts the overwhelming evidence for the heliocentric theory

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Theory of Evolution

• Science has overwhelming evidence that all life is constantly evolving

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Charles Darwin 1809-1882

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HMS Beagle 1831-1836

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Ostrich in Africa Rhea in South America

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Adaptive Radiation

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Land Iquana

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Marine Iquana

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Different Tortoises on Each Island

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Origin of Species 1859

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Natural Selection

• One mechanism of evolution

• Main concepts of natural selection– Overproduction of offspring– Inherited variation in offspring– Competition – Best adapted in a given environment survive

and reproduce to increase their kind• They are naturally selected

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Overproduction of Offspring

• Elephants (very slow reproductive rate)– If all the offspring of one elephant pair survive and all

their offspring survive then:• 750 years = 19,000,000 elephants• 1200 years = Enough elephants to cover the earth!

• Beetles– A handful that weighs 10 mg each– 82 weeks

• 61,000,000,000,000,000,000,000 ton– The weight of the earth!

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Variation of Offspring

• Offspring of the same parents are different from each other

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Competition

• Since more individuals are born than can survive for an extended period of time, they compete for resources– Food– Living space– Mates

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Best adapted to a given environment are selected to survive

• Brown bears– Adapted to survive in

Oklahoma

• Polar bears– Adapted to survive in

Alaska

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Artificial Selection

Collie crossed with Scandinavia Spitz

Sheltie

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Evolution is Change• Changing alleles in a population can

produce new species

• Dogs have evolved from wolves

• Man has artificially selected traits to produce the various dog breeds

• Nature uses natural selection and other mechanisms for evolution

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Natural Selection of

Flies

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• Natural Selection

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Scientific Disciplines That Give Evidence for Evolution

• Paleontology

• Comparative anatomy

• Biogeography

• Molecular biology

• Others

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Paleontology

• Study of fossils – Allows us to see

anatomical similarities between living species and organisms that lived in the past

– Allows us to see how life has changed over time

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Life Has Changed

• Millions of species have been found that are different from life today

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Horse Evolution

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50 Million Years of Change

50 MYA 30 MYA 15 MYA Modern

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Florida Museum of Natural History

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• Whale evolultion

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Comparative Anatomy

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Homologous Structures• Same structures used for different purposes

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Homologous Structures

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HomoplasyAnalogous Structures

Similar structures due to convergent evolution,

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Biogeography

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Why No Polar Bears in Antarctica or No Penguins in Arctic?

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Why marsupials in Australia?

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Molecular Biology

• The study of the molecules of life including DNA and proteins

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DNA Similarity

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Homeobox or HOX

• First discovered in fruit flies in 1983

• Later found in mice, man and other organisms

• Controls embryonic development of different body regions

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Evolution of New Body Plan

• Hox gene Ubx of crustacean mutated in lab

• Caused suppression of leg development

• Mechanism for evolution of insect body plan 400 MYA

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• Homeobox genes

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Comparing DNA

• Human DNA compared to:– Chimpanzee 99% same

– Gorilla 97.7% same

– Orangutan 96.3% same

– Another human 99.9% same

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Comparing Protein Sequences

• Many proteins in all of man are identical

• Organ transplants require similar proteins in the donor and the recipient– A sibling or parent is often the best source for

an organ transplant

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Which would be the closest protein match for an organ transplant?

Assuming all are alive and healthy.

• A persons father

• A persons great grandfather

• A persons 10th great grandfather

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Molecular Clock

• The further you go back in time, the more proteins (and DNA) are different.

• Differences in protein sequences and DNA can be used to estimate time when two species shared a common ancestor

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Related Organisms

• Close similarity of protein sequences indicates close relationship

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Cytochrome C

• Protein used to release energy from food

• 104 amino acids• 20 of the amino acids

occupy the same position in all eukaryotes

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Comparison of Human Cytochrome C

• 100 amino acids different in tuna fish

• 12 amino acids different in a horse

• 8 amino acids different in a kangaroo

• 1 amino acid different in a monkey

• Identical to chimpanzee

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Pattern of Evolution Originally Based on Fossil Record

• DNA comparisons confirm the same pattern

• Protein sequences confirm the same pattern

• 150 years of research by thousands of scientists demonstrate beyond doubt that life evolves.