What is Evolution?

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What is Evolution?
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EVOLUTION the process of change over time

• Evolution is the idea that new species develop
  from earlier species by accumulated changes.

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Charles DarwinThe Father of Evolution

• A scientist that traveled the world making
  observations and collecting evidence about the
  way life changes.

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Darwins Travels

• He sailed from England as a crew member on the
  H.M.S. Beagle
• Wherever the ship anchored, Darwin went ashore to
  collect plant and animal specimens that he added
  to his research collection.

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Darwins Travels cont..

• Darwin selected the Galapagos Islands for study
  because each island had different climates and a
  variety of animal and plant life.
• Darwin observed that the characteristics of many
  animals and plants differed greatly among the
  different islands.

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The Origin of Species

• Darwins book presented evidence that evolution
  has been taking place for millions of years and
  continues in all living things

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Darwin's Hypothesis

• Survival of the fittest (not necessarily the
  strongest) Those with more adaptive traits tend
  to survive longer and/or produce the most
  offspring.

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Artificial NaturalSelection Selection

• Selections by humans for breeding useful traits
  from the natural variations among different
  organisms

• Individuals better suited to their environment
  survive and reproduce most successfully

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Artificial Selection How did humans in
relatively short time produce dogs that are so
radically different from the wolf and each other?

• Sometimes, dogs are born with unusual
  traitsshort, stubby legs, for example.
• In nature, this trait might be harmful but under
  the care of humans, this trait may be desirable,
  so humans will keep the dog alive and use it to
  produce more dogs with short stubby legs.

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Natural selection is based on 4 facts

• 1.Organisms produce more offspring
  than can survive.
• 2.There is variation among offspring.
• 3.There are limited resources
• (not enough food, water, space,
• etc. for everyone).
• 4.The organisms best fit to their environment
  will survive and the others will not.

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Evidence of Evolution

• Fossils are preserved remnants or impressions
  left by an organism that lived in the past.
• The deeper down the fossil
  is, the older it is.

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FOSSIL RECORDS

• The fossil record provides evidence about the
  history of life on Earth.
• It also shows how different groups of organisms,
  including species, have changed over time.

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Homologous StructuresStructures that have
different shape and functions in different
organisms but develop from the same embryonic
tissues.

• Examples The limbs of the modern HUMAN, BIRD,
  PORPOISE and ELEPHANTS are homologous structures
  because they possess the same bones but these
  bones perform different jobs.

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Adaptations Inherited characteristic that
increase an organisms chance of survival

• Why are most animals in the artic white?
• So they blend in with the snow and avoid being
  seen
• Why do sharks have such sharp
• teeth?
• It allows them to catch their prey
• Why do elephants have such big ears?
• To let heat escape their bodies so they can
• stay cool

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Vestigial Organsorgan that serves no useful
functionover generations, they reduce in size
Human Appendix
Whale
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DARWINS Theory Of Evolution

1. Differences between species may be the result of
   natural selection.
2. Organisms produce more offspring than can
   survive, and many that do survive do not
   reproduce.
3. Because more organisms are produced than can
   survive, they compete for limited resources.
4. Individuals best suited to their environment
   survive and reproduce most successfully.
5. Species change over time.

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Gene Pool

• All genes, including all the different alleles
  presents in a population

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Genetic Variations

• Two main sources of genetic variation are
  mutations and the genetic shuffling that results
  from sexual reproduction

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5 Conditions for maintaining genetic
equilibrium

1. Random mating
2. Population must be very large
3. There can be no movement into or out of the
   population
4. No mutations
5. No natural selection

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Results of Evolution -- Speciation!!

• Speciation is the process that creates new
  species!
• A species is a group of organisms that can
  naturally interbreed and produce fertile
  offspring.
• The Liger--the offspring of a tiger and a lion.
• Tigers and lions are still considered separate
  species, because although they can produce
• offspring, the offspring
• is not fertile.

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ENDOSYMBIOTIC THEORY

• Theory that eukaryotic cells formed from a
  symbiosis among several different prokaryotic
  organisms.
• A group of single celled organisms came together
  to make a multicellular organism.

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Types of Evolution

• Convergent Evolution process by which unrelated
  organisms independently evolve similarities when
  adapting to similar environments.
• Ex.. Sharks, Penguins Dolphins

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Types of Evolution

• Coevolution process by which two species evolve
  in response to changes in each other.
• Ex.. Humming Birds Flowers

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Extinction!

• Extinction occurs when there
  are no members of a species
  left alive.