EVOLUTION Objectives: 1.Explain how natural selection works? 2. What observations did Darwin helped him develop the theory of evolution? 3.What does adaptation mean? Give an example of an organism adapting to its environment.

Quiz 1. What don’t harmful mutations accumulate over time? 2. Why can we use observations of bacteria as evidence of evolution? 3. What is the difference between a hypothesis and a theory? 4. What is selective breeding?

Early theories (pre-1700’s)  Before Darwin, nature was seen as not changing but as having originated through spontaneous generation.

1700’s  An understanding of the age of the Earth develops through geology.  The Earth has been and is still gradually changing.  Inheritance of acquired traits (use and disuse). ex. Baby giraffes are born with long necks because their parents stretched their necks to reach leaves (Jean-Baptiste Lamarck, 1801) ex. Baby giraffes are born with long necks because their parents stretched their necks to reach leaves (Jean-Baptiste Lamarck, 1801)

Misconception

Genetics and the Passing on of Traits   Living organisms pass on their traits to their offspring.   Today’s species came about through gradual change.   What drove that change? SURVIVAL/SEX/!!!!

Darwin and the Voyage of the Beagle  December, 1831’s, Charles Darwin, a naturalist in his 20’s began a 5-year journey around the world on a ship called HMS Beagle  Darwin’s role was to observe, record, and collect specimens of rocks, minerals, plants, and animals

 Darwin collected 1000’s of specimens and shipped them to England, mainly from South America and a chain of volcanic islands called Galapagos  He did not realize what he was seeing until years later (ex. didn’t catalogue the finches very well, ate turtles that would later support his theories, etc.)  Darwin spent the next 20 yrs analyzing his findings in light of artificial selection (ex. breeding of pigeons, breeding of dogs, etc.)

Darwin’s Finches  Arrival  Success  Competition  Diversity & Opportunity  Radiation

 Perhaps a single ancestral species transported from nearby land might give rise to a number of similar but distinct new species.

 Hawaiian honeycreeper

What Darwin Observed   1) Homologous Features Homologous features: different functions, but similar structure (flippers, hands, wings) All forelimbs of vertebrates have the same pattern of bones All forelimbs of vertebrates have the same pattern of bones

ex. The flippers of whales, and the wings of birds

  2) Analogous features: similar functions, but different structure (wings of birds and bees)   Darwin’s conclusion: organisms with homologous features likely shared a more recent ancestor, while those with analogous features do not!

  3) Vestigial Features: non-functional structures that are homologous to fully functioning structures in closely related species. Example: whales have pelvic bones that do not attach to legs

  4) Similarities in Early Development (tailbones)   Goosebumps   Darwin’s conclusion: these ‘leftover’ features must have once had a use!

Other Evidence for Evolution…  Stuff that we have seen in our time…

When comparing the DNA of one species to another, more similarities are found in species that are more closely related.

Evidence for Evolution The Fossil Record-Layer show change The Fossil Record-Layer show change Shows numbers extinct animals Shows numbers extinct animals Shows similarities between extinct animals and animals that are alive today Shows similarities between extinct animals and animals that are alive today The earth’s layers show a time scale of species and when they appeared on earth (and when they died out) The earth’s layers show a time scale of species and when they appeared on earth (and when they died out)

Transitional fossils are fossils that show intermediary links between groups of organisms Transitional fossils are fossils that show intermediary links between groups of organisms They can provide a link between the past and present They can provide a link between the past and present

Direct observation of species change Bacteria become resistant to antibiotics Bacteria become resistant to antibiotics Wolves were bred over many generations to become dogs (artificial selection) and then bred further to create a variety of breeds Wolves were bred over many generations to become dogs (artificial selection) and then bred further to create a variety of breeds

But how does evolution really work???  How does evolution really work? ors/teachstuds/svideos.html ors/teachstuds/svideos.html ors/teachstuds/svideos.html

What did Darwin think drove Evolution???   1) Artificial Selection Selecting offspring with desirable traits as breeding stock for succeeding generations Example: corn with higher oil content Darwin’s conclusion: if people could alter the appearance and behaviour of species through artificial selection, then the environment could have a similar selective effect on wild species!

Natural Selection & Artificial Selection Natural variation--differences among individuals of a species Natural variation--differences among individuals of a species Artificial selection- nature provides the variation among different organisms, and humans select those variations they find useful. Artificial selection- nature provides the variation among different organisms, and humans select those variations they find useful.

Evolution by Natural Selection The Struggle for Existence- members of each species have to compete for food, shelter, other life necessities The Struggle for Existence- members of each species have to compete for food, shelter, other life necessities Survival of the Fittest-Some individuals better suited for the environment Survival of the Fittest-Some individuals better suited for the environment

  The Struggle for Survival Plants and animals produce more offspring than are able to survive Favourable variations would tend to be preserved, unfavourable ones would be destroyed. INTENSE COMPETITION!!!!!

Natural Selection as the Cause of Evolution - called “natural selection” because it happens on its own 1. Genetic Variation - there are many varieties of alleles - caused by random mutations - can be passed onto offsprings (inherited variation) 2. Overproduction of Offsprings - organisms make too many offsprings

3. Struggle for existence - competition for limited resources 4. Differential survival and reproduction - only organisms that have certain characteristics will survive to reproduce - non-random, caused by the environment: amount of food, competition (ex. Darwin’s finches)

 PBS Evolution: The Evolutionary Arms Race (12 min)  Answer questions on video.

 Your task… (Due for tomorrow!!!) 1. Read through the handout on Adaptation and Variation 2. Answer questions 1-5 All of this takes a LOOOOOOONG time