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Evolution a change in the genetic makeup of a species overtime 1 History of evolutionary thought Lamarck Inheritance of Acquired Traits: An organism can pass along characteristics acquired during its lifetime to its offspring Driven by a need giraffe would continually stretch its neck until it became a little longer. When it reproduced offspring would be born with longer necks because that trait had been acquired already by parent. 2 Charles Darwin 1831- Beginning of a 5 year exploration around the world on the HMS Beagle Studied the variety of life around the world Spent a large amount of his trip in the Galapagos Islands Made his break through discovery through the different species of finch he found finch he found on each island. All descended from a common ancestor Each species evolved to optimize its adaptations for the different environment found on the different islands Natural Selection-The organisms best adapted to their environment tend to survive to transmit their genetic characteristics to succeeding generations, which results in increasing numbers of organisms with those traits while the genetic characteristics of less adapted organisms tend to be eliminated over time. 3 How Evolution Works Natural Selection: 4 Mechanisms • • • • genetic variation over production of offspring struggle for survival differential survival and reproduction rates 1.Genetic Variation -Different genes create different phenotypes. -Advantage: More likely to pass along genes and trait becomes more common over time -Disadvantage: Less likely to pass along genes and trait diminishes over time 4 2. Overproduction of offspring : Most organisms produce many more offspring than can be supported by the environment 3. Struggle for survival: -Predator/Prey Relationships -Limited Resources -food, shelter, water, territory, sunlight -Environmental Challenges -Temperature, Disease, Pollution, etc. 5 4. Differential Survival and Reproduction Rates -Different Traits create advantages/disadvantages to an organisms ability to survive and to reproduce Survival Traits: Coloring, Physical Traits, Heightened Senses http://www.youtube.com/watch?v= 9iQwKYi6ytg&feature=bf_prev&list=PLCC07E66503F99BB5&lf=results_main Physical Traits- Stronger, Faster, Bigger/Smaller, Growth Rate http://www.youtube.com/watch?v=FfDOMwFX5Hg&feature=results_main&playnext=1 &list=PLCC07E66503F99BB5 Heightened Senses-Better eyesight, sense of smell, hearing, etc. Types of Coloring: Mimicry- When an organism attempts to look like another organism (Copycat) Aposematic- When an organism is brightly colored or has highly contrasting marking to warn other organisms to stay away (WARNING!) Cryptic- When an organism is coloring allows it to blend in with its environment (Camouflage) Counter Shading- When an organism is colored darker on its back and lighter on its front to limit it being seen from above and below (darker back lighter stomach) 6 Mimicry Elephant Hawk Moth caterpillar Dead Leaf Butterfly Owl Butterflies Red Milk Snake (non-venomous) King Snake (venomous) Hawk Moth Alligator Snapping Turtle Death Adder Leafy Sea Dragon 7 Aposematic Poison Dart Frogs Saddleback Caterpillar Monarch Butterfly Caterpillar Stinging Rose Caterpillar Spiny Oak Slug Caterpillar 8 Cryptic Screech Owl Flounder Arctic Fox Leopard Spotted Eel 9 Countershading 10 Differential Survival & Reproduction Rates Cont'd. Sexual Selection: Ability to attract/get a mate -2 types -Between Same Sex (Males) -Attracting Opposite Sex (attracting female) http://app.discoveryeducation.com/player/view/assetGuid/841DDC20C7AE467FA1A5 E731E264B1E5 http://dsc.discovery.com/videos/planetearthjunglesbirdsofparadise.html 11 Natural Selection: "Survival of the fittest." -What does fittest mean? Bigger, Stronger, etc.? Best at hiding from predators? Ability to attract mate? Fittest: The organism that is best adapted to its conditions to survive to pass its genes to the most offspring compared to other organisms of the same species. Who is the most fit? Lived 20 years Offspring: Simba Lived 30 years Offspring: None 12 How do we know evolution exists? Evidence for Evolution -Fossil Record -Biogeography -Chemical & Anatomical Similarities -Documented changes in living species Examing the Fossil Record: Strata-the layers of soil and rock deposited over time Creating a continuum of life through strata The deeper the strata the older it is--fossils found in deeper layer are from older species Radioactive Dating -Using naturally occurring radioactive isotopes (in rocks, fossils, organic matter, etc.) to find the age of the item the isotopes are contained in 13 Radioactive Dating Isotopes- Different versions of the same element that have the same atomic number but different atomic masses Ex. Carbon 12, 13, 14 (atomic mass) Carbon has six protons (atomic number) Carbon 12 has 6 protons 6 neutrons Carbon 13 has 6 protons 7 neutrons Carbon 14 has 6 protons 8 neutrons Radioactive Isotopes-isotopes that are unstable and decay (change by breaking down) to a stable isotope of something over time Half-Life: The amount of time it takes for 1/2 of the radioactive isotopes to decay. How old is a fossil that currently has 12.5 % of its original C14? 5, 730 years per half life x 3 half lives+ 17,190 years old 14 RHEA OSTRICH EMU Biogeography Biogeography- The study of the distribution of species around the world and through history 15 Chemical and Anatomical Similarities Between Species Chemical Similarities: The amount of DNA sequences that are similar between different species -The more recent the common ancestor the more similarity between genome (total DNA) Anatomical Similarities: members of the same class of animals tend to have similar structures and organs, even though they may not look the same externally. 16 Observed Changes In Living Organisms MRSA- Multidrug-Resistant Stapphylococcus Aureus Majority Light Industrial Revolution Majority Dark Majority Light Anti-Pollution Legislation Passed 17 Role of fitness in speciation Speciation- Evolutionary process where new species arise Species- Organisms capable of interbreeding and producing fertile offspring Population Genetics: Disruptive Selection: Often results in 2 new species Stabilizing Selection: Reduces variations no new species Directional Selection: Often results in new species 18