We the Galapagos Islands Definitions to Know Scientific Theory = a well- supported, testable explanation of phenomena that have occurred in the natural world. Evolution = change over time, the process by which modern organisms descended from ancient organisms

We the Galapagos Islands Charles Darwin ( ) British naturalist famous for his theories of evolution and natural selection. Like several scientists before him, Darwin believed all the life on earth evolved (developed gradually) over millions of years from a few common ancestors. In 1831, Darwin took a trip around the world on the ship, the M.S. Beagle, where he collected evidence that led him to propose his famous Theory of Evolution. Charles Darwin

We the Galapagos Islands Darwin’s Voyage on M.S. Beagle Starting point: 1831, England Ending point: 1836, England Darwin’s observations showed him there were patterns to the diversity of life on Earth. Organisms are adapted to the environment where they live. Did you know there are no rabbits in Australia? No kangaroos in England? No monkeys in North America? No elephants in Alaska?

We the Galapagos Islands Fossils Darwin didn’t just observe and collect living animals, he also collected fossils. Fossils = preserved remains of ancient organisms This led to questions like…. –“Where did all these organisms go?” “Why aren’t they still here?” “Why do they resemble organisms we have living today?” Glyptodon = deadArmadillo= alive

We the Galapagos Islands The Galapagos Islands The most important, influential stop on Darwin’s trip was the Galapagos Islands The islands had different climates, and therefore, had different varieties of animals and plants 1.Giant Tortoises2. Iguanas3. Finches

We the Galapagos Islands Galapagos Turtles Pinta Island Intermediate shell Pinta Isabela Island Dome-shaped shell Hood Island Saddle-backed shell Hood Floreana Santa Fe Santa Cruz James Marchena Fernandina Isabela Tower The shape of each turtle’s shell is different and the different shapes depend on the turtle’s habitat.

We the Galapagos Islands Darwin’s Finches Darwin also collected finches, birds, matching their beak and body shapes with different islands- just like the tortoises. Beak shapes in the finches indicated their type of diet, what they ate, and this told him where they lived Ground finch Tree Finch

We the Galapagos Islands Darwin’s Finches FYI, each beak is designed for a different purpose. Leaves Seeds InsectsGrubs Tool using Seeds and Fruit Box 12

We the Galapagos Islands What took him so long? 25 years later…. In 1858, Alfred Wallace sent Darwin an essay with the same ideas about evolution! They presented their work together at a conference, but…. This pushed Darwin to publish his work, before Wallace The Origin of the Species –Proposed a mechanism for evolution, called Natural Selection –Presented evidence that evolution has been happening for millions of years

We the Galapagos Islands Artificial Selection and Natural Selection Variation exists in nature and animal and plant breeders use this through artificial selection –A farmer may like a see a plant with bigger tomato and use the seeds of that plant for next year’s crop –Or he may breed the two best milk cows to get a cow who is an even better producer of milk Darwin’s greatest contribution was his concept of natural selection In the struggle for survival, the most fit- the fastest prey, the strongest predator, the one with the sharpest claws, wins the game of survival. Survival of the fittest. Fitness = the ability to survive and reproduce in a specific environment Adaptation = any inherited characteristic that increases an organisms chance of survival

We the Galapagos Islands Proof for Evolution Fossil record = Darwin argued that the fossil record provided evidence that living things have been evolving for millions of years Geographic Distribution of living species: Descent with modification, says that similar species in similar environments but in different locations, were products of different evolution paths They developed similar characteristics because of their environment. Beaver Muskrat Beaver and Muskrat Coypu Capybara Coypu and Capybara

We the Galapagos Islands Homologous Body Structures What does Homo mean? –Homo = same, similar Remember these? –Homozygous- same allele for a trait, tt, TT –Homologous chromosomes- same chromosome, one from mom one from dad TurtleAlligatorBirdMammal Ancient lobe-finned fish Homolgous structures all develop from the same embryo tissues but have different functions in the adult organism.

We the Galapagos Islands Vestigial organs Why do we need our appendix? It’s useless now, but it may have served some function in our past Vestigial organs = organ with little or no function, left over from the past, ex. appendix If you can live without it, with no medical help, then it’s useless!

We the Galapagos Islands Ch. 16, Evolution of Populations Why are we all so different? Variation in populations is the raw material for evolution 2 main sources of variation: –Mutations = any change in a sequence of DNA, some are harmful, some are beneficial and some don’t have any effect at all –Gene shuffling = mixing of genes due to random sexual mating 23 pairs of chromosomes can produce 8.4 million different combinations of genes Crossing over during Meiosis

We the Galapagos Islands Variation and Gene Pools Genetic variation is studied in POPULATIONS, not individuals Members of a population share a Gene Pool Gene pool = consists of all genes, including all the different alleles that are present in a population –Why? –They descended from a common ancestor Relative frequency of an allele = number of times an allele occurs in a gene pool So, evolution is any change in the relative frequency of alleles in a population

We the Galapagos Islands Natural Selection and Speciation Natural Selection= (Dr. Malone’s definition) when individuals who have what it takes survive and reproduce best; survival of the fittest, it’s a dog eat dog, you got to step on someone else to get where you want to go, world Founder Effect = when a population shrinks down to only a few members, then rebounds so all of the future members have the “founder’s” genes Speciation = when natural selection and other random effects lead to the creation of a new species –Reproductive Isolation = populations become reproductively isolated from each other, so it leads to evolution of a new species

We the Galapagos Islands Speciation Behavioral Isolation = when two populations can interbreed, but their different behaviors, or reproductive strategies, just don’t turn each other on, get it? Geographic Isolation = two populations are separated by geographic barriers, like mountains or oceans and they can’t interbreed Move mountain! It’s too far to fly! Temporal Isolation = two populations are separated by different reproductive times