CHARLES DARWIN’S THEORY OF EVOLUTION

EVOLUTION: A CHANGE IN ORGANISMS OR POPULATIONS OVER A LONG PERIOD OF TIME. Glyptodon Armadillo

CHARLES DARWIN: TRAVELED AROUND THE WORLD ON HMS BEAGLE – 1831 COLLECTED VARIETY OF ANIMALS & PLANTS ALSO COLLECTED FOSSILS (PRESERVED REMAINS OF PLANTS AND ANIMALS)

GALAPAGOS ISLANDS: small group of islands 1000 km west of South America

Darwin’s Famous Finches DARWIN OBSERVED THAT TRAITS VARIED AMONG THE PLANTS AND ANIMALS FOUND ON EACH ISLAND. Darwin’s Famous Finches

EARLY INFLUENCES ON DARWIN: CHARLES LYELL (a geologist): geological processes changed the Earth over a long period of time.

Jean-Baptist Lamarck * Living things changed over long periods of time * All species descended from other species * All organisms somehow adapted to their environment.

He also proposed: The Inheritance of Acquired Traits: - could change the shape of organs by using their bodies in certain ways and that this trait was then passed on to offspring. Ex: long necks of giraffes.

Thomas Malthus: (An economist) if the human population continued to grow unchecked, sooner or later there would be insufficient living space & food creating competition.

Darwin also noted variation among members in a species. Some were inheritable, others were by … Artificial Selection –HUMANS select the most desirable traits to pass on to offspring.

In 1859, Darwin published “On the Origin of Species” in which he proposed the mechanisms of evolution -- Natural Selection * a process by which individuals better suited to their environment survive & reproduce most successfully. (aka “survival of the fittest”)

Fitness: the ability for an organism to survive and reproduce in its environment. It’s a result of adaptation. Adaptation: any inherited characteristic that increases an organism’s chances for survival.

Darwin also argued that living things have been evolving for millions of years and was evident by: * the fossil record * homologous & vestigial structures * embryology. * geographic distribution of living species

Fossil Record: information about past life, structure of organism, what they ate, what ate them, where they lived and order in which they lived. Ex: CEPHALOPODS

Homologous structure: have different mature forms but develop from the same embryonic tissue.

Analogous structures: structures that are similar in function but differ in structure. Ex: insect wings vs. bird wings

Vestigial structures: An organ or structure that serves no useful function in an organism.

Embryology: the early stages are very similar among species.

Genes control the inheritance of traits creating genetic variation. Genetic variation is studied among populations. Population: a group of individuals of the same species that live in same area. Gene Pool: all the genes, including all the different alleles, that are present in a population.

Extinction: the disappearance of a species from all parts of its geographic range. Ex: dinosaurs

Ex: Polar Bears vs. Brown Bears Adaptive Radiation: the process by which a single species evolves into several different forms that live in different ways. Ex: Polar Bears vs. Brown Bears

Convergent Evolution: the process by which unrelated organisms come to resemble one another. Shark Penquin Dolphin

Co-evolution: the process by which two species evolve in response to changes in each other over time, such as plants and pollinators (birds, insects).