Evolution- Chapter 10 Process of biological change that results in descendants being different from their ancestors

Early Scientists  Linnaues- developed classification system  Leclerc de Buffon- argued that species shared ancestors & that the Earth was much older than 6000 years- which most scholars believed  Eramas Darwin- proposed that all living things were descendants of a common ancestor  Lamarck- proposed that all organisms evolved toward perfection and complexity due to environmental changes (long neck of giraffe)  Charles Darwin- developed Theory of E volution

Theories of Geologic Change  Catastrophism- natural disasters that changed Earths landform resulted in species to become extinct; a different species would move into the area  Gradualism- landforms resulted from slow changes over a long period of time;  Uniformitarianism- geologic processes that shape Earth are uniform through time and that they have occurred at a constant rate and are ongoing  Most accepted

Darwin’s Observations  Variation of traits among similar species; Variation-differences in traits  Species from one island looked different from those on nearby islands in the Galapagos Island chain.  Examples:  Saddleback tortoise-long necked lived in area with tall plants  Dome-backed tortoise- short neck lived in wet area with short plants Adaptation- a feature that allows an organism to better survive and reproduce in its environment

Fossil and Geological evidence  Fossils (Paleontology) of huge animals that are similar in appearance to modern animals  Fossils of marine (sea) animals on the top of mountains  Geography-Organisms change to their environment; Species that get separated from each other develop adaptations that favor their environment  Developmental Similarities (notochord, dorsal nerve cord, pharyngeal arches (face in humans, gills)  Homologous structures- hand, bat wing  Analogous structures-perform similar functions (wings of bat to wings of fly)  Vestigial structures- organs not used ( appendix)

Tools to Date Fossils

Theory of Natural Selection- Darwin  Artificial Selection- humans a species by breeding it for certain traits – selective breeding (pugdoodle, racehorses)  Natural Selection- individual organisms that have inherited a beneficial adaptation tend to produce more offspring than other organisms of that species.  Population- all the individuals of a species that live in an area

Main Principles of Natural Selection  Variation-inheritable differences in a population that come from changes in genetic material by beneficial traits passed on or by mutation  Overproduction- many offspring increase chance of survival of species; also results in competition for resources  Adaptation- beneficial trait that gives species an edge on competition; live longer & more offspring  Descent with modification- over time, natural selection will result in species with adaptations that are well suited for survival and reproduction in an environment.

Evolution of Populations – Chapter 11  Genetic variation- more variations in the gene pool the better chance of survival (gene pool- combined alleles of all individuals in a population) Mutations or Recombination during meiosis (crossing over)

Distribution of Traits  Normal Distribution- the frequency is highest near the mean value  Directional Distribution-favors phenotypes at one extreme of a trait’s range drug resistant bacteria  Stabilizing Selection- intermediate phenotype becomes more common  Disruptive Selection- both extreme phenotypes become more common

Other Mechanisms of Evolution  Gene flow- the movement of alleles from one population to another; increases genetic variation (which helps with survival of species)  Genetic Drift- a change in allele frequency due to chance; causes a loss of genetic diversity  Bottleneck effect- event reduces size of population (overhunting, catastrophe)  Founder effect-small number colonize a new area (Amish )

Origin of Life Hypotheses  Organic molecules were produced from lightning passing through atmosphere of methane, ammonia, and water vapor (miller-urey experiment)  Organic molecules arrived by meteorite

From Prokaryote to Eukaryote- How multicellular came from unicellular

Radiation (spreading out) of Multicellular Life  Paleozoic- multicellular organisms first appeared; Cambrian explosion- huge diversity of animal species evolved  Mesozoic- Age of Reptiles  Triassic- earliest crocodiles and dinosaurs and first animals; ended in mass extinction  Jurassic- radiation of other dinosaurs; many underwater dinosaurs  Cretaceous- ended in mass extinction of dinosaurs  Cenozoic-65 million years ago to today - mammals radiate to all parts of earth

Cladograms