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 Evolution

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

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)

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

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