10.1 Early Ideas About Evolution

Spontaneous Generation – living things could come from nonliving things Biogenesis – all living things come from other living things

10.1 Early Ideas About Evolution Observation –Tiny wormlike maggots turned into sturdy oval cases, from which flies eventually emerge Francesco Redi – questioned the belief that flies were generated spontaneously from rotting meat Experimental Group – jars with nets over them that contained meat inside –Netting allowed air to enter but not flies Control Group – uncovered jars with meat inside Result – maggots swarmed over the meat in the open jars while the experimental remained maggot free

10.1 Early Ideas About Evolution Control Experimental A: Independent Variable - cork Experimental B: Independent Variable - net

10.1 Early Ideas About Evolution Hypothesis – microorganisms form not from air but from other microorganisms Spallanzani Experiment – boiled broth in a flask to kill all microorganisms in it Experimental Group – boiled then sealed flask Control Group – boiled then left open Result – sealed flask remained clear and free of microorganisms; open flasks became cloudy *Disagreed – heated the flasks too long, killing the “vital force” in the air inside the flask

10.1 Early Ideas About Evolution Louis Pasteur – Made a goose-neck flask that prevented solid particles from entering but allowed air – remained clear for up to a year – he broke the neck off & the broth became cloudy

10.1 Early Ideas About Evolution Fossil – trace of a long dead organism Found in sedimentary rock – deposited by wind & water Develop from hard body parts Overtime hard minerals replace the tissue leaving rocklike structures Mold – imprint in the rock in the shape of the organism Cast – mold has been filled with hard minerals making a rocklike model

10.1 Early Ideas About Evolution Distribution of Fossils Law of Superposition – successive layers of rock or soil were deposited on top of one another by wind or water Lowest stratum (rock layer) is the oldest Relative age – using law of superposition to figure out the age of one fossil compared to another

10.1 Early Ideas About Evolution Evolution is biological change over time A species is a group of organisms that can reproduce and have fertile offspring.

10.1 Early Ideas About Evolution Naturalist – collect specimens and keep careful records of observations Lamarck: Similar species descended from a common ancestor –Acquired Trait – trait not determined by genes but by experience or behavior –Believed acquired traits could be passed down 10.2 Darwin’s Observations

10.1 Early Ideas About Evolution Charles Darwin Born 1802 Originally studied medicine at Edinburgh University –Hated the sight of blood –later switched to Theology (Divinity) Faith waivered after encountering the evils of slavery on his travels 1931 H.M.S. Beagle 5-year mapping and collecting expedition to South America and South Pacific 10.2 Darwin’s Observations

10.1 Early Ideas About Evolution

Worked on his theories for 20 years Married his first cousin –9 children – 3 died in childhood Died 1882 February 12 th is Darwin Day Did not say “Survival of the Fittest” –Herbert Spencer 1864

10.1 Early Ideas About Evolution Variation is a difference in a physical trait. –Galápagos tortoises that live in areas with tall plants have long necks and legs. –Galápagos finches that live in areas with hard-shelled nuts have strong beaks Darwin’s Observations

10.1 Early Ideas About Evolution An adaptation is a feature that allow an organism to better survive in its environment. –Adaptations can lead to genetic change in a population. –The change in genetic makeup of the population is evolution 10.2 Darwin’s Observations

10.1 Early Ideas About Evolution Darwin’s Theories Descent with Modification – newer forms appearing in the fossil record are actually the modified descendants of older species Natural Selection – Organisms with favorable traits survive, reproduce, and pass the variations to the next generation 10.3 Theory of Natural Selection

10.1 Early Ideas About Evolution Artificial selection is the process by which humans select traits through breeding. neck feathers crop tail feathers 10.3 Theory of Natural Selection 10.4 Evidence of Evolution 10.3 Theory of Natural Selection

10.1 Early Ideas About Evolution The study of geography provides evidence of evolution. –Island species most closely resemble nearest mainland species –Populations can show variation from one island to another  Biogeography - Study of the distribution of organisms around the world Theory of Natural Selection 10.4 Evidence of Evolution

10.1 Early Ideas About Evolution Embryology provides evidence of evolution. Larva Adult barnacle Adult crab –Identical larvae = different adult body forms –Similarites in Biochemistry: DNA, RNA, ATP –Embryos of Vertebrates and gill slits 10.3 Theory of Natural Selection 10.4 Evidence of Evolution

10.1 Early Ideas About Evolution

Anatomy provides evidence of evolution. Human hand Bat wingMole foot –Homologous structures are similar in structure but different in function 10.3 Theory of Natural Selection 10.4 Evidence of Evolution

10.1 Early Ideas About Evolution Human hand Bat wing Mole foot Fly wing –Analogous structures – similar function but different structure 10.3 Theory of Natural Selection 10.4 Evidence of Evolution

10.1 Early Ideas About Evolution Ostrich wings are examples of vestigial structures Vestigial structures are remnants of organs or structures that had a function in an early ancestor but no longer have a function 10.3 Theory of Natural Selection 10.4 Evidence of Evolution

10.1 Early Ideas About Evolution 10.4 Evidence of Evolution

10.1 Early Ideas About Evolution Normal Distribution – Frequency is highest near the average and decreases toward each extreme end of the range Natural selection can change the distribution of a trait in one of three ways 11.2 Natural Selection in Populations

10.1 Early Ideas About Evolution 1.Stabilizing selection favors the average phenotype 10.3 Theory of Natural Selection 11.2 Natural Selection in Populations

10.1 Early Ideas About Evolution 2. Directional selection favors phenotypes at one extreme 10.3 Theory of Natural Selection 11.2 Natural Selection in Populations

10.1 Early Ideas About Evolution 3. Disruptive selection favors both extreme phenotypes 10.3 Theory of Natural Selection 11.2 Natural Selection in Populations

10.1 Early Ideas About Evolution Convergent evolution – Change toward similar characteristics in unrelated species Different species adapt to similar environments. Ex: Aquatic organisms 10.3 Theory of Natural Selection 11.6 Patterns in Evolution

10.1 Early Ideas About Evolution Divergent evolution – 2 or more related populations become more dissimilar –Response to different environments/habitats ancestor red foxkit fox 10.3 Theory of Natural Selection 11.6 Patterns in Evolution

10.1 Early Ideas About Evolution Coevolution – change of 2 or more species in close association with each –occur in beneficial and competitive relationships Theory of Natural Selection 11.6 Patterns in Evolution

10.1 Early Ideas About Evolution Extinction is the elimination of a species from Earth Theory of Natural Selection 11.6 Patterns in Evolution

10.1 Early Ideas About Evolution Mass extinctions are rare –destroy many species at global level –thought to be caused by catastrophic events –at least five mass extinctions in last 600 million years 10.3 Theory of Natural Selection 11.6 Patterns in Evolution

10.1 Early Ideas About Evolution Adaptive radiation – The diversification of one ancestral species into many species. –descendent species usually adapted to wide range of environments 10.4 Evidence of Evolution 11.6 Patterns in Evolution

10.1 Early Ideas About Evolution Punctuated Equilibrium A repeating pattern in the history of life Reflected in the fossil record Shows bursts of evolutionary activity that are followed by long periods of stability.