Evolution Review

Evolution To change over a period of time Geologic Evolution When the earth changes over time. Organic Evolution When a species changes over time. Example of Evidence: Fossils Fossils are not just bones! The remains of an organism that was naturally preserved. Fossils are compared to existing organisms to prove the theory of evolution. Fossil bones –bones, shells, teeth Petrification –minerals replace living material-organism preserved as stone. Tar – when organisms die in a tar pit, the tar hardens/preserves Molds – When sand or mud hardens around an organism and turns to rock. Casts – A mold is filled with minerals hardens to shape of the organism. Imprints – an impression. Examples can be footprints and leaves Sedimentary rock – sedimentary rock forms when small pieces of rock (like sand) are pushed together to form one big rock. Fossils are usually found in sedimentary rock. Almost always happens near water. sediment + pressure (weight) = sedimentary rock Relative dating/correlation – any method of determining the order of events. The order of events are determined using layers of rock. (Top = younger Bottom = older) Absolute dating – any method that determines how long ago an event happened. Ex. Radioactive carbon dating using isotopes Index fossils - Indicate the age of rock that they are in. Patterns in evolution: Early Simple 1-celled Aquatic Late Complex Multicellular Terrestrial Comparative Anatomy - study of structural similarities/differences between living things. Similarities provide evidence for evolutionary relationships Homologous Structures - parts of different organisms that have similar structures and development, but have different forms and functions. Formed from divergent evolution - related Analagous Structures - structures that have similar external forms and functions but are different internal structures. Formed from convergent evolution – not related Vestigial Structures - remnants of structures that were functional in an ancestral form. They are smaller in size and serve little or no function. IE coccyx (tailbone), appendix, etc. Embryological similarities: The presence of similarities between embryos of different species shows evidence for evolution. Molecular evidence… - the best form of evidence for evolution Because all DNA is descended from the DNA carried by the earliest life forms, the DNA of all organism shares a common genetic code. The early hypothesis: It was originally thought that life came from non-living matter. This concept is called spontaneous generation. Examples of spontaneous generation include frogs and snakes coming from mud, fleas and lice coming from sweat, and flies coming from decaying meat. Redi’s experiment Pasteur’s experiment Biogenesis – life from life Heterotroph Hypothesis – theory of how life started on earth The Beginning Now Hydrogen, Water Vapor, Nitrogen, Oxygen, and Carbon Ammonia, and Methane Dioxide Very Hot Much Cooler Sources of energy on primitive earth: -Heat -Radioactive decay -Lightning -Ultraviolet light, visible light, and X-rays Structural adaptation – adaptations that involve the body of the organism. IE. Wings, fins, webbed feet, etc. Camouflage – helps organism blend into the environment Warning coloration – the color of the organism is an indicator to a predator that it does not taste good Mimicry – one organism looks like another that is harmful Physiological adaptation – adaptations that involve the metabolism (life processes) of the organism. IE. Webs, venom, etc. Types of Natural Selection Directional Selection – an extreme phenotype becomes a favorable adaptation. The environment favors the extreme phenotype causing the population to evolve. – Examples are giraffe neck & cheetah/gazelle speed Stabilizing Selection – average phenotype is favorable the extreme phenotypes are unfavorable. Extremes die off. –Example: baby birth weight Disruptive Selection – the average phenotype is not favorable and the two extremes become favorable. This type is very rare. Directional Stabilizing Disruptive Isolation - something that prevents two groups in the same species from breeding. Geographic isolation - happens when a population is divided by a natural barrier. IE mountain, desert, river, etc Reproductive isolation - When groups have been separated for a long time, they lose the ability to breed with each other. Speciation- Speciation can occur suddenly when abnormal meiosis or mitosis results in polyploidy (unusual number of chromosomes). When the offspring can interbreed only among themselves, they are considered a new species. Divergent Evolution - Adaptive radiation - when one species evolves into a number of different species, each occupying a new environment. IE Darwin’s finches Convergent evolution - organisms that are not closely related, but develop similar adaptations due to natural selection. –Produce analogous structures Coevolution - when two species evolve together LaMarck - WRONG Part 1: The law of use and disuse… -The more an animal uses a part of its body, the stronger and more developed it will become. The less an animal uses a part of its body, the less developed it becomes. Part 2: The inheritance of acquired characteristics… -The characteristics an organism developed through use and disuse could be passed on to offspring. DARWIN – (WE THINK) HE’S RIGHT! Overproduction – species produce more offspring than needed, but the population is kept constant because only some live long enough to reproduce Competiton – offspring in each generation must compete for space and food which is why only some live to reproduce Variation – differences (variations) between individuals in a population can affect the ability to survive. Only those with the best variations will live to reproduce. Adaptations – Due to variations, some individuals will be better adapted to survive and reproduce. Favorable adaptations will allow an individual to survive in their environment and live to reproduce. Speciation – Over many generations, favorable adaptations add up. Eventually, this will lead to a new species. The last main point in Darwin’s book was Natural Selection = Survival of the Fittest Gradualism - Evolution occurs slowly and continuously over thousands and millions of years. DARWIN = POSSIBLY RIGHT Punctuated Equilibrium - a species remains the same for an extremely long period of time. Then, in a short period of time, the species changes into a completely new species. LAMARCK = WRONG