Guided Notes: Evolution. is the change in traits through generations over! Occurs in, NOT individual organisms

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1 Guided Notes: Evolution The Theory of Evolution is the change in traits through generations over! Occurs in, NOT individual organisms How Have Organisms Changed? At the time life emerged, the Earth was thought to contain very little o First cells were thought to be o Recall that anaerobic means As the atmosphere of Earth changed, so did the development of organisms These (simple), anaerobic cells were able to exist in Earth s early atmosphere As Earth s atmosphere and conditions changed, prokaryotes evolved, using sunlight to produce food. o What molecule do photosynthetic organisms produce as waste? Eventually, Earth s atmosphere became filled with o organisms evolved This resulted in the evolution of complex organisms we have on Earth today! The Endosymbiotic Theory: The proposes that eukaryotic cells arose from living communities formed by prokaryotic organisms. ~2 billion years ago - of internal membranes in o The result was the ancestor of all cells. Endosymbiotic Theory: Eukaryotic cells formed from a among several different prokaryotic organisms o Prokaryotes that use oxygen to generate energy-rich molecules of ATP evolved into o Prokaryotes that carried out photosynthesis evolved into

2 Evidence of Evolution Fossil Evidence: show us the similarities between organisms of the past and present describe similarities between the anatomical structures of species are anatomical structures that still appear, but are no longer used! o Examples: o Suggests that these structures may have existed at a previous time or in an ancestor; organisms evolved and structures Comparative Embryology: Insects and animals often have very similar development o Ex. o Suggests a Biochemical Evidence: Comparison of and macromolecules between organisms o Through o Tells us what organisms are closely related Evolution and Natural Selection is best known for his contributions to the theory of Evolution On a five year voyage on a ship called the Beagle, Darwin recorded his observations of he found along the way This led Darwin to develop the idea of and means that those organisms best adapted to their environment will survive, reproduce, and o Fittest means, not strongest! Adaptation: Any trait an organism has that helps it to o If an organism does not have adaptations to best fit its environment, it will die o Survival of the Fittest o Example: Bird beaks-imagine that birds had different sized beaks in an area where the food source was seeds. In order to crack them, the birds needed a large, strong beak. Which would survive and reproduce?

3 Species have the potential to increase, but environmental factors maintain lower population numbers o Resources required to sustain o conditions o Relationships among organisms in Changing environments select for specific o Those organisms with favorable survive, reproduce, and pass on their to future generation o Over time, the accumulation of favored alleles leads to a change in (change over time = evolution) Case Study: Antibiotic Resistance Organisms are constantly changing and adapting; reproduce and evolve quickly to adapt to constant changes! Humans often use to combat harmful bacteria (ex. Staphylococcus) Some bacteria are born with a resistance (an adaptation!) to the antibiotic These bacteria will and, creating a group that are resistant to the drugs Other Disease Agents in Natural Selection Resistance in Plants Antivirals Passive Immunity: Immunity to certain diseases is given from to at birth o Continued through antibodies passed through Active Immunity: Immunity acquired through exposure to a o After exposure, your body builds up an o allow you to artificially gain an active immunity without exposure to the actual disease Causes of Variation Genetic Recombination: Dominant and Recessive alleles in genes, along with polygenetic traits and complex genetics, lead to individual organisms with different (and thus, adaptations) Mutations: Changes in DNA sequences can introduce both good and bad new into a population (ex. Immunities, resistant bacteria, pesticide resistant plants)

4 Speciation refers to the process by which new species arise Directional Selection o When phenotype has the best chance to survive o As a result, the (number) of those with that phenotype shift over time o Example: The evolution of horses Using the diagram as evidence, how did the horse evolve over time? Hypothesize why these changes could have happened. Stabilizing Selection o When the phenotype has the best chance to survive o advantage o Example: Birth weight Disruptive Selection o When phenotypes have the best chance to survive o Example: Peppered moth Geographic Isolation When mountains, islands, etc. keep a population Species will meet different environmental challenges, change and evolve than the population Geographic Isolation leads to, when one species evolves into many different species over time due to competition of habitat or food!

5 Variation Differences in within one o Example: o Brown eyes are naturally protected from the sun s glare Coevolution When one evolves due to a specific interaction with o Example: Genetic Drift The change in a of a gene variant (allele) in a population due to random o Due to a random event, a happens to the organisms in a population o Much more frequent in populations! o Example: Founder Effect Bottleneck Effect Classification Systems Classification systems are how we organisms o This is called The classification of organisms has changed and evolved over the years due to new Greater understanding of evolutionary relationships, thanks to, has allowed for more detailed classification The classification of organisms begins with the groupings and moves down to the (domain species) The classification order is as follows: Species: Group of the organisms o Live together o Mate and produce viable o means they can have babies of their own Scientific Name: The scientific name of an organism is the and of an organism o Always written in o Example: Humans are Homo Sapians o Only species are able to!

6 Case Study: Interbreeding o Only species are able to interbreed. Organisms of two different species normally will not o Sometimes, organisms within the same genus are able to, but the offspring are not (they cannot reproduce!) o Example: o These hybrid organisms are much more common in captivity than in the wild Dichotomous Keys A key that helps an organism Uses to lead you to the of an organism By looking at features of an organism, the key will help you determine what it is! Phylogenetic Trees Shows the between organisms Can show which organisms are more closely than other organisms Which organism is more closely related to man? Which organism is man more closely related to: Frog or bird? Why? Cladogram: Shows relationships up-close; they share

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