Biological Evolution and Classification



Biological Evolution and ClassificationNatural Selection and AdaptationStudent PagesPurposeThe purpose of this station is to reinforce your understanding of the relationship of natural selection to adaptation and to the diversification of organisms in an ecosystem.Before You Begin…Check to see that all the items are present and organized according to the Station Information sheet. If you notice a problem, notify your teacher immediately.MaterialsTypes of Evolution cards Natural Selection FlowchartEssential QuestionHow can natural selection affect the frequency of the occurrence of traits in a population over many generations?Discuss the essential question with your teammate(s) and record your answer.Activities and QuestionsNatural selection is sometimes described as “survival of the fittest.” In this context, fitness does not mean strong or fast or anything having to do with being physically fit. In a biological context, fitness refers to an organism’s reproductive capability—the more successful an organism is at producing offspring, the fitter it is. Examine the information about cottontail rabbits presented below.Which is the most “fit”?CottontailRunning SpeedNumber ofAge at Death RabbitOffspringA35 mph5772 monthsB27 mph12043 monthsC20 mph1726 monthsCottontail rabbitsbegin reproducing at 8 months of ageproduce 5 litters per seasonhave 3–8 offspring in a litterlive 3–5 yearscan run up to 35 miles per hour.Which cottontail rabbit—A, B, or C—in the table above is considered the most fit of the three rabbits? Support you answer with data from the table.Locate the Natural Selection Flowchart. Take a minute to examine and discuss the information on the flowchart with your partner.Remove the cards from the envelope labeled Types of Evolution and read the information about the organisms on each card. These cards provide examples of the three types of evolution—convergent, divergent, and coevolution.Review the definition of the types of evolution on the Natural Selection Flowchart and place each card under the arrow that best represents the type of evolution it illustrates.Describe an example of each below:Convergent evolutionDivergent EvolutioncoevolutionRead and discuss the definitions of biological influences and physical influences in the glossary. Explain the role that biological and physical influences play in natural selection and the effect these influences can have on an ecosystem’s populations and species.In the desert biome pictured below, the only food source for a species of deer is the cactus.What is the difference between the cactus on the left and the cactus on the right?Observe the feeding behavior of the deer in the illustration below.What effect does the deer’s feeding behavior have on the ability of each type of cactus to survive and reproduce?Observe the changes in the desert biome in the illustration below.How does the deer’s feeding behavior with respect to the cacti in this desert biome illustrate natural selection or the survival of the fittest?Now that you have completed these questions, return to the Essential Question.Would you like to modify your answer? Write any modifications below.Note—Because other students are going to do the activity after you, be sure to put all the materials at the station back as you found them. Sometimes there will be materials that need to be renewed or replaced. If you need assistance or have any questions, ask your teacher.GlossaryAdaptationAn adaptation is any characteristic that increases the fitness of an organism.Biological InfluencesBiological influences on organisms that are not well adapted to their environment tend to eliminate these organisms. These influences include diseases, competition for resources and mates, and predation.HeritableHeritability of characteristics affects fitness and can be passed on from one generation to the next.Parallel EvolutionParallel evolution involves development of two species from a common ancestor, but the descendants evolve similar body structures over time. An example of parallel evolution is the woolly mammoth and the African elephant.Physical InfluencesPhysical influences, such as fire, drought, and hurricane, on organisms that are not well adapted to their environment tend to eliminate the organisms.SpeciationSpeciation is an interbreeding population of organisms that does not breed with other populations when there is opportunity to do so.VariationOrganisms within populations exhibit variations in appearance and behavior. Variations can include color, success in producing many offspring, body size, and quality of the voice or sound. ................
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