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Transcript
Zoology: an evolutionary perspective Standards and Essential Question Standard • SZ2b. Explain the concepts evolution, adaptation, natural selection, convergence, and speciation. Essential Question • What makes evolution happen? What does the word EVOLUTION mean? Organic Evolution • Change in the genetic makeup of populations of organisms over time. Why is it important? • Source of animal diversity • Explains family relationships within animal groups Who is related to who? Evidence of Relation • Populations are more closely related if they share more DNA. • Example: You are more closely related to your brother or sister than your cousin. What does DNA determine? • Most of your physical traits History of evolution Who came up with the Theory of Evolution? Charles Darwin • Defined evolution as “Descent with Modification” • Focused on a mechanism of evolution known as natural selection or “Survival of the Fittest.” Charles Darwin Darwin’s Early Years & His Journey Early Years • A naturalist • Come from a family of physicians • Contributed to beetle taxonomy Voyage of the HMS Beagle • Ventured to the Galapagos Islands (off the coast of Ecuador) • Wrote a book based on his discoveries titled “On the Origin of Species by Means of Natural Selection” Darwin’s Ideas of Evolution Galapagos Islands • Named after the large tortoises that inhabit them • Convinced Darwin that organisms changed over time Organisms Found & Evidence • Galapagos Tortoise – Different shaped shells • Galapagos Finches– Different shaped beaks • 14 species developed from an ancestral group of finches (adaptive radiation) • The difference was due to environmental factors Natural Selection 4 Basic Principles of Natural Selection • Variation • Heritability • Overproduction • Reproductive Advantage Variation • Individuals in a population differ from one another. • Increased by mutations and sexual recombination. • Example: The students in the classroom all look different. Heritability • Variations are inherited from parents. • Example: Will’s children inherited their light skin tone from their father. Overproduction • Populations produce more offspring than can survive. • Example: Rabbits produce many offspring at once. • Why is it beneficial for rabbits to overproduce? Reproductive Advantage “Survival of the Fittest” • Variations that increase reproductive success and will be more common in the next generation. • Example: If bright plumage in peacocks increases reproductive success. • What will the peacocks in the next generation have? Fitness • The ability to SURVIVE and REPRODUCE in a given environment. • Main concept behind Darwin’s theory of natural selection. • The “fittest” is not always the “strongest” Sexual Selection • When intraspecific competition occurs for mates in one sex and when one sex is selected over another as prey by predators • Often seen in populations where males and females are significantly different in appearance. • Example: Most male birds and their plumage.
