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EVOLUTION & SPECIATION

EVOLUTION & SPECIATION. VOCABULARY REVIEW. EVOLUTION – CHANGE OVER TIME NATURAL SELECTION INDIVIDUALS BETTER ADAPTED TO THE ENVIRONMENT ARE ABLE TO SURVIVE & REPRODUCE A.K.A. “SURVIVAL OF THE FITTEST”. NEW VOCABULARY. POPULATION GROUP OF INDIVIDUALS OF SAME SPECIES THAT INTERBREED

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EVOLUTION & SPECIATION

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  1. EVOLUTION & SPECIATION

  2. VOCABULARY REVIEW • EVOLUTION – CHANGE OVER TIME • NATURAL SELECTION INDIVIDUALS BETTER ADAPTED TO THE ENVIRONMENT ARE ABLE TO SURVIVE & REPRODUCE • A.K.A. “SURVIVAL OF THE FITTEST”

  3. NEW VOCABULARY • POPULATION GROUP OF INDIVIDUALS OF SAME SPECIES THAT INTERBREED • GENE POOL COMMON GROUP OF ALL GENES PRESENT IN A POPULATION

  4. Gene Pool Combined genetic information of all members Allele frequency is # of times alleles occur

  5. Variation in Populations 2 processes can lead to this: Mutations - change in DNA sequence Gene Shuffling – from sexual reproduction

  6. Genetic Drift = changes to allele frequency as a result of chance • Bottleneck effect = dramatic reduction in population size usually resulting in significant genetic drift

  7. Genetic Drift changes populations……. • Random change in allele frequency causes an allele to become common

  8. Founder Effect: - Genetic Drift that occurs when individuals from a large population leave to establish a new population - Allele frequencies of the new population will not be the same as those of the original

  9. Gene Flow: genetic exchange due to the migration of fertile individuals or gametes between populations (reduces differences between populations)

  10. Nonrandom mating: inbreeding and assortive mating (both shift frequencies of different genotypes)

  11. Natural Selection: differential success in reproduction; only form of microevolution that adapts a population to its environment

  12. Sexual selection • Sexual dimorphism: secondary sex characteristic distinction • Sexual selection: selection towards secondary sex characteristics that leads to sexual dimorphism

  13. Evolution of Populations Occurs when there is a change in relative frequency of alleles

  14. Natural Selection on Polygenic Traits • Shifts to middle range • Shifts to 2 extremes • Shifts to 1 extreme

  15. SPECIATION • THE FORMATION OF NEW SPECIES • AS NEW SPECIES EVOLVE, POPULATIONS BECOME REPRODUCTIVELY ISOLATED • REPRODUCTIVE ISOLATION – MEMEBERS OF 2 POPULATIONS CANNOT INTERBREED & PRODUCE FERTILE OFFSPRING.

  16. These squirrels live on opposite sides of the Grand Canyon. This is an example of allopatric speciation.

  17. SPECIATION IN DARWIN’SFINCHES • SPECIATION IN THE GALAPAGOS FINCHES OCCURRED BY: - FOUNDING OF A NEW POPULATION, - GEOGRAPHIC ISOLATION which led to -- REPRODUCTIVE ISOLATION and CHANGES IN THE NEW POPULATION’S GENE POOL due to COMPETITION.

  18. Evidence of Evolution • Fossil Record • Geographic Distribution of Living Species • Homologous Body structures • Similarities in Embryology

  19. Evidence of Evolution Fossil Record provides evidence that living things have evolved Fossils show the history of life on earth and how different groups of organisms have changed over time

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