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UNIT ONE

UNIT ONE. EVOLUTION AND SPECIATION. INTRODUCTION TO EVOLUTION. Microevolution. MICROEVOLUTION. Individuals of all natural populations share a common gene pool but differ in the alleles they each inherit As a result of the variations in genotype, they show variations in the phenotype

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UNIT ONE

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  1. UNIT ONE EVOLUTION AND SPECIATION

  2. INTRODUCTION TO EVOLUTION Microevolution

  3. MICROEVOLUTION Individuals of all natural populations share a common gene pool but differ in the alleles they each inherit As a result of the variations in genotype, they show variations in the phenotype Individuals do not evolve; populations do

  4. MICROEVOLUTION This evolution occurs as a result of a change in the alleles of that population’s gene pool Over the generations, any allele may increase in frequency OR it may become rare or even lost Microevolution refers to changes in allele frequencies as an out come of: Mutation Natural selection Genetic drift Gene flow

  5. INTRODUCTION TO EVOLUTION GENETIC STRUCTURE OF POPULATIONS

  6. GENETIC STRUCTURE OF POPULATIONS Population geneticists study heredity in groups of individuals called a population Populations of the same species (ex: pigeons) share morphological (morpho – form) traits: 2 feathered wings 3 toes forward, 1 toe back Populations also share physiological traits like homeostatic mechanisms that help the body function in it’s environment They also respond the same way to basic stimuli – behavioral traits

  7. GENETIC STRUCTURE OF POPULATIONS The individuals of each population show variations in the details of the traits they share with the other members (i.e.: color/patterning of feathers on pigeon wings) Almost every trait of any species may vary, but the variety is far more pronounced in sexually reproducing species Looking at our definition of a population, this variety is the result of the combining and recombining of the genes of two parents to create offspring

  8. GENETIC STRUCTURE OF POPULATIONS Qualitative Differences Quantitative Differences 2 or more distinct forms (morphs) Dimorphism – persistence of 2 forms of a trait in a population Polymorphism – 3 or more forms of the trait Range of incrementally small variations in each morph Typically unique to specific populations

  9. EVIDENCES OF EVOLUTION

  10. FOSSILS Mold fossils Cast fossils Permineralization (petrification) Replacement fossils Organic matter (teeth, bones) Preservation

  11. COMPARATIVE ANATOMY Comparative Morphology – study of body forms and structures of major groups of organisms Homologous structures – body parts that are structurally similar but different in function; genes for constructing these parts indicates shared ancestry Analogous structures – structures that serve similar functions but have different origins on embryonic forms Vestigial structures – have no apparent function in specific organism

  12. COMPARATIVE EMBRYOLOGY

  13. BIOGEOGRAPHY

  14. COMPARATIVE BIOCHEMISTRY

  15. FOSSIL DATING Relative Dating– dating fossils relative to their location in rock layers and to each other (estimate only) Absolute Dating - determination of actual age of fossil Radioactive dating: use of specific radioactive isotopes Amino acid racemization: ratio of left-handed amino acids (living) to right-handed (dead)

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