Evolution: Lamarck Evolution: Change over time Evolution: Change over time Lamarck Lamarck Use / disuse Use / disuse Theory of inheritance of ACQUIRED traits Theory of inheritance of ACQUIRED traits

Evolution: Darwin Darwin’s Voyage on the HMS Beagle Darwin’s Voyage on the HMS Beagle

Evolution: Darwin / Natural Selection Darwin observed that Darwin observed that organisms produce more offspring than the environment can support organisms produce more offspring than the environment can support organisms VARY in many traits organisms VARY in many traits these variations can be inherited these variations can be inherited Some traits better fit for the environment than other traits Some traits better fit for the environment than other traits

Evolution: Darwin / Natural Selection Darwin = individuals best suited for a particular environment are more likely to survive AND reproduce than those less well adapted Darwin = individuals best suited for a particular environment are more likely to survive AND reproduce than those less well adapted Darwin saw natural selection as basic mechanism of evolution Darwin saw natural selection as basic mechanism of evolution As a result, proportion of individuals with favorable characteristics increases As a result, proportion of individuals with favorable characteristics increases POPULATIONS (not individuals) gradually change in allele frequency in response to the environment POPULATIONS (not individuals) gradually change in allele frequency in response to the environment

Evolution: Natural Selection

Evolution: Natural Selection vs Artificial Selection Artificial Selection Artificial Selection - man creates pressure

Four Evidence of Evolution Biogeography Biogeography Fossils Fossils Comparative Anatomy Comparative Anatomy Homologous Structures Homologous Structures Comparative Embryology Comparative Embryology Molecular Biology Molecular Biology DNA / Proteins / Amino Acid sequences DNA / Proteins / Amino Acid sequences

Evidence for Evolution: Fossils Transitional Fossils Transitional Fossils

Evidence for Evolution: Comparative Anatomy Homologous Structures: Homologous Structures: Similar structure (what does that suggest); different function (what does that suggest)

Evidence For Evolution: Molecular Biology

Convergent vs Divergent Evolution Analogous structure: similar function, different structure Analogous structure: similar function, different structure Ex. Wing of insect and bird Ex. Wing of insect and bird Convergent Evolution Convergent Evolution Divergent Evolution  Homologous Structures Divergent Evolution  Homologous Structures

Microevolution vs Macroevolution Micro = small changes, still same species Micro = small changes, still same species Macro = speciation Macro = speciation Microevolution = change in allele frequencies in a gene pool Microevolution = change in allele frequencies in a gene pool

Microevolution: Gene Pool Gene pool = total numbers of allele in a population Gene pool = total numbers of allele in a population Allele frequency = % of that specific allele in gene pool Allele frequency = % of that specific allele in gene pool

Hardy Weinberg Equilibrium Hardy-Weinberg equilibrium: even if alleles are shuffled in the next generation (new genotypes appear) allele frequency / proportions in the gene pool stay the same from generation to generation Hardy-Weinberg equilibrium: even if alleles are shuffled in the next generation (new genotypes appear) allele frequency / proportions in the gene pool stay the same from generation to generation

Hardy-Weinberg Equilibrium Large population Large population Isolated population Isolated population No genetic mutations No genetic mutations Random Mating Random Mating No Natural Selection No Natural Selection

Hardy-Weinberg Equilibrium ALLELE FREQUENCY ALLELE FREQUENCY p = “A” freq p = “A” freq q = “a” freq q = “a” freq p + q = 1 p + q = 1 GENOTYPE FREQUENCY GENOTYPE FREQUENCY p 2 = “AA” freq p 2 = “AA” freq 2pq = “Aa” freq 2pq = “Aa” freq q 2 = “aa” freq q 2 = “aa” freq p 2 + 2pq + q 2 = 1 p 2 + 2pq + q 2 = 1

Hardy-Weinberg: Genotype & Allele Frequencies

Hardy-Weinberg Practice Problem In a certain population, the frequency of homozygous curly haired (HH) is 64%. What percentage of the population has curly hair? In a certain population, the frequency of homozygous curly haired (HH) is 64%. What percentage of the population has curly hair? Given: p 2 =.64 Find: p 2 + 2pq Given: p 2 =.64 Find: p 2 + 2pq p =.8 q =.2 2(.8)(.2) =.32 or 32% p =.8 q =.2 2(.8)(.2) =.32 or 32% 64% (HH) + 32% (Hh) = 96% curly haired 64% (HH) + 32% (Hh) = 96% curly haired

5 Causes of Microevolution Population becomes SMALL due to chance: GENETIC DRIFT Population becomes SMALL due to chance: GENETIC DRIFT Population is NOT isolated: GENE FLOW Population is NOT isolated: GENE FLOW Mutations occur Mutations occur Mating is NOT random Mating is NOT random Natural selection exists: some traits are better fit than others Natural selection exists: some traits are better fit than others

Causes of Microevolution: Genetic Drift: Gene pool changing due to CHANCE BOTTLENECK EFFECT BOTTLENECK EFFECT Pop shrinks due to natural disaster Pop shrinks due to natural disaster FOUNDER EFFECT FOUNDER EFFECT Colony leaves

Gene Flow & Non Random Mating Gene Flow Gene Flow NONrandom Mating NONrandom Mating

Causes of Microevolution: Natural Selection 3 outcomes of Natural Selection: 3 outcomes of Natural Selection: Stabilizing, Directional, Disruptive/Diversifying Stabilizing, Directional, Disruptive/Diversifying

Macroevolution: Speciation Speciation – the creation of new species Speciation – the creation of new species Species: Species: a population or group of populations whose members can interbreed and produce fertile offspring a population or group of populations whose members can interbreed and produce fertile offspring

Reproductive Barriers Reproductive barriers prevents different species from mating with each other: Reproductive barriers prevents different species from mating with each other: Mating times / seasons different Mating times / seasons different Different habitat Different habitat Different mating behavior so little attraction between species Different mating behavior so little attraction between species

Reproductive Barrier: Geographic Barrier Allopatric Speciation: When a population is cut off from its parent population, species evolution may occur Allopatric Speciation: When a population is cut off from its parent population, species evolution may occur gene pool is changed by natural selection, genetic drift, or mutation gene pool is changed by natural selection, genetic drift, or mutation

Geographic Barrier: Adaptive Radiation Adaptive radiation (ex of allopatric speciation) on an island chain – from one main species there are multiple different species evolving Adaptive radiation (ex of allopatric speciation) on an island chain – from one main species there are multiple different species evolving