Lamarck Lamarck = Inheritance of acquired characteristics Giraffe stretches neck over several generations to reach leaves high in trees

Darwin Natural selection – favorable new traits resulting from random mutations are passed on to succeeding generations

Darwin = Proposes the “Origin of Species” (by natural selection) 5 year world cruise

leaves fruit Vegetarian grubs cactus Uses tools Woodpecker insects seeds Ancestor? Darwin’s Finches Ancestral bird “adapts” (by natural selection) into various habitats

Microevolution: Change in the gene frequency within a population Provides new genetic material for new traits …… without which all life would look the same ….. like the first life.

Many bacteria, including resistant variety Expose all bacteria to antibiotics; most normal die Resistant bacteria multiply and dominate Entire infection evolves into resistant strain

Normal bacteria Resistant bacteria Dead bacteria Add Antibiotic % RESISTANCE Example of microevolution

Causes of microevolution: 1.Mutation – nucleotide or chromosome 2.Non random mating – mate selection 3.Gene Flow - migration 4.Genetic Drift – accidental loss of individuals 5.Natural Selection – most fit reproduce more often

UV light Thymine dimer

Radiation (x-ray) causes chromosome damage

mutation No mutation mutation With and without mutation

Factors that will cause microevolution: 1.Mutation – nucleotide or chromosome change 2.Non random mating – mate selection 3.Gene Flow - migration 4.Genetic Drift – accidental loss of individuals 5.Natural Selection – most fit reproduce more often

Non random mating The wolf is probably close to natural dog if dogs allowed to mate freely Specific breeds of dog result if dogs are only allowed to breed with others in the same breed

 Extreme example of nonrandom mating = inbreeding  Results in mostly homozygous genotypes (e.g. HH or hh)  Cubs low survival rate  Susceptible to disease  Males have low sperm count  Only chance for new genes is through mutation 20,000 Cheetahs

Factors that will cause microevolution: 1.Mutation – nucleotide or chromosome change 2.Non random mating – mate selection 3.Gene Flow - migration 4.Genetic Drift – accidental loss of individuals 5.Natural Selection – most fit reproduce more often

Gene flow (migration) Genes for the brown beetle move to green population Population A = 100% greenPopulation B = 100% brown

Factors that will cause microevolution: 1.Mutation – nucleotide or chromosome change 2.Non random mating – mate selection 3.Gene Flow - migration 4.Genetic Drift – accidental loss of individuals 5.Natural Selection – most fit reproduce more often

Genetic Drift: accidental loss of members of a small population 20% purple 33% purple 32% purple

Small population with 12.5% white and 87.5% dark 75% dark 25% white 100% dark 0% white

Factors that will cause microevolution: 1.Mutation – nucleotide or chromosome change 2.Non random mating – mate selection 3.Gene Flow - migration 4.Genetic Drift – accidental loss of individuals 5.Natural Selection – most fit reproduce more often

Bird eats dark mothBird eats light moth Light moth reproduces more often – why? Dark moth reproduces more often – why? Best adapted moth reproduces more offspring

Natural Selection does not give an organism an adaptation simply because it will do better with it. – Adaptations occur by chance mutations

Factors that will cause microevolution: 1.Mutation – nucleotide or chromosome change 2.Non random mating – mate selection 3.Gene Flow - migration 4.Genetic Drift – accidental loss of individuals 5.Natural Selection – most fit reproduce more often Review

SPECIES = group of interbreeding populations reproductively isolated from other populations Are lions and tigers separate species? Liger = lion x tiger

Are horse and donkey different species?? Horse X Donkey = Mule (sterile) spermegg No meiosis

Ensatina eschscholtzii

Geographic Isolation can lead to differences and new species Becomes separate species as mutations make them different

Kaibab and Abert’s squirrels separated by Grand Canyon = geographic isolation Colorado River

Geographic isolating mechanisms (fences) prevent exchange of genetic differences between dog breeds allowing differences to build-up

If population is geographically isolated long enough, then behavioral isolating mechanisms occur