Lab 8 Intro Genetics and Evolution Evolution Gradual

Lab 8 Intro Genetics and Evolution

Evolution • Gradual changes in a species over time • What’s the evidence?

Fossils • Fossils show us gradual changes – Horse example looked at hoof development – p 203

Comparative Anatomy • Homologous Structures– Similar bone structure, different functions – pp 204 -205

Evidence: Embryological Development (p 205 -206) • Embryos look similar in closely related organisms • Demonstrate links between taxa – Echinoderm larvae are bilaterally symmetrical – Mollusca trochopore larvae are similar to Annelidia

Evolution via Natural Selection 1. Overproduction 2. Variability 3. Differential Survivorship – Those with better adapt traits survive longer and reproduce more 4. Gradual Change – Selection pressures lead to change – Competition, predation, climate, amount of water

Genetics & Variation Genes vs Alleles • Genes – are instructions on how to make proteins or traits • Alleles – Different version of the same gene

Genetics Variation Dominant vs Recessive • Dominant Alleles– An allele that is always expressed when present • Recessive Allele– Is not expressed when there is a dominant allele – Needs two copies of the recessive allele to be expressed R= Round r= Wrinkled

Genetics & Variation • Each organism has 2 copies of every gene – Exceptions are found in plants and fungi • One copy comes from each parent

Genetics & Variation Wife’s Mother Wife

Genetics & Variation Bowman’s Brother

Variation and Evolution • Multiple alleles = multiple phenotypes. • Creates variation within population or species

Allele frequency graph • Change in the frequency alleles over time No Change Changing

Hardy-Weinberg Principle Allele Frequencies remain stable over longterm unless: 1. 2. 3. 4. Mutation Gene Flow (Immigration or Emigration) Genetic Drift Nonrandom Mating (sexual selection, unequal sex ratio, etc…) 5. Natural Selection

Genetic Drift • Random loss of alleles • Go To Simulation: http: //darwin. eeb. uconn. edu/simulations/drift. html Run the simulation with different population sizes (10 times for each population size).

Make sure you read • Read – p 199 -200 (Intro and Darwin) – 203 -213 (Evidence for Evolution to end) • Do Activities – p 208 Genetic Drift (click here) – p 209 Pepper Moth (click here) – p 210 Florida Panther (click here) – p 212 Fuchsia (click here) • Turn in Postlab 8 (given to you last week)