BIOB 272 1st EditionLecture 25 Outline of Last Lecture Natural Selection in the WildI. Modes of Selectiona. Directionalb. Stabilizingc. DisruptiveII. Case Study 1: Diversity in Darwin’s FinchesIII. Case Study 2: Coat Color in the Old Field Mouse: Peromyscus PolionotusIV. Case Study 3: Color Variation in KingsnakesV. Case Study 4: Gall Flies and GallsOutline of Current Lecture Natural Selection AdaptationI. Directional/stabilizing Selection in HumansII. Case Study 2: Humans and Milk- Selective Sweeps- Haplotype- Convergent and Independent EvolutionIII. Agriculture- artificial selection in crop production - Teosinte and Maize- Kernel StructureCurrent LectureThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Natural Selection AdaptationI. Directional/stabilizing selection in humans= fitness landscape- Birth mass correlated with gestation period until a certain point= creates a fitness landscape. I. Case Study 2: Humans and Milk- lactose tolerance correlates with domestication- Domesticated about 10,000 years agoo Needed increase energy foods in harsh environments- Lactose persistence= mutation- affects LCT promoter activity (gene expression)- Finding positive selection in the genome: selective sweeps- Selective Sweeps:o Positive Selection: leaves different things than neutral theory- can identify regions of genome that are different than expected with neutral theoryo Mutation= advantageous= increase frequency and then all variants follow suit= genetic hitchhiking is determined by the extent of recombination (linkage)- Haplotype: selected chromosomal sequenceo Increase frequencyo After sweep= excess of rare genetic variants with no recombination- Convergent and Independent Evolution of human lactase persistence in Africa and EuropeII. Agriculture- artificial selection in crop production - QTL studies indicate that the major phenotypic differences are due to changes at 5 genes (or linked regions)!- Many more small gene.c changes (perhaps at 1,000s of genes) influencea suite of important traits: • o starch production o Climates and types of soil o Length and number of kernels o Kernel size, shape, and color o Resistance to pests - Teosinte and Maize- Kernel Structure- Gradual increase in cob size- Kernel structure changeo Hard to soft shell of kernel- Can do a cross between maize and teosinte and get a
View Full Document