BIO 305 1st Edition Lecture 14 Outline of Last Lecture I. Violations of the Hardy Weinberg Law (Part II.)A. Mating Bias, Migration, MutationB. Genetic Drift, Natural SelectionII. Introduction to Evolutionary GeneticsIII. Vocabulary and Sample QuestionsOutline of Current Lecture I. BDM Model of Reproductive IsolationII. UPGMA Trees Using a Distance MatrixIII. Molecular ClockIV. Evolutionary TreesV. Sample QuestionsCurrent LectureI. BDM Model of Reproductive IsolationHow are protein polymorphisms involving charge analyzed?The exons tend to have small variation; introns have high variation.What is a SNP?What are the causes of genetic variation? Ultimately, mutation!There are three ways genetic variation is maintained, explain each: 1) Over-dominant selection2) Mutation –drift balance3) mutation- selection balanceObserved that allele frequency can change in a year, what is the cause of this difference?Changes in allele frequencies can occur over space and timeWhat factors can lead to formation of new species?The biological species concept: a population or group of populations whose members have the potential to interbreed with one another in nature to produce fertile offspring, but who cannot successfully interbreed with members of other species. Different species are reproductively isolated.What forms of isolation are there?Prezygotic1. Geographic or ecological2. Seasonal or temporal3. Behavioral4. Mechanical5. PhysiologicalPostzygotic1. Hybrid nonviability2. Hybrid sterility3. F2 breakdownThe BDM ModelII. UPGMA Trees Using a Distance MatrixGenetic Differences Reconstruct Evolution: UPGMA treesHow to construct a matrix:1) Find the smallest number2) Group these two animals together in the matrix and in a new tree3) Write the new matrix, for each square you enter the average of those species involvedusing numbers from the ORIGINAL matrix, always the original numbersIII. Molecular Clock Molecular Clock – in a given amount of time, the evolution for a certain amount of protein is a linear increase. We can measure the genetic distance and infer the divergence time between two speciesIV. Evolutionary TreesExample: Relationship of Neanderthal to HumansNeanderthals lived in Europe and western Asia from 300, 000 to 30,000 years ago. They coexisted with anatomically modern humans for at least 30,000 years in several areas.Key: twin branches are closer with each other than any other relationshipSample Questions:1. Which mechanism CANNOT cause prezygotic isolation?a) Geographic isolationb) Ecological isolationc) Behavioral isolationd) Hybrid sterility e) Mechanical isolation3. Molecular clock has been used widely to estimate the divergence time of a pair of species. Fossil records showed that mammals and birds diverged 300 million years ago (MYA). To be able to determine when birds and flies diverged, a genetics student sequenced a protein-coding gene from the human, chicken, and Drosophila, respectively. She found that the human and chicken proteins are 90% identical at the amino acid sequence level, whereas the chicken and fly proteins are 75% identical. From this set of data, one can estimate that birds and flies diverged approximately a) 120 MYA b) 375 MYA c) 40 MYAd) 750 MYA e) 1500 MYAANSWERS:1. D, Hybrid Sterility2. 3. D, 750
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