Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
1) If the father has hemophilia but the mother does not, how will the offspring be affected? a. All daughters have hemophilia b. All daughters are hemophilia carriers c. All sons have hemophilia d. All sons are hemophilia carriers e. Offspring of both sex have hemophilia 2) Which is not a hypothesis proposed to explain the evolution of virulence? a. Coincidental evolution hypothesis b. Short-sighted evolution hypothesis c. Palindrome hypothesis d. Trade-off hypothesis 3) What is genomic sequencing not used for (pick one)? a. Ancient DNA b. Formalin DNA c. eDNA d. genetic hitchhiking e. genomes 4) Which species concept defines species as reproductively isolated from one another? a. Typological species concept b. Biological species concept c. Ecological species concept d. Evolutionary Species concept e. Phylogenetic species concept 5) List two questions you had on the paper this week LECTURE 18 EVOLUTION AND HUMAN HEALTH Genetic factors Many diseases are on sex chromosomes o X, Hemophilia prevents blood clotting, carried through the Royal Family o Sons have hemophilia & daughters are carriers (unless dad has hemophilia & mom is carrier) o If father has hemophilia, daughters will be carriers but sons won’t have (Fig 1) Red headed birds: Males are homochromosome (ZZ), females heterochromosome (ZW) o Red head dominant, black head recessive CRISPR: Clustered Regularly Interspaced Short Palindromic Repeats o Palindrome: sequence that reads the same forwards & backwards Figure 1: Hemophilia Infectious diseases Viruses may have originated from our own DNA, going out and becoming virus, coming back Antagonistic coevolution: evolution of viruses & their hosts o Example of evolutionary arms race o Influenza A virus is a retrovirus with 8 RNA strands (HIV only has 2) Originates in Asia Celliular coat is hemagglutinin (the main target of our immune system) Antigenic sites: regions of protein that can be recognized by our immune system o Walter Fitch examined phylogenetic relationship among flu strains over 20 years using hemagglutinin sites o Hemagglutinin has evolved at a constant rate, constant selection o Flu strains all arise from a single trunk, no branching (fig 2) o Surviving lineage has more mutations at antigenic sites, keeps challenging immune system o Positive selection occurs when replacements exceed synonomous Figure 2: Flu strains o Influenza A, 18 codons exhibit higher rates of substitution arise from single o Human & bird strains recombine in swine host, reinfect humans trunk o Virulence is the affect a pathogen has on its host Rabbits & myxoma virus o 1859, 12 rabbit brought to Oz. 6 years later there were 30,000 o 1950’s, myxoma virus brought to control rabbits & kill most of them o Within 15 years, virus evolves to be less virulent & rabbits recover Coincidental evolution hypothesis: Different environment, different virulence Tetanus is bad pathogen for us, but directed at something else in dirt Short-sighted evolution hypothesis: Increasing virulence are detrimental Trade-off hypothesis: Virulence should evolve to balance transmission LECTURE 19 EVOLUTIONARY GENOMICS Genomics approaches GC is heavier because it has water molecules in it Cot, melting, renaturation When DNA denatured, common sequences quickly come back together but uncommon sequences do not come backtogether (cannot find other strand) Light passes differently through single vs double strands Meselson, Stahl, and the replication of Figure 3: Minor DNA: Used to calculate density of DNA, which is groove is between a number of water molecules in the minor two strands, and groove major is large Isochores cause chromosomal banding space between Figure 4: Top are quickly renatured, medium are less paired strands Sanger sequencing was popular for 20 common repetiive sequences, and slowest are singleyears, powerful technique copy. X axis is time Next generation sequencing (Pyrosequencing): Everything is sequenced in parallel o Plate with holes big enough for a molecule. Plate covered with one nucleotide which attaches to molecule . Cheaper per molecule than other techniques RAD (Restriction site Associated DNA) sequencing o Cut DNA with primer, sequence DNA next to cuts o DNA sequenced with a barcode, can do up to 100 separate individuals with a single run (cheap) o SNP’s allow inference on population structure, gene flow o Structure plot: you set order of individuals (populations) and program picks colors to determine population structure o Chance of restriction enzyme finding gene is very small, most of genome is introns Genetic hitchhiking: Detect genes by landing close with restriction site, see genes that have gotten pulled along with gene being selected for RNA seq: reverse transcribe RNA to determine what genes are being expressed Genomic sequencing is used for: o ancient DNA (Shapiro and her husband Ed Green) o formalin DNA , which has been fixed in formalin o eDNA o genomes LECTURE 20 SPECIES CONCEPTS Speciation occurs when populations evolve reproductive isolating mechanisms Biological Species Concept (BSC) Prezygotic isolation prevents fertilization Postzygotic isolation creates inviable hybrids Leaf density hypothesis: Leaves having veins allowed them to grow better, increased productivity of land organisms, shifted biodiversity from marine ecosystem to terrestrial (Rich Grosberg & Geerat Vermeji) Cryptic species are visually indistinguishable but genetically unique Species concepts Typological Species Concept: Species described by type specimen, voucher specimen o Linnaeus is famous for binomial system (genus-species) o Problems: polymorphisms within population, geographic variation among populations, Sibling species (reproductively isolated groups that are morphologically indistinguishable) Biological Species Concept: Reproductive isolation o Ernst Mayr, Theodosios Dobzhansky are part of the New Synthesis (Integrating genetics into Darwinian Evoution) o Multidimensional is allopatric speciation &/or allochronous (reproduce at different times) o Nondimensional is sympatric speciation & synchronous (reproduce at same time) o Problems: asexual species, reproductive isolation is often incomplete, multidimensional concept difficult to verify (put species together and see If the reproduce?) Evolutionary Species Concept: (Simpson) lineage evolving separately o Problems: arbitrary, does not provide mechanism Ecological species concept: Ecology plays role in shaping species into new ones Phylogenetic species concept: Smallest possible monophyletic group is species o Problems: Which gene to use to make phylogeny Pianka ER 1970 On r- and K-selection. American Society of Naturalists Dobzhansky (1950) stated that natural selection favors low fecundity & slower development in the tropics to make individuals more competitive, and high fecundity & rapid development in temperate regions to overcome environmental struggles MacArthur & Wilson (1967) coined r- & K-selection Perfectly r-selected species put as little energy into each offspring as possible, no densitydependent effects & no competition, leading to high productivity Perfectly K-selected species put lots of energy into a few extremely fit offspring in a highly competitive environment. Efficient utilization of resources Exceptions: o Aquatic organisms, especially fish, span the range of the r-K continuum, why? o Turtles are k selected, but lay lots of eggs (r-selected) o Sturgeon are long-lived (K), but lay lots of eggs & have no parental care (r-selected) o Within gender: Males are r-selected, females are k-selected o Trees produce lots of seeds (r), but live a long time (K) In ecological succession after big disturbance, primary colonizers are r-selected, followed by increasing diversity of flora & fauna, then K-selected R-selected is good at new environments, environmental conditions, while k-selected is good at species competition