Evolutionary Biology BIOL 3350 Dr Lisa Rapaport Lecture 5 Part 2 Notes I Chromosomal mutations A Gene duplications Variation Among Individuals 1 Mutations that occur in a chromosome are usually very major 2 One chromosome that has 2 copies and one chromosome that has no copies 3 This can be a very common mistake especially in situations where there are nucleotide repeats B Unequal crossing over in meiosis 1 End up with 2 slightly different functions rather than just one 2 Microsatellite areas 0 have multiple nucleotide repeats 3 Pseudogenes missing regulatory sequences do not work Important in estimating relatedness in organisms and help to develop phylogenetic cladograms Expect mutations to occur at a constant rate 4 Protein product may change in structure and diverge in function 5 Paralogous functional 6 Pseudogenes nonfunctional 7 Paralogous gene function copies of genes that originated from divergence in function form another gene 8 Both paralogous genes and pseudogenes are formed by gene copying through unequal crossing over 9 Hemoglobin has both paralogous genes and pseudogenes C Myoglobin and hemoglobin 1 Myoglobin is produced in muscle tissues 2 Different globin proteins are produced in different tissues but are structurally similar to hemoglobin D Different functions due to different timing of expression 1 Beta chain is produced at low level in post conceptual age but continues to increase in level to postnatal age 2 Gamma chains are produced 3 Fetal hemoglobin has higher affinity to oxygen than adult hemoglobin facilitates the oxygen exchange between the mother and the fetus which promotes fetal growth II Evolution of trichromatic color vision in primates A Old hypothesis 1 During the evolution of the Old World monkeys gene duplication occurred 2 New World several point mutations small mutations caused the production of several different alleles B Evidence for early trichromatic color vision 1 1 Original condition mutation produce 2 different alleles another mutation 3 different alleles 2 Female can be trichromat if have two different alleles on the same chromosome or dichromat if have two of the same allele 3 Gene duplication error in OWM which created two different genes on the same chromosome 4 Found L and M pigments in both NWM and OWM are almost identical were present in the same common ancestor III Importance of mutation A Importance of mutation as an evolutionary force 1 Neutral mutations don t code for a protein or don t change amino acid that is coded for Mostly acted on by genetic drift 2 Most mutations that arise are neutral 3 About the same amount are slightly beneficial or slightly deleterious than lethal 4 More deleterious mutations than beneficial but more beneficial 5 Beneficial mutations will accumulate in the genome faster than IV deleterious alleles Measuring genetic variation A Natural populations variation B Determining genotypes 1 Natural populations have an enormous amount of genetic 1 Proteins of DNA are negatively charged so they will be attracted to the positive end of the gel plate and will move at a certain speed depending on the size C PCR Polymerase chain reaction 1 Use gel electrophoresis to see how fast the bands move down the polarized gel plate 2 Often times a species will have a lot of this microsatellite variation 3 Can look at relationship between species and hybridization 4 Can look at alleles in a population across the same species Not usually clear demarcations of the different subspecies but can see different frequencies of alleles at these microsatellite markers D Alaskan sled dog genetics 1 Sled dogs are not bred for their looks at all they are bred for their behavior endurance speed enthusiasm stamina etc 2 Some are bred for long distance endurance races and some are bred to spring over short distances for speed 3 Despite these differences there are clear genetic markers that identify Alaskan sled dogs from other breeds 4 Compared the genetic markers of the sled dogs to almost 150 different kinds of dog breeds 2 5 Based this on 96 different microsatellite markers 6 Found a number of different breeds contributed to sled dog genomics 7 Genetic profile of dogs bred for sprinting looked very different than that of the dogs bred for distance running E Microsatellite versus minisatellite markers 1 Microsatellite marker small repeats typically 2 base pairs 2 Minisatellite marker more variation within the marker a complicated repeat F Phylogenetic trees nucleotide sequence of alleles 1 Can determine relationships between different populations and different species based on the differences and similarities in sequences of nucleotides 2 Longer for the difference between B and C to occur than the difference between A and B G Phylogenetic analysis of salamanders in the Southern Appalachians Jones et al 2005 1 As they spread into these different areas they will become more and more different from each other because they are geologically isolated from each other 2 Scientists found Chattahoochee Drainage population was the most closely related to the black bellied salamander which are on opposite sides of the continental divide 3