Introduction to evolution · What is evolution? o There are many definitions, e.g .: " the process by which different kinds of living organism are believed to have developed from earlier forms during the history of the earth (Oxford English Dictionary) " change in the gene pool of a population from generation to generation by such processes as mutation, natural selection, and genetic drift (dictionary.com) o The simplest and most general: " A change in allele or genotype frequencies o Evolution is an ongoing process, that affects all populations and can lead to significant changes over "ecological" timescales o Evolution occurs in human populations (e.g. inbred European royalty tended to have distinct Habsburg chins before the 19th century; Ellis-van Creveld syndrome (extra digits) is common amongst danish people due to genetic drift happening in these populations) o All forms of life and biodiversity exist due to evolutionary processes o Evolution occurs in economically and medically important organisms, e.g. farm animals, antibiotic resistance in pathogens o Population & evolutionary genetics help in understanding the pandemic: · Where did SARS-COV-2 originate? How many introductions have there been to a region? " What are the implications of mutations for public health (e.g. vaccine development, changes in infectivity or virulence)? " Can we predict whether these mutations will spread? " What human genetic factors and what environmental factors affect the severity of the disease? " The diagrams below show different variants of SARS-COV-2. The one on the right is a phylogeny of the different strains. The original strain is roughly in the middle, and we can see how it has mutated and diversified and the other variants that have emerged. Strains closer together are more closely related. The pie charts on the map on the left show the frequency of a particular variant in a particular region. We can see evidence of variation in different regions. Population genetics can help us understand the frequency of mutations as they occur, help us predict which variants are likely to spread, and understand gene flow between different populations - how often a variant is likely to be Evolution of SARS-COV-2 introduced & how often mutations Canada might occur. The North Atlantic image on the bottom Ocean shows the frequency Sudan Ferner 2020-Snp of different variants 2020-Del over time Anguie 2021-Mar South Atlantic Namibia · What is population genetics? Ocean Frequencies Icolored by Clade ? 100% 194 60% 198 204 201001Y 2020-AM 2020-va 2006-Sep
o Study of patterns of genetic variation and of the mechanism of evolution, i.e. of allele and genotype frequency changes o Processes: " Mutation and Recombination Genetic drift Selection Gene flow Non-random mating · Summary: o Evolution is an ongoing process. o Population Genetics studies the mechanism of evolution. · Evolution occurs in all organisms, including humans, and medically and economically important systems Genetic variation and Hardy-Weinberg equilibrium · Genetic variation is everywhere o E.g., seen below in shells with lots of colour variation within the species; as well as sickle cell anaemia, a