One of the topic which we have to study, which is evolution, alright so, evolution is ofcourse you know, a big interesting topic in itself, I do not think I can do justice tothis whole topic.And the whole subject even in, in the time which is available to us but let us get afeel and the glimpse of the, the Darwin theory and origin of species.So, it is actually, essential for us to on one hand, know the latest technologies andtools and a study biology and know the latest technology, how it can influence biology,at the same time, lot of fundamental research happening at the developmental biology levelor evolutionary biology actually, once in a while pays off for example, just imagineall of us sudden H1N1 strain came and we had no idea that you know this particular strain,how you know is getting in; affecting individuals.People are all dyeing you know all over the world and little there was no informationthat how this virus came, lot of evolutionary biology they keep studying evolution of youknow different organism including viruses and you know those evolutionary biologistwere actually studying may be denote the trace of what happens to different family of H andN viruses and they realise that they actually, they do have a lot of gene recombination’shappening.And they make different strains and as a result may be in a very short time people were ableto decode that what can be sequence of these viruses and what can be their origin and then,what could be the possible ways of preventing that particular one, so this is how your basicunderstanding for the systems over the period can actually help you to really understandsome concept.So, H1N1 influenza, even HIV viruses, all of these are various examples in which wayour studies of knowing these viruses over the period has really helped to save lot oflives, so evolutionary concept; they are the major part of the modern biology and biotechnologyexperiments.So, Darwin is of course you know, one of the authority in the field who has made his theory,origin of species, which we will talk in detail but before Darwin came and, and what he proposedthe theory is, the thing which we are known that you know in the earth ancient atmosphereprobably, there has been many changes happened over the period also, in the Jurassic eraand that is where, lot of these dinosaurs and you know lot of these trees you know diedand then became fossil forms.And then, we have understanding that you know, many of these species having certain similaritysome characteristics which are common.A scientist Lamarck mention that inheritance of acquired characteristics it means, overthe period if certain giraffe, you know for his food habit, if it needs to climb up probably,you know it has a long neck because it needs to eat and that is the trees which are havingvery long overall branches and the leaves.And as a result it has to really climb up and therefore, to evolve over the period forthat kind of acquired characteristics which has resulted into the characteristics goinginto the inheritance.So that was the earlier understanding of our evolution and our you know for the systemsbut then Darwin came and he studied these things in a very different manner and he waskind of somebody who likes to observed the, the natural systems and he in fact, left hismedical studies and focus mainly on the looking at different invertebrates, different; lookingat different geological features of different organisms.And then, fortunately he was offered to take a 5 years long sea trip to explore the seaexpedition on a ship HMS Beagle and his job was actually to be a naturalist, who willobserve all these creatures and these different organisms which are present in those environments,alright, his book was actually you know one of the most read more sold book, origin ofspecies and if you look at just his journey, I think he is you know the voids that thesea trip has the tree made huge impact on his observations for the nature.And then, kind of based on those observation, he was documenting which he was kind of youknow, making from different islands while travelling and those has resulted into youknow this particular book which is origin of species where he put there is lot of evidencesthat how life would have evolved all, this became one of the you know, most famous drawingwhich show the tree of life in which way it would have branched.And he first time in vision that in which way branching pattern would have been usedfor the evolution to happen.So, during his voyage of the Beagle, what is the; shown here in the map in which wayhe was travelling across different continents, Darwin collected various species of birds,insects, spider's plans etc. and then he was documenting those that you know in which environmentthey are more adapting, so what is actually leading them is a certain kind of a speciesto have much more inclination to grow in that environment as compared to other.And looking at those, then he kind of wrote this book, origin of species in 1859, wherehe provided the evidences which is for the todays organisms, how they are descendingfrom the ancestral species and he proposed that through a process of natural selectionwhich is happening, so to reach out of these conclusions he had collected many of theseorganisms as I mentioned.For example, he observed that in different Galapago island in different birds speciesare there and those birds, one of them let us say cactus eater, so this is actually attractivehaving different type of beak as compared to other bird which is insect eater or seedeater, so they are living in different islands and they have different beak behaviour andthat is probably because their food habits required these kind of adaptation to happen,so and that is where they are more naturally found in those kind of environment.So, he made those observations very scientifically, he documented those and proposed that lifediversity arose from these ancestral species by the process of natural selection whichwas different view than the previous Lamarckism and the other view thinking that how the acquiredinheritance may happen and first time he actually, publishes his work only after he realisedthat another scientist Wallace who is also working in the similar theme.And he is convinced with Darwin’s idea because Darwin’s idea were first time going to youknow make your changes in the previously known theories, so first time he propose that evolutioncould occur by the natural selection process, so the natural selection is essentially aprocess where individuals having certain heritable traits as I showed you in those Galapago island,these birds having specific features, different type of peaks.And those were actually required for their food habits in which way they can surviveand those traits could be actually heritable now for their survival and further it is actuallybeing carried in the next generation after a production and therefore, these traits arebeing inherited.So, over the time, the natural selection can increase a good match between the organismand in which environment they want to live and survive, if the environment changes orthe individuals move to a new environment probably, adaptation has to happens, so naturalselection may result into the adaptation to the new condition and sometime that may resultinto the new species formation.So, these are the kind of his theory, which ideally said if you are able to adapt andmove to the new situation, new environment then that is a natural selection, you areable to adapt to the right condition, if you cannot then you will be wiped out, you willleave out from that particular population and that that is where the natural solutionis going to favour, those who are having superior ability of adaptation.Just showing you here a couple of examples, one for natural selection versus artificialselection, so natural selection here you know, different type of environment you can seefor the related species of insects which are living there but they can change the coloursas per their environment and the shape in fact and these are the natural selection whereas,if you look at here, the cabbage and various type of broccoli etc. derived, they are fromthe wild mustard.But we are you know, for our food habits for our you know food requirements, we grow themin different environments and different type of vegetables have been produced which couldbe the example of artificial selection, this is natural selection for the environment whereone like to adapt for that survival, this is artificially selected just for our requirementsfor the food and other practices.There are scientists who have been studying the gene behaviour and their overall impactto the population and looked at the things in much more numerical ways.And these are, are known as Hardy Weinberg law, so an allele and the genotype frequenciesof a overall population will remain constant, so leaving Hardy Weinberg law is applicableif population is large, mating is random, there is no mutation assumed, there is nogene flow and no natural selections, so things are very static, now going back to your originalexample of you know red versus white genes for that flower characteristic.In this way the p and q represent frequencies of 2 possible alleles for the red gene andthe white gene here, let us assume this one is 0.8 and this one is 0.2, so the Hardy Weinberglaws says p square + 2pq + q square is going to be 1 for all of these genes in the randompopulation.So, if you have 1 homozygotes genes, which is p square, another one is q square and heterozygoteis 2pq, so you can actually calculate overall gene frequencies and the some of the frequenciesof 3 genotypes has to be = 1, so if a population is in the Hardy Weinberg equilibrium and allthe members actually mate randomly, so then you will have the gene, genotype frequenciesthat will remain consistent in the population.Coming back to this particular example please do try this yourself, just imagine if theallele or the frequency here is 0.8 for the red and 0.2 for the white, if you do thiscross here again, the punnet square, you can see that you know, the p square is going tobe 0.64, q square going to be 0.04 and you have the pq which will be 0.32.So, this is something exactly what I have mentioned in my next slide which you can actually,calculate and you can see that overall it will be 1 and like that if you have been givencertain you know, the frequencies or certain type of allele behaviour, you can look atin the Hardy Weinberg equilibrium, how you can calculate those genotypes.Another terminology which is relevant here in the context of evolution is convergentversus diverted evolution, so convergent evolution is when we have similar traits but they arefound in the independent species growing in independent environments for example, hereyou can see in Australia versus North America, these squirrels and the gliders, they arehaving similar traits now, divergent evolution is that there are certain traits which arecommon across different species.But they evolve into different type of properties, so if you look at anatomically, all of thesewhether some human hand or cat or whale or bat, they look very similar in their anatomicalway but they have been adapted to do different activities and therefore, something can beused for flying or for you know, swimming or for you know various activity which wedo or even climbing up in the cat space, so these are the divergent evolution examples.Let us now look into hardy Weinberg law in some more detail, refresh the concept, soas you can solve some analytical problems.Learning evolution at the genetics level; Hardy Weinberg; law population genetics law.What is the key conditions for Hardy Weinberg law, let us review these 5 conditions forHardy Weinberg law, first; population must be very large, second; population must beisolated from other population, so there is no migration, third; there is no mutation,fourth; random mating, fifth; no natural selection it means, every individual has an equal chanceof survival.The Hardy Weinberg equation states that the frequency at which a specific genotype codesoccurs can be expressed as a ratio, genotype divided by total number of alleles in thepopulation.Let us review this concept before performing analytical problems, Hardy Weinberg equation;p square + 2pq + q square = 1, also p + q = 1, where p is the frequency of dominantallele, q is the frequency of recessive allele, 2pq is the frequency of heterozygous dominantgenotype, p square is the frequency of homozygous dominant genotype, q square is the frequencyof homozygous recessive genotype.Let us now solve some problems based on the Hardy Weinberg law, you should try yourselffirst but a TA will also guide you to show the solution, so let us start now.There is a herd of zebras in the Masaimara region of Africa, assuming that this populationis following the Hardy Weinberg equilibrium, 49% of the zebras are homozygous dominantfor a trait XX, the gene for which is present as 2 different alleles, what percentage willbe homozygous recessive?50%, 60%, 5% or 9%.In a city, the population that do not have freckles equal to 60%, freckles are dominanttraits and this indicates that 60% of the population is homozygous recessive, then whatis the percentage of recessive allele in the population?100%, 60%, 20% or 35%.In a small group of mountain climbers; 10 people are there, 6 of them have a dominanttrait of enhanced oxygen uptake, if the dominant allele frequency is 6, what recessive allelefrequency respected?60%, 20%, 35% or 70%.So, inthis way, you can even integrate the concepts of biology like evolution into mathematicalmodels and predict the genetic frequencies of a population.Learning key concepts of evolution on one hand will make you appreciate the fact thatlife began as the single cell but manifested into such diversity additionally, by integratingkey mathematical aspects, you may be able to predict traits and inheritance patterns.