1. The process of evolution n Macroevolution –The creation of new species and the extinction of old ones. The accumulation of genotypic and phenotypic changes large enough to create new species genera and higher taxonomic categories. –Also called speciation. n Microevolution –Evolution within species. –Driven by natural selection which acts on allele frequencies within populations of species. operates on heritable variations within species, produces steady, gradual change in existing species.

2. The process of evolution n Gene mutations Change in the base sequence of the DNA –Phenylketonuria Recessive disease. Homozygous individuals lack an enzyme needed to convert phenylalanine to tyrosine. Causes abnormal brain development and mental retardation in infants. –Industrial melanism recessive trait produces a light colored moth because of a lack of an enzyme that is necessary in the production of melanin. n Chromosome mutations –Changes in whole chromosomes Klinefelters syndrome

3. The process of evolution n Variation –The result of recombination during meiosis and fertilisation n Species –A population of physically similar interbreeding organisms that are reproductively isolated from other such groups n Population –A group of individuals of a single species that interact and interbreed in a particular area. n Gene pool –All genes available for reproduction in a given population at a given time.

4. The process of evolution n Natural selection –leads to the increased reproduction of individuals with favourable variations n Adaptation (micro- evolutionary steps) –may occur as the result of an allele frequency increasing in a population´s gene pool over a number of generations. –leading to reproductive or genetic isolation

5. Speciation n Speciation –The evolution of one species into another species involves the accumulation of many advantageous alleles in the gene pool of a population over a period of time n Migration –Movements into or out of the population n Geographical isolation –Isolation because of sea, mountains... n Ecological isolation –isolation because of the use of different habitat

6. The pace of evolution n Gradualism –The slow change from one species to another n Punctuated equilibrium Eldredge and Gould –Long periods with no change and short periods of rapid evolution.

7. The Hardy- WeinbergPrinciple n The frequencies of alleles in a given population will stay the same if mating is random and there are no outside forces. n The requirements are: –Large population. –Random mating. –Allele frequency is constant over time. No allele specific mortality. No mutation. No emigration. No immigration.

8. The Hardy- WeinbergPrinciple n A significant deviation from the principle is a sign of evolution. n It is a Null Hypothesis –It predicts that there is no change in phenotypic or genotypic frequencies between generations. –If there is a change then evolution must be happening. –The principle can be used to calculate genotype and phenotype frequencies for genes with two alleles or more.

9. The Hardy- Weinberg Principle n The Hardy-Weinberg equation is derived from the fact that in a closed population the combined frequencies of an allele must be 1. p = frequency of dominant allele q = frequency of recessive allele p + q = 1 p(A) = 0.67 q(a) = 0.33 A A AA A A A A A A A a a a a a a Gene pool A

10. The Hardy- Weinberg Principle n The genotypic and phenotypic frequencies can also be calculated –The probability of two alleles coming together in a genotype is the probability of one multiplied by the probability of the other n In future generations AA : Aa : aa = p2 : 2pq : q2 Since the recessive phenotype is only shown in homozygous individuals we can use q2 to find q and then to find p.

11. The Hardy- Weinberg Principle n Transient Polymorphism –When alleles are not at equilibrium –Industrial melanism is an example the environment keeps changing and so does the allele frequency n Balanced Polymorphism –When alleles are at equilibrium –Sickle cell anaemia in Africa the effect of malaria keeps the heterozygote fitter the homozygotes –ABO blood groups