1. Population Genetics

3. Biochemical

4. Physiological

5. Developmental

7. Biochemical Variation 4 Eg. Coat colour in quolls Eg. Human ABO blood groups Ability to produce enzyme phenylalanine hydroxylase

8. Physiological Variation Eg. Red-green colourblindness Eg. Ability to taste PTC or other toxins Interestingly, brussel sprouts contain a very similar plant tannin and appear to have the same bitter taste to some people. 5

9. Behavioural Variation 6 Eg. Horses: trotters vs pacers Eg. What certain dog breeds can be trained to do Eg. Domesticable animals Eg,

10. Developmental Variation 7 Eg. Adult vs juvenile appearance Pythons Human proportions

11. Variation 8 Geographical variation Not a way in which species will vary, but often a result of one of the aforementioned types of variation occurring in geographically isolated populations

12. Variations on Variation 9 How many variants? Monomorphic (only one type, eg. Galahs) Polymorphic (more than 1 type) Continuous or discontinuous Continuous (eg. Height in humans) Discontinuous (eg. ABO blood groups) B O AB A Height in cm

13. Causes of Variation 10 Environmental Eg. Identical twins looking different Eg. Bees: caste determination by food Eg. The arrowleaf plant Eg. Hydrangeas Grown in water Grown in soil Alkaline soil Acidic soil

14. Causes of variation 11 Genetic Monogenic traits (controlled by one gene) Eg. ABO and Rh blood groups Eg. Cleft chin, detached ear lobes No of alleles and relationship between them determines the number of variations possible Polygenic traits (controlled my more than one gene) Eg. Height and skin tone in humans

15. Skin tone (simplification) 12 Hypothetically controlled by two genes each with two alleles (+ / -). (+ = dark, - = light), Incomplete dominance How many possible outcomes?

16. Genes in populations 13 Gene pool All the alleles in a given population Allele frequency The proportions of each allele for a given gene in a population Calculating allele frequency Divide number of particular allele by total number of alleles. All allelic frequencies must add up to a total of 1.0

17. Calculating Allele Frequency Alleles are assigned the letters p and q In this population of sheep Total no. of alleles is 20 W = 14, w = 6 Allele frequency for W (p) p = 14/20 = 0.7 Allele frequency for w (q) q = 6/20 = 0.3 14

18. Calculating Allele Frequency We don’t need to be given both p & q If only given p or q, we know that p + q = 1.0 The real world Unfortunately we rarely know the actual genotype for most individuals displaying the dominant phenotype Calculating expected allele frequency We are able to count the number of homozygous recessive individuals and assign them the value q2 The Hardy-Weinberg formula predicts that √ q2 will provide us with an approximation of q 15

19. Hardy-Weinberg Equilibrium A population in H-W equilibrium will be expected to maintain near-identical allelic frequencies from one generation to the next. A population is said to be in H-W equilibrium if: The population is large Mating is completely random All matings are fertile The population is closed A population will maintain H-W equilibrium unless an agent of change enacts upon it. 16

20. Agent of change #1 - Selection Selective pressure can be as a result of many things Competition for food, habitat or mates Pressure exerted through predation Death or illness do to parasitic organisms or infectious disease As a result of these pressures, due to genetic variability, some phenotypes may have a selective advantage Greater contribution to next gen = greater fitness No phenotype has a set fitness level – depends on circumstances 17

21. 18 It would appear that these beetles are at a distinct disadvantage

22. 19 ... and now?

23. Selection in human populations Case study – Malaria and Sickle Cell Anaemia Sickle cell anaemia is a debilitating genetic disease that causes the red blood cells to take on a sickle shape that is particularly unconducive to carrying oxygen The alleles Haemoglobin A is found in normal RBCs Haemoglobin S is found in sickle cell RBCs The effect Malarial parasites can inhabit only non-sickled RBCs The HA and HS display incomplete dominance 20

24. To whom goes the advantage? Non-malarial environment Most to least successful genotypes HAHA – no sickling, plenty of oxygen HAHS – some sickling, less oxygen HSHS – complete sickling, very little oxygen Malarial environment Most to least successful genotypes HAHS – some sickling, but resistant to malaria HSHS – complete sickling, quite debilitating HAHA – no sickling, high risk of malaria 21

25. Natural Selection When an environmental agent enacts on a wild population causing differential reproduction When one phenotype produces more viable offspring than another Agents of natural selection Same as the sources of selective pressure Results over time In the short term can result in one phenotype being more common than another Over longer periods can result in phenotypically variant groups becoming so different that they can no longer mate = speciation 22

26. Natural Selection When an environmental agent enacts on a wild population causing differential reproduction When one phenotype produces more viable offspring than another Agents of natural selection Same as the sources of selective pressure Results over time In the short term can result in one phenotype being more common than another Over longer periods can result in phenotypically variant groups becoming so different that they can no longer mate = speciation 23

27. Artificial Selection Individuals are selected for desired traits and used as parents for the following generation Often the traits for which these animals have been selected would be disadvantageous in a natural environment. Not even going to go there Masters of predator evasion So what if he can’t breath or smell, he looks so cuuute! 24

28. Artificial selection Further difficulties arise when a species reaches its desired form. In the case of crops, this creates a “monoculture” where each individual has the same advantages and disadvantages. An example of this going wrong was in the case of the great potato famine in Ireland The outbreak of the fungus that causes potato blight decimated the crop of the entire country. Over one million people died of starvation International seed and sperm banks are being created in an effort to maintain genetic diversity 25

29. Migration (aka gene flow) Capable of changing allele frequencies far more rapidly than selection Immigration Disproportionate quantity of certain alleles are brought in to a population Emmigration The departing group do not represent the population as a whole with regard to allelic proportions 26

30. Human Migration The first great migration in hominid history was Homo Erectus’ departure from sub-Saharan Africa approx. 2 million years ago The second was H. Sapiens making the same journey approx. 130,000 years ago Interesting results of human migration People of Celtic ancestry adapted to an environment with far less solar radiation than Australia The HS allele is in drastic decline in US Black populations due to lack of selective pressure. 27

31. Chance events: Genetic Drift When a population experiences a calamitous event that decimates the population indiscriminately, the repercussions can be interesting. Examples of such events are fires, floods, earthquakes, etc. 28

32. Bottleneck Effect Natural disasters do not favour any particular phenotype The resultant reduced population may be unrepresentative of the original population A bottleneck essentially eliminates thousands of years of divergent evolution. The next generation have very few mating options and as a result the growing population will be genetically very simillar Time 29

33. Founder Effect At times members of a population migrate, to another location and become isolated. These new populations may not be representative of the population from which they originated. eg. On the Antarctic peninsula most macaroni penguins have black faces, a very few have white faces. All the macaroni penguins on Macquarie Island have white faces 30

34. Evolution within a species Once there was a population of red circles They were a fairly homogenous population but they used to make fun of the “pinkies” One day the pinkies got sick of this and left 31

35. Evolution within a species A few generations later The pinks met a really nice clan of blues and started having a fling here and there Meanwhile, a dark red had some mutant oval offspring 32

36. Evolution within a species A few generations later The introduced alleles were producing some varying phenotypes in the formerly pink population Meanwhile, skinny was the new black with the reds and the streamline mutants were quite popular 33

37. Evolution within a species A few generations later The green offspring’s photosynthetic abilities gave them a great upper hand and they grew big and strong Meanwhile, skinny was the new black with the reds and the streamline mutants were quite popular 34

38. Evolution within a species A few generations later The most successful greens were the ones with a larger surface area. They could just sit on their ass and photosynthesize all day The reds just kept hooking up with skinny chicks 35

39. Evolution within a species A few generations later One day members of the divided populations decided to check out what sort of action they could get from across the river Apart from the fact that they found each other incredibly Unattractive, their bits didn’t even match any more! 36

40. Species vs Sub-species Two populations that are isolated are often exposed to different agents of change They may stay biologically compatible for thousands of years, but will not be attracted to each other. They are now different sub-species Speciation only occurs once the two populations become reproductively isolated (can no longer produce viable offspring). 37

41. mtDNA Is only maternally inherited Therefore does not recombine Each cell contains hundreds of copies Some regions have a high mutation rate Can be used to trace evolutionary origins 38

42. mtDNA The longer two populations are geographically isolated, the more uniquedifferences they accumulate. mtDNA sequence only found in certain populations are known as haplogroups Haplogroups are compared against the originally sequenced Cambridge Reference Sequence (CRS) Haplogroups can be traced back to their point of origin 39

43. Origin and movement of haplogroups 40

44. Homo neanderthalensis In 1997 it was confirmed via mtDNA that neanderthals were a separate species to modern humans In a sequence of mtDNA 397 base pairs long, there were 27 differences. This is in contrast to the average of 8 differences between human populations 41