Selection Intensity & Frequency based Selection in evolution
- 1. Selection Intensity & Frequency based Selection GPB 607 (3+0) - Crop Evolution Dr. K N Ganeshaiah
- 2. Background Peppered moth Biston betularia Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah
- 3. Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah Lichens Not seen under polluted conditions
- 4. Background Industrialization London / Europe Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah
- 5. Biston betularia F.typica light-coloured species with dark patches, that help them to camouflage against the lichens on the barks of the trees Biston betularia F.carbonaria sub species of F.typica mutated into dark coloured moth with light-coloured patches. Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah
- 6. The proportion of the white (Bb) and black (Bb) after the predation will be used to re-populate next generation Assumptions Predation rate The rate at which the birds prey on the moth Biston betularia is constant for all generations Repopulation No Death There will be no decline in the population of the Bb in any generation due to any other factors like disease or natural calamities 10% wn:bn::Wn+1:Bn+ 1 Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah
- 7. BIRD ‘A’ Results of demonstration / experiment conducted by group A Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah
- 8. Study - 1% Frequency How selection against white (Bb) increased black (Bb) proportion Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah
- 9. ● Population curves (frequency) remain stable until predation of Black (Bb) ● Predation of Black (Bb) in 13th generation ● No individual of Black (Bb) to repopulate the 14th generation Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah
- 10. ● Population curves (frequency) remain stable until predation of Black (Bb) ● Predation of Black (Bb) in 13th generation ● No individual of Black (Bb) to repopulate the 14th generation Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah
- 11. Study - 5%Frequency How selection against white (Bb) increased black (Bb) proportion Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah
- 12. Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah Faint lines represent the normalized polynomial curve ( to the power of 3) for which the equations are represented below in the graph 1. White (Bb): Observe the sharp decline in the population curve after 10th generation 1. Black (Bb): Observe the sharp increase in the population curve after 10th generation We shall discuss this later - collectively 10th generation
- 13. Study - 10% Frequency How selection against white (Bb) increased black (Bb) proportion Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah
- 14. Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah Faint lines represent the normalized polynomial curve ( to the power of 2) for which the equations are represented below in the graph 1. White (Bb): Observe the sharp decline in the population curve after 12th generation 1. Black (Bb): Observe the sharp increase in the population curve after 12th generation We shall discuss this later - collectively 12th generation
- 15. Study - 20% Frequency How selection against white (Bb) increased black (Bb) proportion Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah
- 16. Faint lines represent the normalized polynomial curve (to 4th degree) for which the equations are represented below in the graph 1. White (Bb): Observe the gradual decline in the population curve 1. Black (Bb): Observe the gradual increase in the population curve We shall discuss this later - collectively Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah
- 17. Study - 50% Frequency How selection against white (Bb) increased black (Bb) proportion Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah
- 18. Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah Faint lines represent the normalized linear curve for which the equations are represented below There is a sharp increase in selection against the White (Bb) The Black (Bb) population is reaching the saturation and stability from the 14th generation onwards
- 19. Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah
- 20. Collective discussion Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah Trying to explain SELECTION INTENSITY and FREQUENCY based SELECTION
- 21. Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah 12 Dif. Population White (Bb) Black (Bb) 0 G0 = (initial population) 90 10 12 G12 = (12th generation) 80 20 5 G17 = (17th generation) 70 30 3 G20 = (20th generation) 60 40 10 G31 = (31st generation) 1 99 17 20 31
- 22. Difference Population White (Bb) Black (Bb) 0 G0 = (initial population) 90 10 12 G12 = (12th generation) 80 20 5 G17 = (17th generation) 70 30 3 G20 = (20th generation) 60 40 10 G31 = (31st generation) 1 99 Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah 10
- 23. Difference Population White (Bb) Black (Bb) 0 G0 = (initial population) 90 10 12 G12 = (12th generation) 80 20 5 G17 = (17th generation) 70 30 3 G20 = (20th generation) 60 40 10 G31 = (31st generation) 1 99 Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah 10
- 24. Difference Population White (Bb) Black (Bb) 0 G0 = (initial population) 90 10 12 G12 = (12th generation) 80 20 5 G17 = (17th generation) 70 30 3 G20 = (20th generation) 60 40 10 G31 = (31st generation) 1 99 Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah 10
- 25. Difference Population White (Bb) Black (Bb) 0 G0 = (initial population) 90 10 12 G12 = (12th generation) 80 20 5 G17 = (17th generation) 70 30 3 G20 = (20th generation) 60 40 10 G31 = (31st generation) 1 99 Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah 60
- 26. Difference Population White (Bb) Black (Bb) 0 G0 = (initial population) 90 10 12 G12 = (12th generation) 80 20 5 G17 = (17th generation) 70 30 3 G20 = (20th generation) 60 40 10 G31 = (31st generation) 1 99 Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah 60 10 Initially where it took ≅ 10 generations (G0-G12)to reduce the population by 10 individuals, later the 10 generations (G20-G31) reduced the population by 60 individuals (6x increase)
- 27. Which means that - ‘with increasing number of generations, there is incremental selection against the White (Bb) population’ i.e ., favouring Black (Bb) population Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah 12 17 20 31 This constitutes SELECTION INTENSITY
- 28. This selection intensity is in-turn dependent on the frequency of the population of Whites and Blacks Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah 12 17 20 31
- 29. Population White (Bb) Selection Intensity G5 = (5th generation) 86 - G6 = (6th generation) 85 1 G7 = (7th generation) 84 1 G26 = (26th generation) 34 - G27 = (27th generation) 28 6 G28 = (28th generation) 22 6 Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah Therefore, when there is lower frequency of white population, there is higher probability that the white moths are preyed upon - frequency based selection
- 30. FREQUENCY based SELECTION { The selection intensity and frequency based selection are interdependent “The lower frequency of the population increases the selection intensity” { Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah
- 31. BIRD ‘B’ Results of demonstration / experiment conducted by group B Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah
- 32. 20% Population frequency 10% Selection intensity Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah 40 (White):10 (Black) I case White – Chickpea Black - Horsegram II case White – Chickpea Black - Soybean
- 33. 40:10 (White: Black) ● Gradual changes till 6th generation ● After 25:25 changes were sharp at 6th generation ● By the 15th generation, Black moths were more than white moths ● Stability may be achieved Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah
- 34. Selection intensity >>>>> Distinction between moths I case - Predominant distinction between moths - Discrimination also increases - Selection intensity is more II case - Distinction between moths is less - Discrimination is gradual (The earliest stage of melanization - Selection intensity is less Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah
- 35. Study - 1% Frequency 99 (White):1 (Black) Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah
- 36. 99:1 (White : Black) ● Stabilization till the 5th generation ● Random chance ● Leads to random genetic drift ● Is there any chance of the occurrence of black moth again?? Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah
- 37. Study - 5% Frequency 95 (White):5 (Black) Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah
- 38. 95:5 (White : Black) ● Gradual changes ● 22nd generation >>> sharp changes ● Converge at 50:50 Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah
- 39. Study - 10% Frequency 90 (White):10 (Black) Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah
- 40. 90:10 (White : Black) ● Sharp decrease and increase in white moths and black moths population ● Converge at 50:50 Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah
- 41. Study - 50% Frequency 50(White):50 (Black) Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah
- 42. 50:50 (White : Black) ● Initial sharp changes in both the populations ● Later the changes were gradual Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah
- 43. ● The rate of reproduction is more when white moths is 90 and the rate of elimination of white moths when it is 10 is lesser due to the reproduction ● But when both white and black moths are at the same population composition (50: 50) the chance of elimination and chance of reproduction will be equal then there will sharp/ exponential change. Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah Generations No. of generations White Black G1 – G8 8 90 - 80 10- 20 G8- G18 10 80-60 20-40 G-18 – G21 3 60-50 40-50 >>>G-21 - 50 50 Generations No. of generations White Black G1-G4 4 50-40 50-60 G4-G6 3 40-30 60-70 G6-G9 3 30-20 70-80 G9-G12 3 20-10 80-90 G12-G21 10 10-0 90-100 90:10 50:50
- 44. The black moths population rate will be sharp as the number of black moths in the initial population increases
- 45. THANK YOU Department of Genetics and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah Brahmesh Reddy B R Aishwarya G Sinchana K PhD Scholars UAS,GKVK, Bangalore