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A present-day view of evolutionary theory Vidyanand Nanjundiah Centre for Human Genetics Bangalore Indian National Science Academy,

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Presentation on theme: "A present-day view of evolutionary theory Vidyanand Nanjundiah Centre for Human Genetics Bangalore Indian National Science Academy,"— Presentation transcript:

1 A present-day view of evolutionary theory Vidyanand Nanjundiah Centre for Human Genetics Bangalore (vidya@ces.iisc.ernet.in) Indian National Science Academy, Delhi 3 November 2014

2 The problem To account for the presence on earth of the highly improbable forms of matter known as living creatures

3 (http://www-images.warwick.ac.uk/about/environment/faqs/biodiversity.jpg) Living Matter

4 Clue: the forms of living matter are interrelated Principle of continuity

5 Vertebrate forelimbs http://home.comcast.net/~mkent595/circum1.gif

6 The answers 1.Principles of physics and chemistry. 2.Chance. 3.Natural selection.

7 The answers 1.Principles of physics and chemistry. Ahistorical 1.Chance. 2.Natural selection.

8 D’Arcy Thompson, “On Growth and Form”

9 http://cargocollective.com/turing/Belousov-Zhabotinsky-reaction and http://www.metafysica.nl/dissipative_systems.html

10 http://www.wired.com/2011/02/turing-patterns/

11 http://www.pnas.org/content/107/20/9370.figures-onlyhttp://www.pnas.org/content/107/20/9370.figures-only and http://www.veritas-ucsb.org/

12 The answers 1.Principles of physics and chemistry. 2.Chance. Ahistorical: accidents whose outcomes persisted; ‘random walk’ 1.Natural selection.

13 http://www.biomedcentral.com/1741-7007/8/45/figure/F1

14 (cytochrome C) http://fishgenomes.blogspot.in/2011/03/workshop-on-molecular- evolution-north.html

15 Luidia sarsi (zygote develops into juvenile starfish with radial symmetry inside a larva with bilateral symmetry; Williamson & Vickers, Am Sci 95(6):509-517, 2007)

16 The answers 1.Principles of physics and chemistry. 2.Chance. 3.Natural selection. Historical: accidents, advantageous outcomes; ‘biased random walk’

17

18 Alfred Russel Wallace (1823-1913)

19 Why does natural selection occur? Because the individuals of a species are not all alike; because they differ in their ability to survive and reproduce; because they can pass on these traits to their children. These are testable statements!

20 Genes and Organisms Genes  Proteins  Organelles  Cells   Tissues  Organisms

21 The essence of neo-Darwinian theory 1.Living organisms carry DNA or RNA sequences (genes) that can be copied inside a cell. The sequences differ from one individual to another. 2.Genes specify proteins. 3.Proteins ‘build’ bodies and confer various properties on organisms. 4..Some individuals leave behind more children than others because they have different properties. 5.Then the protein composition of a population, and so also the genetic composition, changes in time.

22 Environmental pressure: relative, external Genetic variation: random, internal Response: systemic, internal

23 We cannot run faster than him!

24 I don't want to run faster than him; I want to run faster than YOU !

25 The signature of natural selection: Adaptation (http://www.agen.ufl.edu/~chyn/age2062/lect/lect_11/18_20.GIF)

26 Does the neo-Darwinian framework require modification? Do many roads lead to Rome?

27 Heritable variation without genes: epigenetic inheritance Ciliary row pattern in Tetrahymena (http://www.bioone.org/na101/home/literatum/publisher/bioone/journals/content/)

28 Environment created by organism: Niche construction snailstales.blogspot.com

29 Egyptian plover and Nile crocodile (http://bookbuilder.cast.org/bookresources/12/12710/46346_1.jpg) Co-evolution

30 Variation dependent on the environment: phenotypic plasticity http://www.kyoto-su.ac.jp/english/department/graduate/g_eng/fm/kimura.html

31 Environment-induced modification Daphnia; https://wiki.cgb.indiana.edu/display/DGC/Projects

32 Self-organisation R. Blanton

33 Scope of evolutionary thinking : 1.Mathematics 2.History 3.Culture 4.Behaviour 5.Psychology

34 What next?

35 Echinoidea; Van Valen, L. 1973. Evol. Theory 1: 1-30.

36 Summing up

37 Following slides ‘extras’, to be used only if the subject crops up during question time

38 What next?

39 The brain

40 Evolution is also concerned with dead matter

41

42 Vertebrate forelimbs http://home.comcast.net/~mkent595/circum1.gif

43 ‘Plasticity’

44 Phenotypic plasticity (PANC-1 cells express FGF-2 (red) or FGF-2 receptor (green), but not both) Hardikar et al. (2003) PNAS 100(12): 7117–7122

45 Spontaneous self-organisation

46 Life cycle of slime mould

47 Reproduction “1  1+1” “1  1/2”

48 Asexual reproduction (mitosis): 1  1+1

49 Sexual reproduction (meiosis): 1  1/2

50 Molecular biology applied to evolutionary questions

51 Behaviour too has evolved www.animals.howstuffworks.com

52 The nerve cell

53

54

55 Natural selection can be compared to climbing Getting to the next peak involves crossing a valley

56 OK, I'll try to divert him. And you'll see, my genes can spread better than yours!

57 The signature of natural selection: Adaptation Adaptation works only in the short term. Natural selection has no way of planning for the long term.

58 Natural selection Natural selection depends on particular properties of living matter: Variation Almost faithful reproduction Differences in ability to survive and reproduce


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