WHAT IS EVOLUTION? Change over time. evolution 1

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1 WHAT IS EVOLUTION? Change over time. evolution 1

2 WHAT IS BIOLOGICAL EVOLUTON? Changes in the genetic makeup of a population of organisms over time! evolution 2

3 A FACT Biological organisms evolve evolution 3

4 A FACT Biological organisms evolve evolution 4

5 A FACT Biological organisms evolve The details are under discussion evolution 5

6 ANOTHER FACT Nature does not have a plan; it is more like a blind watch maker evolution 6

7 WHAT IS ADAPTATION? Def n - properties of an organism that allow it to survive and reproduce. evolution 7

8 ANOTHER FACT At present, evolutionary theory is the ONLY unifying theory in biology evolution 8

9 WHAT IS A THEORY? A coherent system of general propositions. evolution 9

10 FATHERS OF THEORY OF NATURAL SELECTION Charles Darwin Alfred Russell Wallace Patrick Matthew evolution 10

11 THEORIES GET ACCEPTED AS A FUNCTION OF: Supporting evidence Current views on the matter evolution 11

12 DEFINING SPECIES Def n - a group of actual or potentially interbreeding organisms evolution 12

13 REMEMBER: When we speak of evolution, we mean change across but not within generations. The latter is referred to as ontogeny evolution 13

14 DARWINIAN DEFINITION OF EVOLUTION: Def n - Descent with modification. evolution 14

15 THE FIVE STAGES OF EVOLUTIONARY BIOLOGY Pre- Darwinian Darwinian Eclipse of Darwin Modern Synthesis Post-Modern evolution 15

16 LAMARCK S TRANSFORMATION THEORY Species changed due to : Programmed internal forces Acquired characteristics evolution 16

17 LAMARK S INTERNAL FORCES THEORY Trait Value sp 1 sp 2 time 17

18 LAMARCK S INHERITANCE OF ACQUIRED CHARACTERS Effects of unique events get passed on to offspring. evolution 18

19 CUVIER S APPROACH Whole species were frequently wiped out by catastrophe and then, miraculously, new ones appeared evolution 19

20 DARWIN S VOYAGE evol_2 20

21 UNDENIABLY SIMILAR evol_2 21

22 GALAPAGOS MOCKINGBIRDS evol_2 22

23 GALAPAGOS FINCHES evol_2 23

24 ONE GREAT IDEA! Various finches evolved from a common ancestor evol_2 24

25 FROM HIS READINGS, DARWIN KNEW Earth is very old - lots of time for change Enormous reproductive potential for organisms - why aren t we covered in flies? Extant variation can be selected artificially evol_2 25

26 A QUOTE: Darwins view of Nature kept faith with the competitive, capitalist, Malthusian dynamics of a poor-law society and that his theory would make him an ally of the middle and upper class evol_2 26

27 A PROPOSAL When together in a habitat, two similar species do better when each specializes on different resources Seed Size Beak Size evol_2 27

28 EVIDENCE FROM FINCHES Compare alone vs. shared evol_2 28

29 STICKLEBACKS They come in different shapes and sizes SHALLOW DEEP evol_2 29

30 INTERESTING PATTERN When alone in lakes each species is intermediate in size When together in lakes each species displays much more size extremes - benthic species is much bigger and feeds deep and the limnetic species is smaller and feeds shallow Coincidence? evol_2 30

31 IS BEING EXTREME BENEFICIAL? evol_2 31

32 HOW THE STONEFLY GOT ITS WINGS evol_2 32

33 MISSING LINK? evol_2 33

34 WEISMANN SHOWED Acquired characters are NOT heritable evol_2 34

35 THE BIG PROBLEM: Linking Mendelian inheritance to natural levels of within-population variability evol_2 35

36 LEADERS OF THE MODERN SYNTHESIS R. Fisher J. Haldane S. Wright From The World Book (TM) Multimedia evol_2 36

37 BIG ACHIEVEMENT Demonstration that it was that it was mathematically possible to achieve everyday patterns of variation without having to resort to acquired characteristics or hopeful monsters evol_3 37

38 INDUSTRIAL MELANISM evol_3 38

39 POST-MODERN FEATURES Demonstration of inheritance mechanism (birth of molecular biology) Better integration of evolutionary and ecological theory Studies on the adaptive nature of behavior (in the broad sense) Studies on phenotypic plasticity The species concept evol_3 39

40 SCPECIES CONCEPT OLD - A set of similar organisms (measured against some time) NEW - A group of interbreeding organisms evol_3 40

41 DARWIN S THEORY IS ELEGANT It requires no demons to make it work! evol_3 41

42 A SUMMARY OF DARWIN S THEORY Organisms have enormous repro. potential Their full potential isn t being met All populations contain variants Some variants outperform others If variation is heritable, they leave more offspring and become more common Given enough time, new species can arise evol_3 42

43 DARWIN S ALGORITHM Substrate neutrality Underlying mindlessness Guaranteed results. evol_3 43

44 ALWAYS REMEMBER: Can t have evolution by Natural Selection without variation Can t have evolution by Natural Selection without variation being heritable Natural Selection works on existing variation i.e. it is not progressive evol_3 44

45 THOUGHT EXPERIMENT 1: SELECT FOR SIZE NO VARIATION - NO EVOLUTION!! 45

46 THOUGHT EXPERIMENT 2: SELECT FOR SIZE HIGH MEDIUM LOW NO HERITABILITY - NO EVOLUTION!! 46

47 THOUGHT EXPERIMENT 3: SELECT FOR SIZE HIGH MEDIUM LOW NO CONSISTANCY - NO EVOLUTION!! 47

48 THOUGHT EXPERIMENT 4: SELECT DE NOVO FOR PATTERN CURRENT STOCK GOAL NO PROGRESSIVE EVOLUTION!! 48