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Biology 2900 Principles of Evolution and Systematics

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Title: Biology 2900 Principles of Evolution and Systematics


1
Biology 2900Principles of Evolutionand
Systematics
  • Dr. David Innes
  • Jennifer Gosse
  • Valerie Power

2
Announcements
  • Lab 4 Group 2 starts Monday, March 10
  • Download from Webpage
  • Pass in a copy of article used for Lab 5
    presentation ( 2 marks)

3
Evolution in the News
  • Globe and Mail

Darwin the Evolution Revolution March 8 to
August 4, 2008Garfield Weston Exhibition
HallThe most in-depth exhibition ever mounted on
Charles Darwin!
4
Topics
  • Diversity
  • Classification and phylogeny (Lab 4)
  • Species and speciation
  • Patterns of evolution
  • Evolution in the fossil record
  • History of life on earth
  • The geography of evolution
  • The evolution of biodiversity

5
Species and Speciation
  • Species (Ch. 15)
  • What Are Species?
  • Barriers to Gene Flow
  • How Species Are Diagnosed
  • Differences among Species
  • Genetic Basis of Reproductive
  • Barriers
  • Molecular Divergence among
  • Species
  • Hybridization

Speciation (Ch. 16) Modes of
Speciation Allopatric Speciation
Alternatives to Allopatric Speciation
Polyploidy and Recombinational
Speciation How Fast Is Speciation?
Consequences of Speciation
6
Modes of Speciation
Gene flow
  • Allopatric isolated populations geographic
    barrier
  • Peripatric peripheral isolated population
    founder effect
  • Parapatric neighbouring populations
  • Sympatric single population

X
X
?
? ??
7
Vicariance Separation of a population by a
barrier to gene flow
8
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9
Allopatric Speciation
  • Allopatry defined by the reduction in movement
    of
  • individuals or gametes
  • Genetic divergence occurs forming new species
  • Range expansion ? secondary ? reinforcement of
  • contact
    prezygotic RIB
  • Thought to be the most common mode of
    speciation

10
Allopatric Speciation
  • Hawaii
  • Achatinella tree snails

YouTube Allopatric Speciation
11
Evolution of Reproductive Isolation
12
Ecological Speciation
  • A form of allopatric speciation
  • Association between ecological adaptation and
    reproductive isolation
  • Example Three-spined sticklebacks
  • Gasterosteus

13
Ecological Speciation
  • Parallel speciation Ecomorphs
  • benthic (bottom-feeding)
  • limnetic (open water)

Mating preference
Dolph Schluter UBC
14
Sympatric Speciation
  • Speciation with gene flow
  • Controversial limited evidence
  • Insect host races - adaptation
  • Native host Hawthorn --- host shift to apples
  • Rosaceae

Apple maggot Rhagoletis pomonella
15
Rate of Speciation
  • Various approaches for estimating
  • Rates vary greatly
  • Mutation and drift ? very slow
  • Natural selection ? faster
  • Geological evidence
  • Big Island of Hawaii 800,000 years
  • Endemic Drosophila species

16
Hawaiian Drosophila (adaptive radiation)
http//www.bio.ilstu.edu/Edwards/HawaiianDrosophil
a/index.shtml
17
Biological Speciation Interval Time for
Speciation
Net speciation speciation - extinction
Rate of Speciation
Millions of Years
18
Consequence of Speciation
  • Biological Diversity
  • "Without speciation, there would be no
    diversification.no adaptive radiation.
  • The species is the keystone of evolution "
  • Ernst Mayr (1963)

19
Topics
  • Diversity
  • Classification and phylogeny (Ch. 2)
  • Species and speciation (Ch. 15, 16)
  • Patterns of evolution (Ch. 3)
  • Evolution in the fossil record
  • History of life on earth
  • The geography of evolution
  • The evolution of biodiversity

20
Patterns of Evolution
  • Topics
  • Evolutionary History
  • History of Character Evolution
  • Evolutionary Trends
  • Adaptive Radiation

21
Evolutionary History
  • Phylogenies Provide
  • 1. Branching relationships among taxa
  • 2. History of change in characteristics
  • in the absence of ___________
  • Many characteristics leave no _______
  • What sorts of characters?

22
Fig. 3.1
What common feature unites the great apes? The
term is __________
23
Patterns of Evolution
  • Example Observed genome size variation
  • Is there
  • any pattern?
  • What is it?

Fig. 19.7
Complexity
Genome Size (pg of DNA)
24
Evolutionary History and Classification
  • Major features of evolution
  • Cladogenesis branching
  • Anagenesis change within descendants
  • Anagenesis often the result of
    adaptation
  • Difficult to combine cladogenesis and anagenesis
    in a classification. Why?
  • Example?

25
Evolutionary History and Classification
  • Cladistic Systematics
  • Classification based on monophyletic groups
  • and the abolition of paraphyletic taxa
  • Taxa Monophyletic
  • Paraphyletic
  • Polyphyletic
  • Example?

26
Taxon
?
?
?
27
Example
  • Class Reptilia (reptiles)
  • air-breathing, cold-blooded vertebrates
  • skin covered in scales
  • tetrapods (descended from vertebrates with
    four limbs)
  • amniotes (embryos surrounded by an amniotic
    membrane)
  • Why is Reptilia considered paraphyletic?
  • How can it be made monophyletic?

28
History of Character Evolution
  • Character mapping
  • Phylogeny used to infer the history of
    evolutionary change of characteristics
  • Map character state changes on tree such that the
    homoplasy is minimized

29
Two vertebrates lacking legs
Snake
Caecilians (Amphibian)
Loss of legs An example of________
Tetrapods
Snakes
Common ancestor
30
Patterns of Evolutionary Change
  • Features are modified from pre-existing features
  • example of __________
  • Homoplasy is common (example__________)
  • 3. Homoplasy often initial evidence for
    adaptive significance of feature Example ?

31
Hummingbird
South American honey creeper
Sunbird (Africa)
Hawaiian honey creeper
Australian honeyeater
32
Patterns of Evolutionary Change
  • 4. Rates of Character evolution differ (Examples)

33
Patterns of Evolutionary Change
  • 5. Evolution often gradual (gradualism)

Male flies Species of Zygothrica
Sandpiper species
34
Patterns of Evolutionary Change
  • 6. Change in form correlated with change in
    function

Ichneumon wasp ovipositor
Wasp stinger
35
Patterns of Evolutionary Change
  • 7. Species similarities change during ontogeny

36
Patterns of Evolutionary Change
  • 8. Development and patterns of morphological
    evolution
  • - based on an analysis of embryonic
    development
  • a. Individualization serial homology
  • b. Heterochrony paedomorphosis
  • c. Allometry allometric growth

37
Allometry
  • Allometric growth differential rate of growth
    of different parts of an organism during ontogeny

38
Allometry
39
Patterns of Evolutionary Change
  • 9. Increases and decreases in complexity

stigmas
anthers
Evolutionary Trends
40
Patterns of Evolutionary Change
  • 1. Features are modified from pre-existing
    features
  • 2. Homoplasy is common
  • 3. Homoplasy ?evidence for adaptation
  • 4. Rates of character evolution differ
  • 5. Evolution often gradual (gradualism)
  • 6. Change in form correlated with change in
    function
  • 7. Species similarities change during ontogeny
  • 8. Development and patterns of morphological
    evolution
  • 9. Increases and decreases in complexity
  • 10. Many clades display Adaptive Radiation

41
Adaptive Radiation
  • Divergent evolution of numerous related lineages
    over a relatively short time period
  • Examples 1. Galapagos finches
  • 2. Hawaiian silverswords
  • 3. African Cichlid fish

42
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43
Adaptive radiation in Hawaiian Silverswords
Diversity of life forms herbs, shrubs, trees
Link All species genetically very similar but
morphologically different
Evolved from a small herbaceous ancestor
44
Adaptive Radiation in African Cichlid Fishes
Species Lists
est. of species Lake
Victoria gt200 Lake Tanganyika gt140 Lake
Malawi 500 - 1000
45
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46
Summary
  • Phylogeny (based on gene sequences)
  • Species characteristics (morphology etc.)
  • Describes past changes among species

47
Topics
  • Diversity
  • Classification and phylogeny (Ch. 2)
  • Species and speciation (Ch. 15, 16)
  • Patterns of evolution (Ch. 3)
  • Evolution in the fossil record (Ch. 4)
  • History of life on earth
  • The geography of evolution
  • The evolution of biodiversity

48
Evolution in the Fossil Record
  • Living organisms ? History of evolution
  • Fossils ? direct evidence of evolution
  • Paleontology
  • - documents details of evolutionary history
  • What else does paleontology tell us?

49
Books on fossil hunting
The Bone Hunters Heroic Age of Palaeontology in
the American West by Url Lanham
Donald Johanson (1982)
David Wallace
Lucy Austalopithecus afarensis
50
Evolution in the Fossil Record
  • Topics
  • Geology
  • The fossil record
  • Evolutionary trends
  • Rates of evolution

51
Geology
  • Rocks Igneous
  • Sedimentary
  • Metamorphic
  • Most fossils found in which rocks?

52
Geological Time Scale
  • Most eras and periods named before Darwins time
  • Geological eras and periods
  • identified by distinctive fossils
  • Boundaries marked by changes in fossil
    composition

Map
53
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54
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55
Geological Time Scale
  • Phanerozoic
  • Myr Eras Periods
  • 66 - Cenozoic Quaternary, Tertiary
    (Epochs)
  • 251 - 145 Mesozoic Cretaceous, Jurassic,
    Triassic
  • 542 - 299 Paleozoic Permian, Carboniferous,
    Devonian, Silurian, Ordovician, Cambrian
  • ----------------------
  • 2500 Proterozoic trace fossils earliest
    eukaryotes
  • Archean earliest life (prokaryotes)

56
Geological Time Scale
  • Futuyma Every student of evolution should
    memorize the sequence of eras and periods as well
    as a few key dates
  • Beginning of
  • Paleozoic era (Cambrian period) 542 Mya
  • Mesozoic era (Triassic period) 251 Mya
  • Cenozoic era (Tertiary period) 65.5 Mya
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