Evidence for Evolution

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Evidence for Evolution

• Starr/Taggarts
• Biology
• The Unity and Diversity of Life, 9e
• Chapter 20

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Lines of Evidence

• Fossil and geologic records
• Anatomical comparisons
• Embryological comparisons
• Biochemical comparisons
• Population genetics (later)
• Molecular biology (later)
• Bacterial resistance (later)

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Fossils Evidence of Ancient Life

• Fossilization is slow process with trends
• Stratification
• Layering of sedimentary deposits (old?new)
• The older the layer, the older and more simple
  the fossils
• Geologic Time Scale
• Based on sequences of fossils in sedimentary
  rocks
• Transitional fossils

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Evidence for a Changing Earth

• Uniformity Theory
• Age of the Earth and evolution
• Evolution takes time
• Changes relate to the changing environment
• Pangea and biogeography
• 6 realms and study of past and present
  distribution of species

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Comparative Morphology

• Comparison of body forms and structures
• Morphological divergence
• Change from body form of a common ancestor
• Morphological convergence
• Body parts in remote lineages become similar
  under similar selection pressures
• Vestigal structures
• Structures of marginal, if any, importance to an
  organism. Historical remnants of structures that
  had importance to ancestral organisms.

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Comparative Morphology

• Homology
• Similarity in body parts in different organisms
• Attributable to descent from a common ancestor
• Analogy
• Similarity in body parts in different organisms
• Attributable to similar environmental pressures

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Homologous Structures

• Vertebrate forelimbs

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Analogous Structures

• The fin of a penguin is a modified wing and the
  flipper of a porpoise is a modified leg.

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Comparative Embryology

• Early vertebrate embryos strongly resemble one
  another
• Same plan of development
• Developmental plan coded for by common genes

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Evidence from Comparative Biochemistry

• Similarities in sequences imply a common ancestor
• The more in common, the more recent the ancestor
• Protein comparisons
• Cytochrome C
• Nucleic Acid comparisons
• Base-pairing of DNA or RNA from one species to
  another

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Classification Basics

• Now that we understand micro- and
  macroevolutionary theory, as well as speciation,
  we can discuss the organizational strategies of
  scientists.
• Taxonomy is the science of identifying, naming
  and grouping organisms.
• Taxonomy is the science of classification.

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Classification Basics

• When classifying according to the Linnaean
  system, organisms are placed in groups called
  taxa (singular taxon).
• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• Species

Genus Species binomial nomenclature
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Binomial nomenclature

• Examples
• Humans Homo sapiens
• Horses Equus caballus
• Donkeys Equus asinus
• Mules Equus asinus x caballus

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Classification Basics

• How are organisms placed in taxa?
• Physical characteristics
• Cellular characteristics
• Biochemistry (DNA, proteins, etc.)
• A more modern way to approach classification is
  to assign organisms to taxa based on evolutionary
  relationships. This is called an organisms
  phylogeny.

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How Many Kingdoms?

• Five-Kingdom Scheme
• Monera
• Protista
• Fungi
• Plantae
• Animalia

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Six Kingdom Scheme

• Includes the Archaebacteria as a separate kingdom
  due to DNA evidence.

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Three Domain Scheme

• Domains are taxonomic categories above the
  kingdom level.
• This system is favored by microbiologists.
• Eubacteria
• Archaebacteria
• Eukaryotes

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Classification Basics

• Naming and grouping organisms leads to
  dichotomous keys as a method to identify
  organisms.
• You will learn to use and create keys.
• Salamander key
• Mythical creature key
• Sea shell key

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Classification and Cladistics

• Cladistics is a part of evolutionary systematics
  which is the identification of patterns of
  diversity over time.
• Evolutionary systematics and cladistics use
  information from an organisms
• Taxonomy/Classification
• Phylogeny
• One task in cladistics is to construct cladograms.

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Classification and Cladistics

• Cladograms are diagrams that portray relative
  evolutionary relationships between groups.
• Cladograms rely on derived characteristics or
  traits which are novel features that evolved once
  and are shared by descendants of the ancestral
  species.

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Classification and Cladistics

• Cladograms require the identification of the
  ingroup or the group of species you are studying.
• Cladograms also require the identification of
  outgroups which are species closely related to
  group of species being studied but clearly are
  not as closely related as the study group members
  are to each other.
• Lets look at some examples.

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Constructing Cladograms
TAIL LOSS!!
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Constructing Cladograms
turtle, gorilla, trout, cat, lugfish, human
lamprey
jaws
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Constructing Cladograms
turtle, gorilla, cat, lugfish, human
lamprey
trout
lungs
jaws
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Constructing Cladograms
turtle, gorilla, cat, human
lamprey
trout
lungfish
limbs
lungs
jaws
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Constructing Cladograms
gorilla, cat, human
lamprey
trout
lungfish
turtle
hair
limbs
lungs
jaws
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Constructing Cladograms
turtle
cat
gorilla
human
lungfish
tail (loss)
trout
hair
lamprey
limbs
lungs
jaws
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turtle, gorilla, cat, lugfish, human
turtle, gorilla, trout, cat, lugfish, human
lamprey
lamprey
trout
lungs
jaws
jaws
gorilla, cat, human
turtle, gorilla, cat, human
lamprey
lamprey
trout
trout
lungfish
lungfish
turtle
hair
limbs
limbs
lungs
lungs
jaws
jaws
lamprey
trout
lungfish
turtle
turtle
cat
gorilla
human
cat
gorilla
human
lungfish
tail (loss)
trout
hair
lamprey
limbs
node 1
lungs
node 2
jaws
Fig. 20.15, p. 324-25
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Practice Cladograms
Pine Trees
Flowering Plants
Ferns
Mosses
Flowers
Seeds
Vascular Tissue
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Practice Cladograms
Birds
Mammals
Reptiles
Amphibians
Mammary glands
Fish
Endothermic
Terrestrial eggs
Terrestrial adult
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Practice Cladograms
Pachycephalosaurus
Parasaurolophus
Triceratops
Stegosaurus
Shelf at base of skull
Allosaurus
Unequal enamel layer on tooth
Posterior process of pubis
Hole in hip socket
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Phylogeny

• Recall that phylogenies of organisms reflect the
  evolutionary relationships among organisms.
• Phylogenies are directly related to
  macroevolutionary theory.
• Lets look at the phylogeny of all life on Earth!

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Phylogeny of the Diversity of Life
Halophiles
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Methanogens
3
Thermophiles
Animals
2
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Hetero. Protists
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10
Fungi
Photo. Protists
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Plants
Eubacteria 1
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Eubacteria 2
1
5
Eubacteria 3 (hetero.)
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Phylogeny Review

• 1 DNA characteristics
• 2 Origin of nucleus
• 3 High heat survival enzymes
• 4 Low oxygen vs. salinity survival enzymes
• 5 Photosynthesis vs. heterotrophism
• 6 Photosynthetic style
• 7 Incorporation of chloroplasts
• 8 Uni- vs. multicellular
• 9 No cell walls for animals
• 10 Cell walls are chitin vs. cellulose