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The Fossil Record, Phylogeny and Systematics

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Title: The Fossil Record, Phylogeny and Systematics


1
The Fossil Record, Phylogeny and Systematics
2
Phylogeny and Systematics
  • Phylogeny - Tribe/Origin
  • Study of evolutionary history of species
  • Tracing the origin of species
  • Systematics Study of biological diversity
  • Done in an evolutionary scale and scope
  • Focus on Fossil Record, Global Change over time

3
The Fossil Records
  • Fossils are arranged in the strata of sedimentary
    rock
  • Oldest layers on the bottom, newest on top
  • Occurs at intervals
  • Different periods of sedimentation form strata
  • Mark the passing of Geological Time
  • Tiny fraction of living organisms become fossils

4
Fossil Review
4 Types of Fossils Cast Mold Imprint Actual Body
Parts
5
Geological Time
  • Fossils in strata are representative orgs from
    that time period
  • Index Fossils Fossils in one strata can be
    compared in age (geo time) to fossils in other
    strata
  • Geological Time Scale based on strata layering,
    scientists can determine historical periods
  • Layers not complete gaps
  • Sea level may have effected whether sedimentation
    formed at all, etc

6
Geoloigical Time Scale
  • Periods of strata are organized into 4 Eras
  • Precambrian
  • Paleozoic
  • Mesozoic
  • Cenozoic
  • Boundaries of Eras are marked by explosions of
    new fossil species
  • Organization done by Relative Dating
  • Comparison of index fossils
  • Older fossils in deeper strata
  • Vary in length based on fossil record
    characteristics
  • Eras divided into Epochs

7
Table 25.1 The Geologic Time Scale p. 467
8
Absolute Dating
  • Age of Fossils in years
  • Radiometric Dating
  • Charts the decay of isotopes present in all forms
    of life
  • Half life of years for ½ of amount of element
    originally present in org to decay
  • Carbon 14 5600 years
  • Uranium 238 4.5 billion years
  • Amino Acid Conversion know the rate of
    conversion
  • Only certain structure made during life (L-type)
  • Measure amount of amino acids converted to dead
    structure (R-type)

9
Fossil Record Uses, Problems
  • NOT representative of all species ever lived
  • Skewed in favor of orgs that lived long, had hard
    parts, abundant and widespread
  • DOES document phylogeny over vast time
  • Sequences biological change over time
  • Can be dated
  • Charts environmental changes chronologically

10
Phylogeny and Continental Drift
  • Biogeography distribution of species with
    adaptation specific to their environments
  • Continental Drift movement of earths surface
    by hot mantle currents
  • Affected geo distribution of life
  • Fossil records on different continents correlate
  • Evolutionary Episodes affected as well
  • Mass extinction
  • Explosive increases

11
Figure 25.4 The history of continental drift p.
470
12
Pangea
  • End of Paleozoic Era (250 MYA)
  • Plates brought all earths land together
  • Called Pangea means all land
  • Supercontinent
  • Major Environmental Change
  • Ocean Basin Deepened draining shallow waters
  • Terrestrial weather draughts, erratic
  • Caused extinction
  • Selection for orgs that were adapted, survived

13
Continental Drift
  • Mesozoic Era (180 MYA)
  • Pangea breaks up, drifts
  • Each continent becomes separate evolutionary area
  • Distinct barriers, biogeography
  • Divergent evolution based on new environments
  • Ex Australian Marsupials
  • Evolved and Migrated from N. America during
    Pangea
  • During Drift, marsupials separated with Australia
  • Unique species formed due to environment

14
Mass Extinctions and Adaptive Radiations
  • Adaptive Radiations explosion in diversity and
    species number
  • Follow Introduction of Evolutionary Novelty
  • Follow Environmental Change
  • Follow Mass Extinctions reducing of orgs
  • Adaptive Zone Habitat or place which opens up to
    orgs
  • Changes Predator/Prey Relationship
  • Changes biogeography of org
  • Ex Wings in insects opened up areas reachable by
    flight
  • Cambrian Explosion hard parts develop,
    diversity of sea animals increases
  • Pre-cambrian Extinction shown in fossil record
  • Explosion of new species, characteristics seen in
    Cambrian Period

15
Examples of Mass Extinction
  • 1. Permian Extinction (250 MYA)
  • Boundary between Paleozoic and Mesozoic Eras
  • 90 marine animals extinct, reduction in insects
  • Occurred in 5 million years quick!
  • Radical Environmental change
  • Pangea broken up
  • Extreme volcanic activity
  • High levels CO2 in atmosphere
  • Global warming of climate
  • Temp. discrepancies reduced ocean mixing
  • Reduced amount of Oxygen in water

16
Figure 25.5 Diversity of life and periods of
mass extinction
17
Examples of Mass Extinction
  • 2. Cretaceous Extinction 65 MYA
  • Boundary between Mesozoic and Cenozoic Era
  • Marine, terrestrial animals (Dinos), plant life
  • Impact Hypothesis Asteroid strike cause dust
    cloud which blocked sun darken for years
  • Evidence Clay between Meso/Ceno has Iridium
  • Large crater in Chicxulub Mexico
  • Actual impact (quick) severe extinction in
    proximity
  • Global (slower) Climate cooled, photosynthetic
    orgs died
  • Led to differing extinction rates in the same
    period
  • Debate still over environmental change theory vs.
    impact

18
Figure 25.6 Trauma for planet Earth and its
Cretaceous life
19
Figure 25.6x Chicxulub crater
20
Phylogeny and Systematics
  • Phylogeny - Tribe/Origin
  • Study of evolutionary history of species
  • Tracing the origin of species
  • Systematics Study of biological diversity
  • Done in an evolutionary scale and scope
  • Focus on Fossil Record, Global Change over time

21
Timeline of Classification
  • 1. 384 322 B.C. Aristotle
  • 2 Kingdom Broad Classification
  • 2. 1735 - Carl Linnaeus
  • 2 Kingdom Multi-divisional Classification
  • Kingdom, Phylum, Class, Order, Family Genus,
    Species
  • 3. Evolutionary Classification (After Darwin)
  • Group By lines of Evolutionary Descent
  • 4. 5 Kingdom System 1950s
  • 5. 6 Kingdom System 1990s
  • 6. 3 Domain System 1990s

22
Modern Taxonomy Carl Linnaeus
  • Carl Linnaeus (1735) Swedish Botanist
  • Reworked Classification system from Aristotles
    basic Kingdom System
  • Called his classification Systema Naturae
  • Used Comparative Morphology
  • Used a hierarchy of categories to classify
  • Binomial Nomenclature Genus species
  • Ex Homo Sapien

23
Figure 25.7 Hierarchical classification
Overview of Classification Systems Linnaeus
Kingdom Species Modern Classification Added
Domain after rRNA sequences est. and compared
24
Example Classification
  • Lion DOMAIN EUKARYA
  • Kingdom Animalia (all Animals)
  • Phylum Chordata (All vertebrate animals)
    Class Mammalia (All Mammals mammary glands)
  • Order Carnivora (Meat eaters)
  • Family Felidae (includes all Cats)
  • Genus Panthera (Includes all roaring Cats)
  • Species leo (Lions)

25
Taxons
  • Within each category, a particular group is
    called a Taxon
  • Many Taxons for each category
  • Carnivora is the Taxon for the Order category in
    Lions

26
Tools Used to Classify Organisms
  • 1. Comparative Morphology
  • Compares Physical Structures, Traits
  • 2. Evolutionary Relationships
  • Related Organisms with common ancestors, Derived
    Characters
  • 3. DNA/RNA comparison

27
Phylogeny
  • Goal of systematics Classification reflects
    evolutionary history
  • Relation of modern orgs. Shown
  • Common Ancestors indicated
  • Divergent characteristics ( derived characters
    determined)
  • Show this by constructing Phylogenetic Trees

28
Phylogenic Trees
  • Diagrams that trace evolutionary relationships
    between the Taxons
  • Use fossil record and extant (living) orgs
  • Comparing Homologous DNA
  • Homologous DNA sequences in specific parts the
    same
  • Can determine where mutations (new
    characteristics) have occured - of mutations is
    the evolutionary distance
  • Few differences close relation
  • Ex Mitochondrial DNA
  • Compare Protein Amino Acid Sequences
  • DNA sequences
  • DNA-DNA hybridization
  • DNA sequence analysis

29
Figure 25.14 Simplified versions of a
four-species problem in phylogenetics
30
Figure 25.15b Parsimony and molecular
systematics (Layer 3)
31
Molecular Clock can Determine Relationships and
Derived Characters of Species
New mutations (or characteristics) are added over
evolutionary time the more recent the organism,
the more mutations are seen
Like Derived Character -
We Know how newer species are related to ancestor
orgs due to mutation patterns
32
Classification Key
  • Also Known as
  • Dichotomous Key, Biological Key
  • Useful in Identifying Organisms in the field
  • Based on Comparison of Morphological Traits
  • Use physical features to compare, contrast
  • Determine if Organism is in group or not, based
    on Key criteria
  • At each level you only have a few contrasting
    characteristics to choose from
  • Body shape plans, Characteristics such as fur

33
What are these organisms and how are they
classified?
34
Cladistics
  • Part of Systematics
  • Clade evolutionary branch
  • Organizes Orgs. In order of evolution
  • Defined by novel homologies
  • Introduced characteristics called derived
    characters
  • Shows evolution of orgs as well as the novel
    characters which define their grouping

35
Cladogram vs. Comparative (Traditional)
Morphology p.452
Derived Characters
Common Ancestor ?
lt-- Common Ancestor
? ?
Common Ancestor ?
Common Ancestor ?
36
Outgroup Comparison
  • Outgroup org. related but not closely to orgs
    of interest
  • Outgroup org. has basic characteristics of orgs.
    Of interest
  • Orgs of interest have derived characters which
    differentiate from Outgroup org.
  • Outgroup and interest orgs compared
  • Characteristics in common suggest presence in
    common ancestor
  • Those characters are shared primitive characters

37
6 Kingdom System
Animalia Plantae Fungi Protista Eubacteria Archaea
bacteria
38
From 2 Kingdoms to 6p. 458
39
Three Domain System
  • 1990s
  • Domain is larger classification than Kingdom
  • Used Technology to compare Ribosomal RNA
    sequences of organisms from bacteria to animals
  • Determined how long organisms had been evolving
    independently
  • Shows Evolutionary Relationships
  • Uses molecular clock to determine how long ago
    orgs were related
  • Based on how many sequences are different ( of
    mutations, order of mutations)

40
4. Three Domain System
  • 1. Domain Bacteria
  • Corresponds to Eubacteria Kingdom
  • Unicellular Prokaryotic Organisms
  • No Nucleus
  • Ecologically Diverse live everywhere!
  • Metabolically Diverse
  • Cell Walls contain substance called Peptidoglycan
    special protein and sugar
  • Trait used to distinguish between
  • Bacteria and Archaea
  • Target of many Antibiotics

41
Three Domain System
  • 2. Domain Archaea Ancient Bacteria
  • Corresponds to Kingdom Archaeabacteria
  • Unicellular, Prokaryotes
  • Metabolically Diverse
  • No nucleus
  • Live in Extreme environments like those of early
    Earth
  • Cell walls without Peptidoglycan
  • A trait used to distinguish between Archaea and
    Bacteria Domains

42
Three Domain System
  • 3. Eukarya
  • Contains Kingdoms
  • Protista, Fungi, Plantae, Animalia
  • Eukaryotic, single or multi-cellular Organisms
  • Nucleus
  • Most visible life
  • Humans are in Domain Eukarya

43
Three Domains of LifeP. 460-461
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