Phylogeny and Systematics

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Phylogeny and Systematics

• D.5
• Chapter 15

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D.5.1 Outline the value of classifying organisms

• If a new organism is discovered, its
  characteristics can be compared with existing
  organisms.
• Similarities allow it to be linked with other
  organisms
• Organization of data
• assists in identifying organisms
• suggests evolutionary links
• allows prediction of characteristics shared by
  members of a group.

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D.5.2

• Explain the biochemical evidence provided by the
  universality of DNA and protein structures for
  the common ancestry of living organisms
• There are remarkable similarities between living
  organisms in their biochemistry

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D.5.2

• There are remarkable similarities between living
  organisms in their biochemistry which suggest a
  common ancestor
• All use
• DNA or RNA as genetic material
• universal genetic code
• same 20 amino acids in proteins
• Left (not right) handed amino acids
• Ex some proteins created in one organism
  (insulin in bacteria) can be used in other
  organisms (for therapy in humans)

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D.5.3 Explain how variations in specific
molecules can indicate phylogeny

• Phylogeny Evolutionary history of a species or
  group of related species
• Look at
• Proteins close match in amino acid sequence in
  different species indicated a common ancestor
  (hemoglobin, cytochrome c, chlorophyll)
• DNA differences in base sequence
• More useful than protein for comparison because
  protein only reflects a small part of DNA

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D.5.4 Discuss how biochemical variations can be
used as an evolutionary clock

• The more similar the DNA or protein is the more
  closely related the organisms
• Differences in protein sequence accumulates
  steadily and gradually over time due to mutations
  which occur generation to generation in a species
• Mutations occur at various rates so the
  information is just an estimation of time. The
  biochemical data is compared to fossil evidence
  and radioisotope dating.

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D.5.4 Discuss how biochemical variations can be
used as an evolutionary clock

• Compare DNA of different species
• Count the number of base pairs that dont match
• The more differences more time between split
  (less related)
• DNA Hybridization fuse one strand from species A
  and a homologous strand from species B
• Fuse match
• Repel difference in DNA sequence

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D.5.5 Define clade and cladistics

• Cladistics system of classification which groups
  taxa together according to the characteristics
  which have recently evolved (natural
  classification)
• Clade groups of most recent common ancestor of
  the group and its descendents (can be one species
  or several species)

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D.5.6 Distinguish between analogous and
homologous structures

• Homologous structures
• Likeness in structure from having a common
  ancestor
• Ex fingers on mammals, eyes on verts inverts
• Analogous structures
• Structures serve similar function but NOT
  resulting from a common ancestor
• Ex wings on insects birds, fins on aquatic
  organisms

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D.5.7 Outline the methods used to construct
cladograms and the conclusions that can be drawn
from them

• Cladograms show evolutionary relationships
  between organisms
• Method
• Make a list of organisms
• List characteristics of each organism
• Choose one primitive characteristic common to all
  organisms
• Complete a comparative table of the organisms
• Build a cladogram from the table

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D.5.7 Outline the methods used to construct
cladograms and the conclusions that can be drawn
from them

• The first branch from the bottom belonging to the
  organism with fewest derived traits
• Most derived traits at the top of the last branch
• Each new line is a clade

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D.5.8 Construct a simple cladogram

• Morphological or biochemical data can be used
• See Island Biogeography Lab for practice

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D.5.9 Analyze cladograms in terms of phylogenic
relationships

• Common ancestry
• More evolved organisms based on more evolved
  characteristics
• More nodes between organisms, the less related
  they are
• Closer the lines more related

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D.5.10 Discuss the relationship between
cladograms and the classification of organisms

• Cladistics uses biochemical data (versus
  morphological data used in Linnean system) to
  classify organisms
• Classification system center around
• Shared derived characteristics
• Parsimony least complicated explanation for a
  phenomenon