Classification

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Classification
This is Panorpa japonica. Commonly known as the
scorpion fly.
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Developing the scientific naming system Binomial
Nomenclature.

• Before Carolus Linnaeus introduced his scientific
  naming system, naturalists named newly discovered
  organisms however they wanted.
• Because they had no agreed-upon way to name
  living thingsit was difficult for naturalists to
  talk about their findings with one another.

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Carolus Linnaeus

• Swedish botanist and doctor
• Got his medical degree in 6 days and specialized
  in the treatment of syphilis.
• Created the classification system and binomial
  nomenclature.
• http//cmapspublic3.ihmc.us/rid1JHS4QF2G-PKSLMW-5
  1M/loganl20biology20semester20220c20map.cmap

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Binomial Nomenclature

• Binomial nomenclature is a system that gives each
  species a two-part scientific name using Latin
  words.
• The first part of the name is the genus.
• A genus includes one or more physically similar
  species that are thought to be closely related.
• Genus names are always capitalized.
• The second part of the name is the species.
• It can refer to a trait of the species, the
  scientist who first described it, or its native
  location.
• It is always lowercase.

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Taxonomy

• Taxonomy is the science of naming and classifying
  organisms.
• Taxonomy gave scientists a standard way to refer
  to species and organize the diversity of living
  things.

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Linnaeus classification system has seven levels

• From the most general to the most specific
• Kingdom
• Phylum (Division for plants and fungi)
• Class
• Order
• Family
• Genus
• Species.
• The Linnaean system is a nested hierarchy.
• This means that if gray wolves are in the same
  genus, Canis, as dogs and coyotes, they are also
  in the same family, order, class, phylum, and
  kingdom.

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Cladistics

• The most common method used to make evolutionary
  trees is called cladistics.
• Cladistics is classification based on common
  ancestry.
• The goal of cladistics is to places species in
  the order in which they descended from a common
  ancestor.
• A cladogram is an evolutionary tree that proposes
  how species may be related to each other through
  common ancestors.

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Derived Characters

• The traits that can be used to figure out
  evolutionary relationships among a group of
  species are those that are shared by some species
  but are not present in others.
• These are derived characters.
• Cladograms are made by figuring out which derived
  characters are shared by which species.
• The more closely a related species are, the more
  derived characters they will share.
• A group of species that shares no derived
  characters with the other groups being studied is
  called an outgroup.

Derived Characters Organisms that branch off
after a hash mark share the derived character
represented by the hash mark. A bony skeleton is
a derived character. Sharks do not have this
derived character.
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Interpreting a Cladogram

• Derived Characters
• Groups of species are placed in order by the
  derived characters that have added up in their
  lineage over time.
• This order is hypothesized to be the order in
  which they descended from their common ancestor.
• Derived characters are shown as hash marks
  between the branches of a cladogram.
• All species above a hash mark share the derived
  character it represents.

Derived Characters
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Interpreting a Cladogram

• Nodes
• Each place where a branch splits is called a
  node.
• Nodes represent the most recent common ancestor
  shared by a clade.
• Identifying Clades
• You can identify clades by using the snip rule.
• Whenever you snip a branch under a node, a
  clade falls off.
• A clade is a group of organisms that share
  certain traits derived from a common ancestor.

Nodes In a cladogram, a node is the intersection
of two branches. This node represents the most
recent common ancestor shared by the entire
mammalian clade.
Clade A clade is a group of organisms that share
certain traits derived from a common ancestor.
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The Linnaean classification system has
limitations.

• The Linnaean system focuses on physical
  similarities alone.
• Physical similarities between two organisms are
  not always a result of species being closely
  related. (convergent evolution)
• Today, scientists use genetic research to help
  classify organisms.
• Genetic similarities between two organisms are
  more likely than physical similarities to be due
  to a common ancestor.
• EX. Giant panda and raccoon. (not related)
• EX. Red panda and raccoon. (related)

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Phylogeny

• The evolutionary history for a group of species
  is called phylogeny.
• To classify species according to how they are
  related, scientists must look at more than just
  physical traits.
• They use living species, the fossil record, and
  molecular data.
• Phylogenies can be shown as branching tree
  diagrams.
• They are similar to family trees.
• The branches of an evolutionary tree show how
  different groups of species are related to each
  other.

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Molecular evidence reveals species relatedness.

• An evolutionary tree is always a work in process.
• Hormones, proteins, and genes are all used to
  help learn about evolutionary relationships.
• DNA is considered to be the last word when
  figuring out how related two species are to each
  other.
• The more similar to each other the genes of two
  species are, the more closely related the species
  are likely to be.

Bonobo
Chimpanzee
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Molecular Clocks

• Molecular clocks are models that use mutation
  rates to measure evolutionary time.
• Mutations are nucleotide substitutions in DNA,
  some of which cause amino acid substitutions in
  proteins.
• These mutations tend to add up at a constant rate
  for a group of related species.
• The more time that has passed since two species
  have diverged from a common ancestor, the more
  mutations will have built up in each lineage, and
  the more different the two species will be at the
  molecular level.

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Linking molecular data with real time.

• Scientists must find links between molecular data
  and real time.
• A geologic event that is known to have separated
  the species scientists are studying, allows
  scientists to give a real date to the rate of
  mutation.
• For example Scientists know that the marsupials
  of Australia and those of South America diverged
  about 200 million years ago, when these two
  continents split.
• A link can also come from fossil evidence.
• Molecular data can be compared to the first
  appearance of each type of organism in the fossil
  record.

South American Monito del MonteMonkey of the
Mountains. A marsupial.
Austrailian bandicoot. A marsupial.
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Mitochondrial DNA (mtDNA)

• Mitochondrial DNA is found only in mitochrondria.
• The mutation rate of mtDNA is about ten times
  faster than that of nuclear DNA, which makes
  mtDNA a good molecular clock.
• mtDNA is always inherited from the mother.
• mtDNA from sperm cells is lost after
  fertilization.
• mtDNA is passed down unshuffled through many
  generations.
• Mutations in mtDNA have been used to study the
  migration routes of humans over the past 200,000
  years.

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Ribosomal RNA (rRNA)

• Ribosomal RNA is found only in the ribosomes of
  cells.
• rRNA is useful for studying distantly related
  species.
• rRNA accumulates mutations VERY slowly.
• Over long periods of geologic time, mutations
  that do build up in the rRNA of different
  lineages are relatively clear and can be compared.

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Classification is always a work in progress.

• 1753two kingdoms
• Animalia and Plantae
• 1866three kingdoms
• Animalia, Plantae, Protista
• 1938four kingdoms
• Animalia, Plantae, Protista, Monera
• 1959five kingdoms
• Animalia, Plantae, Protista, Monera, Fungi
• 1977six kingdoms
• Animalia, Plantae, Protista, Archaea, Bacteria,
  Fungi

This is wrong! ?
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The Three Domains

• Bacteria
• Single-celled prokaryotes.
• Largest groups of organisms on Earth.
• There are more bacteria in your mouth than there
  are people that have ever lived!
• Archaea
• Single-celled prokaryotes.
• Cell walls are chemically different from
  bacteriaallows achaea to live in extreme
  environments.
• Archaea are found in deep sea vents, hot geysers,
  Antarctic waters, salt lakes, and in the middle
  of volcanoes.
• Eukarya
• All organisms with eukaryotic cells.
• May be single-celled, colonial, or multicellular.
• Includes the kingdoms Protista, Plantae, Fungi,
  and Animalia.

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Dichotomous Keys

• Dichotomous keys are used to identify objects or
  organisms that have already been described by
  another scientist.
• A dichotomous key is made up of paired
  statements. (di two)
• Each object must fit into one category or the
  other, but not both.

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