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Biology Exam Study Guide

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Exam study guide for BIOLOGY CHAP 23
Two distinct, related patterns of evolution on Earth
1. the nested pattern of similarities found among species in present day Earth
2. Historical pattern of evolution recorded by fossils
Phylogeny
history of descent with branching, can use the fossil record to prove inferences from
patterns of relatedness seen in nature.
Node
fork in a phylogenetic tree that indicate a common ancestor
Systematics
the study of evolutionary relationships among organisms
Disciplines of Systematics
1. Taxonomy
2. Phylogenetics
Taxonomy
recognize and name groups of individuals as a species and, subsequently, group
closely related species into more inclusive taxonomic groups:
Phylogenetics
aims to discover the pattern of evolutionary relatedness among groups of species or
other groups by comparing their anatomical or molecular features and to depict these
groups as a phylogenetic tree.
Phylogenetic Tree
a hypothesis about evolutionary history, or phylogeny, of a species. Best model or
explanation based on existing data.
Tree of Life goal
reconstructing phylogenetic relationships for all species in order to understand how
biological diversity has evolved since life originated
How is a phylogenetic tree/tree of life built and tested?
built from analyses of morphological and molecular attributes of species. Tested by
gathering information about anatomical and molecular traits.
Criteria for closest relatives
if they share a common ancestor not shared by any other species or group
Sister Groups
groups that are more closely related to each other than either of them is to any other
group
Phylogenetic hypotheses amount to:
determining sister groups. Which of any 3 species are more closely related than either
is to the third?
Closeness of relationship is determined by:
looking into how recently two groups share a common ancestor
Evolutionary relatedness is determined by following nodes from:
tips to the root of the tree and is not determined by the order of tips from top to bottom
of the page. Nodes can rotate.
Taxon (plural: taxa)
all species in some taxonomic entity under discussion
Monophyletic Group

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all members share a single common ancestor not shared with any other species or
group of species. (Making one cut on tree)
Paraphyletic Group
includes SOME, but not all, of the descendants of a common ancestor. (Making two or
more cuts on tree-cutting away a small branch, not root)
Polyphyletic Group
groupings that do not include the last common ancestor of all members. (Making two or
more cuts without a common ancestor or root)
Taxonomic classifications from smallest to largest limb:
species<genus<family<order<cass<phylum<kingdom<domain
Which group (monophyletic, paraphyletic, or polyphyletic) is the main goal of
phylogenetics and why?
Monophyletic because they alone show the evolutionary path a group has taken since
its origin.
Domain
Three largest limbs on phylogenetic tree
Taxonomy makes a nested hierarchy but ranks above species level are arbitrary
because?
there is nothing particular about a group that makes it a class rather than an order. They
are not equivalent in any meaningful way, unlike sister groups.
Homology
similarity by common descent
Characters
an anatomical, physiological, or molecular features that make up organisms (ex: flower
petals)
Character States
several observed conditions of characters (ex. arrangement of flower petals)
Ways in which character states can be similar:
1. Common ancestry
2. Convergent Evolution
Common ancestry
character state present in common ancestor of two groups was retained over time
Convergent Evolution
character state independently evolved in the two groups as adaptation to a similar
environment
Homologous Trait
characters similar because of descent from a common ancestor
Analogous Trait
characters similar due to independent adaptation by different species
Synapomorphies
homologies that are shared by some, but not all, of the members of the group under
consideration. They are the only useful homologies for constructing phylogenetic trees.
What kind homologies/analogies are not useful for constructing phylogenetic trees?
1. Homologies unique to one species- can't tell us about sister group because they
evolved after divergence from sister group
2. Homologies formed in common ancestor and present in all descendants- do not help

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Exam study guide for BIOLOGY CHAP 23 Two distinct, related patterns of evolution on Earth 1. the nested pattern of similarities found among species in present day Earth 2. Historical pattern of evolution recorded by fossils Phylogeny history of descent with branching, can use the fossil record to prove inferences from patterns of relatedness seen in nature. Node fork in a phylogenetic tree that indicate a common ancestor Systematics the study of evolutionary relationships among organisms Disciplines of Systematics 1. Taxonomy 2. Phylogenetics Taxonomy recognize and name groups of individuals as a species and, subsequently, group closely related species into more inclusive taxonomic groups: Phylogenetics aims to discover the pattern of evolutionary relatedness among groups of species or other groups by comparing their anatomical or molecular features and to depict these groups as a phylogenetic tree. Phylogenetic Tree a hypothesis about evolutionary history, or phylogeny, of a species. Best model or explanation based on existing data. Tree of Life goal reconstructing phylogenetic relationships for all species in order to understand how biological diversity has evolved since life originated How is a phylogenetic tree/tree of life built and tested? built from analyses of morphological and molecular attributes of species. Tested by gathering information about anatomical and molecular traits. Criteria for closest relatives if they share a common ancestor not shared by any other sp ...
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