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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

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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Tags: evolution on Earth evolution recorded by fossils fossil record study of evolutionary relationships closely related species