Classification and phylogeny

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Classification and phylogeny
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Early classification schemes
Fish whales Flies birds Frogs
alligators Squirrels monkeys
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Early classification schemes
Fish whales Flies birds Frogs
alligators Squirrels monkeys
Swim in water Fly in air Crawl in mud Climb in
trees
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Early classification schemes
Honeybee Apis pubescens, thorace subgriseo,
abdomine fusco, pedibus posticis glabris utrinque
margine ciliatis Apis mellifera
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Early classification schemes
Honeybee Apis pubescens, thorace subgriseo,
abdomine fusco, pedibus posticis glabris utrinque
margine ciliatis Apis mellifera
Linnaeus introduced binomial nomenclature hi
erarchical classification
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Hierarchical classification
Kingdom Phylum Class Order Family
Genus Species
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How the leopard got its spots
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Phylogenetic trees are a visual representation of
the fact that species are related by descent from
a common ancestor
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Phylogeny
Anagensis (phyletic evolution) - successional
changes within a single lineage Cladogenesis
(phylogenetic branching) - splits along ancestral
line that cause species multiplication (ie.
appearance of new clades, clusters of species)
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homology - same feature in different species,
derived from common ancestor parallelism -
similar feature occurs in different species, but
common ancestor was different convergence -
similar feature arose independently in different
species
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Phylogeny
Monophyletic - organisms derive from a single
ancestral population Paraphyletic - does not
include all descendents from the ancestral
population Polyphyletic - organisms arrived
independently at a particular grade of
organization
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Monophyletic
Paraphyletic
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Paraphyletic groups
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Phylogeny
Phenetics - applies numerical taxonomy to
arranging groups into genera higher
ranks Cladistics - every significant
evolutionary step marks a dichotomous
branch Evolutionary classification -
incorporates genealogical relationship between
groups with evolutionary distance
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Phenetics
Character a b c d 1 1 1 0 0 2 1 1 0 0 3 1 1 1 0
4 1 1 1 0 5 1 1 1 0 6 1 1 1 0 7 0 1 0 0 8 0
1 0 0 9 0 1 0 0 10 1 0 1 0 11 1 0 0 1
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Phenetics
a b c d a - 6 7 3 b - 4 0 c - 5 d -
B (BA BC)/2 B 5 D 0
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Phenetics
Phenograms do not necessarily represent
phylogenetic relationships Similarity - number
of character states 2 species share Relationship
- how recently they diverged from a common
ancestor
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Cladistics
Character a b c d 1 1 1 0 0 2 1 1 0 0 3 1 1 1 0
4 1 1 1 0 5 1 1 1 0 6 1 1 1 0 7 0 1 0 0 8 0
1 0 0 9 0 1 0 0 10 1 0 1 0 11 1 0 0 1
0 pleisomorphic 1 apomorphic
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Cladistics
a b c d a - 6 4 0 b - 4 0 c - 0 d -
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Synapomorphies arise at evolutionary branch points
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Taxonomy
Characters must be independent homologous
Evolutionary relationships only revealed by
shared, derived traits synapomorphies
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Terminology
plesiomorphy symplesiomorphy apomorphy synapomo
rphy autapomorphy
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Principles of evolutionary change, inferred from
systematics 1 homologous features are derived
from common ancestors
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Principles of evolutionary change, inferred from
systematics 1 homologous features are derived
from common ancestors 2 homoplasy is common in
evolution
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Homoplasy
Convergent evolution (convergence) Parallel
evolution (parallelism) Evolutionary reversals
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Principles of evolutionary change, inferred from
systematics 1 homologous features are derived
from common ancestors 2 homoplasy is common in
evolution 3 rates of character evolution differ
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Principles of evolutionary change, inferred from
systematics 1 homologous features are derived
from common ancestors 2 homoplasy is common in
evolution 3 rates of character evolution
differ 4 evolution is often gradual
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Principles of evolutionary change, inferred from
systematics 1 homologous features are derived
from common ancestors 2 homoplasy is common in
evolution 3 rates of character evolution
differ 4 evolution is often gradual 5
characteristics often owe their change in form to
change in function
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Principles of evolutionary change, inferred from
systematics 1 homologous features are derived
from common ancestors 2 homoplasy is common in
evolution 3 rates of character evolution
differ 4 evolution is often gradual 5
characteristics often owe their change in form to
change in function 6 phylogenetic analysis
documents evolutionary trends
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Principles of evolutionary change, inferred from
systematics 1 homologous features are derived
from common ancestors 2 homoplasy is common in
evolution 3 rates of character evolution
differ 4 evolution is often gradual 5
characteristics often owe their change in form to
change in function 6 phylogenetic analysis
documents evolutionary trends 7 most clades
display evolutionary radiation
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Cladistics
Character a b c d 1 1 1 0 0 2 1 1 0 0 3 1 1 1 0
4 1 1 1 0 5 1 1 1 0 6 1 1 1 0 7 0 1 0 0 8 0
1 0 0 9 0 1 0 0 10 1 0 1 0 11 1 0 0 1
0 pleisomorphic 1 apomorphic
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Cladistics
a b c d a - 6 4 0 b - 4 0 c - 0 d -