Classification of Animals

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Classification of Animals
Creating Order out of Chaos
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Table 10.1
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What is a species ?
Smallest distinct grouping of animals sharing a
pattern of ancestry and descent Form a
reproductive community that excludes members of
other species How can you tell??
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Fig. 10.2
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Typological Species Morphological characters
based on type specimen (specimen first described
and deposited in a museum) Biological
Species Reproductive community (interbreeding
population), reproductively isolated from
others and that occupies a specific niche in
nature. interbreeding ? genetic continuity lack
of interbreeding ? genetic divergence Problems
Fossil Record (only have morphology) What
about asexual species Evolutionary Species
Single lineage of ancestor-descendant
populations that maintains its identity from
other lineages and that has its own evolutionary
tendencies. Problem Great concept, how do you
test it? Phylogenetic Species An irreducible
grouping of organisms diagnosably distinct from
other such groupings and within which there is
a parental pattern of ancestry and descent (no
branching). (emphasis is on common descent)
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Phylogenetic Reconstruction using Taxonomic
Characters
Depends on finding among organisms shared
features that are inherited from a common
ancestor (homology) Determine which variant form
of each character was present in the
common ancestor of the entire group
(ancestral) All other variant forms arose later
within the group (derived) Method Outgroup
comparison outgroup- phylogenetically close, but
not within group any character possessed within
the group and by the outgroup is
ancestral Characters absent in the outgroup are
considered derived Organisms that share the same
derived characters form a clade Clade- a unit of
common descent, all descendants of an ancestral
lineage
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Fig. 10.4
Cladogram A nested Hierarchy of Clades
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Sources of Phylogenetic Information (variable
character states)
Morphology- macro and microscopic fossilizes! Bio
chemistry- allozymes Molecular- DNA sequence
data nuclear and mitochondrial genetic
polymorphisms
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Fig. 10.5
Cytochrome C
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Fig. 10.6
Most recent common ancestor And all descents
Most recent common ancestor But not all
descendants
Does not contain most recent common ancestor
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Fig. 10.9
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Fig. 10.11
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Animal of the Day
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Chrysemys picta (Painted Turtle)
Phylum Chordata Class Reptilia
Order Chelonia Family Emydidae