FORS2355 Vertebrate Natural History -- Lecture 2 (August 25)
Taxonomy and Classification:
Taxonomy -- naming of organisms; assigning names together.
Classification - makes statements about relationships among organisms (putting like species together).
Phenetic Classification -- are based only on similarities and do not necessarily reflect genealogy. They may look similar but not actually related.
Usually in morphology/observable trait.
Phylogenetic -- classifications do reflect genealogy (i.e., evolutionary history).
Taxonomic Hierarchy --
1. Kingdom Phylum 3. Class 4. Order 5. Family 6. Genus 7. Species
Binomial Nomenclature -- two-part Latin name:
Genus Specific Epithet No two species have the same binomial epithet (genus and species). Cannot reassign same name to a different species.
Historically -- bookkeeping task.
Assumption -- species are static entities.
Problem -- species are NOT static. New species arise via ancestor-descendant relationships.
Linnaeus classified animals before Darwin (pre-Darwinian) suggested the concept of evolution. Linnaeus said that the cardinal is a cardinal and that it would remain a cardinal (will not change over time).
Based on similarities among species, but some similarities are more significant than others. For example, nearly all vertebrates have paired limbs, only some have fur. Knowing which species have fur tells you more about closeness of relationship, which means more weight given to that character.
Phylogenetic Systematics: also known as Cladistics, it is an evolutionary lineage. It is a nested series of ancestor-descendent relationships. Also called a Cladogram.
Ray-finned Rodents Sharks fish AmphibiansPrimates &rabbits Crocodile
mniotic egg
Four limbs
Bony skeleton
Vertebrae
This is a cladogram. Each branching point is a node. Each branch starting at the node, is a clade.
Phylogeny -- hypothesis on evolutionary relationships of groups.
Relationships trace evolutionary history of the group. Define clades only on basis of derived characters (i.e., different from ancestral condition); when there is a new branching off, there is a new clade = different from ancestral condition.
Terms to Know:
Apomorphic Chafracters -- the descendent character; derived from the ancestral condition -- used to find new clade (different from ancestor).
Synapomorphy - shared, derived character (defining a group)
Plesiomorphic Character -- ancestral character; unaltered from ancestral condition = did not change.
Symplesiomorphic Character - ancestral character found in more than one lineage and shared across multiple lineages (fishes -> mammals).
Cladistics -- emphasizes importance of monophyletic evolutionary origin.
Monophyletic -- ancestor and all of its descendants.
Monophyly -- ancestor and all of its descendants. Each ring forms a monophyletic group.
Aves (avian/birds) - paraphyletic group because related to reptiles.
Hierarchical Classifications
Depict placement of groups. Each level of indentation corresponds to sister taxa on an evolutionary tree. The longer the tree, the older it is. The group is more basal. The closer something is to something else, the more related they are and the further away they are from each other, the less related they are to each other.
mmals (Metatheria
ders(Urodela
Lungfishes (Dipnol)
Sharks, rays, and ch
as (Chondrichthyes)
A traditional classification - good for listing names for taxa. May not reflect well the relationships