lecture 4 - systematics Flashcards
(12 cards)
What is systematics?
The science of classifying organisms to reflect their evolutionary relationships and diversity. It includes taxonomy, cladistics, and molecular systematics.
Define taxonomy and its key components.
Taxonomy: The science of classifying organisms.
Taxon (plural: taxa): Any named group (e.g., species, genus).
Goal: Reflect evolutionary relationships, not just naming.
How are species names formatted? Provide examples.
Format: Genus species (italicized, e.g., Tyrannosaurus rex).
Trinomial: Includes author + year (e.g., T. rex Osborn 1905).
If reclassified, original author in parentheses: Anatosaurus annectens (Lull and Wright 1942).
What is a type specimen (holotype)?
A physical reference specimen used to define a species, ensuring consistency in classification.
Contrast “splitters” and “lumpers” in taxonomy.
Splitters: Divide specimens into many taxa (new species).
Lumpers: Group specimens into fewer taxa (synonyms).
Rule of Priority: The oldest published name is retained.
What is cladistics, and what are its key principles?
Goal: Classify organisms based on shared evolutionary history.
Key terms:
Synapomorphy: Shared derived trait (e.g., hair in mammals).
Symplesiomorphy: Shared ancestral trait (e.g., vertebrae in vertebrates).
Cladogram: Branching diagram showing relationships.
How do you read a cladogram?
Nodes: Represent common ancestors.
Tips: Represent taxa.
Sister groups: Taxa sharing an immediate ancestor.
Outgroups: Primitive relatives used for comparison.
Define monophyletic, paraphyletic, and polyphyletic groups.
Monophyletic: Includes ancestor + all descendants (natural group).
Paraphyletic: Includes ancestor + some descendants (e.g., “reptiles” without birds).
Polyphyletic: Includes unrelated taxa (e.g., “flying animals” like bats and birds).
How does molecular systematics work?
Compares DNA, protein sequences, or other molecules.
Closely related species have more similar sequences.
Used to resolve relationships between higher taxa (e.g., mammals vs. reptiles).
What is phenetics, and why is it controversial?
Method: Classifies based on overall similarity (statistical analysis).
Criticism: Ignores evolutionary history; lacks phylogenetic context.
Classify humans using Linnaean ranks.
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Family: Hominidae
Genus: Homo
Species: Homo sapiens
Which is correct: T-Rex, T. rex, or T. Rex?
T. rex (genus abbreviated with a period, species lowercase).
