Classification & Cladistics Lecture Review

Comprehensive vocabulary flashcards covering biological classification, cladistics, the three-domain system, and molecular evidence based on the lecture notes.

Global biodiversity

The vast diversity of life on Earth, including many species that remain undiscovered.

Classification

The organisation of organisms into logical groups.

Taxonomy

The science of classification.

Taxon (plural: taxa)

A named biological group formed by taxonomists based on shared features.

Hierarchy of Taxa

The traditional ranks of biological classification: Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species.

Convergent evolution

The independent evolution of similar body shapes or traits in unrelated species, such as streamlined bodies in dolphins and sharks.

Analogous features

Similar features in different species that evolved independently rather than through a recent common ancestor.

Introgression

The transfer of genes from one species to another when a hybrid breeds repeatedly with one of its parent species.

Cladistics

The branch of science that classifies organisms into clades based on evolutionary relationships.

Clade

A group containing a common ancestor and all of its descendants, grouped by shared evolutionary descent.

Monophyletic

A term describing a group that contains a common ancestor and every one of its descendants.

Common ancestor

An ancestral species shared by two or more descendant lineages.

Sequence data

Objective evidence from DNA, mRNA, or amino acids used to identify clades and evaluate closeness of relationships.

Primitive traits

Traits that evolved early in a lineage and occur widely within a clade.

Derived traits

Traits that evolved later in evolutionary history and serve to distinguish smaller groups within a clade.

Molecular clock

A method of estimating divergence time between species based on the accumulation of mutations at an approximately constant rate.

DNA hybridisation

A process that compares corresponding single DNA strands from two species to identify non-matching regions and sequence differences.

Cladogram

An evolutionary tree diagram showing the probable order of divergence and relationships between species.

Node

The point on a cladogram where branches separate, representing a common ancestor.

Principle of parsimony

The scientific principle favoring the simplest explanation, choosing the evolutionary tree that requires the fewest evolutionary changes.

Paraphyletic

A classification group that does not contain all descendants of a common ancestor, as seen in the historical Scrophulariaceae family.

Scientific falsification

The process where earlier classification claims are revised because new DNA evidence contradicts historical morphological observations.

Archaea

A domain of prokaryotic organisms whose cell walls lack peptidoglycan and whose membranes contain glycerol-ether lipids.

Eubacteria

A domain of prokaryotic organisms possessing peptidoglycan in their cell walls and glycerol-ester lipids in their membranes.

Eukaryotes

A domain of organisms with eukaryotic cell types, linear nuclear DNA associated with histones, and $80\text{S}$ ribosomes.

Binomial nomenclature

The universal naming system where each species is given a two-part scientific name consisting of a capitalised genus and a lower-case species epithet.

Standard deviation (SD)

A statistical measure showing the spread of measurements around the mean; a smaller value indicates data is more tightly clustered.

Degenerate genetic code

The property of the genetic code where different codons can specify the same amino acid, allowing proteins to remain similar despite DNA sequence mutations.