Glossary

- taken & adapted from Hillis et al (1996), Majerus et al (1996) and Walker (1989)

Gaps: Editing symbols that are inserted into sequences in the process of alignment in order to compensate for presumptive insertion and deletion events.

Gel electrophoresis: A technique used to detect differences in proteins and polypeptide chains based on differences in the size and electrical charges of the molecules.

Gene flow: Genetic exchange between populations resulting from the dispersal of gametes, zygotes or individuals.

Genome: The entire complement of genetic material in a cell.

Genotype: The genetic make-up of an individual in respect of one genetic locus, a group of loci or even its total genetic complement.

Homology: Common ancestry of two or more genes or gene products.

Homoplasy: A collection of phenomena that leads to similarities in character states for reasons other than inheritance from a common ancestor.

Ingroup: An assumed monophyletic group, usually comprising the taxa of primary interest.

Jackknifing: A statistical method of numerical resampling based on deleting a portion of the original observations in subsequent samples.

Maximum likelihood: A method of determining which of two or more competing hypotheses (such as alternative phylogenetic trees) yields best fits to the data.

Maximum parsimony: A criterion for estimating a parameter from observed data based on the principle of minimising the number of events needed to explain the data. In phylogenetic analysis, the optimal tree under the maximum parsimony criterion is the tree that requires the fewest number of character-state changes.

Mitochondrial DNA: The circular, double stranded genome of eukaryotic mitochondria.

Molecular clock: A theoretical clock based on the assumption that the rates at which nucleotide (or amino acid) substitutions become fixed in evolutionary lineages is approximately constant for a given DNA sequence (or polypeptide chain) and reflects the time since data diverged.

Molecular systematics: The detection, description, and explanation of molecular biological diversity, both within and among species.

Monophyletic: A group of taxa that contains an ancestor and all of its descendants.

Mutation: Any change which alters the identity or order of nucleotide bases within a chromosome.

Natural selection: According to Charles Darwin, the main mechanism giving rise to evolution. The mechanism by which heritable traits which increase an organism's chances of survival and reproduction are more likely to be passed on to the next generation than less advantageous traits.

Nucleotide base: The structural unit of a nucleic acid. The major nucleotide bases in DNA are the purines adenine and guanine, and the pyrimidines cytosine and thymine, of which the latter is replaced by uracil in RNA.

Orthology: Homology that arises through speciation.

OUT: Operational taxonomic unit, usually synonymous with terminal taxon.

Outgroup: One or more taxa assumed to be phylogenetically outside the ingroup.