Unit III Key Terms Ecology and Evolution

Homoplasy

Characteristic that is similar between organisms by convergent evolution, not due to the same evolutionary path

ancestral

the version of the character found in older ancestors (“older” version)

Basal taxon

branch on a phylogenetic tree that has not diverged significantly from the root ancestor

binomial nomenclature

system of two-part scientific names for an organism, which includes genus and species

branch point

node on a phylogenetic tree where a single lineage splits into distinct new ones

character

attributes that potentially allow its differentiation or potential differentiation from others

character state

the different conditions of a character

derived

the version found in more recent ancestors/descendants (“newer” version)

genus

division of family in the taxonomic classification system; the first part of the binomial scientific name

homology

similarity in characteristics resulting from a shared ancestry

horizontal gene transfer (HGT)

transfer of genes between unrelated species

Carl Linnaeus

taxonomist who first developed a hierarchical model for naming species

maximum parsimony

applying the simplest, most obvious way with the least number of steps

monophyletic group (clade)

organisms that share a single ancestor

most recent common ancestor (MCRA)

youngest extinct common ancestor for a particular group of taxa

phylogenetic tree

diagram that reflects the evolutionary relationships among organisms or groups of organisms

phylogeny

evolutionary history and relationship of an organism or group of organisms

polytomy

branch on a phylogenetic tree with more than two groups or taxa

root

single ancestral lineage on a phylogenetic tree to which all organisms represented in the diagram relate

shared ancestral character

when an ancestral character state is shared by two or more taxa in a phylogeny, these taxa may or may not form a monophyletic group

shared derived character

when a derived character state is shared by two or more taxa in a phylogeny, these taxa may or may not form a monophyletic group

sister taxa

two lineages that diverged from the same branch point

systematics

field of organizing and classifying organisms based on evolutionary relationships

taxon

single level in the taxonomic classification system

taxonomy

science of classifying organisms