Classifications and Phylogeny Key Definitions

These flashcards cover key definitions and concepts related to classifications and phylogeny, aiding in the understanding of evolutionary relationships, speciation, and phylogenetic methods.

Cladogram

A diagram that shows evolutionary relationships between taxa.

Phylogeny

The history of descent with branching.

Taxon

A taxonomic group of any ranking (plural: taxa).

Taxonomy

The scientific study of organizing groups of biological organisms based on shared characteristics.

Phylogenetic trees

Diagrams that show evolutionary relationships between taxa throughout time, with branch length corresponding to time.

Systematics

The science of organizing the history of organismal evolution using phylogenies.

Node

A branch point on a cladogram that represents a common ancestor.

Polytomy

Describes unresolved branches on a cladogram, where three or more species branch from one node.

Synapomorphy

A shared derived trait among a group of descendants, indicating common ancestry.

Homologous traits

Similar traits that result from common ancestry, due to divergent evolution.

Analogous traits

Similar traits that do not result from common ancestry but arise from convergent evolution.

Morphological data

Species descriptions based on physical form and structure.

Molecular clock

Theory stating that molecular differences between pairs of species are proportional to the time of their separation.

Biological species concept

A species is a group of organisms that can interbreed and produce fertile offspring.

Ecological species concept

A species is a group of organisms that share a distinct ecological niche.

Phylogenetic species concept

A species is a group of organisms bound by a unique ancestry.

Morphospecies concept

The idea that members of the same species usually look alike to each other more than to other species.

Prezygotic isolation

Occurs when individuals of different species are prevented from mating and thus forming a zygote.

Postzygotic isolation

Occurs when individuals from different populations mate, but the hybrid offspring have low fitness or do not survive.

Allopatric speciation

Speciation that occurs when populations are physically isolated from each other.

Sympatric speciation

Speciation that occurs when populations become isolated while living in the same area.

Hybrid zone

A geographic area where interbreeding between two isolated populations occurs.