Taxonomy, phylogenetics, and speciation

Morphological species concept

-organisms are classified as the same species if their anatomical traits are very similar

-drawbacks: number of traits to consider and degree of variation between species in not simple

Biological species concept

species are grouped based on their ability to interbreed with one another

Evolutionary lineage species concept

-species are defined by their unique evolutionary lineage

-different branching represents new lineages

Ecological species concept

a species as a group of organisms that occupy the same ecological niche—a set of resources and conditions they use or require to survive and reproduce

General lineage concept

-uses multiple criteria to distinguish species (morphology, reproductive, isolation, ecology, DNA, etc)

-incorporates species concepts

-received significant support due to its generality

Sympatric speciation

speciation due to geographic isolation

Allopatric speciation

-speciation occurs even though there are no physical barriers

-can occur through polyploidy (genetic abnormality), hybrid speciation, adaptation to local environments, sexual selection

Taxonomy

naming and classifying organisms

Systematics/phylogenetic

study of diversity and evolutionary relationships

Phylogeny

evolutionary history of organisms

Cladistics

groupings of organisms based on evolutionary relationships

Monophyletic groups

contains common ancestor and all descendants

Paraphyletic groups

contains common ancestor, but not all descendants

Polyphyletic groups

contains species of different common ancestors

Shared primitive characteristics

a traits that is shared and inherited from a common ancestor

Shared derived characteristics

a trait that is shared and unique to a group (often defines a group)