Biological Principles II: Speciation and Phylogenetics

Vocabulary flashcards covering key terms and concepts from speciation and phylogenetics.

Speciation

The evolutionary process by which one lineage splits into two or more reproductively independent lineages, leading to new species (macroevolution).

Macroevolution

Large-scale evolution, including the origin of new species, occurring above the level of populations.

Microevolution

Small, within-population genetic changes that alter allele frequencies over time (observed as changes in the gene pool).

Biological Species Concept (BSC)

Species are groups that are reproductively compatible and produce fertile offspring; barriers to reproduction separate species.

Morphospecies Concept

Species defined by morphological similarity; can be misled when similar-looking species have different chromosomes.

Ecological Species Concept (ESC)

A species is linked to a unique ecological niche; one-to-one relationship between species and niche.

Phylogenetic Species Concept (PSC)

Species defined as the smallest monophyletic group on a phylogenetic tree; useful for asexually reproducing species.

Hybridization

Interbreeding between closely related species; produces hybrids; reveals incomplete reproductive isolation.

Prezygotic barrier

Barriers that prevent fertilization from occurring; examples include behavioral, mechanical, gametic, temporal, and ecological barriers.

Postzygotic barrier

Barriers after fertilization; hybrids may be inviable or sterile, reducing successful reproduction.

Allopatric speciation

Speciation that occurs when populations are geographically separated, preventing gene flow.

Sympatric speciation

Speciation that occurs without geographic separation, due to reproductive barriers within the same area.

Vicariance

A geographic barrier splits a population, promoting allopatric speciation.

Dispersal

Colonization of a new geographic area by individuals, initiating allopatric speciation.

Behavioral barrier

Prezygotic barrier where mating is prevented by differences in behavior or mating signals.

Mechanical barrier

Prezygotic barrier where reproductive organs are incompatible; prevents mating.

Gametic barrier

Prezygotic barrier where gametes are incompatible and cannot fertilize.

Temporal barrier

Prezygotic barrier where species breed at different times, preventing interbreeding.

Ecological barrier

Prezygotic barrier where species are separated by different ecological niches within overlapping ranges.

Hybrid inviability

Postzygotic barrier where hybrids fail to develop or survive to reproductive age.

Hybrid sterility

Postzygotic barrier where hybrids are viable but infertile (e.g., mules).

Liger

Hybrid offspring of a male lion and a female tiger; typically larger than either parent; illustrates hybridization.

Tigon

Hybrid offspring of a male tiger and a female lion; differs from a liger based on parental combination.

Node

In a phylogenetic tree, the point where a branch splits, representing a common ancestor.

Root

The base of a phylogenetic tree representing the most distant common ancestor of all included taxa.

Phylogeny

The evolutionary history of a species or group, depicted as a tree showing descent relationships.

Taxonomy

The science of identifying, naming, and classifying organisms; hierarchical grouping into taxa.

Binomial nomenclature

Two-part Latin name for a species: genus name (capitalized) and species epithet (lowercase); both italicized.

Nested patterns

Phylogeny and taxonomy reveal nested similarities and descent relationships across groups.

Systematics

Study of biodiversity and origins using taxonomy and phylogeny to understand evolutionary relationships.