Speciation

SPECIATION

Speciation

Process by which one species splits into two or more species.

Biological species concept

Defines species as a group of populations that can interbreed in nature and produce viable, fertile offspring.

Morphological species concept

Characterizes species by body shape or other structural features.

Ecological species concept

Characterizes species by how it interacts with the environment.

Phylogenetic species concept

Defines species as the smallest group that shares a common ancestor.

Reproductive Isolation

Barriers that prevent gene flow between two species.

Prezygotic barriers

Barriers that occur before the formation of a zygote.

Habitat isolation

Species live in different habitats and do not meet.

Temporal isolation

Species breed at different times.

Behavioral isolation

Species have different courtship rituals.

Mechanical isolation

Incompatible reproductive anatomy prevents mating.

Gametic isolation

Gametes from different species cannot unite.

Postzygotic barriers

Barriers that occur after the formation of a zygote.

Hybrid inviability

Hybrid zygote fails to develop properly.

Hybrid infertility

Hybrid is born but is sterile.

Allopatric speciation

Speciation that occurs when a population is geographically divided.

Sympatric speciation

Speciation that occurs in the same geographic area, often through habitat differentiation or sexual selection.

Phylogeny

Evolutionary history of a species or group of species.

Systematics

Discipline of classifying organisms and determining evolutionary relationships.

Taxonomy

Discipline of classifying and naming organisms.

Binomial nomenclature

Two-part scientific naming system developed by Carolus Linnaeus.

Hierarchical classification

Groups organisms into categories such as Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species.

Phylogenetic tree

Branching diagram showing evolutionary history.

Cladistics

Classifying organisms by inferring phylogeny from homologous characters.

Monophyletic

Group consisting of an ancestor species and all its descendants.

Paraphyletic

Group consisting of an ancestor species and some, but not all, of its descendants.

Polyphyletic

Grouping that includes organisms from different ancestors.

Homology

Phenotypic and genetic similarities due to shared common ancestry.

Analogy

Similar adaptations that evolved independently due to convergent evolution.

Maximum parsimony

Principle that the simplest explanation is preferred when constructing phylogenetic trees.

Domain Archaea

One of the three domains of life, consisting of prokaryotic organisms.

Domain Bacteria

Another domain of life, also consisting of prokaryotic organisms.

Domain Eukarya

Domain that includes all eukaryotic organisms.

Eon

The largest division of geological time.

Cambrian Explosion

A significant increase in the diversity of animal phyla during the Cambrian period.

Adaptive radiation

Rapid speciation to fill emptied habitats after a mass extinction event.

Anthropocene

Proposed epoch that marks the significant impact of humans on the Earth's geology and ecosystems.