Biogeography
Fossil Records
Comparative Anatomy
Homologous Structures
Analogous Structures
Vestigial Structures
Embryology
Adaptation
Reproductive Success
Genetic Variation
Prezygotic
Ecological Isolation
Behavioral Isolation
Temporal Isolation
Mechanical Isolation
Gametic Isolation
Postzygotic
Zygote mortality
Hybrid Inviability
Hybrid Infertility
Geographical isolation
Adaptive Radiation
Polyploidy
Mutations
Gene pool
Change in allele frequency