Term | Definition |
macroevolution | Large-scale evolutionary change, such as the formation of new species. |
speciation | Origin of new species due to the evolutionary process of descent with modification. |
morphology | Physical characteristics that contribute to the appearance of an organism. |
morphological species concept | Definition of a species that defines species by specific diagnostic traits. |
diagnostic traits | Characteristics that distinguish species from one another. |
evolutionary species concept | Every species has its own evolutionary history, which is partly documented in the fossil record. |
phylogenetic species concept | Definition of a species that is determined by analysis of a phylogenetic tree to determine a common ancestor. |
biological species concept | The concept that defines species as groups of populations that have the potential to interbreed and that are reproductively isolated from other groups. |
reproductive isolation | Model by which new species arise when gene flow is disrupted between two populations, genetic changes accumulate, and the populations are subsequently unable to mate and produce viable offspring. |
prezygotic isolating mechanism | Anatomical, physiological, or behavioral difference between two species that prevents the possibility of mating. |
Habitat Isolation | Species occupy different habitats. |
Temporal Isolation | Each reproduces at a different time. |
Behavioral Isolation | Courtship patterns for recognizing mates differ. |
Mechanical Isolation | Incompatible animal genitalia or plant floral structures. |
Gamete Isolation | Gametes that meet do not fuse to become a zygote. |
postzygotic isolating mechanism | Anatomical or physiological difference between two species that prevents successful reproduction after mating has taken place. |
Hybrid Inviability | Hybrid zygote is not viable and dies. |
Hybrid Sterility | Hybrid zygote develops into a sterile adult. Example Mule cross between female horse and male donkey. |
speciation | Origin of new species due to the evolutionary process of descent with modification. |
allopatric speciation | Model that proposes that new species arise due to an interruption of gene flow between populations that are separated geographically. |
sympatric speciation | Origin of new species in populations that overlap geographically. |
polyploidy | Having a chromosome number that is a multiple greater than twice that of the monoploid number. |
autoploidy | Polyploid organism with multiple chromosome sets all from the same species. |
alloploidy | Polyploid organism that contains the genomes of two or more different species. |
adaptive radiation | Rapid evolution of several species from a common ancestor into new ecological or geographical zones. |
ecological release | In an ecosystem, the freedom of a species to expand its use of available resources due to an elimination of competition. |
convergent evolution | Similarity in structure in distantly related groups generally due to similiar selective pressures in like environments. |
analogous, analogous structure | Structure that has a similar function in separate lineages but differs in anatomy and ancestry. |
homologous, homologous structure | A structure that is similar in different types of organisms because these organisms descended from a common ancestor. |