A paraspecies (a
paraphyletic species) is a
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
, living or fossil, that gave rise to one or more daughter species without itself becoming
extinct.
Geographically widespread species that have given rise to one or more daughter species as peripheral isolates without themselves becoming extinct (i.e. through
peripatric speciation
Peripatric speciation is a mode of speciation in which a new species is formed from an isolated peripheral population. Since peripatric speciation resembles allopatric speciation, in that populations are isolated and prevented from exchanging g ...
) are examples of paraspecies.
Paraspecies are expected from evolutionary theory (Crisp and Chandler, 1996), and are empirical realities in many terrestrial and aquatic taxa.
Examples
* A well-documented example of a living mammal species that gave rise to another living species is the evolution of the
polar bear from the
brown bear
The brown bear (''Ursus arctos'') is a large bear species found across Eurasia and North America. In North America, the populations of brown bears are called grizzly bears, while the subspecies that inhabits the Kodiak Islands of Alaska is ...
.
* An example of a living reptile paraspecies is New Zealand's North Island tuatara ''
Sphenodon punctatus
Tuatara (''Sphenodon punctatus'') are reptiles endemic to New Zealand. Despite their close resemblance to lizards, they are part of a distinct lineage, the order Rhynchocephalia. The name ''tuatara'' is derived from the Māori language and m ...
'', which gave rise to the Brothers Island tuatara ''
Sphenodon guntheri''. An example of a living bird paraspecies is ''
Empidonax occidentalis'', the
Cordilleran flycatcher.
* An example of a living plant paraspecies is ''
Pouteria cuspidata
''Pouteria'' is a genus of flowering plant, flowering trees in the gutta-percha family (biology), family, Sapotaceae. The genus is widespread throughout the tropical regions of the world. It includes the canistel (''Pouteria campechiana, P. campe ...
'', the
pouteria trees or eggfruits.
See also
*
Cladogenesis
Cladogenesis is an evolutionary splitting of a parent species into two distinct species, forming a clade.
This event usually occurs when a few organisms end up in new, often distant areas or when environmental changes cause several extinctions, ...
*
Anagenesis
Anagenesis is the gradual evolution of a species that continues to exist as an interbreeding population. This contrasts with cladogenesis, which occurs when there is branching or splitting, leading to two or more lineages and resulting in separate ...
, also known as "phyletic change", where no branching event occurred (or is known to have occurred)
Notes and references
{{Reflist
Evolutionary biology