what is a type species in zoology and what is it useful for?
In: Biology
Type species is by definition a species from a given genus that is a basis for that’s entire genus description.
It’s kindof archaic term that’s not really used now because most of our current taxonomical classification is derived from genetic data not morphological similiarities.
In taxonomy genus is one step above species, meaning a group of closely related populations with high enough diffrencess between them to regard them as separate species. For example red junglefowl, household chicken(domesticated junglefowl) and grey junglefowl are all species from genus gallus – also know as junglefowl or chicken, and they are all related to a close common ancestor.
And a type species for a given genus is an arbitrarly choosen species that is a ‘core’ of the entire group – a given animal must be similiar enough to the ‘core’ to be classified in the same genus, for example a type species of genus gallus is the household chicken, and only animals similiar to it, to the point that a description of most notable features of a chicken could be mostly applied to them, can be considered as part of the same genus.
In practice type species don’t hold any biological significance. Usually they are either the first discovered species from a given genus or the most common one, and often they don’t create a good enough descriptor of their genus – they can exclude species that are closely related but not similiar emough, or include species that aren’t related but are look-alikes because of evolutionary contingency.
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