[Taxacom] It is possible to describe a new species?

Richard Pyle deepreef at bishopmuseum.org
Fri Dec 30 15:31:06 CST 2016


Hi Antonio,

> On the other hand, the definition of
> species is clear: If there are no crosses are different species. This is a
> situation that exceeds my knowledge, my experience.

Unfortunately, the definition of a species is not so clear.  Even in the context of the biological species concept (which you refer to), it presumes there is an opportunity to cross before one can assert that they don't cross (and therefore should be considered distinct species).  For example, in species that occur on islands (separated by physical space), there may be two populations on different islands that are very similar to each other (morphologically & genetically).  Because of the spatial separation, they don't cross with each other, because they don't have opportunity to cross with each other.  But just because they are physically unable to cross, doesn't mean we automatically consider them to be distinct species.  Generally, they are considered distinct species only when there are consistent differences (morphological or genetic) between them.  Such differences presumably accumulated over many generations without any crosses between them (via evolution), and therefore represent distinctions that biologists recognize through naming them as distinct species.

The example you gave seems to be very analogous, except instead of spatial barriers to crossing, the barrier is temporal.  Like the populations on separate islands, simply the existence of a (potential) barrier is generally not used to justify assigning distinct species names to each population.  Instead, it's generally best to document morphological or genetic differences (as an indication of divergent evolution) between individuals of the two populations, and using those differences as the main justification for regarding them as distinct species.

Since the time of Linnaeus (and further supported by Darwin and others), the de-facto definition for a species is that "a species is what a competent taxonomist or community of taxonomists says it is".  In answer to your question about whether to describe a new tree species to recognize them as distinct, I think the question you need to answer is "Would the morphological differences between the two forms, absent any detectable genetic differences, be sufficient to treat them as distinct species if they were separated geographically, rather than by time of pollination?"  Or, more generally, "Would labelling these two forms with distinct species names increase the effectiveness of communication among biologists, or would doing so add more confusion?"

Neither of these questions has a "correct" answer.

Aloha,
Rich

Richard L. Pyle, PhD
Database Coordinator for Natural Sciences | Associate Zoologist in Ichthyology | Dive Safety Officer
Department of Natural Sciences, Bishop Museum, 1525 Bernice St., Honolulu, HI 96817
Ph: (808)848-4115, Fax: (808)847-8252 email: deepreef at bishopmuseum.org
http://hbs.bishopmuseum.org/staff/pylerichard.html






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