FAQs on New Species
by Emilio Garcia
How Do New Species Occur?
In l942 E. Mayr published the classic book, Systematics and
the Origin of Species. In it he states that there have to exist
two factors for speciation: "the development of diversity
and the establishment of discontinuity between diverging forms."
Although geographic isolation is the more common means of establishing
discontinuity between populations, Mayer later observes that
changes in ecology and/or reproductive patterns may also contribute
to the process of speciation.
What Is A New Species?
It is the problem of those who describe new species, the taxonomists,
to decide if the differences in populations due to geographic
or ecological isolation are sufficient to have created a new
species. The act of describing the new species, therefore, indicates
that the taxonomist has reached the conclusion that they are
sufficient.
Many species have specific differences from all others. However,
with closely related species, extremely similar in appearance,
the taxonomist ideally will have to inspect the original material
from which each related species was described before reaching
a final decision. Furthermore, the taxonomist should have access
to series of specimens of the species that have already been
described to make sure that this new species does not fit into
any of the variations of named species. Along this line, it
is also preferable to have more than one specimen of the new
species to be sure that one is not dealing only with a unique
aberration. A good description of a new species will establish
constant and clear differences between it and all other closely
related species.
What is a subspecies?
When two or more populations of a species are geographically
isolated and show consistent differences between them, they
are given subspecific names. For example, there is a population
of the spider conch Lambis crocata that inhabits the Marquesas
Islands. The specimens are much larger than those of contiguous
populations. The population is called Lambis crocata pilsbryi.
Therefore, the species Lambis crocata is divided into two subspecies:
Lambis crocata crocata and Lambis crocata pilsbryi. Many taxonomists
no longer accept the validity of a subspecies, arguing that
the isolated populations have either become different species
or are only forms of the original species and therefore have
no taxonomic validity.
Holotypes and paratypes:
The author of a new species will choose a single specimen which
he considers to be the best representative of the species he
is describing, and he will name it the holotype. Then he may
choose other specimens from the type series that will reinforce
the understanding of the species, and he will name them paratypes.
After the species is published, anyone who wants to describe
a new species closely related to this one, or who wants to question
the validity of the new species, will have to consult this type
material. Holotypes and paratypes should be deposited in public
institutions so that they are readily accessible to any worker
who needs to inspect them.
Lumpers and splitters:
Many species described in the past as new were later found to
be only forms of species already described. At times, everyone
agrees; at other times, however, the relationship between very
closely related species is not clear and taxonomists (and amateur
collectors) disagree as to whether a certain species is valid
or only a form of an already described species. Those who think
that the differences between two or more species are minor and
that they all should be treated as one are called lumpers, and
those who think the differences, and thus the species, are valid
are called splitters. Such controversies are more prevalent
with popular families such as Cypraeidae (cowries), Conidae
(cones), Volutidae (volutes) and Muricidae (murex and rock shells).
