The fundamental unit of study in taxonomy, comprising all the populations of one breeding group that normally are permanently separated from other such groups by marked discontinuities. If crossing between species does occur then the resulting hybrids are normally sterile so maintaining the reproductive barrier between species. This broadly genetic definition of a species cannot be applied to species that reproduce by self-fertilization or by asexual means or to extinct species. In such cases and when breeding patterns have not been studied, a species is delimited by observation of the similarities between its members and dissimilarities between it and other species. In botanical nomenclature the specific epithet forms the second part of the binomial (the first being the generic name) and it is always written lower case. The ending of the specific epithet always agrees with the gender of the generic name. Unlike the situation in zoology, it is not legitimate for the specific epithet to repeat the generic name. There are several infraspecific categories in the taxonomic hierarchy, but * subspecies is probably the most widely used. Groups of similar species are placed in genera (see genus). |
