Tax­on­omy

The tra­di­tional method of species descrip­tion is under dis­cus­sion today.


The tra­di­tional tax­o­nomic method­ol­ogy is a museum task which includes the eval­u­a­tion of body struc­tures, the count­ing of fin rays but also the descrip­tion of colour pat­terns. There­fore it is related only to the phe­no­type and does not con­sider genetic infor­ma­tion. Fur­ther­more, the behav­iour is often not con­sid­ered at all, because dead, pre­served fish (museum spec­i­mens) play the major role in the process of descrip­tion. But we know about sig­nif­i­cant dif­fer­ences in behav­iour between dif­fer­ent species, for exam­ple dur­ing courtship, which will undoubt­edly play an impor­tant role in the future sys­tem­at­ics. Thus pre­vi­ous licorice gourami clas­si­fi­ca­tion has to be regarded with con­sid­er­able reservations.

Many areas of biol­ogy have already left behind these seri­ous lim­i­ta­tions of the ear­lier stages of sci­ence. For exam­ple, for the clas­si­fi­ca­tion of flow­er­ing plants today, genetic infor­ma­tion is often essen­tial. The clas­si­fi­ca­tion of birds has been turned upside down in a few decades by tak­ing into account knowl­edge about DNA, but also by com­par­a­tive stud­ies on bird song. There­fore it is expected that new meth­ods of tax­on­omy, which reveal the struc­ture of genomes or con­sider behav­ioural pat­terns, will change the clas­si­fi­ca­tion of licorice gouramis sig­nif­i­cantly in the future. Even today it is likely that, based on more accu­rate descrip­tions of behav­iour, the parvalus-​ornicaudata–group may have to be dif­fer­en­ti­ated from the rest of the species.

Nev­er­the­less, the clas­si­cal tax­on­omy based on phe­no­type, will remain an indis­pens­able method of the descrip­tion of plants and ani­mals. If sig­nif­i­cant dif­fer­ences can be found by care­ful obser­va­tion, this leads to the assump­tion that genetic dif­fer­ences also exist. In most ofcases, dif­fer­ent appear­ance also indi­cates an inter­nal diver­sity. And inter­nal dif­fer­ences man­i­fest in most cases an exter­nal diver­sity as well.

How­ever, even under crit­i­cal con­sid­er­a­tion of the lim­i­ta­tions of phe­no­log­i­cal tax­on­omy, we would not doubt that it has been an indis­pens­able method of bio­log­i­cal descrip­tion up to now. It will be help­ful in the future as well. There is a need to upgrade it by includ­ing new meth­ods in ichthy­ol­ogy, but it will never be com­pletely replaced.

(PF)

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