apomictic microspecies

[Torbjörn Tyler]

At 05.49 +0200 on 2002-05-25, Ken Kinman wrote:


>       While on the subject of Hieracium, don't some botanists consider many
> apomictic microspecies as infraspecific (like subspecies).  If you regard
> them all as separate species, isn't this an extreme form of the phylogenetic
> species concept?
>       And if we studied other "clonal" organisms (like bryozoans) as
> intensely, would we also find genera with hundreds or thousands of such
> microspecies?
>         ---- Just curious,
>                     Ken Kinman


Yes, there are certainly several different traditions and schools concerning the rank of apomictic micro-species. In the Nordic countries and the UK such taxa have for long generally been regarded as species, however, on the European continent the tradition have been, and partly still is, to treat them as infraspecific taxa.

The greatest problem with infraspecific treatment is, in my opinion, that infraspecific treatment intrinsically infers a known hierachic evolutionary relationship between taxa, i.e. subspecies of the same species are more closely related then subspecies of different species. If case one wants to have monophyletic species this may become even more complicated. Because in most apomictic groups, the evolutionary relationships between the microspecies are not known and can hardly be inferred by morphology alone and the mode of evolution (hierachic or reticulate) is usually not well known either. In the Central European school of Hieracium studies, each microspecies is treated as a subspecies under one of a relatively limited number of species which in turn are put in a hierachy of infrageneric taxa. In addition, a large number of micro-species are treated as subspecies of 'zwichenarten' i.e. presumed notho-species. This has been done based on morphology alone but since there are thousands of micro-species and a limited number of morphological characters, the evolution and genetic background of which are generally unknown, and there are indications that evolution is largely reticulate, I think it is simply stupid to claim that certain microspecies are subspecies of species A wheras others belong to species B. Mainly for this reason I definitely prefer to treat apomictic micro-species at the rank of species.

One may further agrue that since apomictic taxa do not exchange genes they are more like biological species than like subspecies, however, that would be the case for any clonal group of organism...


-------------------------------------------------------------------

Torbjörn Tyler   /  Projekt Skånes Flora

Department of Ecology
Systematic Botany
Ecology Building                                	
Sölvegatan 37         	
SE-223 62 Lund                          	
                        	
tel. +(0)46-222 09 10
fax + (0)46-222 44 23
e-mail: torbjorn.tyler at sysbot.lu.se

Private adress: Bredgatan 12B, SE-243 32 Höör (=Hoeoer), tel. +(0)413-23123.
___________________________________________________________________