Biology Reference
In-Depth Information
Figure 2.3. The polyopisthocotylean monogenean Neogrubea seriolellae from the gill
filaments of Seriolella brama in New Zealand. The two valves of its clamps close in
around gill filaments and ''grasp'' them. Attachment to flat surfaces, such as the bony
gill arches, is impossible This results in strict site specificity of the parasite. From
Rohde, Roubal, and Hewitt (
1980
). Reprinted by permission of the Royal Society
of New Zealand.
suitable habitats were already filled, although the existence of many
vacant niches on the gills makes such an assumption unlikely.
Moreover, the hypothesis cannot be rejected that some of the extant
species are newcomers that have competitively replaced others in the
past. In other words, the extant community may well be a subset of the
species that could have assembled because they are suitable for the habitat.
Which means that, in the absence of fossil data, it is impossible to test
whether populations in a habitat consist of all species that have happened
to arrive there, or only of a subset of those species with characteristics that
permit their coexistence (Roughgarden
1989
, see above).
Concerning plant communities, according to Palmer (
2001
), ''in
caricature, the equilibrium paradigm of community ecology states that
