Biology Reference
In-Depth Information
10
.
An autecological comparison: the
ecology of some Aspidogastrea
In the
previous chapters
,
we have evaluated evidence for equilibrium
and nonequilibrium conditions, and for the significance of interspecific
competition, using ecological and macroecological/biogeographical, as
well as some experimental studies. Here we look at two closely related
species using everything that is known about them, including phylogeny
based on DNA and morphology (including ultrastructure), life cycles,
morphology and ecological evidence, in order to arrive at an under-
standing of whether and to what degree competition can be implicated
in the evolution of the species' characteristics, i.e., we use an auteco-
logical approach.
Hengeveld and Walter in a number of papers (e.g.,
1999
), advocated a
radically new approach to ecology (see pp. 10-11). They distinguish two
coexisting but mutually exclusive paradigms, the demographic and the
autecological paradigm. Autecology, the study of the ecology of a single
species, its phylogenetic history and adaptations, is an old concept, new is
the radical view that these two approaches are incompatible. According
to Hengeveld and Walter, the demographic approach is based on unrealistic
premises and cannot answer many of the questions posed by the way
species are distributed and how common they are.
The examples selected are two species of the Aspidogastrea. I chose this
group for various reasons. Firstly, I am very familiar with it, having done
a lot of work on its phylogeny based on molecular, morphological, and
ultrastructural data, as well as on the taxonomy, development, and ecology
of several species. Secondly, the group is better known than many others,
although much remains to be done particularly on the physiology and
ecology of many species. Thirdly, the group is small, comprising only
12 genera (in 4 families) and about 80 described species, and its relative
uniformity permits insights into some essential aspects of its ecology.
A ''Tree of Life'' webpage at http://tolweb.org/tree/eukaryotes/animals/
platyhelminthes/aspidogastrea/ contains a complete list of references
and illustrated discussions of the morphology, taxonomy, pathology,
