Biology Reference
In-Depth Information
Figure 4.1. Computer simulations of the relationship between infra- and
component community richness. The assumption is that each infracommunity can be
recruited from any species in the component community, in any order, but species
have different likelihoods of appearing in an infracommunity due to different
transmission rates and intrinsic life spans. The richness of a community can vary
between 1 and 9 species. 1000 iterations. (a) all species have a 100% likelihood of
appearing in the infracommunity; (b) 7 species have an 80% likelihood, and 2 have a
30% likelihood of appearing in the infracommunity; (c) 2 species have a 40%
likelihood, and 7 have a 10% likelihood of appearing. Note the asymptotic
relationships for the means and maxima of all infracommunities except a maximum
and mean and b maximum, although no assumptions on interspecific effects have
been made. The conclusion must be that interspecific competition is not necessary to
explain the asymptotic patterns. For access to program see www.
personal.une.edu.au/
krohde/ (1) Infra- vs component community richness
program (Macintosh only). Reprinted from Rohde (
2002
), with permission of
Elsevier.
because of different life spans and colonization probabilities (Figure
4.1
).
But these results do not necessarily mean that the distinction of type I and II
communities is wrong. What they mean is that, before the occurrence of
type II communities due to competition can be assumed, results have to be
tested against a null model in which species differ only in their likelihood of
occurrence as a result of different life spans and colonization rates. But for
how many systems have these parameters for all species been determined?
