Hiroyuki Matsuda in Ecology
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Community structure is not randomly constructed.
Under the assumptions that predators choose
prey species and prey pay anti-predator effort
to maximize their own fitness, I try to explain
some properties of community structures.
The relationship between predators that share
a common prey has been considered to be competition
(exploitative competition). However, if a
prey has anti-predator effort and if anti-predator
effort against one predator is not effective
against the other (predator-specific defense),
the relationship can be mutualistic. The
exploitative mutualism can promotes coexistence
of predators and complex community structure.
Suppose that two clones of cellular slime
molds aggregate to form a fruiting body.
About 2/3 of cells become spores and the
remainder becomes stalk which support spores
but leave no descendants. Why should a clone
make any stalk that support spores of the
other clone? I explain this by evolutionarily
stable stalk/spore ratio (ESSR). I obtained
the condition that ESSR is size invariant.
In ESSR, the number of spores produced by
each clone can be equalized. I argue that
larger individuals do not necessarily enjoy
higher fitness than the smaller ones. This
is called the law of equalization in net
incomes.
Ever since "Selfish Gene" by R.
Dawkins, it is well known that selection
may decrease the population size. I argue
that evolutionary dynamics based on individual
selection may make (1) evolutionarily unstable
fitness maxima and stable minima and (2)
self-extinction of asymmetric competitors
or herbivores.
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