PARASITES
BENEFIT HOSTS WITH SURVIVAL INSURANCE
Post #11
Donald
A. Windsor
Parasites
benefit their hosts at the species level by insuring that they
survive, thus ensuring their own survival. Parasites also help
ecosystems survive by preventing monocultures.
Insurance
provides benefits, but paying the premiums is a burden. Parasites
act as insurance agents for their hosts and indeed, these agents
certainly burden their hosts with payments. Parasites enable their
host species to survive catastrophes that otherwise could have
rendered them extinct. The result of this insurance is the enormous
array of biodiversity that our biosphere exhibits.
Catastrophes
are not common, but when they do occur, they can be fatal. Insurance
is not used to compensate for the routine day-to-day hassles, just
for serious calamities. Parasites have to confer benefits only when
their hosts are at risk of extinction.
Individual
organisms do not receive benefits from parasites. Species receive
the benefits. The reason is that individuals do not evolve. Species
evolve. Individuals die, but their species lives on, until it goes
extinct. Individual parasites harm their individual hosts, by
definition. By sharp contrast, at the species level, parasites
benefit their hosts.
Insurance
agents dole out money, but they also make money. Parasites insure
hosts, but the parasites also get benefits. When a host species goes
extinct, the species parasitizing that host also risk extinction.
Parasitic species persist over long time periods by either keeping
their host species extant or by switching to other host species.
Parasitic species that do both increase their chances for survival.
Hosts
and their parasites do not dwell in isolation. They live in
ecosystems and they interact with other organisms. When their
resident ecosystems collapse, they risk dying out. Consequently,
species within ecosystems must cooperate to insure the survival of
their ecosystems. Each species must fit in with the other species.
They
fit in by not forming monocultures. Parasites prevent monocultures.
When competition and predation are not able to retard rampant
population growth, disease breaks out and monocultures are prevented.
Our biosphere is biodiverse because of this process. Diseases are
caused by pathogenic parasites attacking hosts already weakened by
their normal parasites.
A
good conceptual model is provided by financial systems. Unregulated
capitalism results in wealth accumulation by a few people while most
people wallow in poverty. Government regulation, taxes, black
markets, and illegal schemes act as parasites on the capitalists,
redistributing the wealth. Parasites fulfill this role in
ecosystems.
The
end result is that parasites insure that biodiversity prospers in our
biosphere.
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