[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: Long, long last gasp.
accidentally sent this only to John Bois...
> John Bois (firstname.lastname@example.org) wrote:
> <OK. So what do you call it? For sake of argument, assume that zebra
> mussel populations thrive because other mussels are limited by
> This allows zebra mussels to take all the resources--including
> substrate--from the native mussels. Is this predation or competition.>
> Capitalization. They are taking advantage of a situation they do not
> actually have a part in. As such happens during several faunal
> interchanges, opportunity to exapt new territory or food availability,
> even when they did not slam the land masses together to acheive that
> effect, still permits the organisms their availabilities; still, they
> not survive the interchange, and can easily be knocked out by unrelated
> events to competition. An absence of a predator species can lead to a
> vacuum that must be filled; other species expand to compensate. There
> still is not species to fill in the role the American cheetah played,
> that seems null because of the expansion of the wolf to hunt deer and
> antelope in America which the cheetah likely did. Does not mean the wolf
> outcompeted and caused the death of the cheetah. Despite access, wolves
> not hunt in Africa, and this may be reflective of recent competitive
> forces, though those forces (cheetahs, leopards, likely the Asiatic
> do not appear to be in abundance.
> <Surely, the zebra mussels are currently outcompeting local species.>
> If they're better at feeding on a food source, or attracting it, and
> thereby overtly preventing other species from food, or occuring at spots
> where food would be retained more easily and thereby prevent flow into
> other species, sure. But not so given examples where food is evenly
> available. Given even access, different species should only be limited
> their own abilities, and thus competition can occur. Given lack of
> to prevent another species from capitalizing on a food source, does not
> mean that species is "out competing" anything; it just lacks the ability
> to capitalize and risks death. Thus, mutation. If some population
> to develop a physical or geographical "upper hand," and unless that
> population prevents another predator from attaining the same goal by
> action (like, the rainforest biome, where competition among tree species
> for light often leads to stunted or dying growth, lack of undergrowth,
> grasses, etc.), then competition is not the means of success, its
> capitalization. Lions and hyenas compete, since they actively hunt one
> another to prevent the other's success and for the most part the same
> foods. Classic example. On the otherhand, zebra mussels do nothing to
> prevent the other species ability to function, and cannot actively
> compete; they merely capitalize on opportunity, as given the example
> <Practically _all_ niche delineations of today are assumed to have been
> the result of unobservable "ghost" competition. If we can't observe it
> even in extant species, how can we ever observe it in extinct species.
> This is an unrealistic expectation. Yet, this doesn't reduce its
> If we do not observe it, how can we in any reasonable frame of mine
> assume it could happen at all? It's a possibility, but one not easily
> favorable, as you say. Yet you say. Competition of species would require
> extensive ecological sampling well below the million-year-markers
> available, and layer by layer, bonebed by bonebed show that one species
> was knocking the other off the face of the Earth. Show where this has
> happened, been proven, and not a pipe dream. Of all the possibilities
> why favor competition to knock out the pterosaurs? Obviously the
> bird/ptero argument is a neat one, since there is _some_ support for it,
> but it is an ill-favored argument that would have it so that both
> knocked _each other_ off the face of the Earth, one less adaptable to
> survival I must immediately argue against it for the lack of a viability
> that could ever occur. Only humans, in our infinite stupidity thanks to
> our ability to act against nature, can kill off our own species. Others
> seek to permit and endorse survival.
> <No. My hypothesis is that both were reduced by a third group:
> Ah, one still ill-favored to experience. The evidence for this, or
> to formulate the hypothesis, is based on what?
> <Yes. But also by past competitive interactions, i.e., niche
> Natural partitioning can occur through geographical means, as much as
> species competition, and unrelated natural means, as in metabolic
> reducing populations at the poles, not that the species there prevent
> others from invading. Other species just can't cope with the weather and
> cold, and as such stay away; this favors the "competition with Gaia"
> that the Earth is a proving ground, so that all species are in
> with the Earth's "design." A good example is that Wallace's Line is
> not crossed much at all, not that the birds or lizards or fish there are
> being prevented; they just DON'T.
> <Yes. But there was most likely niche partitioning (or geograhical>
> isolation) among the ratites themselves.>
> That each appears to be geographically isolated from the others, or
> tinamous are smaller and flight-capable than rheas, and that cassowaries
> prefer denser territory than sympatric emus, yes. Kiwis favored smaller
> size, but may not at all be the "shruken" moa of some thought. They eat
> diet of grubs, and are essentially predartory, whereas the extinct moa
> species have largely been shown to be herbivores, partitions by body
> weight, geography (valley to valley, some species of insects are known
> diversity and becoming parapatric without competing, but simply by
> monopolizing a "chance" diversity not previously exploited by a similar
> insect), or specialization, by whatever [unobservable] means.
> is one, largely unprovable, means; capitalization, usually in a vacuum,
> another, more easily testable means.
> Jaime A. Headden
> Little steps are often the hardest to take. We are too used to making
> leaps in the face of adversity, that a simple skip is so hard to do. We
> should all learn to walk soft, walk small, see the world around us
> rather than zoom by it.
> "Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)
> Do you Yahoo!?
> Yahoo! SiteBuilder - Free web site building tool. Try it!
Jaime A. Headden
Little steps are often the hardest to take. We are too used to making leaps
in the face of adversity, that a simple skip is so hard to do. We should all
learn to walk soft, walk small, see the world around us rather than zoom by it.
"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)
Do you Yahoo!?
Yahoo! SiteBuilder - Free web site building tool. Try it!