Skip to comments.Toothy Spiral Jaw Gave Ancient Sea Predator an Edge
Posted on 02/28/2013 11:45:33 AM PST by EveningStar
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OOps, his name is spelled Schaffer...
Allen J. C., Schaffer, W. M. and D. Rosko. 1993. Chaos reduces species extinction by amplifying local population noise. Nature. 364: 229-232.
May give you some insight into the value of Panda low reproduction rates.
That presumes the predator would only eat Pandas, which isn't realistic. Tigers and leopards both existed in the panda's historical range and did/do eat pandas. Smaller predators have been known to take panda cubs.
What else eats bamboo? Little competition could be an advantage, bamboo grows quickly, and the sedentary nature and stored energy permits the Panda to survive periodic reductions in bamboo availability. It is doubtless a vulnerability. A bamboo killing fungus would probably kill the panda too.
Yes, digesting bamboo has its positives, but eating almost nothing but bamboo has big negatives. There is little nutritional value in it. Its odd that Pandas are genetically and functionally omnivores and can digest meat and other plants, they just oddly choose not to. A very odd adaptation that I can't even suppose any advantage to.
By comparison, consider the hoofed rat (aka whitetail deer). It overbreeds, and then starves absent predation. Hunting rules change to adapt to wide variation in its numbers, in an attempt to reduce mass starvation incidents.
I'm not sure there is any proof of natural overpopulation. Deer, like many species, have been greatly augmented by mankind. We create large amounts of available food and we have killed of their primary predators. Meanwhile, we limit our predation on them to protect the newest generation.
Pressure from natural overpopulation is thought to be a reason for large animals on islands to get smaller. The pygmy elephant from Java being an example.
Another reason for pressure from over population is destruction of habitat. Either affects a species the same way as it is the ratio that describes the pressure.
On the other hand, being freed from competition or predation seems to give some species an opportunity to get larger. Rats on islands (sometimes the same islands as where the pygmy elephant evolved) often get bigger. The Moa of New Zealand may be an example of this also.
It is hard to predict what will happen in any particular event. It is easy to backtrack that big rats evolved from smaller rats, or small elephants evolved from normal elephants.
One might even conclude that the inability to predict is an indication of a lack of scientific support for the reasoning. Yes, both environmental pressure theories seem logical, but that doesn't make them true. When you have a logical theory to cover every base you can't go wrong. If they get bigger, the theory works. If they get smaller the other theory works.
What if they changed size for a different reason, but we never explored it because we already accept the catch all theories. The presumption is that they had to change for the better, but we never assume that extinctions were the result of evolution gone awry.
Yes they are insightful theories and might be correct, but I always question theories that can't be disproven.
The classic way to disprove the evolutionary time line is to find the classic violations: monkeys fossiles with dinosaur fossils for example.
Of course such findings have not been found, but the absence of evidence is not the evidence of absence.
The things we know in science are by its nature, unsure: they can be overturned tomorrow by a good experiment, and unexpected data.
The errors of the past we have confidence that they are errors because of past good experiments and data that was once unexpected, and used to develop a new theory that explains or permits the known data.
The Lodka Volterra equations explain year to year variation in species populations. Back some 40 years ago, it was presumed that eventually all the swirly motion would damp out and you had some kind of equilibrium point.
_ _ ________
/ \ / \_/
After the Chaos work of the last 35 years we have a different understanding: that there is no equilibrium point to find, that swirly motion of Lodka Volterra equations is the natural state of things. That makes predicting an equilibrium point impossible (or trivially easy since they are all equally wrong!)
The problem is that the new theories are hardly ever simpler than the old ones, so there is the concern that we may be adding the equivalent of ‘retrograde motions’ to the stars to explain the variance of crude or messy data to our beautiful theories.
That attempt at ‘ringing with damping’ didn’t come out too well. Try again...
Well stated. My apprehension is just that. It's not that logical explanations for evolution are too few or difficult, but rather so plentiful and easy.
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