Hi Don,The only thing that I found particularly surprising about the article was that they found no evidence that adult insects tended to fly upstream before ovipositing. So with so much drift taking place, why doesn’t the upper parts of streams become depopulated as a result?
I have read some comments reporting that nymphs and larvae that drift downstream have a behavioral tendency to crawl back upstream in the shallows, but given the speed of drift and the slowness of any crawling (few immature insects are adept swimmers) I tend to think that there must be some behavioral pattern that “restocks” the insect population upstream, whether this study observed it or not.
If someone has another answer (other than redistribution by the nymph fairy) then I would love to hear it.
You picked up on another fault of the article. You are, of course, correct.
If there is NO upstream migration of the female egglayers, then eventually, all the population must end up at the ocean or lake that the river system empties into. There is not other logical possibility. Therefore, whether there is experimental proof or not, there must be a mechanism for upstream migration of the nymphal, larval or adult stage of all aquatic insects.
The article is, therefore, misleading in this regard. I quote, “Drift became the subject of serious study after Muller (1954) proposed that compensatory upstream flight by adult insects was necessary to maintain populations. Study has shown that this does not seem to be the case.” Unfortunately, like many articles there is no citation of the “study” at the end of the article.
So I did some searching of my own. I found this article as the first citation when searching for the Muller reference on compensatory upstream flight.
Muller (1954) proposed that compensatory upstream flight - Google Search
JSTOR: Access Check
You would think that this study would be about mayflies, caddis or stoneflies; but you would be wrong. It is about water striders.
JOURNAL ARTICLE: A Test of the Hypothesis of Compensatory Upstream Dispersal Using a Stream-Dwelling Waterstrider, Gerris remigis
D. J. Fairbairn
Vol. 66, No. 1 (1985), pp. 147-153
The abstract states: “This paper reports the results of 2 experiments designed to determine if adult Gerris remigis (Hemiptera, heteroptera), a stream-dwelling waterstrider, tend to disperse preferentially upstream, as predicted by the colonization cycle hypothesis summarized by Muller (1982). Mark-recapture observations and experimental removals were used to assess the distance and direction of movement of adult G. remigis along a small mountain stream, over a full year. These experiments indicated that adult G. remigis show a significant upstream bias in movement distance, but not in numbers of animals moving. This upstream bias is characteristic of pre-reproductive, sexually immature adults of both sexes, and occurs primarily in association with movements to and from diapause sites. Although the existence of a significant upstream bias in movement distances tends to support the colonization cycle hypothesis, the data from the removal experiments clearly show that upstream dispersal is not sufficient to compensate entirely for downstream drift.”
And if you actually read the body of the paper, it states: ”Recent studies have shown statistically significant preferences for upstream flight among adults of many species of stream-dwelling aquatic insects, particularly mayflies… caddisflies… black flies… and stoneflies…” This statement is then followed by a series of citations of prior studies dating from 1957 to 1983.
Obviously, it is nice to have studies that demonstrate the obvious but really do we need studies to demonstrate the obvious? As fly fishers we know that for the hundreds of thousands and possible millions of years that these insects have existed that they have continued to populate our rivers and streams. I have observed upstream egg laying flights of mayflies and caddisflies. Do I then believe it when an article that states “Study has shown that this (meaning upstream flight) does not seem to be the case.” Not one bit!
Again you have given me an opening. The question is really whether we humans have free will or whether any alien or any thing in our universe can have free will. I believe in free will otherwise my life means nothing. I would be nothing but an automaton.Silver, are you implying insects do not have free will??????
"It constantly amazes me that someone as smart as Stephen Hawking who is a theoretical physicist actually believes that this makes him an expert in other fields beyond his expertise, such as existentialism in which he has had no education."Again you have given me an opening. The question is really whether we humans have free will or whether any alien or any thing in our universe can have free will. I believe in free will otherwise my life means nothing. I would be nothing but an automaton.
HOWEVER, would it interest you the none other Stephen Hawking believed that there can not be "free will" in a deterministic universe. His argument is, at it core, very simple. The physical laws of the universe are deterministic and therefore if the basic laws of physics are determined. Since biology is the result of the work of physics (Time + energy + matter); then biology is deterministic and our behavior is predetermined by physical laws.
Open all the prisons! There are no such beings as criminals. We are all "dancing to our DNA" to paraphrase Richard Dawkins.
“DNA neither cares nor knows. DNA just is. And we dance to its music.”
― Richard Dawkins, River Out of Eden: A Darwinian View of Life
Stephen Hawking on Free Will - The Three Illusions
Hey, we can all blame those poor casts and blown presentations on determinism. It's not my fault at all!
“Come On” Stephen Hawking: The Quandary of Free Will In an Apparently Deterministic Universe – Cultural Maturity
It constantly amazes me that someone as smart as Stephen Hawking who is a theoretical physicist actually believes that this makes him an expert in other fields beyond his expertise, such as existentialism in which he has had no education.
a philosophical theory or approach which emphasizes the existence of the individual person as a free and responsible agent determining their own development through acts of the will.
Thanks for posting the original article. Some of our comments may be critical of specific statements, but that is no way reflects on our overall interest and the fact that you shared it with the rest of us.With all due respect, and clearly not on task for this thread, I am convinced scientifically that evolution is a pile of pig whooie.
That being said, this article is not a comprehensive source of info, but it clearly gives data that a larger chunk of the nymph population moves in traditionally non-fished times. My hope is that more anglers will think of taking new times to fish, and get more fish as a result.
Best wishes to you too, Sir. Merry Christmas to you and your family.Thanks for posting the original article. Some of our comments may be critical of specific statements, but that is no way reflects on our overall interest and the fact that you shared it with the rest of us.
I tend to agree with most, but not all, aspects of the theory of evolution, but I have been observedly wrong on many other issues, so we can proceed from there. There is plenty of room for doubt about any of our conclusions,se nothing that was said here should be interpreted as sneering at anyone’s beliefs.
I think you accomplished your intent by posting the article.