I, too, have noted the species specific behaviors you describe, perhaps most interesting the roll that jays play in alerting crows (both corvids, by the way, and clever as the dickens) and other species to the presence of raptors. It seems to be a case of "Hey, let's you and him fight!"
Our local jays sometimes mimic raptor calls in order to temporarily clear the feeders of competing species :): lying a blue streak, I suppose. Chimps have also been observed in this sort of deceptive distress vocalization in order to abscond with food.
It has always seemed to me that the crucial metrics were size, flight prowess, and numbers: the mobbing bird must be large enough to threaten the predator but sufficiently more maneuverable to avoid retaliation. The third ingredient seems to be numbers: you can attract gnatcatchers, warblers, and other songbirds during spring breeding season by imitating the call of the Eastern Screech-Owl, though the same call gets a lukewarm response other times of the year.
Small and not as omnivorously beak-equipped as the crows and kingbirds, these songbirds seem to mob only when they are numerous and when the reproductive stakes are high. Only a few of them are unlikely to inflict appreciable damage on any larger bird, while crows can deliver a nasty wound to a larger raptor, as can kingbirds to crows: even a single crow will play Red Baron to a raptor.
I once saw a murder of crows scramble to chase off a Cooper's Hawk, only to be in turn mobbed by kingbirds when they returned to the treeline. Cooper's Hawks prey on smaller birds, while all corvids are notorious nest predators.
Sorry I have no data to offer...just many long days of watching.
This has been already discussed on mimicry thread... You can also read on "Mimicry and neodarwinism" summary of the research that eyspots have no aposematic effect on predators.
If you have a rebuttal in another thread, you should link to that specific post: you are presenting your case here, and it is not my job to go chasing through your other posts, especially when the topic is mammals and your reference is to butterflies.
We know related species of butterflies of which one possess eyspots and other do not.We also know that on the same area live and thrive species with eyspots and without eyspots. Look around on meadow in summer - you will notice very different colourfull species on the same place. It's hardly to believe (for anti-darwinist like me) that all of these gay and bright patterns are outcome of merciless struggle of life. And that they are outcome of selection. And all of them have color patterns that are best adapted to given area - patterns are so different you know. We can discern them very well, not even vision-oriented birds.
Your incredulity is worthless here.
We know that predators and prey alike depend upon all varieties of camouflage and deceit to survive. Whatever studies you refer to show about the impact of eyespots on butterfly survival now, they do not address the situation that existed when the eyespots evolved: perhaps the predators who provided the selective pressure have evolved to compensate for the eyespots. Perhaps your studies are not sound--in this thread, so far, they are only unexamined assertions.
The genetic "code" is not useless in understanding the phenomenon because we know it determines the expression of features such as eyespots, we know it is inheritable, and we know it mutates. Things change, inside and out, and that is why claiming that a characteristic cannot have evolved because it does not currently impact survival begs the question--assuming that lack of impact has been demonstrated in the first place.
Even if such formula exists (I doubt about it) does it help us to underestand how eyspots are percieved by - let say birds? How it functions in given niche?
Such information is as useless as information that this my post is coded in ASCII by 0010101000100101001110.... You will read and underestand (I hope) my text because of words you see and not because some binary codes 100111... are behind them as their technical code. Such information wouldn't help you to underestand meaning of a written text at all.
Well, that's just a failure of imagination; perhaps that's why you have so much incredulity.
If I am attempting to decode a text of completely unknown origin, and I discover that a binary "technical code" is employed in its transmission, then I do indeed know something about the text and its author that I did not know before--I know that it comes from an author with a particular level of mathematical and technological accomplishment. I may then look for further clues to the meaning of the text by inspecting it for other mathematical characteristics.
quote: If you have a rebuttal in another thread, you should link to that specific post: you are presenting your case here, and it is not my job to go chasing through your other posts, especially when the topic is mammals and your reference is to butterflies.
We discussed the issue more in details there. So it is not necessary to discuss it here in another examples.
You were not asked to discuss it again. You claim to have established a fact elsewhere. None of your respondents are obliged to sift through an entire thread to find your supposedly irrefutable proof.
The only reason I can see to refuse to post a link is that the supposedly irrefutable proof does not exist. When a man claims to hold all aces but will not show his hand, he loses the game.
I see you failed to respond to the fact that present ecological interaction is not the sine qua non of evolutionary explanation (there, a little Latin to match your romantic German :))...
Yet other conception is self-representation (die Selbstdarstellung) of species. It is more credulous explanation, why we obviously do not observe any advantage/disatvantage of such color patterns.
As I stated earlier, many species depend on color and pattern for successful predation and its avoidance, as well as for an edge in sexual competition.
Are you claiming that genetic inheritance produces no difference in survival?
Do you claim that handsome men do not bed more women?
You see no disadvantage to albinism in a tropical species?
Do you believe an arctic animal that sheds its white winter coat too soon is unaffected by the loss of camouflage?
Hi, Mike. Welcome to EvC and thanks for the informative posts.
It's odd to see my topic subtitle for Msg. 148 persist. There I said:
quote:I have it on high authority that there are, in fact, many vision-oriented mushroom eaters in Central Europe.
True, some of them are a bit squirrely, but aren't we all?
We return you now to your regularly programmed MartinV (for eVasive) replies.
I confess that my own study of mushrooms has been largely culinary and...ah...experiential, thus the "Colors var. fancy" subtopic. Still, it seemed absurd to read a human being deny the existence of visual predators of mushrooms other than squirrels--and in Europe, of all places!
More seriously, I especially enjoyed your discussion of pigmentation as a secondary effect, since my hunch when Martin raised the issue was that pigmentation changes could result indirectly from chemical consequences of other selectors rather than via direct selection of color itself. But a hunch is only a hunch, and it is invaluable when someone with in-depth knowledge steps forward.
We earned money to attend summer BS camp by directing parking at the Indy 500 (mid 60s).
My first direct experience with beer came from a drunken race fan saying, "O my God, a friggin' Boy Scout!" who then poured a bottle of beer on my head :)
At summer camp, we learned lessons that later saved my life (drop and roll when you're on fire) and my little brother's life (Lifesaving Merit Badge--how to break a choke hold from a drowning swimmer).
We were sent into the woods with a fishing line, knife, and a few other basics to demonstrate our knowledge of how to survive in the wilderness: what plants could be eaten, how to purify water, build a shelter, etc.
I found my way back to the dining hall and liberated copious foodstuffs: wild carrots and dandelion greens are all very well, but peanut butter rocks.
I didn't get caught, though I did later confess. I still got my survival badge: the proof was in the pudding (lemon).
So why do chameleonic abilities appear so often in nature?
We cannot infer from it that coloration of mushrooms has the same function as it have in chameleons.
Ah, let us pause to savor this moment.
MartinV, you went squirreling after mushrooms to evade the telling points being made by others in the discussion of mammal evolution (the actual topic).
So isn't it grand to see you now weasel about the applicability of chameleonic abilities to mushroom discussions? I don't know, maybe it's just me.
Anyway, I mentioned chameleons to cut to the chase (and the camouflage that is sometimes involved). No one here has argued that prey v. predator relationships determine all color attributes of life. However, you have broadly denied any role by natural selection in this phenomenon.
So chameleons are especially relevant: If color is never determined by natural selection, and has no impact on survival, why do chameleonic abilities exist? Note that these abilities do not just exist in chameleons. Perhaps you should shift the discussion to diatoms.