|
It's pretty well established that the mimicry is a defense against potential predators... and the patterns ARE similar enough to fool mammilian and Avian predators...
The real question is... Are the north american animals mimicing corals... or are corals themselves among the mimics?
It's been established through the years and with multiple tests that the banded pattern of many tricolors causes a reaction in mammals and birds, the conclusion drawn from this is that the color patterns have existed as warning colors for long enough to have been ingrained into the genetic patterns of the potential predators.
This supports an argument that all other tricolors are mimicing corals- predators which are stimulated into a feeding response by the sight of a tricolor snake are eventually weeded out of the breeding population as they encounter the wrong type and essentially make themselves a genetic dead end. This leaves a breeding population which is inclined to avoid snakes with these markings and thus means success for both the actual venemous species as well as the mimics (meaning that nonvenomous species which just coincidentally looked a bit like a coral became more and more similarly patterned as the predator pool evolved to avoid eating anything which resembled them).
The second argument which does not contradict the first but rather places the emphasis elsewhere looks at the area of origination for some of these species... North American snakes tended to evolve in the tropics as a species, moving northward afterwards (as most things do) according to the fossil trail, where it's known... In South and Central America there are a number of rear fanged colubridines which share the tri-color banding of the totally harmless species as well as the deadly ones... The thought here is that individual predators which are inclined to make a meal of a snake AND are capable of learning (birds and mammals learn from their parents for example) run into one of the species which is painfully but not deadly venomous, are envenomated and then learn to avoid similar situations in the future... This would indicate that corals themselves are mimics of the less toxic species (because dead predators can't learn).
The truth is likely something in between... Vis, that the painfully venomous but non-deadly species have had a greater impact on the development of the aversion of mammilian and avian predators and that the corals themselves (keep in mind that there are MANY coral species, not all of them look that similar) have had an impact on the predatory species which learn on a slower genetic scale through the modification of the breeding population's instinctive responses.
|