Macroevolution: Its all around us...

OK. For all of you that would deny speciation (= macroevolution) is occuring all around us, all the time, check this out - from the current volume of "Science", a *somewhat* respected publication, even among non-scientists.Assortative Mating in Sympatric Host Races of the European
Corn BorerThibaut Malausa,1,2* Marie-There`se Bethenod,3
Arnaud Bontemps,1,3 Denis Bourguet,2 Jean-Marie Cornuet,2
Sergine Ponsard1ABSTRACT
Although a growing body of work supports the plausibility of sympatric speciation
in animals, the practical difficulties of directly quantifying reproductive
isolation between diverging taxa remain an obstacle to analyzing this process.
We used a combination of genetic and biogeochemical markers to produce a
direct field estimate of assortative mating in phytophagous insect populations.
We show that individuals of the same insect species, the European corn borer
Ostrinia nubilalis, that develop on different host plants can display almost absolute
reproductive isolationthe proportion of assortative mating was >95%even in the absence of temporal or spatial isolation.Science 2005, v308: 258-260.Let me spell this out for you.As the insects feed on different plants, they seek mates only on those plants. This 'host plant fidelity' serves as a wedge to separate populations, preventing gene flow between them. Once you have no more gene flow between plant-associated populations, 'poof' you have separate species. It's almost as awe-inspiring as the 'poof' of creation in which all species were instanteously created in immutable forms....

Quoting.....Songbird shows how evolution worksScientists may be witnessing one of the fundamental forces of evolution: the divergence of one species into two.The new data comes from the songs of the greenish warbler, a bird that lives in the foothills of the Himalayas. Researchers have noticed that its song changes gradually throughout its territory.At the extreme ranges of its habitat, the greenish warbler will sing very different songs. This means there are some birds in the territory which, although they belong to the same species, will not mate because they do not recognise each other's calls. Eventually, the two singing groups will become two separate species....Read the complete article at:http://news.bbc.co.uk/1/hi/sci/tech/1123973.stm

Thread moved here from the Proposed New Topics forum.

You're gonna want to put in these earplugs. When the creationists start moving the goalposts all over the place, the noise gets pretty loud.

I am ready. Still waiting for the first nibble, though.I originally thought that ongoing speciation would be a controversial topic for all creationists, but I have recently learned that some have circumvented this (to me) undeniable contradiction with creation by claiming that it was only the higher 'kinds' of organisms (approximately family level) that were 'created', species being free to 'change' and 'diverge'. A convenient cop-out I suspect, in the face of insurmountable evidence. Holding creation responsible only for higher taxa conveniently re-inforces their contention that 'missing links' are everywhere. Its of course impossible to demonstrate macroevolution occurring in real time at higher taxa...

What's your point?
Ants sometimes drink plant sap?

This leaf is fairly bare but the similar one that must be somewhat related, (maybe have a foot shorter height but with a fuzzy underside and generally similar leaf shape and branching scheme), in its fuzzyness had little cellulose projections that I guess kept these ants from eating the other plant. I have no idea how the sap differed. They both were somewhat sweet to human taste.It seemed to me to be a case of 'host plant fidelity' as you said. I could imagine that there might be a restriction of gene flow going on at in those two populations. I meant it as a possibly more visible example of what you posted. It is somewhat rare to actually discover something new.I once found a larval insect with shit on its back and took it to Tom Eisner
Page not found | Department of Neurobiology and Behavior
who simply walked to his file cabinet and pulled out a reprint where he had published on it.I do not know the speices of ant or plant but if ID'D one might be able to proceed with a similar discussion along with the one you mentioned. What was SO VERY STRIKING was that (as) the ants "marched" up the stems of these plants (this leaf was not the only plant they were feeding from/on) they only made holes in the three veins (AND EVERY LEAF THAT HAD A HOLE had these three positioned holes). It was a small sample (This message has been edited by Brad McFall, 04-19-2005 06:55 AM

That looks a lot like a grape leaf.
The "cellulose projections" you describe sound a lot like domatia,
that grape leaves are known to have.
They actually serve as refuges that protect predatory mites on the plant.
Payoff for the plant is they eat the plant-feeding mites.Here is an abstract describing the significance of domatia for plants.http://www.amjbot.org/cgi/content/abstract/85/1/70Now, as for the ants, most are very generalist, opportunistic feeders. They will puncture plant veins and drink sap for the sugar content. Matter of fact, so do many other, normally predatory insects. However, speciation mediated by host plant fidelity only works for specialized plant feeders with very narrow host ranges. Your ants may keep returning to the same plant where they have opened some feeding sites, but that is just becuase they are following a chemical trail laid down by the original foragers that cut the holes, not because adjacent plants wouldn't necessarily be suitable for feeding in the same way. Also, since ants are eusocial insects all those foraging workers are sterile - speciation via host plant fidelity is a mechanism whereby reproductive insects encounter mates that orient specifically to the same species of plant.Hope you find this informative.PS: How do you paste a picture into a post like that?
My computer wouldn't let me.
Wanted to post a picture of a ladybeetle drinking from a plant.This message has been edited by EZscience, 04-19-2005 07:47 AM

See dBCodes Help page.

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--	Percy
	EvC Forum Director

thanks for the reference!Another "poof! here is another species" article i came across recently is given below. Imagine, 200 species of guppy in a single (muddy) lake!Title:The effect of selection on a long wavelength-sensitive (LWS) opsin gene of Lake Victoria cichlid fishes
Author(s):Terai Y, Mayer WE, Klein J, Tichy H, Okada N
Source:PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 99 (24): 15501-15506 NOV 26 2002
Document Type:Article
Language:English
Cited References: 30 Times Cited: 11
Abstract:In East African Lake Victoria >200 endemic species of haplochromine fishes have been described on the basis of morphological and behavioral differences. Yet molecular analysis has failed to reveal any species-specific differences among these fishes in either mitochondrial or nuclear genes. Although the genes could be shown to vary, the variations represent trans-species polymorphisms not yet assorted along species lines. Nevertheless, fixed genetic differences must exist between the species at loci responsible for the adaptive characters distinguishing the various forms from one another. Here we describe variation and fixation at the long wavelength-sensitive (LWS) opsin locus, which is selection-driven, adaptive, and if not species- then at least population-specific. Because color is one of the characters distinguishing species of haplochromine fishes and color perception plays an important part in food acquisition and mate choice, we suggest that the observed variation and fixation at the LWS opsin locus may have been involved in the process that has led to the spectacular species divergence of haplochromine fishes in Lake Victoria.

Yes, but unfortunately visually-based species recognition is being threatened by human activity causing eutrophication in the lake.see:
Just a moment..."Cichlid Fish Diversity Threatened by Eutrophication That Curbs Sexual SelectionOle Seehausen, * Jacques J. M. van Alphen, Frans WitteCichlid fish species of Lake Victoria can interbreed without loss of fertility but are sexually isolated by mate choice. Mate choice is determined on the basis of coloration, and strong assortative mating can quickly lead to sexual isolation of color morphs. Dull fish coloration, few color morphs, and low species diversity are found in areas that have become turbid as a result of recent eutrophication. By constraining color vision, turbidity interferes with mate choice, relaxes sexual selection, and blocks the mechanism of reproductive isolation. In this way, human activities that increase turbidity destroy both the mechanism of diversification and that which maintains diversity. "This really ties in to another thread we have going under 'sexual selection'. In this case, sexual selection is essential to the maintenance of species identity.

What you're talking about is micro-evolution, the only testable, observable, and proven aspect of evolution (also known as a variation). When fish, or insects inter-breed it may form a new species but it's still a fish, it's still an insect, it's still the same kind of animal. Science is observable and testable. Macro-evolution is not.

Let's make sure we are talking about the same thing.
Here I simply use macroevolution to refer to the process of speciation.
We can definitely observe that happening in some cases.
And thatis not equivalent to microevolution or 'intra-specific variation'. Also, you talk about hybridization as a path to new species, but it probably isn't an important mechanism in nature.
Factors leading to reproductive isolation of sub-populations in space
and time are.If you are talking about macroevolution in terms of the divergence of higher level taxa over evolutionary time, then I agree that is not something we can directly observe or test with extant life. We can directly view the process of speciation, but nothing beyond.However, different 'taxonomic distance' estimates can be inferred indirectly w/r/t the degree of relatedness of high level taxa and the degree to which they converge on a single 'tree' can give us some degree of confidence in that tree. Genetic markers and sequences are especially valuable in this regard and can generate very plausible phylogenetic trees for higher level taxa. Are they testable? Only to the extent that they can are subsequently supported or refuted by other independent lines of inference.So with respect to macro-evolution of higher taxa, there is perhaps no definitive testability at this time. But we sure have the tools to accumulate a lot of independent lines of evidence that, in many case, converge on a 'most likely' phylogeny for particular groups. It's the best existing procedure for approximating actual cladistic relationships.I know that many creationists would like to 'retreat' to a defense of creation acting only at higher level taxa, but that is still a cop-out. Molecular biology is rapidly quantifying degrees of relatedness among families and orders. At the level of primary biological enzymes, for example, even we humans we don't look that much different from some bacteria.

quote:

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When fish, or insects inter-breed it may form a new species but it's still a fish, it's still an insect, it's still the same kind of animal.

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So are humans and chimpanzees both "primate kinds of animals?"By conatrast, are my housecats and a Siberian tiger the same "cat kind of animal?"Certainly, humans and chimpanzees are much closer genetically than domestic housecats and Siberian tigers, right?So, what system should I use to know if something is the same "kind" or not? What criterion should I use?This message has been edited by schrafinator, 05-02-2005 06:21 PM