I’ve seen a number of post that can be paraphrased as:
These posts seem to ignore the observed instances of one species evolving into another.
There may be rebuttals to these observed instances.
If you have beliefs similar to what I’ve paraphrased above, please share your thoughts.
Perhas it would help if you gave an example of an ‘observed instance of one species evolving into another.’ I have to admit I can’t think of any.
While I know of examples of microbes producing novel enzymes (digesting nylon for example), I’ve never heard anyone suggest that this amounts to a species level distinction.
I also know of a cases of fruit fly being bred so that they are no longer phyically capable of breeding. Again I’ve never hard that any taxonomist has proposed that one of these strains be re-classified as a new species.
I know that there is an overwhelming amount of fossil evidence to suggest species-species transition, but this doesn’t amount to an ‘observed instance of one species evolving into another’ either.
I’m no creationist, but I have to admit serious skepticism about your claim that there has been even one incidence where a species has ben observed to change sufficiently to warrant official taxonomic re-clasification as a novel species.
If evolutionary change and mutation were not immediately apparent and observable, The medical community wouldn’t be up in arms about misuse of antibiotics. Speciation is a bit trickier. Evolution is generally accepted as Darwinian survival of the fittest and left at that. Change supposedly occurs over a lengthy period of time in a linear fashion. There are other theories gaining acceptance that question if this is the, or the only, process at work. The one that comes to mind is “Punctuated Equilibrium.” It is hard to hang out on the water’s edge for a millenia with half a lung and half a gill. Punctuated Equilibrium implies a long plateau of no change followed by a metamorphesis like a tadpole changing into a frog. That’s a bit simplified, but it is fairly widely accepted now and explains the difficulty in catching that big change as it happens. Oh, but there is still a world of genetic evidence to trace the evolutionary tree.
There’s certainly scads of evidence for evolution.
But can you think of an example where a new species has been observed to change to such a degree as to be classified as distinct from an ofiically described ancestral population?
I can’t.
Interesting.
Hardly compeling though. The examples of actual taxonomic speciation seem to be all chromosomal ‘abnormalities’ and/or hybrids which, although evolution in the broadest sense, probbaly won’t convince a skeptic. Re-arrangement of existing material to produce something that’s incompletely fertile with its ancestors is hardly likely to be viewed as the source of all diversity.
I realise this isn’t your point, but you can see it coming can’t you.
Traditional clinal speciation can be demonstrated by the existence of “Ring Species” ( which are pretty uncommon, but still a decent example ). One writeup, discussing Ensatina salamanders ( an okay example ) and Greenish Warblers ( a slightly better one ):
http://www.actionbioscience.org/evolution/irwin.html
Some related ponderings…
The root of the problem in the OP is “observed” and the implication that we’re limited to recorded human history…even more, we’re limited to human history with an appreciation for scientific detail…even more, we’re limited in that we haven’t even finished cataloging the species that exist, let alone have anything more than a toddling idea of what to look for in the species with the here and know that would indicate speciation in the act.
Also, since humans have wandered around and laid claim to the globe, we have also done a great deal to homoginize, introduce non-native species, and just pretty much act in reverse of all of the selective pressures that had contributed to speciation before we started doing things like drive around with pampas grass tied to our car antanae.
Just things to consider when you are looking for such evidence.
No one’s ever directly observed an atom. Is there any doubt that they exist.
Punctuated Equilibirum is not a theory about process. It still relies on natural selection. It is a theory about pacing: speciation occurs via cladogenesis (branching lineages), rather than anagenesis (transforming lineages). Cladogenic speciation is more rapid (geologically speaking) than anagenesis, thus partially accounting for the spottiness of the fossil record.
In reference to the OP, I would simply state that direct observation is unnecessary. Evolution, like astronomy or geology, is a historical science. History, for the most part, is inferred from results. No one currently living was around when the ancient Egyptians were building pyramids, but that certainly doesn’t mean we cannot deduce a great deal of information about the people who built those pyramids. Similarly, we may not catch speciation “in the act”, but that is a poor reason to rule out that it can occur (in theory), or that it has occurred (in fact).
Technically, speciation is just a set of criteria that we use to catalog biological life forms. The rules are completely and arbitrarily assigned by us.
So I guess you are asking if we have evidence of the rules that we invented applying to a history we didn’t invent?
Whether we classify a progressive change in an organism as a species or not, you surely don’t deny that organisms don’t change… I mean look at how short your grandparents are.
> No one’s ever directly observed an atom. Is there any doubt that they exist.
Actually, they have.
> Whether we classify a progressive change in an organism as a
> species or not, you surely don’t deny that organisms don’t
> change… I mean look at how short your grandparents are.
That’s not a result of genetics, that’s about nutrition and surroundings (i.e. the environment).
Wasn’t there an example of one species of owl being introduced to the east coast and west coast of the USA about 50 years apart? When they met in the center, they were unable to reproduce.
I believe that Klingons have the ability to evolve very quickly…
Otherwise, what is the difference between “evolution” and “genetic mutation”?
Evolution in a given population does not require mutations to proceed: it requires only genetic diversity/variation (though in the long run, mutation is what increases and replenishes variation).
Well, according to our good buddy Jack Chick, since no one’s ever seen a gluon, they don’t exist, and therefore Jesus holds atomic nuclei together.
What, all off them? He must be busy.
According to Milum, he understands evolution better than most of us on this board.
I really, really hope that he will participate.
No. You must be misremembering something.
I can’t wait to be enlightened!