Would it be possible to recognize a transitional change at the time it was happening?

While it might be easy to recognize certain major physical changes, a lot of evolutionary changes are fairly subtle. For example, not only did brain size increase in some species (notably one we all know and love) but also the brain itself changed in both function and capabilities.I wonder if during the period of change, it would be likely that we would notice that a change was going on?

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Aslan is not a Tame Lion

Thread moved here from the Proposed New Topics forum. There was a message 2, by me, which was deleted before the move. The topic title has a mis-spelling, but I can't edit it. This comment is here to help us tune the approvals system; not as a spelling flame. Thanks for the topic![This message has been edited by AdminSylas, 05-01-2004]

Won't let me edit it either.To all. please excuse spelling errors. Anyway, anyone so limited as to be able to spell a word only one way is severely handicapped. fixed title for you Jar - The Queen[This message has been edited by AdminAsgara, 05-01-2004]

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Aslan is not a Tame Lion

The higher the taxon that we are looking for a transitional between the less likely it is going to happen "before our eyes". That is my conjecture anyway. And it is based on the current method of grouping species into higher taxa.Everything above species is just a grouping of species. I don't know enough about taxonomy to say that it is impossible for a change to happen quickly that would force the defintion of, say, a new family. I doubt it is all.When we have a lot of full genomes then we may be able to define genetic differences and use those to define the taxa with a hard quantitative value. If this is the case it maybe possible to see something above genus arise.I think we have seen genus arise. I just can't find a reference that isn't just a discovery of an existing one.

In one sense every individual is a transitional specimen, as they have mutations that differ from the rest of the population. These are the seeds of transition. For a transition event to occur there needs to be some selection pressure to differentiate a sub-group from the main group or acting on the whole species set to encourage change. Even if a species is divided into two groups geographically but in similar environments there will be genetic drift that will cause speciation. Certainly in such cases there need not be a visible difference. For instance, I wonder if the European House Sparrow and the Starling in N.America are still compatible with the original European stock after a physical separation of 150 years - don't know if that has been checked.Sexual selection of soft tissue aspects (facial, hair, rump colors, size of breasts and sexual organs, etcetera) would not fossilize so a fossil record is likely to miss many such transitional triggers. These would be fairly obvious to an observer however.I would say some you would and some you would not recognize at the time it was happening.

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we are limited in our ability to understand
by our ability to understand RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}

Do ring species count?In Great Britain there are two species of sea gull - the herring gull and the blackheaded gull. If you go west, to Greenland through North America, through Siberia and Northern Europe, you see a ring of different subsecies, where the Herring Gull can breed with the sub-species in Greenland, the Greenlander subspecies with the one in North America, and so forth, until you get to the one in Europe breeding with the Blackheaded Gull. But the Herring Gull and the Blackheaded Gull do not interbreed. If it weren't for the intervening subsepcies, we would consider the two gulls to be different species.There is also a group of salamander species in California that also show this.

Alas and alack, let there be wailing and gnashing of teeth and rending of garments, for it appears that The herring gull complex is not a ring species. This is pretty recent work and there may be more to the story, but there certainly is some reason to question whether the herring gull is indeed a ring species. Those evilutionists -- always changing their theories when new data comes in!

It's a little hard to tell from the abstract because it provides so little background, but he provides hints of a scientific debate on the issue of "isolation by distance" versus "long-distance-colonization events". Lacking clear definitions of these terms I can only comment that they seem that they'd have very similar outcomes, but he uses the difference to draw a distinction between the the ring species concept that he seems to feel uses the "isolation by distance" concept to conclude that because genetic studies indicate that the herring gull derives from two, not one, ancestral lineages, it therefore doesn't constitute a ring. But the abstract doesn't state how he concludes that the "ancestral lineages" were so distinct from one another as to comprise different starting lineages, since they were obviously closely related.These genetic studies usually contain sufficient ambiguity as to cause endless discussion and argument amonst geneticists. I suspect the authors might be using their discovery that the herring gull story is more complex than originally thought (isn't everything ) to make an attention getting conclusion.Whether or not the herring gull is a ring species, the concept and all examples of it, including partial rings, are very useful for illustrating evolution, because change normally distributed over time is instead distributed over space and is therefore contemporaneously visible.--Percy

You may be interested in Gulls not a ring species (a little discussioin on talk.origins) and Phylogeography and colonization history of Lesser Black-backed Gulls (Larus fuscus) as revealed by mtDNA sequences (a PDF, by some of the authors of the Royal Society paper).

Great question, jar.My opinion is that identifying living transitional species is an exercise in pure speculation. Beyond the rather trivial "every living organism is a transitional", that is. The only way you can say that a living species is a transitional is to know in advance what the species is transitioning to. We can readily see living populations changing, in the sense of diverging from the source population (at least in organisms where the populations have heterogenous distribution) both in morphology and behavior. Such change may ultimately derive the origination of a new species. However, this doesn't make them transitionals. Even organisms whose current adaptations are highly suggestive that they represent a transition from one major niche to another (for example, sugar gliders showing "transitional" adaptations from tree-dwelling climber to glider to powered flight), I would argue are not true transitionals as most of us understand the term. The short reason is that we can't say that they ARE transitioning to flight. They may be representative of an evolutionary dead end, or remain static as a species, or whatever. Only by examining the PAST changes leading up to modern species can we say that species B is transitional between extinct species A and modern species C. IOW, unless we're going to change the operational definition of transitional, all we can say is that species B exhibits traits characteristic of what we would expect to see if the species was transitional between A and C. We can't even (usually) say that B was in the direct line of descent between A and C (or for that matter, that A was the direct ancestor of either one). All we ever see is a snapshot in time - whether in the rocks or among living species.

Thanks, JonF. But even if they are not a true ring species (whatever the actual criteria are), they are still an example of speciation occurring right before our eyes, no? We have a complete set of geographic breeds, each of which can and do interbreed with the neighboring breeds, except for the pair that coexist in Britain.