Specialization and speciation
15-04-2008 16:41
The title refers to an interesting recently
commentary in the Journal of Biogeography*, where
Michael Patten argues that speciation and
specialization are the same phenomenon. I'm not going
to repeat his arguments here, but some of his
conclusions are mind-provocative.
The first is that a simple geographic barrier becomes inadequate to 'explain' divergence between populations. If subtle differences in climate lead to subtle difference in vegetation, which in turn leads to different behaviour. In most cases one have to think in geological timescales to imagine how these subtle differences lead to larger differences and effective speciation comes into play.
I always wonder how these general theories work out in malacology. Just an example that puzzles me, possibly speciation still at work.
Imagine you see the shells above. The only thing you know is that they all occur in the same region, more or less at the same altitude, but at two sides of a river. I have plotted the (approximate) localities (taken from labels and collected some 40 years ago) on this map:
Now the question is, what would you call it? One species? Four subspecies? Two subspecies? I'm inclined to say the latter, but this case clearly needs further investigation. It would be nice to study these populations genetically to see to what extent the morphological differences can be explained. The only problem is: these animals occur high up in the Andes, Río Rimac valley, 3300-3400m. Any volunteers for collecting?
Reference:
Patten, M. A. (2008). The intersection of specialization and speciation. J. Biogeogr, 35, 193-194.
The first is that a simple geographic barrier becomes inadequate to 'explain' divergence between populations. If subtle differences in climate lead to subtle difference in vegetation, which in turn leads to different behaviour. In most cases one have to think in geological timescales to imagine how these subtle differences lead to larger differences and effective speciation comes into play.
I always wonder how these general theories work out in malacology. Just an example that puzzles me, possibly speciation still at work.
Imagine you see the shells above. The only thing you know is that they all occur in the same region, more or less at the same altitude, but at two sides of a river. I have plotted the (approximate) localities (taken from labels and collected some 40 years ago) on this map:
Now the question is, what would you call it? One species? Four subspecies? Two subspecies? I'm inclined to say the latter, but this case clearly needs further investigation. It would be nice to study these populations genetically to see to what extent the morphological differences can be explained. The only problem is: these animals occur high up in the Andes, Río Rimac valley, 3300-3400m. Any volunteers for collecting?
Reference:
Patten, M. A. (2008). The intersection of specialization and speciation. J. Biogeogr, 35, 193-194.