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Message: <blockquote data-quote="l_raty" data-source="post: 1151072" data-attributes="member: 24811">No rejection on my side - at least, not of the involved processes. (I'm not rejecting ring speciation either, yet this also cannot be handled correctly by taxonomy, and whether it represents speciation or not is also open to discussion.)One problem with sympatric speciation is that it has the potential to be local with respect to the mother species - it could happen within a subpart of this species only, and if there are other populations of the mother species elsewhere that remain untouched, their classification will unavoidably become problematic. (Creating, for example, situations in which we could be "forced" to elevate two subspecies to species level, just because of something that happened to a third one...) This is quite different from a global process that splits a whole species in two (or more) units, that will then make their way up the whole hierarchy of differentiation. But of course this doesn't make the process impossible - just difficult to represent in the taxonomic system.About the BSC and to take things from another angle: The ultimate test of speciation under the BSC is persistence in sympatry. But if the entire process of differentiation can happen in sympatry, then we cannot continue to assume that this is an unambiguous indication of a deep divergence. Instead, we must expect that among the organisms that persist in sympatry, some will be at a very early stage of differentiation - potentially less differentiated than allopatric taxa we would at best treat as subspecies; potentially not far enough in the process to make its irreversibility even remotely certain.For an example of a model of ecological sympatric speciation, you can see: <a href="http://www.iiasa.ac.at/~dieckman/reprints/DieckmannDoebeli1999.pdf" target="_blank">http://www.iiasa.ac.at/~dieckman/reprints/DieckmannDoebeli1999.pdf</a>The individuals in this model (and the resulting sympatric "species") differ only by a quantitative character, that must have a potential of heritable variation, and must determine and limit the part of the resources each individual will be able to use efficiently ("as for example when beak size in birds determines the size of seeds consumed"). The available resources must also present a range of variation broad enough that individuals using the opposite extremes will not be in competition anymore. Under these conditions, frequency-dependent competition is expected to induce an evolutionary branching - the expected outcome is two distinct morphs exploiting the opposite ends of the resources. The transition from one to two morphs can be fast if mating probabilities are directly linked to the ecological character (see Fig 3a). Nothing qualitatively "new" arises during this process - it's all just a game of allele frequencies; the potential of giving rise to a population similar to each of the morphs was already entirely present in the mother population.Of course it's only a model. But if this type of thing can happen, I would not really feel comfortable calling the two resulting morphs "species" at this point of their evolution. Even if they don't interbreed.--Best,Laurent -</blockquote>

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