Coexisting ecotypes

Moore et al. in a 1998 issue of Nature talk about the co-occurrence of ecotypes, specifically, the coexistence of two, physiologically-distinct, bacterial ecotypes in the North Atlantic. This coexistence helps the population, on the whole, to persist over a wider range of light conditions than would otherwise be possible if the population was homogeneous.

Are there other examples of closely related ecotypes that exist together in a community, but are not necessarily specialists nor distinct species? Do figs qualify? According to Janzen (1970) the co-occurrence of closely related species makes little sense in the context of community disease resistance.

Is plasticity compromised for coexistence?

There is the example of two species of lizard from the genus Anolis (described in a 2003 Ecology article written by Cavender-Bares & Wilczek) that coexist on islands in the Lesser Antilles, but only when one species is large and the other small. The reasons for their coexistence differ from the northern to the southern islands. Lone island-inhabiting lizards, meanwhile, are of an intermediate size. Which lizard population, the lone or the coexisting, has a better chance of survival, all else being equal? Is the lone more phenotypically plastic? Or does the ability to coexist require or impart behavioral flexibility? Do the coexisting and closely related exchange useful information (more readily than the coexisting and distantly related)? Surely any information exchanged between the closely related and co-occurring will have greater ecological relevance than that exchanged between the distantly related and co-occurring.

If the principle of phylogenetic repulsion ensures that communities are made up of distantly related species which compete only to some tolerable extent, then what happens when the process is disrupted by anthropogenic activity? Deforestation in West Africa, for instance, is bringing guenon species into contact with one another and resulting in hybridization. Will these hybrids become more disease-prone or will they persist over a wider habitat range, including within agricultural ecotones? Are these hybrid guenons fluid ecotypes? Yes.