J. J. Wiens and C. H. Graham
“Niche conservatism is the tendency of species to retain ancestral ecological characteristics.” This means that close species should have close ecological traits. With rapid species radiation as with island endemics there is niche diversification rather than niche conservatism(1,6). Niche conservatism also fails where the ecological trait itself is labile or plastic (3). Niche conservatism shows that island radiation and invasive species have much the same structure(6). This directly connects conservation biology with a great deal of studies of species radiation and makes invasive species a special case of species radiation.
Niche conservatism can be thought of as a generator of allopatry (4). To me, based on what I’ve seen, allopatry is a necessary but not always sufficient condition for speciation. Non-vicarious allopatric events like niche conservation run at a time scale much faster than most speciation so there is allopatry followed by sympatry with some gene flow allowing for many other possibilities including another round of allopatry which can or cannot end in speciation. But I think that allopatry must come first.
Niche conservatism allows for a test for parapatric vs allopatric speciation (4). The problem with parapatric speciation is that there is no way to tell if a parapatric relationship didn’t have a past allopatric component. This will at least resolve the question of parapatry in many cases.
Niche conservation and philogenetic signal can be a measure of the plasticity of a trait. Philogenetic signal is a generalization of niche conservation for all traits, not just environmental. Close species should have close traits. Philogenetic signal is a measure of how traits match philogeny. So what is happening when there is no match? This shows up in species radiation (6), in island endemics (2), in invasive species (6) and in community structure (3). This has to be plasticity.
- Testing for phylogenetic signal in comparative data: behavioral traits are more labile, S. P. Blomberg, T Garland, Jr., and A. R. Ives
- Community Assembly Through Adaptive Radiation in Hawaiian Spiders, R. Gillespie, et al.
- Absence of phylogenetic signal in the niche structure of meadow plant communities, J. Silvertown, et al.
- Does Niche Conservatism Promote Speciation? A Case Study In North American Salamanders, K. H. Kozak and J. J. Wiens
- Speciation Aand Ecology Revisited: Phylogenetic Niche Conservatism And The Origin Of Species, J. J. Wiens
- Phylogenetic analysis of the evolution of the niche and of species associations in lizards of the Anolis sagrei group, J. H. Knouf et al.