Abstract
The term niche refers to the distribution of resources utilized by a species, for instance the distribution of seed sizes utilized by a seed eating bird. The niche is determined by some property of the species, like the beak size of the bird. Typically, two species cannot share the the same niche, because one of them will out-compete the other, but niches can be partly overlapping. A classical problem in theoretical ecology is how closely species can be "packed" into a resource space. The general issue is whether there is an upper bound on the number of species that can coexist by exploiting a given resource spectrum. The problem was originally studied, using mathematical models of community dynamics, by Robert MacArthur and Bob May in the late 1960's and early 1970's. I will describe that work, as well as more recent developments about the influence of the shape of competition kernels on species packing. I will suggest that waste and inefficiency in competition can play an important role in limiting the number of species that can coexist.
I will also describe recent work on the evolution of phenotypic clusters along an environmental cline. This work throws light on the analysis of clustering by Doebeli and Dieckmann (2003; Speciation along environmental gradients, Nature 421: 259-264), which was challenged by Polechova and Barton (2005; Speciation and competition: a critical review, Evolution 59: 1194-1210). I will make the point that there is a close theoretical relation, involving competition kernel shapes, between species packing and clustering along an environmental gradient.
Other information
The CEES seminar room has a coffee-machine – it is therefore recommended that you come a bit earlier and get yourself a good cup of coffee (for the price of 3 NOK).