1. INTRODUCTION
Ecology and biogeography are two fields with many obvious connections, but the relationship between them has often been troubled [1]. On the one hand, those studying large-scale historical (i.e. phylogenetic) biogeography have tended to ignore ecology entirely, with little or no consideration of the idea that distri- butions of organisms are influenced by factors such as habitat tolerances or species interactions. This is well- illustrated in the excellent and integrative textbook by Lomolino et al.[2],inwhichecologygoeslargely unmentioned in the chapter on historical biogeography. On the other hand, ecologists have often tended to ignore biogeography (but with some important excep- tions; [3,4]). For example, ecologists often do not study how large-scale biogeographic history influences the patterns of diversity and community structure that they study, nor how ecological processes create biogeo- graphic patterns (review in [1]). One place where these two fields should come together (but often fail to) is in the concept of the niche. Based on Hutchinson’s [5] general concept, the niche describes the set of abiotic and biotic conditions where a species can persist [6]. Many ecologists favour a concept of the niche based on resources and species interactions at the local scale (i.e. an Eltonian niche concept; [7]). On the other hand, more biogeo- graphically oriented ecologists often prefer a concept
focusing on the environmental conditions determining the large-scale distribution of species (i.e. a Grinnellian niche concept; [7]). I consider these to represent equally validconceptualizationsofdifferentaspectsofthegeneral Hutchinsonian niche concept [6], and they clearly have many important intersections (e.g. local-scale biotic interactions may set range limits). In this paper, I will review what the niche can tell us about biogeography and what biogeography can tell us about the niche. I have previously written about the gulf between biogeography and ecology [1] and how the niche and biogeography may be related [8]. Those papers focusedlargelyon climatic niches, with relatively little emphasis on the potential role of biotic factors and species interactions in creating biogeographic patterns. Here, I will first focus on the importance of the niche to biogeographic patterns, and the factors that set the range limits of species and clades