title: Latitudinal gradients in biotic niche breadth vary across ecosystem types.
abstract: Several properties of food webs-the networks of feeding links between species-are known to vary systematically with the species richness of the underlying community. Under the 'latitude-niche breadth hypothesis', which predicts that species in the tropics will tend to evolve narrower niches, one might expect that these scaling relationships could also be affected by latitude. To test this hypothesis, we analysed the scaling relationships between species richness and average generality, vulnerability and links per species across a set of 196 empirical food webs. In estuarine, marine and terrestrial food webs there was no effect of latitude on any scaling relationship, suggesting constant niche breadth in these habitats. In freshwater communities, on the other hand, there were strong effects of latitude on scaling relationships, supporting the latitude-niche breadth hypothesis. These contrasting findings indicate that it may be more important to account for habitat than latitude when exploring gradients in food-web structure.
authors.affiliation: Centre for Integrative Ecology, School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand Department of Biology, Life Science Centre, Dalhousie University, 1355 Oxford St., PO BOX 15000, Halifax, Nova Scotia, Canada B3H 4R2 alyssa.cirtwill@gmail.com.
authors.forename: Alyssa R
authors.initials: AR
authors.lastname: Cirtwill
authors.affiliation: Centre for Integrative Ecology, School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand.
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Stouffer
authors.affiliation: Department of Biology, Life Science Centre, Dalhousie University, 1355 Oxford St., PO BOX 15000, Halifax, Nova Scotia, Canada B3H 4R2.
authors.forename: Tamara N
authors.initials: TN
authors.lastname: Romanuk
mesh_terms: D059001:Aquatic Organisms / Q000502:physiology*; D044822:Biodiversity; D017753:Ecosystem; D020387:Food Chain
keywords: food webs; generality; link density; scaling; trophic level; vulnerability