Dietary specialization mirrors Rapoport’s rule in European geometrid moths

Aim: Latitudinal clines in dietary specialisation and range size are used to explain biodiversity distributions at large spatial scale, such as the latitudinal diversity gradient. The aim of this study was to test whether diet breadth (as a dimension of niche breadth) and range size decrease towards lower latitudes in a species-rich clade of herbivorous insects as predicted by the latitude – niche breadth hypothesis and Rapoport’s rule, respectively. We further aimed at studying if these species characteristics are positively linked with each other as stated by the niche breadth – range size hypothesis.
Location: Europe (35°N – 71°N)
Time period: Present-day
Major Taxa: Geometrid moths (Lepidoptera, Geometridae)
Methods: For every species, we compiled information on latitudinal distribution and host-plant use based on available literature and online sources. We estimated each species’ level of fundamental dietary specialisation while accounting for phylogenetic relationships among util...