Macronutrient niches and field limitation in a woodland assemblage of harvestmen

1. Description of animals’ trophic niches help us understand interactions between species in biological communities that are not easily observed. Analyses of macronutrient niches, i.e. the range of macronutrient (protein:lipid:carbohydrate) ratios selected by generalist feeders, may be a useful alternative approach to inter-species comparisons of diets, especially within taxonomic assemblages of predators where species with similar nutritional requirements are likely to accept similar types of prey.

2. Here we analysed the macronutritional niches of a woodland assemblage of seven harvestman species, all supposed to be predators with omnivorous tendencies. Five species (Mitopus morio, Leiobunum gracile, Oligolophus tridens, O. hanseni, Paroligolophus agrestis) were native and two species (Opilio canestrinii, Dicranopalpus ramosus) were recent invaders into the community.

3. We compare the fundamental (FMN) and realized (RMN) macronutritional niche positions of the species using a ‘...