A key debate in ecology centres on the relative importance of niche and neutral processes in determining patterns of community assembly with particular focus on whether ecologically similar species with similar functional traits are able to coexist. Meanwhile, molecular studies are increasingly revealing morphologically indistinguishable cryptic species with presumably similar ecological roles. Determining the geographic distribution of such cryptic species provides opportunities to contrast predictions of niche versus neutral models. Discovery of sympatric cryptic species increases alpha diversity and supports neutral models, while documentation of allopatric/parapatric cryptic species increases beta diversity and supports niche models. We tested these predictions using morphological and molecular data, coupled with environmental niche modelling analyses, of a fig wasp community along its 2700 km latitudinal range. Molecular methods increased previous species diversity estimates from eight to eleven species, revealing morphologically cryptic species in each of the four wasp genera studied. Congeneric species pairs that were differentiated by a key morphological functional trait (ovipositor length) coexisted sympatrically over large areas. In contrast, morphologically similar species, with similar ovipositor lengths, typically showed parapatric ranges with very little overlap. Despite parapatric ranges, environmental niche models of cryptic congeneric pairs indicate large regions of potential sympatry, suggesting that competitive processes are important in determining the distributions of ecologically similar species. Niche processes appear to structure this insect community and cryptic diversity may typically contribute mostly to beta rather than alpha diversity.

Euk_MorphMorphological measurements for ovipositor and tibia of Eukobelea fig wasps. Includes species assignment codesPhib_MorphMorphological measurements of ovipositor and tibia lengths for Philotrypesis ‘black’ wasps. Includes species assignment.Phiy_MorphMorphological measurements of ovipositor and tibia lengths for Philotrypesis ‘yellow wasps. Includes species assignment.SycLS_MorphMorphological measurements of ovipositor and tibia lengths for Sycoscapter ‘long’ and ‘short’ wasps. Includes assignments to either long or short ovipositor wasp groupings.SycSH_MorphMorphological measurements of ovipositor and tibia lengths for Sycoscapter ‘short’ wasps only. Includes species assignment designations.Wat_MorphMorphological measurements of ovipositor and tibia lengths for Watshamiella wasps. Includes species assignment designations.Table_LocationsGPS location data for all non-pollinating fig wasps in study.Eukobelea_cytbSequence data for cytochrome b for Eukobelea individuals.Eukobelea_ITS2Sequence data for ITS2 for Eukobelea individuals.Philotrypesis_cytbSequence data for cytochrome b for Philotrypesis individuals.Philotrypesis_ITS2Sycoscapter_cytbSequence data for cytochrome b for Sycoscapter individuals.Sycoscapter_ITS2Sequence data for ITS2 for Sycoscapter individuals.Watshamiella_cytbSequence data for cytochrome b for Watshamiella individuals.Watshamiella_ITS2Sequence data for ITS2 for Watshamiella individuals.