Species interactions during diversification and community assembly in Malagasy Miniopterus bats

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The habitat first rule (HFR) proposes that radiating species initially diversify into habitat specialists and later into dietary specialists within a given habitat, whereas the general vertebrate model (GVM) adds divergence of sexually selected traits as a possible third axis of specialization subsequent to habitat and dietary divergence. In this study, using 12 Miniopterus spp. from Madagascar we test predictions of the HFR and GVM from ecological and evolutionary perspectives on Grinnellian and Eltonian niche structures. We used environmental niche models (ENMs) to quantify the Grinnellian niche, both for current and last inter-glacial climates. We used null models to examine Eltonian niche patterns of sympatric species in terms of their phylogenetic relatedness and phenotypic and sensory characters associated with the trophic niche—body size, skull morphology and echolocation. As predicted by the HFR, we found evidence for labile Grinnellian niches: there was no similarity in ENMs between sister species; overlap in ENMs was significantly low in >65 % of all possible species pairs; there was no relationship between ENM niche overlap and phylogenetic distances between species; and there was no phylogenetic signal in suitable bioclimatic zones among species. Conversely, we found equivocal support for the HFR regarding Eltonian niche patterns. Closely related species tended to be distributed among ensembles rather than within ensembles, although there was no evidence for overdispersion in phylogenetic patterns in ensembles. In <50 % of the observed combinations of sympatric Miniopterus spp., we found significant signal for overdispersion of phenotypic and sensory characters. We hypothesize that selective processes associated with the adaptive radiation of Miniopterus spp. on Madagascar may have favoured bats to diversify first into broad scale habitat specialists, but argue that understanding the relative influence of bionomic processes at a local spatial scale will require more reciprocal comparisons of Eltonian niches.