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Abstract Mammalian olfactory receptor genes (ORs) are a diverse family of genes encoding proteins that directly interact with environmental chemical cues. ORs evolve via gene duplication in a birth-death fashion, neofunctionalizing and pseudogenizing over time. Olfaction is a primary sense used for food detection in plant-visiting bats, but the relationship between dietary specialization and OR repertoire diversity is unclear. Within neotropical Leaf-nosed bats (Phyllostomidae), many lineages are plant specialists, and some have a distinct OR repertoire compared to insectivorous species. Yet, whether specialization on particular plant genera is associated with the evolution of specialized, less diverse OR repertoires has never been tested. Using targeted sequence capture, we sequenced the OR repertoires of three sympatric species of short-tailed fruit bats (Carollia), which vary in their degree of specialization on the fruits of Piper plants. We characterized orthologous vs duplicated receptors among Carollia species, and explored the diversity and redundancy of the receptor gene repertoire. At the species level, the most dedicated Piper specialist, Carollia castanea, had lower OR diversity compared to the two generalists (C. sowelli and C. perspicillata), but we discovered a few unique sets of ORs within C. castanea with high redundancy of similar gene duplicates. These unique receptors potentially enable C. castanea to detect Piper fruit odorants better than its two congeners. Carollia perspicillata, the species with the most generalist diet, had a higher diversity of intact receptors, suggesting the ability to detect a wider range of odorant molecules. Variation among ORs may be a factor in the coexistence of these sympatric species, facilitating the exploitation of different plant resources. Our study sheds light on how gene duplication and changes in OR diversity may play a role in dietary adaptations and underlie ecological interactions between bats and plants. 

Despite the widespread notion that animal-mediated seed dispersal led to the evolution of fruit traits that attract mutualistic frugivores, the dispersal syndrome hypothesis remains controversial, particularly for complex traits such as fruit scent. Here, we test this hypothesis in a community of mutualistic, ecologically important neotropical bats ( Carollia spp.) and plants ( Piper spp.) that communicate primarily via chemical signals. We found greater bat consumption is significantly associated with scent chemical diversity and presence of specific compounds, which fit multi-peak selective regime models in Piper . Through behavioural assays, we found Carollia prefer certain compounds, particularly 2-heptanol, which evolved as a unique feature of two Piper species highly consumed by these bats. Thus, we demonstrate that volatile compounds emitted by neotropical Piper fruits evolved in tandem with seed dispersal by scent-oriented Carollia bats. Specifically, fruit scent chemistry in some Piper species fits adaptive evolutionary scenarios consistent with a dispersal syndrome hypothesis. While other abiotic and biotic processes likely shaped the chemical composition of ripe fruit scent in Piper , our results provide some of the first evidence of the effect of bat frugivory on plant chemical diversity. 

Africa has undergone a progressive aridification during the last 20 My that presumably impacted organisms and fostered the evolution of life history adaptations. We test the hypothesis that shift to living in ant nests and feeding on ant brood by larvae of phyto‐predaceousLepidochrysopsbutterflies was an adaptive response to the aridification of Africa that facilitated the subsequent radiation of butterflies in this genus. Using anchored hybrid enrichment we constructed a time‐calibrated phylogeny forLepidochrysopsand its closest, non‐parasitic relatives in theEuchrysopssection (Poloyommatini). We estimated ancestral areas across the phylogeny with process‐based biogeographical models and diversification rates relying on time‐variable and clade‐heterogeneous birth‐death models. TheEuchrysopssection originated with the emerging Miombo woodlands about 22 million years ago (Mya) and spread to drier biomes as they became available in the late Miocene. The diversification of the non‐parasitic lineages decreased as aridification intensified around 10 Mya, culminating in diversity decline. In contrast, the diversification of the phyto‐predaceousLepidochrysopslineage proceeded rapidly from about 6.5 Mya when this unusual life history likely first evolved. The Miombo woodlands were the cradle for diversification of theEuchrysopssection, and our findings are consistent with the hypothesis that aridification during the Miocene selected for a phyto‐predaceous life history in species ofLepidochrysops, with ant nests likely providing caterpillars a safe refuge from fire and a source of food when vegetation was scarce.