chemosensation

Diversity in olfactory receptor repertoires is associated with dietary specialization in a genus of frugivorous bat

Mammalian olfactory receptors (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 repertoires 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 more specialized OR repertoires has never been tested. Using targeted sequence capture, we sequenced the OR repertoires of three sympatric species of short-tailed leaf-nosed bats (*Carollia*), which vary in their degree of specialization on the fruits of *Piper* plants. We characterized orthologous versus duplicated receptors among *Carollia* species, and identified orthologous receptors and associated paralogs to explore the diversity and redundancy of the receptor gene repertoire. The most dedicated *Piper* specialist, *Carollia castanea*, had lower OR diversity compared to the two more generalist species (*sowelli*, *perspicillata*), but we discovered a few unique sets of ORs within *C. castanea* with exceptional redundancy of similar gene duplicates. These unique receptors potentially enable *C. castanea* to detect *Piper* fruit odorants to an extent that the other species cannot. *C. perspicillata*, the species with the most generalist diet, had a larger diversity of functional receptors, suggesting the ability to detect a wider range of odorant molecules. The 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 plays a role in dietary adaptations and underlies patterns of ecological interactions between bats and plants.

Molecular adaptation and convergent evolution of frugivory in Old World and neotropical fruit bats

Although cases of independent adaptation to the same dietary niche have been documented in mammalian ecology, the molecular correlates of such shifts are seldom known. Here, we used genomewide analyses of molecular evolution to examine two lineages …

Evaluating the performance of targeted sequence capture, RNA-Seq, and degenerate-primer PCR cloning for sequencing the largest mammalian multigene family

Multigene families evolve from single‐copy ancestral genes via duplication, and typically encode proteins critical to key biological processes. Molecular analyses of these gene families require high‐confidence sequences, but the high sequence …

Expressed vomeronasal type-1 receptors (V1rs) in bats uncover conserved sequences underlying social chemical signaling

In mammals, social and reproductive behaviors are mediated by chemical cues encoded by hyperdiverse families of receptors expressed in the vomeronasal organ. Between species, the number of intact receptors can vary by orders of magnitude. However, …

Vomeronasal and olfactory structures in bats revealed by diceCT clarify genetic evidence of function

The degree to which molecular and morphological loss of function occurs synchronously during the vestigialization of traits is not well understood. The mammalian vomeronasal system, a sense critical for mediating many social and reproductive …

Strength of selection on the Trpc2 gene predicts accessory olfactory bulb form in bat vomeronasal evolution

Vestigial characters are common across the tree of life, but the underlying evolutionary processes shaping phenotypic loss are poorly understood. The mammalian vomeronasal system, which detects social chemical cues important to fitness, is an …

The Molecular Evolution of Bat Chemosensory Pathways Reveals Sensory Innovation and Loss

Chemosensation detects environmental chemical cues and mediates many behaviors directly related to fitness (e.g. finding food, mates). Mammals have a secondary chemosensory system known as vomerolfaction that is primarily attributed to detecting …

Trpc2 pseudogenization dynamics in bats reveal ancestral vomeronasal signaling, then pervasive loss

Comparative methods are often used to infer loss or gain of complex phenotypes, but few studies take advantage of genes tightly linked with complex traits to test for shifts in the strength of selection. In mammals, vomerolfaction detects chemical …

A Cluster of Olfactory Receptor Genes Linked to Frugivory in Bats

Diversity of the mammalian olfactory receptor (OR) repertoire has been globally reshaped by niche specialization. However, little is known about the variability of the OR repertoire at a shallower evolutionary timeframe. The vast bat radiation …