RESUMEN
Premise: Imaging technologies that capture three-dimensional (3D) variation in floral morphology at micro- and nano-resolutions are increasingly accessible. In herkogamous flowers, such as those of Theobroma cacao, structural barriers between anthers and stigmas represent bottlenecks that restrict pollinator size and access to reproductive organs. To study the unresolved pollination biology of cacao, we present a novel application of micro-computed tomography (micro-CT) using floral dimensions to quantify pollinator functional size limits. Methods: We generated micro-CT data sets from field-collected flowers and museum specimens of potential pollinators. To compare floral variation, we used 3D Slicer to place landmarks on the surface models and performed a geometric morphometric (GMM) analysis using geomorph R. We identified the petal side door (an opening between the petal hoods and filament) as the main bottleneck for pollinator access. We compared its mean dimensions with proposed pollinators to identify viable candidates. Results: We identified three levels of likelihood for putative pollinators based on the number of morphological (body) dimensions that fit through the petal side door. We also found floral reward microstructures whose presence and location were previously unclear. Discussion: Using micro-CT and GMM to study the 3D pollination biology of cacao provides new evidence for predicting unknown pollinators. Incorporating geometry and floral rewards will strengthen plant-pollinator trait matching models for cacao and other species.
RESUMEN
Borrelia burgdorferi sensu lato (Bbsl) is a bacterial species complex that includes the etiological agents of the most frequently reported vector-borne disease in the Northern hemisphere, Lyme borreliosis. It currently comprises > 20 named and proposed genospecies that use vertebrate hosts and tick vectors for transmission in the Americas and Eurasia. Host (and vector) associations influence geographic distribution and speciation in Bbsl, which is of particular relevance to human health. To target gaps in knowledge for future efforts to understand broad patterns of the Bbsl-tick-host system and how they relate to human health, the present review aims to give a comprehensive summary of the literature on host association in Bbsl. Of 465 papers consulted (404 after exclusion criteria were applied), 96 sought to experimentally establish reservoir competence of 143 vertebrate host species for Bbsl. We recognize xenodiagnosis as the strongest method used, however it is infrequent (20% of studies) probably due to difficulties in maintaining tick vectors and/or wild host species in the lab. Some well-established associations were not experimentally confirmed according to our definition (ex: Borrelia garinii, Ixodes uriae and sea birds). We conclude that our current knowledge on host association in Bbsl is mostly derived from a subset of host, vector and bacterial species involved, providing an incomplete knowledge of the physiology, ecology and evolutionary history of these interactions. More studies are needed on all host, vector and bacterial species globally involved with a focus on non-rodent hosts and Asian Bbsl complex species, especially with experimental research that uses xenodiagnosis and genomics to analyze existing host associations in different ecosystems.
