RESUMEN

Divergent patterns of phenotypic selection on floral traits can arise in response to interactions with functionally distinct pollinators. However, there are a limited number of studies that relate patterns of phenotypic selection on floral traits to variation in local pollinator assemblages in pollination-generalized plant species. We studied phenotypic selection on floral traits of Viscaria vulgaris, a plant that interacts with a broad range of diurnal and nocturnal pollinators, and related divergence in phenotypic selection on floral traits to the expected level of divergence in local pollinator assemblages. We detected phenotypic selection on floral traits involved in the attraction of pollinators and the mechanics of pollen removal and deposition, and demonstrated that floral traits are subject to spatiotemporal variation in the strength and direction of phenotypic selection. We revealed that diurnal and nocturnal pollinators, when considered in isolation, mediated divergent patterns of phenotypic selection on floral traits. Consistent with the Grant-Stebbins model, we observed that divergence in phenotypic selection on floral traits increased with the expected level of divergence in local pollinator assemblages. Thus, generalized plant-pollinator interactions can mediate phenotypic selection on floral traits and distinct local pollinator assemblages can generate a geographic mosaic of divergent patterns of phenotypic selection. We underscore that these outcomes are not exclusive to specialized plant-pollinator interactions and can emerge at a local geographic scale.

RESUMEN

Resolving the consequences of pollinator foraging behaviour for plant mating systems is a fundamental challenge in evolutionary ecology. Pollinators may adopt particular foraging tactics: complete trapline foraging (repeated movements along a fixed route), sample-and-shift trapline foraging (a variable route that incorporates information from previous experiences) and territorial foraging (stochastic movements within a restricted area). Studies that integrate these pollinator foraging tactics with plant mating systems are generally lacking. We investigate the consequences of particular pollinator foraging tactics for Heliconia tortuosa. We combine parentage and sibship inference analysis with simulation modelling to: estimate mating system parameters; infer the foraging tactic adopted by the pollinators; and quantify the impact of pollinator foraging tactics on mating system parameters. We found high outcrossing rates, ubiquitous multiple paternity and a pronounced departure from near-neighbour mating. We also found that plants repeatedly receive pollen from a series of particular donors. We infer that the pollinators primarily adopt complete trapline foraging and occasionally engage in sample-and-shift trapline foraging. This enhances multiple paternity without a substantial increase in near-neighbour mating. The particular pollinator foraging tactics have divergent consequences for multiple paternity and near-neighbour mating. Thus, pollinator foraging behaviour is an important driver of the ecology and evolution of plant mating systems.

Asunto(s)

RESUMEN

Animal-mediated pollination is essential for the maintenance of plant reproduction, especially in tropical ecosystems, where pollination networks have been thought to have highly generalized structures. However, accumulating evidence suggests that not all floral visitors provide equally effective pollination services, potentially reducing the number of realized pollinators and increasing the cryptic specialization of pollination networks. Thus, there is a need to understand how different functional groups of pollinators influence pollination success. Here, we examined whether patterns of contemporary pollen-mediated gene flow in Heliconia tortuosa are consistent with the foraging strategy of its territorial or traplining hummingbird pollinators. Territorial hummingbirds defend clumps of flowers and are expected to transfer pollen locally. In contrast, traplining hummingbirds forage across longer distances, thereby increasing pollen flow among forest fragments, and are thought to repeatedly visit particular plants. If trapliners indeed visit the same plants repeatedly along their regular routes, this could lead to a situation where neighboring plants sample genetically distinct pollen pools. To test this hypothesis, we genotyped 720 seeds and 71 mother plants from 18 forest fragments at 11 microsatellite loci. We performed TwoGener analysis to test pollen pool differentiation within sites (among neighboring plants within the same forest fragment: Φ SC ) and between sites (among forest fragments: Φ CT ). We found strong, statistically significant pollen pool differentiation among neighboring mother plants (Φ SC = 0.0506), and weaker, statistically significant differentiation among sites (Φ CT = 0.0285). We interpret this pattern of hierarchical pollen pool differentiation as the landscape genetic signature of the foraging strategy of traplining hummingbirds, where repeatable, long-distance, and high-fidelity routes transfer pollen among particular plants. Although H. tortuosa is also visited by territorial hummingbirds, our results suggest that these pollinators do not contribute substantially to successful pollination, highlighting differences in realized pollination efficiency. This cryptic reduction in the number of realized pollinators potentially increases the vulnerability of pollination success to the decline of populations of traplining hummingbirds, which have been shown to be sensitive to forest fragmentation. We conclude that maintaining habitat connectivity to sustain the foraging routes of trapliners may be essential for the maintenance of pollen-mediated gene flow in human-modified landscapes.

RESUMEN

El tumor pseudopapilar del páncreas es una entidad muy poco frecuente que afecta preferentemente a mujeres jóvenes. Se trata de un carcinoma quístico con bajo potencial maligno que se diagnostica generalmente de forma incidental pues no hay signos ni síntomas patognomónicos de dicha enfermedad. La resección quirúrgica es curativa en la mayoría de los casos y el pronóstico es excelente aun si hay metástasis al momento del diagnóstico. Se presenta el caso de una paciente de sexo femenino de 21 años de edad, sin antecedentes personales de importancia, quien consultó por dolor abdominal agudo. Se realizó tomografía computarizada, la cual reportó una masa de 75 x 80 x 76 mm en la cola del páncreas, por lo que se llevó a cirugía realizándose pancreatrectomía distal con resección completa del tumor y preservación esplénica. El estudio de anatomía patológica reportó tumor pseudopapilar del páncreas. La paciente tuvo una evolución satisfactoria y hasta el seguimiento a los 16 meses persiste asintomática y no ha presentado recurrencia.

Pseudo papillary tumor of the pancreas is a rare entity most commonly seen in young females. This neoplasm it is a cystic carcinoma of low malignant potential usually diagnosed incidentally because an abscense of typical signs or symptoms. Surgical resection it is usually curative with excellent prognosis even when metastasis are present at the time of diagnosis. We report the case of a 21-year-old female who presented with abdominal pain with no previous history of any abdominal discomfort or pain. Computed tomography showed a 75 x 80 x 76 mm solid mass located at the tail of the pancreas. A distal pancreatectomy with preservation of the Spleen was performed. Pathology reported: pseudo papillary tumor of the pancreas. Evolution was satisfactory with no complication and the follow up at 16 months showed no recurrence. Histological examination confirmed the diagnosis and the complete resection of this tumor has an excellent prognosis with rare recurrences.

Asunto(s)