Fenología reproductiva y efecto del robo de néctar en el éxito reproductivo de Guettarda clarensis, en Santa Clara, Villa Clara, Cuba
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Fecha
2013-07-06
Autores
Martínez Pérez, Llilian
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Editor
Universidad Central ¨Marta Abreu¨ de Las Villas
Resumen
El robo de néctar ocurre cuando algunos visitantes florales, no pueden acceder al
néctar legítimamente y perforan la corola para obtenerlo. Puede tener efectos
positivos, negativos o neutros con implicaciones ecológicas y evolutivas para las especies que lo sufren. Guettarda clarensis Britt. (Rubiaceae) es una especie endémica de las serpentinitas de la antigua provincia de Las Villas, en la que se han
detectado evidencias de robo de néctar. Si el robo de néctar afectara la evolución de determinados caracteres florales, la producción de néctar y la ecología de la
polinización de dicha especie, podría influir en su éxito reproductivo y, por tanto, en su conservación. Como objetivo principal nos propusimos caracterizar la fenología reproductiva y el efecto del robo de néctar en el éxito reproductivo de la especie. Para ello se calcularon parámetros fenológicos como sincronía y duración de la floración, a partir de censos semanales a 74 plantas; se realizaron mediciones morfométricas a flores de dos poblaciones y se evaluó la producción de néctar en distintos horarios del día. También se caracterizó el sistema reproductivo mediante
seis tratamientos de polinización, se realizaron observaciones de visitantes florales y se evaluó comparativamente la producción de frutos a partir de flores con y sin evidencias de robo. Se determinó un alto índice de sincronía floral, lo que pudiera aumentar la atracción de los robadores por las flores. Además, existen diferencias en
cuanto a diámetro, apertura y longitud de corola, entre flores con y sin robo de néctar, lo que corrobora resultados anteriores de selección de corolas grandes por parte de los robadores. Las producciones de néctar fueron bajas, y frecuentes entre el momento de la antesis floral y las 0730 h, lo que ratifica a los polinizadores nocturnos para esta especie. El sistema reproductivo de la misma resultó ser autoincompatible, como se manifiesta en otras especies heterostilas. Se concluyó que: durante la corta floración de G. clarensis, los robadores seleccionan corolas más
largas, anchas y de mayor recompensa, e influyen negativamente en la fructificación, por lo que podrían afectar la evolución de los caracteres florales de la especie.
Nectar robbing occurs when some floral visitors, unable to access the nectar legitimately, perforate the corolla to obtain it. It can have positive, negative or neutral effects with ecological and evolutionary implications for the species that suffer it. Guettarda clarensis Britt. (Rubiaceae) is an endemic species of the serpentine of the ancient province of Las Villas, in which nectar robbing has been detected. If this phenomenon could affect the evolution of determined floral characters, the production of nectar and the ecology of the pollination of said species, it could influence its reproductive success and, therefore, its conservation. Like main objective we intended to characterize the reproductive phenology and the effect of nectar robbing in the reproductive success of the species. For it, phenological parameters such as synchrony and duration of flowering were calculated from weekly censuses to 74 plants; morphometric measurements to flowers from two populations were carried out and the production of nectar at different hours of the day was evaluated. Also, the reproductive system was characterized through six pollination treatments, observations of floral visitors were carried out and the production of fruits from flowers with and without evidences of robbing was evaluated. It was found a high index of floral synchrony, what could mean an increase of the attraction of the robbers for the flowers. There were differences in diameter, opening and length of corolla, between flowers with and without nectar robbing. That corroborates previous results, from other authors, of selection of big corollas by robbers. The nectar productions were low, and frequent between the moment of floral anthesis and 0730 h; that ratifies nighttime pollinators for this species. Its reproductive system turned out to be selfincompatible, as it is shown at other heterostylous species. It was concluded that: during the short flowering of G clarensis, nectar robbers select longer, broad and bigger-reward corollas, and influence negatively the fructification, which is why they could affect the evolution of the floral characters of the species.
Nectar robbing occurs when some floral visitors, unable to access the nectar legitimately, perforate the corolla to obtain it. It can have positive, negative or neutral effects with ecological and evolutionary implications for the species that suffer it. Guettarda clarensis Britt. (Rubiaceae) is an endemic species of the serpentine of the ancient province of Las Villas, in which nectar robbing has been detected. If this phenomenon could affect the evolution of determined floral characters, the production of nectar and the ecology of the pollination of said species, it could influence its reproductive success and, therefore, its conservation. Like main objective we intended to characterize the reproductive phenology and the effect of nectar robbing in the reproductive success of the species. For it, phenological parameters such as synchrony and duration of flowering were calculated from weekly censuses to 74 plants; morphometric measurements to flowers from two populations were carried out and the production of nectar at different hours of the day was evaluated. Also, the reproductive system was characterized through six pollination treatments, observations of floral visitors were carried out and the production of fruits from flowers with and without evidences of robbing was evaluated. It was found a high index of floral synchrony, what could mean an increase of the attraction of the robbers for the flowers. There were differences in diameter, opening and length of corolla, between flowers with and without nectar robbing. That corroborates previous results, from other authors, of selection of big corollas by robbers. The nectar productions were low, and frequent between the moment of floral anthesis and 0730 h; that ratifies nighttime pollinators for this species. Its reproductive system turned out to be selfincompatible, as it is shown at other heterostylous species. It was concluded that: during the short flowering of G clarensis, nectar robbers select longer, broad and bigger-reward corollas, and influence negatively the fructification, which is why they could affect the evolution of the floral characters of the species.
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Palabras clave
Fenología, Néctar, Guettarda clarensis, Santa Clara