Responses of a carnivorous plant to prey and inorganic nutrients in a Mediterranean environment

Abstract

We have analysed the eect of prey and fertilization by inorganic nutrients on the survival, growth, reproduction (sexual and vegetative) and mucilage secretion of Pinguicula vallisneriifolia (Lentibulariaceae), a carnivorous plant inhabiting rocky substrates of southern Spain. We tested the hypothesis that carnivorous plants are more prey dependent when root access to nutrients is strongly limited by (1) analysing the importance of the carnivorous habit to the ®tness of P. vallisneriifolia in its natural rocky habitat, and (2) determining whether the eect of trapped prey varies with soil nutrient levels. Our 2-year experimental results indicated prey to be limiting to P. vallisneriifolia growth on its natural rocky substrate. Animal food supply substantially increased the chance of survival, growth, vegetative propagation, sexual reproductive success and mucilage secretion. The dierences between prey levels were more evident at the end of the experiment when all the surviving Prey-exclusion plants had lost weight, and the probability of sexual reproduction and of vegetative propagation by axillary buds had accordingly diminished. Furthermore, there were clear bene®ts from carnivory at the population level, since both the expected individual life span and the lifetime vegetative and sexual output correlated positively with the quantity of prey trapped. Application of insects to non-fertilized plants stimulated growth, but similar application to fertilized plants grown on a complete nutrient solution failed to enhance growth. There was no obvious bene®t from the provision of a balanced mineral nutrient solution (alone or with prey). The greatest absolute growth and sexual and vegetative output resulted from providing a surplus of insects to plants on their natural rocky substrate. The strong dependence of P. vallisneriifolia on prey can therefore be considered a useful preadaptation enabling colonization of rocky substrates.

Nitrogen availability alters the expression of carnivory in the northern pitcher plant, Sarracenia purpurea

“…Other carnivorous plants also have been shown to vary their production of carnivorous structures in response to nutrient availability, including species in the globally widespread genera Utricularia (13)(14)(15) and Pinguicula (40,41). Carnivorous plants occur in nutrient-poor habitats on every continent except Antarctica (42); further research on the morphological responses of these unique plants to nutrients could lead to the development of inexpensive biological indicators for a broad spectrum of anthropogenic nutrients.…”

Importancia de la heterogeneidad ambiental en la ecología de plantas carnívoras mediterráneas: implicaciones para la conservación

“…A estas interacciones (herbivorismo, polinización), comunes con cualquier otra planta, una planta carnívora añade un plus adicional de diversidad, ya que se comporta como un depredador (sit-and-wait predator), atrapando a los insectos de pequeño tamaño que se posan en sus hojas (usualmente de menos de 5 mm de longitud en el caso de P. vallisneriifolia, Zamora 1995). Las secreciones glandulares permiten la digestión de la presa, y los nutrientes extraidos de la misma son fundamentales para el crecimiento y reproducción de la planta (Zamora et al 1997(Zamora et al , 1998. Esta interacción trófica puede ademas volverse mucho más barroca, ya que aparecen animales oportunistas cleptoparásitos (babosas y lagartijas fundamentalmente) que sacan partido de los restos animales atrapados en la hojas.…”

“…El hábito carnívoro de P. vallisneriifolia puede considerarse como una preadaptación provechosa al permitir la colonización y mantenimiento de poblaciones viables a lo largo del tiempo en las substratos rocosos, donde la captación de nutrientes via raices está muy limitada. Como resultado de vivir en estas condiciones extremas, P. vallisneriifolia parece haber desarrollado una mayor dependencia de las presas animales como fuente de nutrientes para su crecimiento y reproducción que otras especies del género Pinguicula que crecen en suelo (Zamora et al 1997). El carácter perenne de esta planta le permite ralentizar la extinción de las poblaciones, incluso en ausencia de reclutamiento vía plántula (e.g., lugares secos y soleados), o incluso cuando su crecimiento vegetativo y desarrollo reproductor está muy limitado (e.g., lugares muy sombreados).…”

Effect of light environment on intra-specific variation in herbivory in the carnivorous plantPinguicula moranensis(Lentibulariaceae)

“…This is because damaged ranged from 0% to nearly 40% of total leaf area. The extreme herbivory in some individuals could reduce the area available for catching prey and the fitness gains derived from carnivory (Aldenius et al 1983;Zamora et al 1997;Thorén & Karlsson 1998;Méndez & Karlsson 1999). Herbivory could also reduce the capacity of plants to obtain energy directly by the reduction in photosynthetic tissue and fitness components such as survival, growth and reproductive success, depending on the ability to compensate foliar damage (Crawley 1989;Marquis 1992;Berenbaum & Zangerl 1998;Delaney & Macedo 2001).…”