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| Author(s): |
Caio Guilherme Pereira
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia |
| Defense date: | 2013-05-16 |
| Examining board members: |
Rafael Silva Oliveira;
André Victor Lucci Freitas;
Bruno Henrique Pimentel Rosado
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| Advisor: | Rafael Silva Oliveira |
| Abstract | |
Carnivorous plants are plants that have the ability to capture and digest small animals, usually insects and other invertebrates. The studies with these plants began in the nineteenth century and until today it is unknown the underlying mechanisms that determine the evolution and the geographical distribution of these singularities. The cost--benefit models are, accordingly, acting as guidelines to various studies in recent decades and seem to be able to clarify many obscure points concerning the ecology and the evolution of these plants. The three species of the genus Philcoxia, endemic to campos rupestres -- fire prone and nutrient--poor environments usually associated with rocky outcrops and white sand formations -- have unique characteristics and adaptations that eventually led to several questions regarding the physiology of these plants. With growing accumulation of evidence, scholars started to consider the possibility that such plants could present active mechanisms for capturing and digesting prey. The present study aimed to determine if Philcoxia minensis exhibits the syndrome of carnivory and to analyze the costs and benefits of this habit in the theoretical context suggested by Thomas J. Givnish for the evolution of carnivory. In order to do so, we have made a detailed anatomical description of the leaves of P. minensis, in which we observed a clear pattern of enzyme production possibly associated with prey digestion, including phosphatases. We also characterized the glandular structures that are responsible for the production of the enzymes as well as the nematodes that are considered, until now, the only prey of P. minensis. Concerning the absorption of nutrients derived from prey, we observed an incorporation of 5% of the nitrogen of the nematodes (Caenorhabditis elegans) in 24h, and 15% in 48h in an experiment with stable isotopes. To evaluate the energy balance of this species, we analyzed correlations between leaf traits associated with the processes of photosynthesis and respiration. Generally speaking, we found a strong correlation between the photosynthetic capacity (Amass and Aarea) and the LMA (leaf mass per area) values for neighboring non--?carnivorous plants, with a distancing of P. minensis individuals, which showed very low photosynthetic rates. Regarding the correlations between the contents of nitrogen and phosphorus with photosynthetic capacities, we observed that the individuals of P. minensis showed extremely low photosynthetic rates for their nutrient concentrations and, although a tendency could be observed, there is no correlation between photosynthetic capacity and the foliar contents of nitrogen and phosphorus. Finally, we have conclusively determined the carnivorous nature of P. minensis and we placed this species along the leaf economics spectrum, both in local and global scale. Our results illustrate how much there is still to be discovered about the origin, distribution and frequency of the carnivorous syndrome (AU) | |
| FAPESP's process: | 12/08632-3 - Photosynthetic costs and benefits of the carnivorous syndrome in the species Philcoxia minensis P. Taylor & V. C. Souza (Plantaginaceae) |
| Grantee: | Caio Guilherme Pereira |
| Support Opportunities: | Scholarships in Brazil - Master |