Mitigating the Pollinator-Prey Conflict in Drosera capillaris: A Study on Physiological Plasticity and Phylogenetic Conservatism within Drosera

Mario A. Sandoval Molina 

Premise: Carnivorous plants face a dilemma: acquiring nutrients from insect prey while simultaneously relying on insect pollinators for reproduction. Thus, carnivorous plants have evolved mechanisms to avoid/reduce pollinator-prey conflict. This study aims to understand how carnivorous plants deal with this conflict through: macroevolutionary adaptations (floral stalk length) or short-term physiological adaptations, such as modulating trap stickiness. Methods: I conducted a field experiment with Drosera capillaris, comparing reproductive and non-reproductive plants. I quantified prey capture, counted the number of traps/flowers, and measured adhesive trap strength (stickiness). Additionally, I performed a phylogenetic analysis of 68 Drosera species to assess the evolutionary conservatism of floral stalk length. Results: Contrary to initial predictions that reproductive plants would reduce trap stickiness to reduce the probability of catching pollinators, these plants exhibited significantly stickier traps than non-reproductive. Despite this increase in adhesive strength, reproductive plants showed a trend toward lower prey capture probability. Phylogenetic analysis revealed high conservatism in floral stalk length across the genus, suggesting that spatial separation is a stable, long-term evolutionary trait. Conclusions: This represents a novel, within-species physiological adjustment previously unreported. These findings demonstrate that D. capillaris employs a complex, dual strategy to mitigate the pollinator-prey conflict. This combination allows the plant to maximize nutrient acquisition for the high energetic demands of reproduction without jeopardizing pollination success.