The Size-Number Trade-Off and Resource Allocation in Saponaria officinalis Under Continuous Pollination

Abstract

The size-number trade-off in plant reproduction indicates a necessary balance between producing a few large offspring versus many small ones, each with distinct survival and reproductive implications. This trade-off may be particularly important in species that reproduce continuously throughout the growing season, like Saponaria officinalis. Plants must dynamically adjust their resource allocation strategies to optimize reproductive success across multiple reproductive cycles. Although reproductive strategies in plants have been widely studied, little is known about how continuously reproducing species adjust their resource allocation in response to pollinator availability. This study seeks to clarify how Saponaria officinalis allocates resources under continuous pollination and whether this leads to a trade-off between seed number and seed size throughout the growing season. To explore this, my study used 60 plants that were located within a field of 1600 S. officinalis plants at Queen’s University Biological Station (QUBS). Plants were divided into control (30) and treatment (30) groups, with treatment plants receiving continuous pollination to simulate constant pollinator availability; and control plants receiving natural open-pollination. During my project, seed pods were categorized as empty or filled, and seeds were counted and weighed to assess reproductive output. I expected to find an increase in reproductive success in the treatment group, with steady production of larger seeds due to increased resource availability from continuous pollination. However, contrary to these expectations, there was no significant difference in seed weight between the treatment and control groups. This research contributes to a deeper understanding of the ecological and evolutionary mechanisms driving reproductive strategies in continuously reproducing species. The insights gained can inform broader ecological theories and have practical applications in conservation and agricultural management, where optimizing reproductive success under varying conditions is essential.