Floral traits and reproductive ecology of the Mediterranean subendemic orchid Serapias neglecta De Not.

Miriam Bazzicalupo ¹, Alex Alberto ², Maria Guerrina ³, Carla Villa ³, Francesco Saverio Robustelli della Cuna ⁴, Jacopo Calevo ¹

Royal Botanic Gardens, Kew ¹, Unimont - Universita' degli Studi di Milano ², Universita' degli Studi di Genova ³, Universita' degli Studi di Pavia ⁴

Effective conservation strategies require an understanding of a species' reproductive biology to identify intrinsic and ecological factors that influence its persistence. Currently, limited data are available on the biology of Serapias neglecta De Not., a subendemic Mediterranean orchid that is facing local extinctions in Northern Italy and experiencing overall declining trends in Europe. The goal of our work was therefore to collect information on the species' reproductive ecology, investigating which traits could play a role in plant-pollinator interactions, fructification, and seed germination. Field activities were carried out at three sites in Liguria (Italy). We conducted macro- and micro-morphological analyses of the floral tissues; we performed hand-pollination and tested self-compatibility with viability assays and symbiotic germination trials; we investigated the composition of floral VOCs using SFME followed by GC/FID and GC/MS. Seventy-five compounds were identified in the VOC profile, with saturated and unsaturated hydrocarbons dominating the spectrum, including compounds recognized as insect pheromones. Dark spots on the petals, together with the floral tube's depth, mimic the appearance of a bee's nest. Light-reflective elongated trichomes with dome-like protuberances covered the surface of the central labellum. We recorded several classes of secondary metabolites in the floral tissues, including compounds with a putative role in herbivory avoidance. Although we observed accidental autogamy induced by animal visits, no spontaneous self-pollination occurred. Autogamous and geitonogamous pollination led to the production of viable seeds that were able to germinate, but cross-pollination consistently improved seed quality and germination performance. Inbreeding depression was high across all studied populations. We observed no pollination events by hymenopterans during our surveys, but we recorded coleopterans with pollinia on their heads; coleopterans and spiders were seen using the cavity as a resting place or shelter. These findings suggest that S. neglecta mostly relies on pollinators for reproduction and attracts them through a combination of floral traits. The species' declining trends may be linked to a reduced local pollinator population during the flowering period, increased competition from taller grasses, and limited adaptability to changes in habitat management.

Main author career stage: Postdoc / Fellow

Contribution type: Talk

First choice session: 2. Ecology

Second choice session: 3. Biodiversity and global change