Format: ORAL

Anabela Martins1, Jairo Patio2, Ana Losada-Lima3 Manuela Sim-Sim1,4

1 cE3c - Centre for Ecology, Evolution and Environmental Changes & CHANGE - Global Change and Sustainability Institute /MUHNAC - Museu Nacional de História Natural e da Ciência, Universidade de Lisboa, Rua da Escola Politécnica, 58, 1250-102 Lisboa, Portugal 2Island Ecology and Evolution Research Group. Instituto de Productos Naturales y Agrobiología (IPNA-CSIC). c/ Astrofísico Francisco Sánchez 3, La Laguna, Tenerife, Canary Islands, 38206, Spain 3 Departamento de Botánica, Ecología y Fisiología Vegetal, Universidad de La Laguna, 38200 Tenerife, Spain 4cE3c - Centre for Ecology, Evolution and Environmental Changes & CHANGE - Global Change and Sustainability Institute, Departamento de Biologia Vegetal, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal

Oceanic islands host remarkable biodiversity richness and represent important hotspots. Laurel forests are the relicts of an evergreen humid forest community, which occurred across the Mediterranean basin about 20 million years ago. Since the onset of the Mediterranean climate, laurel forests only persisted in Macaronesia, where the oceanic environment buffered the climatic oscillations of the Pleistocene, and where these forest ecosystems are closely associated with the elevational belt of orographic cloud formation. The Macaronesian laurel forest harbors an exceptionally high diversity of bryophytes, with approximately 33 threatened endemic bryophyte species, the majority of which are dioecious. Dioecious bryophyte species often face challenges in sexual reproduction. Traditionally, asexual reproduction is thought to help maintain well-adapted phenotypes in stable environments, while sexual reproduction enhances genetic variability, increasing the populations chances of survival in new colonizing areas or during periods of environmental change. In contrast to flowering plants, most dioecious bryophytes exhibit a female bias among sex-expressing individuals. However, in a few cases, sex ratios have been found to be evenly balanced or that there is a male bias, as demonstrated in population studies of leafy liverworts. A significantly broader taxonomic range of moss species has been examined, but there is a noticeable lack of data for leafy liverworts. This research will be the first to investigate patterns of sex expression in Macaronesian laurel forest endemic bryophytes. Through the integration of data obtained from fieldwork conducted on the islands of Madeira and Tenerife, along with herbarium material (AZU, C, E, LD, LISU, E, TFC, VAL), we aim to examine the patterns of sex expression and sex ratio in four laurel forest bryophytes (Exsertotheca intermedia [endemic], Frullania polysticta [endemic], Frullania teneriffae, Porella canariensis), exploring their implications for effective sexual reproduction across their entire range.