Uneven patterns of palm species loss due to climate change are not driven by their sexual systems

As plants are sessile organisms, their response to environmental change may be mechanistically mediated by reproductive traits. The spatial segregation and physiological specialization of the sexes in dioicous plants, for instance, create mismatches in individual responses to environmental change. Conversely, the ability of self-fertilization circumvents the need for sexual partners and has been linked to the dominance of hermaphrodites in habitats with drought stress. Sexual systems (dioecy, hermaphroditism, monoecy, and polygamy) are key drivers of plant distribution, which raises the question of how they will respond to climate change. Here, we leverage the diversity of the sexual systems of palms (Arecaceae) to test their role on species distribution potential under climate change, comparing distribution patterns among biogeographic realms. Additionally, we evaluated how climate change will affect the palm richness patterns worldwide. We fitted ecological niche models to species' occurrence and climate and soil data from present-day conditions, then projected onto climate change projections referred to years 2050 and 2090. We found that different sexual systems of palms respond similarly to climate change, with reductions in potential distribution expected for all sexual systems. Most species (354 out of 540) are expected to lose suitable areas, particularly in Neotropics, where palm richness is concentrated. Sharp richness loss is projected for Amazonia and Neotropical savanna - Cerrado, which can lose up to 50 and 40 palms, respectively. As sexual systems responded similarly to climate change, their role in species' response to climate change remains elusive. Our work does show that threats of climate change to global palm richness are ubiquitous, yet uneven geographically.