|Tuesday, July 06|
Where do they live? Discerning the unknown distributions of bryophytes
* Nicole J. Fenton, Institut of Forest Research, Université du Québec en Abitibi-Témiscamingue, Canada
The number of bryologists per km2 varies widely across the planet. Consequently, while some parts of the globe have a very detailed knowledge of the distribution of bryophyte species, other areas are still discovering new species. When detailed spatialized knowledge of species distributions is lacking or impossible, species distribution models are an essential tool to determine the distribution of species. However, species distribution models rely on detailed knowledge of habitat requirements, and interactions between micro and macro factors that determine habitat suitability for an individual species. In the absence of this information, the potential distribution of many species becomes simply “eastern boreal North America”. Drawing on a variety of approaches, we are (1) increasing the documentation of species distributions, (2) describing landscape and cross scale factors influencing bryophyte habitat occupation, and (3) developing novel remote sensing tools to map distributions of bryophyte species in eastern boreal North America. The results of these research projects will help determine the actual distribution of bryophyte species, essential for their eventual conservation, and will suggest methods that could be applied to other regions of the globe where there are gaps in our knowledge of bryophyte distributions.
What we want to know about bryophyte life history traits and how they relate to bryophyte sex ratios, dispersal ecology and extinction risks
* Irene Bisang, Swedish Museum of Natural History, Sweden
Out of the 50 question that eventually qualified as the “fundamental research questions in bryology” from more than 220 suggestions, almost 30% (14) sort under the wide general topic “GT2 Bryophyte Ecology, Physiology and Reproductive Biology”. In my presentation I will focus on the first subsection and outline how an improved understanding of bryophyte life history traits is essential for the advance of many other fundamental future topics identified in this project. Briefly, Life History Theory seeks to explain how natural selection shapes organisms to achieve survival and reproductive success. Bryophyte life histories are tightly linked to the bryophyte life cycle; the latter is unparalleled among land plants and has a major bearing on nearly every aspect of bryophyte biology. Among such unique characteristics, I will highlight the roughly similar frequencies of hermaphroditic and dioicous mating systems expressed in the gametophyte, and the high proportions of non-reproductive individuals and populations in many, especially dioicous, species. It is therefore critical to distinguish between genotypic and phenotypic (functional; realised) sex. I will present examples of genotypic and phenotypic sex ratio variation along environmental factors, and of possible phylogenetic constraints on sex ratios. I will also illustrate relationships between life history traits and dispersal capacity. Finally, I will present an approach to disentangle species’ life histories traits, habitat specificity and environmental factors that affect rarity and vulnerability of European bryophytes. Studying species and organisms with widely varying life histories, beyond the common model species, will contribute evidence to general life history and ecological theory.
Bryophyte conservation in a biodiversity crisis
* Lars Hedenäs, Swedish Museum of Natural History, Sweden
According to the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services IPBES, corresponding with the UN Intergovernmental Panel on Climate Change, IPCC, we risk losing one million or c. 12 % of our world’s species. Like climate change, the loss is gradual and if we do not act the loss is inevitable. After a general introduction to the theme, I will address in some detail four of the 14 identified fundamental questions in bryology that concern bryophyte conservation and management. How will global climate change affect extinction risk of bryophyte species and, consequently, their ability to adapt to changing environmental conditions? What are the key drivers of decline in bryophyte species and intraspecific diversity, at both the global and regional level? What are the highest priority areas for the conservation of bryophytes in the face of land-use change, habitat destruction and climate change? Where are the global hotspots of rare or threatened bryophyte species and how do these relate to hotspots of species and intraspecific diversity? These questions are currently addressed by descriptive or statistical comparisons, red-listing, spatial analyses, monitoring, and modelling approaches. Considering the current rapid biodiversity loss, we need ways of pin-pointing the most efficient conservation measures. Important issues include, which species are most important to conserve, how should genetic diversity be considered, can diversity at one level be forecasted by diversity at another level, and which factors are most important to explain the observed and predict the future bryophyte diversity loss?
Bryophyte biotic interactions and productivity with a focus on mycorrhizal-like associations
* Silvia Pressel, The Natural History Museum, London, United Kingdom
Katie Field, University of Sheffield
Martin Bidartondo, Imperial College London and Royal Botanic Gardens, Kew
William Rimington, The Natural History Museum, London and Imperial Collage London
Jill Kowal, Royal Botanic Gardens, Kew
Grace Hoysted, University of Sheffield
Jeffrey Duckett, The Natural History Museum, London
Bryophytes are key components of several biomes worldwide, where they contribute significantly to biomass and productivity and are thought to exert a major influence on ecosystem processes, including water, carbon and nitrogen cycles. Appreciation of the roles of bryophytes and their interacting microbiomes in ecosystem functioning has increased dramatically in the last few decades; however fundamental questions still remain as to the mechanisms involved and on how diverse microbes and types of interaction influence bryophyte development, community composition and functional significance across ecosystem types. Here we will discuss latest advances in understanding and future major challenges in the broad context of bryophyte biotic interactions and productivity focusing particularly on mycorrhizal-like associations. While it has been known for a very long time that the rhizoids and/or thalli of liverworts and hornworts are colonised by filamentous fungi with characteristic morphologies, only in the last decade has the mycorrhizal-like nature of these associations in liverworts and the diversity of fungal symbionts involved been demonstrated through extensive global sampling combined with cytological, physiological and molecular investigations. This diversity includes endogonaceous members of the fungal sub-phylum Mucoromycotina, alongside Glomeromycotina arbuscular mycorrhizal fungi and members of the Dikarya. Mucoromycotina symbionts form distinct partnerships with an apparently prominent role in liverwort nitrogen nutrition and, given their distribution in the liverwort phylogenetic tree, most likely represent the ancestral type. Whether the Glomeromycotina and Mucoromycotina endophytes of hornworts also exchange resources with their hosts and possibly interact with their hosts’ ubiquitous cyanobacterial symbionts remains to be determined.
Beyond the sphinxes: current (and renewed) challenges in bryophyte systematics and evolution
* Rafael Medina, Complutense University of Madrid, Spain
In recent years we have witnessed a substantial step forward in our understanding of bryophyte evolution and systematics, facilitated by the advances of molecular phylogenetics. This responds to the interest of bryophyte specialists, but also to the growing attention received by non-vascular systems: bryophytes provide contrast to better known models and help us determine the universality or distinctiveness of plant evolutionary mechanisms. However, some fundamental questions, from the most ancient branches of the bryophyte tree of life to the ongoing microevolutionary processes, are yet to be answered. This presentation focuses on a few of these stimulating themes to demonstrate that even what seemed well-settled principles are now being questioned and re-examined with new evidence. This is the case, for example, of the early branching pattern of the three bryophyte lineages, a long-standing matter with deep implications in our understanding of plant evolution. Some other seemingly basic aspects of this tree are poorly understood: bryophytes have the potential to undergo rapid diversifications, and we now have evidence of many examples of such events in their history. However, it is still not clear which phenomena, both intrinsic or extrinsic, have triggered said radiations, nor the role that extinction played shaping them. Finally, as we learn more about bryophyte speciation and microevolution, we need to reflect on how to integrate this knowledge in new species descriptions to effectively advance towards the completion of the global bryophyte assessment.