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Project

Function and taxonomic relevance of spore ornamentation in bryophytes

Dispersal is a key evolutionary force that determines the survival, growth, and reproduction of individuals, the temporal and spatial cycles of colonization and extinction of populations, and ultimately, the emergence of new species via genetic drift or natural selection. In the context of global change, dispersal dynamics are especially important as the long-term survivability of species depends on their ability to effectively shift, and even augment their distributions according to changes in local climatic conditions. For both responses to climate change, dispersal is a central process; it determines the potential spread rate of a population and, as the mechanism by which genes are moved between populations, it influences the rate of adaptation to changing conditions and the potential for evolutionary rescue. Thus, understanding, predicting and managing biodiversity responses to rapid climate change demands a full consideration of species’ dispersal traits.
A common way to approach and predict the potential distance that an airborne particle is able to travel is by evaluating its settling velocity. The settling velocity of diaspores is a key parameter for the measurement of dispersal ability in wind-dispersed plants and one of the most relevant parameters in explicit dispersal models. We observed, in the course of a previous investigation (Zanatta F, Patiño J, Lebeau F, Massinon M, Hylander K, Degreef J, Vanderpoorten A. Measuring spore settling velocity for an improved assessment of dispersal rates in mosses. Submitted to Annals of Botany), that the settling velocity of moss spores with low ornamentations was consistent with theoretical expectations, whereas spores with more conspicuous ornamentations exhibited either higher or lower settling velocities. This suggests that variation in spore ornamentation affects the balance between density and drag and results in different dispersal capacities, which may be correlated with different life-history traits or ecological requirements.
In the present project, we intend to conduct a large-scale investigation on spore morphology to determine the role of complex spore ornamentation patterns in the drag-to-mass ratio and ultimately identify what is the still poorly understood function of the striking and highly variable ornamentation patterns of the outer layer of bryophyte spores.
Using SEM, we will document the fine-scale structure of the spores of each of the 284 and 297 moss and liverwort species sampled in the course of the Moss and Liverwort Tree of Life projects (Laenen B et al. 2014. Nature Communications 5: e6134), from which phylogenetic information will be derived. We will then use phylogenetic comparative analyses to determine the phylogenetic signal in the variation of spore morphology and the link between spore morphology, dispersal capacities, and species life-history traits.
Date:8 Nov 2021 →  6 Nov 2023
Keywords:SEM microscopy, spore ultrastructure, B230-microbiology, dispersal strategy, life-history traits, B290-physiology-of-nonvascular-plants, B225-plant-genetics