Ascospore size declines with elevation in two tropical parmelioid lichens

Abstract

Spore size and shape are biometric parameters frequently used in lichen taxonomy, especially in species characterization. However, the influence of environmental factors on the intraspecific variability of these characters remains very little investigated in lichenology. The elevational variation in spore length, width, volume and shape (length/ width ratio) of two species of the genus Hypotrachyna ( H . aff. damaziana et H . altorum ) occurring on Réunion Island (Indian Ocean) were studied. Spore length, width and volume significantly decrease with elevation in H . aff. damaziana , and spore width and volume also significantly decrease with elevation in H . altorum . There is no relation between spore shape and elevation in either of the two species. A significant correlation was further observed between the intra-individual variability in spore size of H . aff. damaziana and elevation. For this species, inter-individual variability in spore volume is also correlated with mean annual temperature and mean annual precipitation of the sampling locations, and spore width and length are correlated with mean annual temperature.

Keywords

• ascomycota
• parmeliaceae
• hypotrachyna
• réunion island
• spore morphometry
• intraspecific variation