Effect of habitat differences on morphology, anatomy and fecundity of lichens

Abstract

The effect of habitat differences on morphology, anatomy and fecundity of the lichen species have been rarely studied. However, this would help understand the mechanisms by which some lichens thrive while some get eliminated from the habitat. The objectives of the study were 1) to identify the lichen species common to a site in the middle of the Kandy City (KC) and a site inside the University of Peradeniya (UP, 2) to compare their morphology, anatomy and fecundity of common species between sites. Lichen species were randomly sampled from tree barks and fallen branches and identified using standard keys. Morphological and anatomical characteristics of the lichen thallus, sexual and asexual reproductive structures such as number of apothecia, and ascospores were compared between 2 sites using hand lens, dissecting microscope and compound microscope. Among 39 species found in University premises and 15 species around the Kandy Lake, 5 species, Physcia sp, Parmotrema sp, Lecanora sp, Graphis sp, and Lepraria sp, were common to both sites. As expected, mean thallus area of 4 species, except Lepraria was significantly smaller in KC site than UP site. The change of colour in Thallus (green to grey) were significant in all species between KC and UP. Thickness of upper cortex (significant, P=0.041), medulla layer and lower cortex were higher in KC site than UP site in Parmotrema sp. while thickness of algal layer is smaller in KC site. A decrease in apothecial number was observed in Lecanora sp. at KC site compared to UP site. The current study showed that changes in certain morphological, anatomical and reproductive characteristics can be triggered by the changes in the environment and may attributed to recorded air pollution in KC site suggesting that such species can be used to monitor the quality of the environment.