GEOGRAPHICAL DISTRIBUTION AND RELATIONSHIP WITH ENVIRONMENTAL FACTORS OF SHEATHIA IN THE WORLD

Sheathia is a representative genus of freshwater red algae with a large number of species and a wide distribution. It grows most commonly in clean freshwater such as streams, rivers and springs with low levels of light, low temperatures and high levels of dissolved oxygen. It has been recorded from Asia, Europe, Africa, North America and Oceania. Its harsh habitat makes it easy for the Sheathia to fail to grow normally when the external environment is altered. With the increasing pollution of the global water environment, the scarce freshwater resources have been severely damaged and the number of freshwater Sheathia is also decreasing. At the moment, many species have been added to the list of endangered plants. In this paper, 116 species of samples of Sheathia around the world were used as the research object. A variety of statistical analyses, including One-way ANOVA, correlation analysis, stepwise regression analysis, principal component analysis and linear discriminant analysis were used to analyze the variability and interrelationships between the geographical distribution of different species and latitude, longitude, altitude, water temperature, current velocity and pH. According to the results of One-way ANOVA and linear discriminant analysis, the geographical distribution and growth environment of Sheathia arcuata, S. boryana, S. confusa, S. dispersa, S. longipedicellata and Remainder were significantly different. Combining the results of correlation analysis, stepwise regression analysis and principal component analysis, altitude, water temperature, current velocity and pH were important environmental factors affecting the geographical distribution of Sheathia. This study has analyzed the important environmental factors affecting the geographical distribution of Sheathia at the species level, provide more scientific basis for understanding the mechanism of freshwater red algae adaptation to the environment, enrich the data on the geographical distribution of freshwater red algae, establish a relatively perfect freshwater nature sanctuary and protect the freshwater red algae groups with special habitats.