POLYPLOIDY IN MOSSES

Patterns were examined in published karyological data for 1451 moss sp ecies (approximately 16% of the total number of species) from all regi ons of the world. Assuming that x = 7 is the original basic chromosome number in mosses, all gametophytic numbers n > 9 were supposed to mar k polyploids. It was found that 84% of the species had undergone polyp loidy in their history. It is assumed that most polyploids in mosses a re autopolyploids. Among the polyploids, 28% are high polyploids (spec ies with n > 15). In pleurocarpous mosses, 16% are high polyploids, wh ereas in acrocarpous mosses 27% are high polyploids. There is no diffe rence in frequencies of high polyploids between the two subgroups of a crocarpous mosses: Haplolepideae-acrocarpae (26%) and Diplolepideae-ac rocarpae (27%). A clear correlation was found between the frequency of high polyploids (n > 15) and latitude. The frequency of high polyploi ds increases from the equator towards the North and South Poles. The p ercentage of high polyploids jumps dramatically from tropical and subt ropical zones (similar to 13%) to temperate and cold climatic zones (o ver 30%).