Spore-killing meiotic drive factors in a natural population of the fungus Podospora anserina

In fungi, meiotic drive is observed as spore killing. In the secondarily ho mothallic ascomycete Podospora anserina it is characterized by the abortion of two of the four spores in the ascus. We have identified seven different types of meiotic drive elements (Spore killers). Among 99 isolates from na ture, six of these meiotic drive elements occurred in a local population. S pore killers comprise 23% of the natural population of P. anserina in Wagen ingen, The Netherlands, sampled from 1991 to 1997. One Spore-killer type wa s also found in a French strain dating from 1937. All other isolates found so far are sensitive to spore killing. All seven Spore killer types differ in the percentage of asci that show killing and in their mutual interaction s. Interactions among Spore killer types showed either mutual resistance or dominant epistasis. Most killer elements could be assigned to linkage grou p III but are not tightly linked to the centromere.