Viral pathogens and the advantage of sex in the perennial grass Anthoxanthum odoratum

Abstract

The ubiquity of sexual reproduction among plants and animals remains one of the major unresolved paradoxes of modern evolutionary biology. In order for sex to be maintained in populations, sex must confer immediate and substantial fitness benefits. Theoreticians have proposed numerous mechanisms to explain how such advantages arise, but experimental data are few. In one well-studied population of the perennial grass Anthoxanthum odoratum in a mown North Carolina field, sexual offspring have been found to have significantly higher fitness than asexual offspring. More recent field experiments show that an aphid-transmitted virus, barley yellow dwarf (BYDV)-strain SGV, specifically transmitted by Schizaphus graminum, frequently infects Anthoxanthum progeny soon after transplantation into the field, BYDV infection is asymptomatic in Anthoxanthum, but BYDV-inoculated clones planted directly in the field had significantly lower fitness than healthy controls.