The role of ants in the reproductive biology of the hemiparasitic annual, Melampyrum lineare

xisting theories posit that either stressful environments or third species antagonists are responsible for driving the evolution of mutualisms. Favorable nest environment and predator avoidance hypotheses are here tested to determine which of the choices is most important to ant dispersal in Melampyrum lineare Desr. Results of higher germination success (p = 0.0025), higher amount of survival to reproduction (p = 0.0025), and greater fecundity (0.005 ;The shape of the dispersal-distance distribution curve for M. lineare is similar to reports for other myrmecochores, albeit with smaller mean (1.08 m) and range (;In some nutrient-poor boreal forest communities, 21-33% of the herbaceous ground cover species are myrmecochorous. This is a high proportion relative to reports from elsewhere in the world. Epigaea repens, Polygala paucifolia, and M. lineare together make elaisosome tissue available throughout most of the growing season. Diaspores of these species differ significantly in their removal frequency by ants; E. repens is greater than M. lineare, which is greater than P. paucifolia.;Though seed predators can have an effect in reducing seed pool numbers (50-70% in ant exclosures), it is suggested that because of the timing of seed release and the thorough nature of dispersal by ants (85-100% in rodent exclosures), third species antagonists are presently less important in this mutualism. Historically, as suggested by the prevalence of morning (vs. evening, p...