Gender differences and a new adult eukaryotic record for upper thermal tolerance in the desert moss Syntrichia caninervis

1.Two competing hypotheses relating to thermostress were proposed to understand skewed sex ratios in Syntrichia caninervis, a reproductive investment hypothesis and a wildfire selection hypothesis.2.Nearly all shoots from both sexes remained viable (regenerated in culture) following exposure to 120 °C for 30 min, thus setting a new upper thermotolerance record for adult eukaryotic organisms for a minimum 30 min exposure time.3.Males regenerated faster than females, produced more biomass, and suffered less fungal attack than females. Findings support the wildfire selection hypothesis.