The primary focus in my lab is an investigation into unbalanced sex ratios in bryophytes with particular attention to sex-specific responses to stress as mediated by the costs of sexual reproduction. Species under study are the cosmopolitan moss Bryum argenteum, the desert moss Syntrichia caninervis, the rare species Pterygoneurum lamellatum, the model organism Physcomitrella patens, and a variety of species in the genera Tortula, Aloina, Funaria and others. Types of stress responses that may be helpful in understanding the female-biased sex ratio that characterizes most bryophyte species include gametophytic and sporophytic desication tolerance (DT), thermotolerance, nutrient stress, microsite disturbance, and overgrowth competition. Current problems under study include the relationship between stress and offspring sex ratios, the cost of inducible vs. constitutive DT systems, plasticity of phenology patterns, sex allocation in mosses, experimental demonstrations of rhizautoicy and self-compatibility in mosses, and the timing of the DT response in both generations of mosses. My graduate students are studying (i) predictive models of species distribution in deserts and (ii) heat shock protein expression during thermal stress.
Desiccation tolerance is the ability of an organism or structure to dry out entirely while retaining viability throughout this dried state. My research focuses on the ecology of tolerating desiccation in the mosses. It includes assessments of constitutive (native) vs. inducible (stimulated) desiccation tolerance, the desiccation tolerance of vegetative and reproductive phases, and phenomena such as hardening and dehardening to desiccation tolerance (becoming increasingly or decreasingly desiccation tolerant). Specifically, my laboratory is investigating how the three components of desiccation tolerance, (i) the rate of drying, (ii) the duration spent in the dried state, and (iii) the equilibrium relative humidity reached, affect the capacity of a species or species structure to tolerate desiccation. We focus on desert mosses.