Structure of proposed research on dryland mosses
Our overall goal is to understand the evolutionary and ecological mechanisms that have produced and maintained dryland moss diversity at the genetic, phylogenetic, and functional levels, while exploring potential ecological and evolutionary tradeoffs (Table 1). To this end, we will sample along natural environmental gradients allowing us to study variability in genomes, population demographics, desiccation tolerance, and fitness metrics (growth and reproduction), all within a phylogenetic context. Culture techniques and water stress experiments will be used to quantify the functional diversity of DT and community resilience of biocrusts.
We chose dryland mosses in the genus Syntrichia for our study system, a group with great ecological diversity and a rich history of study. We will focus heavily on two species that have been subjects of intensive study in water relations and reproductive biology over the last several decades, Syntrichia ruralis and Syntrichia caninervis, because they are both dominant components of biocrust communities and because they both include considerable geographic variation across their broad ranges. In reality both are species complexes, giving us the opportunity to study fine scale diversification processes. Larger scale diversification and adaptation questions will be addressed by setting these two species complexes into a broader phylogenetic context of the rest of the genus Syntrichia. The major questions to be addressed are in Table 1.
Our research seeks to build an integrated understanding of the following questions relating to the role of desiccation tolerance, developmental phases, and reproductive tradeoffs in structuring patterns of biodiversity in dryland mosses. Major questions are given here; specific hypotheses are presented next.
1. What are the genetic mechanisms underlying traits (including phenotypic plasticity) that drive diversification, reproduction, habitat selection, and physiological processes?
2. How does genetic diversity, clonal vigor, and sex ratio compare among populations inhabiting environments with varying degrees of water stress? Could tradeoffs between DT and sexual reproduction have shaped these diversity patterns?
3. Is functional diversity of desiccation tolerance evident among lineages and do these differences vary by life phase or sex, providing evidence for fitness tradeoffs over evolutionary time scales?
4. Does the phylogenetic history of Syntrichia suggest diversification (possibly convergent) in physiological traits, OR conservation of physiology and subsequent colonization of suitable environments by specialized lineages?
5. Do high levels of genetic, functional, and phylogenetic diversity improve the resilience of moss-dominated biocrusts to climate change?