Ongoings | MEEP Lab @ SFSU

Dust, biocrusts, and Valley Fever

Mon, 01 Jan 0001 00:00:00 +0000

Biological soil crusts help stabilize dryland soils, shape belowground microbial communities, and reduce dust emissions. As climate change and land disturbance alter biocrust integrity, these changes may have consequences that extend beyond ecosystem function to human exposure to dust and dust-associated microbes. This project explores links among biocrust condition, soil fungal communities, dust generation, and environmental health in the southwestern United States. A central goal is to understand whether biocrust disturbance changes the composition of soil fungal communities in ways that may influence the movement or environmental occurrence of dust-associated pathogens, including the fungus that causes Valley Fever. The project combines ecological sampling, fungal community profiling, spatial analysis, and targeted work in microhabitats where soil disturbance and fungal reservoirs may overlap. A growing component of this work focuses on community-engaged dust monitoring, household and neighborhood-scale exposure questions, air-quality data, dust analysis, and possible intervention approaches such as indoor air filtration. This project asks how changes to desert surfaces may connect ecosystem degradation, airborne dust, microbial exposure, and environmental justice.

Evolution of cosexuality and sex chromosomes in mosses

Mon, 01 Jan 0001 00:00:00 +0000

Mosses have diverse reproductive systems, making them useful for studying how sexual strategies evolve. This project examines transitions among reproductive modes in mosses, with a focus on connections among sexual system, genome structure, and chromosome evolution. We are especially interested in cases where mosses depart from separate male and female functions and evolve cosexual or otherwise complex reproductive strategies. Using comparative genomics, phylogenetic approaches, and analyses of reproductive traits, this work asks how often these transitions occur, what genomic changes accompany them, and whether similar evolutionary patterns appear across independent moss lineages. A related part of this project explores sex chromosomes and intragenomic conflict in mosses, asking how reproductive traits and genome evolution influence one another over evolutionary time. Together, this research connects moss reproductive biology to larger questions about trait evolution, genome evolution, and the origins of biological diversity.

Fog, atmospheric moisture, and epiphytic cryptogams

Mon, 01 Jan 0001 00:00:00 +0000

Atmospheric moisture can be an important water source for mosses, lichens, and other poikilohydric organisms, especially in habitats where rainfall is strongly seasonal. This project examines how fog, marine-layer exposure, and fine-scale microclimate variation shape epiphytic cryptogams and their associated microbial communities. We are interested in whether visible patterns of moss and lichen occurrence reflect underlying changes in morphology, reproduction, chemistry, and host-associated microbiomes. Using field surveys, microclimate monitoring, trait measurements, molecular identification, and microbial community data, this work explores how coastal-to-inland variation affects cryptogam performance and symbiosis. A major goal is to understand how non-rainfall water inputs influence small but ecologically important organisms that live at the boundary between plants, atmosphere, and microbial life. This work connects to broader questions about how changing coastal fog regimes may affect biodiversity, organismal function, and microbial associations in moisture-sensitive communities.

Mosses under snow

Mon, 01 Jan 0001 00:00:00 +0000

High-elevation mosses experience intense summer drying, high solar radiation, freezing temperatures, and long periods beneath winter snow. This project focuses on alpine and subalpine mosses that persist across these seasonal extremes. We are interested in whether mosses beneath winter snow remain physiologically active during parts of the cold season or instead enter a mostly dormant state until conditions become more favorable. To explore this question, we combine field monitoring of winter microclimates with laboratory assays of photosynthetic performance, cold tolerance, and stress recovery. We are also investigating molecular and genomic features that may contribute to cold-stress responses in alpine mosses. By linking field conditions with physiological and molecular responses, this work asks how changing snowpack, winter temperature, and seasonal water availability may affect moss survival in high-elevation habitats.

Systematics and population genomics of western Syntrichia

Mon, 01 Jan 0001 00:00:00 +0000

Western North America is home to diverse and ecologically important mosses in the genus Syntrichia, including species that dominate biological soil crusts, tolerate extreme drying, and occupy a wide range of dryland and montane habitats. This project investigates relationships among western Syntrichia lineages, with an emphasis on species complexes where morphology, geography, ecology, and evolutionary history may not tell the same story. We use field collections, herbarium material, genomic data, and comparative analyses to clarify patterns of relatedness, population structure, and trait variation. A major goal is to understand how evolutionary history and environmental variation interact to shape traits involved in stress tolerance, reproduction, and habitat use. This work also incorporates controlled growth studies to distinguish flexible environmental responses from more fixed differences among lineages or populations. This project connects moss systematics with questions about adaptation, biogeography, and the evolution of survival strategies in dry and variable environments.

Variation in biocrust photosynthesis

Mon, 01 Jan 0001 00:00:00 +0000

Desert mosses experience long periods of drying interrupted by brief windows of hydration, making photosynthesis highly dependent on when, where, and how water becomes available. This project examines how biocrust-forming mosses vary in photosynthetic traits across desert environments that differ in precipitation seasonality, temperature, and atmospheric drying demand. We are especially interested in whether seasonal shifts in photosynthetic performance reflect flexible physiological plasticity, longer-term differentiation among populations, or some combination of both. Using field collections, controlled growth experiments, pigment analyses, and chlorophyll fluorescence approaches, this work asks how desert mosses balance carbon gain with protection from excess light, heat, and drought. By comparing natural variation with responses under shared growth conditions, we aim to better understand how much of this variation is environmentally responsive and how much may reflect fixed differences among populations. This project contributes to broader efforts to predict how changing precipitation regimes and warming may affect biocrust carbon balance in dryland ecosystems.