Archaeal and Bacterial Diversity and Distribution Patterns in Mediterranean-Climate Vernal Pools of Mexico and the Western USA

Abstract

Biogeographic patterns in microorganisms are poorly understood, despite the importance of microbial communities for a range of ecosystem processes. Our knowledge of microbial ecology and biogeography is particularly deficient in rare and threatened ecosystems. We tested for three ecological patterns in microbial community composition within ephemeral wetlands—vernal pools—located across Baja California (Mexico) and California (USA): (1) habitat filtering; (2) a latitudinal diversity gradient; and (3) distance decay in community composition. Paired water and soil samples were collected along a latitudinal transect of vernal pools, and bacterial and archaeal communities were characterized using 16S rDNA sequencing. We identified two main microbial communities, with one community present in the soil matrix that included archaeal and bacterial soil taxa, and another community present in the overlying water that was dominated by common freshwater bacterial taxa. Aquatic microbial communities were more diverse in the north, and displayed a significant but inverted latitudinal diversity pattern. Aquatic communities also exhibited a significant distance-decay pattern, with geographic proximity, and precipitation explaining part of the community variation. Collectively these results indicate greater sensitivity to spatial and environmental variation in vernal pool aquatic microbial communities than in soil microbial communities. We conclude that vernal pool aquatic microbial communities can display distribution patterns similar to those exhibited by larger organisms, but differ in some key aspects, such as the latitudinal gradient in diversity.

Environmental DNA (eDNA) detects temporal and habitat effects on community composition and endangered species in ephemeral ecosystems: A case study in vernal pools

“…The parameters of zone and pool had large discriminatory power on composition in addition to sampling period, which supports previous findings that in spite of the complexity of vernal pools, community compositional variation can be driven by few environmental parameters (Montiel‐Molina et al, 2021; Platenkamp, 1998). Temporal variation in beta diversity was strong in 18S and 16S results and was significant for interactions with zone in FITS and 18S results.…”

“…The of zone and pool had large discriminatory power on composition in addition to period, which supports previous findings that in spite of the complexity of vernal pools, community compositional can be driven by few environmental parameters (Montiel-Molina et al, 2021;Platenkamp, 1998).…”

“…Vernal pools outside of California have been found to possess similar hierarchical environmental drivers (e.g., Ohio, USA: Carrino‐Kyker & Swanson, 2008). Within vernal pools across Baja California and California, microbial communities have been found to vary by climate, with higher species diversity in wetter climates, and to vary linearly by distance (Montiel‐Molina et al, 2021). Additional temporal and spatial sampling is necessary to confirm whether the sampling periods represented interannual variation.…”

“…Despite the importance of vernal pools for hosting endemic and endangered diversity, how diversity is distributed temporally and spatially in vernal pool ecosystems is not well understood (Carl & Blumenshine, 2005). In particular, bacterial and fungal microbes, algae, and meiofauna species thought to be foundational to biodiversity maintenance (Majdi et al, 2020; Wagg et al, 2019) have only recently begun to be surveyed and are in great need of study in vernal pool systems (Carper, 2013; Montiel et al, 2019; Montiel‐Molina et al, 2021). Species diversity patterns in vernal pools have been shown to follow island biogeography patterns (i.e., local adaptation, high levels of endemism and limited dispersal, species‐area relationships) in some studies (Helm, 1998; Holland & Jain, 1981; Montiel‐Molina et al, 2021), but not in others (Brose, 2003; Carl & Blumenshine, 2005).…”

Exploration of Microbial Biodiversity in Ephemeral Pools

“…Our results identified Proteobacteria, Actinobacteria, and Acidobacteria to be major contributors to the ephemeral pool microbial community. These phyla are ubiquitous in soil and water ecosystems, primarily serving as decomposers (Carrino-Kyker & Swanson, 2008;Ghai et al, 2014;Montiel-Molina et al, 2021, andIbekwe et al 2006), supporting the observation that ephemeral pools are generally heterotrophic environments (Carrino-Kyker & Swanson, 2008). Further study of the specific genera of these bacteria will help illuminate their environmental niche in these unique environments, Our study has provided valuable groundwork in not only understanding the composition of these fragile ecosystems, but in providing insight into the microbial component of potential conservation efforts.…”