Biology subjects

Rivera, S. R.

Publications and source records attributed to Rivera, S. R..

3 recordsLinked to original sources

bioRxiv2026

Mapping frog genomic diversity on a continental scale

Genetic variation is a key component of population resilience and thus an essential tool for wildlife management. For most species, however, we lack information about their current range-wide genomic diversity and how historical and contemporary factors have shaped those patterns. To address these gaps, we built new georeferenced genomic datasets for 2,481 individuals from 46 frog species to develop a genomic diversity atlas representing 43% of species native to the United States and Canada. We identified geographic "hotspots" of high genomic diversity and "coldspots" of low genomic diversity across species and analyzed potential explanations for these patterns. Our results show that several species have their lowest diversity at northern latitudes, at range edges, or within fragmented populations, suggesting areas in need of careful monitoring. More than half (56.8%) of species exhibited a latitudinal gradient in genomic diversity, but we found little evidence for an association between genomic diversity and human disturbance. Furthermore, discordant latitudinal patterns among species suggest that a combination of factors, including range center-edge dynamics and range fragmentation, interact to produce variable diversity patterns. Our study provides a general framework for mapping range-wide genomic diversity of multiple species to support genetically informed biodiversity conservation.

evolutionary biology↗

bioRxiv2023

THE DUAL ROLE OF THE MICROCYSTIS AERUGINOSA MICROBIOME ON CYANOTOXIN PRODUCTION: COMPETITION FOR AND REMINERALIZATION OF ORGANIC NITROGEN

Nutrient-induced blooms of the globally abundant freshwater toxic cyanobacterium Microcystis are the cause of worldwide public and ecosystem health concerns. The response of Microcystis growth and toxin production to new and recycled nitrogen (N) inputs, and the impact of heterotrophic bacteria in the Microcystis phycosphere on these processes are not well understood. Here, using microbiome transplant experiments, cyanotoxin analysis, and stable isotope tracing to measure N incorporation and exchange at single cell resolution, we monitored the growth, cyanotoxin production, and microbiome community structure of several Microcystis strains grown on amino acids and proteins as the sole N source. We demonstrate that 1) organic N availability shapes the microbiome community structure in the Microcystis phycosphere; 2) external organic N input leads to lower bacterial colonization of the phycosphere; 3) certain Microcystis strains can directly uptake amino acids, but with lower rates than heterotrophic bacteria; 4) biomass-specific microcystin production is not impacted by N source (i.e., nitrate, amino acids and protein) but rather by total N availability; and 5) some bacterial communities compete with Microcystis for organic N, but others remineralize organic N, in the process producing bio-available N for Microcystis. We conclude that organic N input can support Microcystis blooms and toxin production, and Microcystis-associated microbial communities play critical roles by influencing cyanobacterial succession through either decreasing (via competition) or increasing (via remineralization) N availability, especially under inorganic N scarcity.

microbiology↗

bioRxiv2022

The Western Lake Erie Culture Collection: A promising resource for evaluating the physiological and genetic diversity of Microcystis and its associated microbiome

Cyanobacteria harmful algal blooms (cyanoHABs) dominated by Microcystis spp. have significant public health and economic implications in freshwater bodies around the world. These blooms are capable of producing a variety of cyanotoxins, including microcystins, that affect fishing and tourism industries, human and environmental health, and access to drinking water. In this study, we isolated and sequenced the genomes of 21 unialgal Microcystis cultures collected from western Lake Erie between 2017-2019. While some cultures isolated in different years have a high degree of genetic similarity (Average Nucleotide Identity >99%), genomic data shows that these cultures also represent much of the breadth of known Microcystis diversity in natural populations. Only 5 isolates contained all the genes required for microcystin synthesis while 2 isolates contained a previously described partial mcy operon. Microcystin production within cultures was also assessed using Enzyme-Linked Immunosorbent Assay (ELISA) and supported genomic results with high concentrations (up to 900 g L-1) in cultures with complete mcy operons and no or low toxin detected otherwise. These xenic cultures also contained a substantial diversity of bacteria associated with Microcystis, which has become increasingly recognized as an essential component of cyanoHAB community dynamics. These results highlight the genomic diversity among Microcystis strains and associated bacteria in Lake Erie, and their potential impacts on bloom development, toxin production, and toxin degradation. This collection significantly increases the availability of environmentally relevant Microcystis strains from temperate North America, which is changing rapidly due to climate change. HighlightsO_LITwenty one xenic Microcystis cultures were isolated from western Lake Erie and capture the diversity of Microcystis strains observed in natural populations as well as their associated bacteria C_LIO_LIMicrocystis strains show variability in core and accessory gene content, and genetically similar strains produce varying concentrations and congeners of microcystins C_LIO_LIThis collection is a valuable resource for studying strain diversity and interactions between Microcystis and associated bacteria C_LIO_LIOur collection increases the availability of environmentally relevant strains from temperate North America, which is historically underrepresented in culture collections. C_LI

microbiology↗