Biology subjects

Fifer, J. E.

Publications and source records attributed to Fifer, J. E..

3 recordsLinked to original sources

bioRxiv2023

Marine heatwaves threaten cryptic coral diversity and erode associations amongst coevolving partners

Climate change-amplified heatwaves are known to drive extensive mortality in marine foundation species. However, a paucity of longitudinal genomic datasets has impeded understanding of how these rapid selection events alter species genetic structure. Impacts of these events may be exacerbated in species with obligate symbioses, where the genetics of multiple co-evolving species may be affected. Here, we tracked the symbiotic associations and fate of reef-building corals for six years through a prolonged heatwave. Coral genetics strongly predicted survival of the common coral Porites through the event, with strong differential survival (15 to 64%) apparent across morphologically identical -but genetically distinct- lineages. The event also disrupted strong associations between coral lineages and their symbiotic partners, homogenizing symbiotic assemblages across lineages and reducing the specificity of coral-algal symbioses. These results highlight that marine heatwaves threaten cryptic genetic diversity of foundation species and have the potential to decouple tight relationships between co-evolving host-symbiont pairs.

ecology↗

bioRxiv2022

Starvation Decreases Immunity and Immune Regulatory Factor NF-κB in the Starlet Sea Anemone Nematostella vectensis

Lack of proper nutrition (malnutrition) or the complete absence of all food (starvation) have important consequences on the physiology of all organisms. In many cases, nutritional status affects immunity, but, for the most part, the relationship between nutrition and immunity has been limited to studies in vertebrates and terrestrial invertebrates. Herein, we describe a positive correlation between nutrition and immunity in the sea anemone Nematostella vectensis. Gene expression profiling of adult fed and starved anemones showed downregulation of many genes involved in nutrient metabolism and cellular respiration, as well as immune-related genes, in starved animals. Starved adult anemones also had reduced protein levels and DNA-binding activity of immunity-related transcription factor NF-{kappa}B. Starved juvenile anemones had increased sensitivity to bacterial infection and also had lower NF-{kappa}B protein levels, as compared to fed controls. Weighted Gene Correlation Network Analysis (WGCNA) revealed significantly correlated gene networks that were inversely associated with starvation. Based on the WGCNA and a reporter gene assay, we identified TRAF3 as a likely NF-{kappa}B target gene in N. vectensis. Overall, these experiments demonstrate a correlation between nutrition and immunity in a basal marine metazoan, and the results have implications for the survival of marine organisms as they encounter changing environments. Significance StatementAdequate nutrition is required to sustain proper biological function. One factor threatening many marine organisms, as a result of modern day anthropogenic environmental changes, is nutrient availability. Here, we characterize transcriptional changes following food deprivation in the cnidarian model sea anemone Nematostella vectensis. We show that starvation is correlated with decreased expression of genes associated with nutrient metabolism and immunity, among others. Moreover, starvation reduces the level of expression and activity of immune regulatory transcription factor NF-{kappa}B and causes anemones to have increased susceptibility to bacterial infection. These results demonstrate that this basal organism responds at the transcriptional level to the absence of food, and that, in addition to changes in metabolic factors, starvation leads to a reduction in immunity.

immunology↗

bioRxiv2021

Demographic Inferences and Loci Under Selection in a Recently Expanded Coral Population

Coral poleward range expansions in response to warming oceans have been historically observed, however contemporary expansion rates of some coral species have become more rapid as global temperatures rise at unprecedented rates. Range expansion can lead to reduced genetic diversity and surfing of deleterious mutations in expanding populations, potentially limiting the ability for adaption and persistence in novel environments. Successful expansions that overcome these founder effects and colonize new habitat have been attributed to multiple introductions from different sources, hybridization with native populations, or rapid adaptive evolution. Here, we investigate population genomic patterns of the reef-building coral Acropora hyacinthus along a latitudinal cline that includes a well-established range expansion front in Japan using 2b-RAD sequencing. A total of 184 coral samples were collected across seven sites spanning from [~]24{degrees}N to near its northern range front at [~]33{degrees}N. We uncover the presence of three cryptic lineages of A. hyacinthus, which occupy discrete areas within this region. Only one lineage is present at the expansion front and we find evidence of its historical occupation of marginal habitats. Within this lineage we also find evidence of bottleneck pressures associated with expansion events including higher clonality, increased linkage disequilibrium, and lower genetic diversity in range edge populations compared to core populations. Asymmetric migration between populations was also detected with lower migration from edge sites. Lastly, we describe genomic signatures of local adaptation potentially attributed to lower winter temperatures experienced at the more recently expanded northern populations. Together these data illuminate the genomic consequences of range expansion in a coral and highlight how adaptation to colder temperatures along the expansion front may facilitate further range expansion in this coral lineage.

evolutionary biology↗