Biology subjects

Bates, A. E.

Publications and source records attributed to Bates, A. E..

8 recordsLinked to original sources

bioRxiv2024

Cool ocean temperatures fail to buffer the impacts of heat exposure during low tide on the behaviour and physiology of a keystone predator

Air temperatures are warming at faster rates than ocean temperatures, and this "land-sea warming contrast" may create reprieves from thermal stress by providing cool underwater refugia during extreme heat events. Here we tested the impacts of the "land-sea warming contrast" on physiology (metabolism) and behaviour (feeding) in the juvenile life stage of a keystone intertidal predator, Pisaster ochraceus, by experimentally manipulating air ([~]20, 25, 30) and water ([~]15, 20) temperatures (at independent rates) representing early summer, late summer, and heatwave conditions in Barkley Sound (British Columbia, Canada). We further made observations of air temperatures, sea surface temperatures, and Pisaster moribundity at our study location to support interpretation of our results. We predicted metabolism and feeding would increase with early and late summer temperatures, but decrease during heatwave conditions as animals surpass their thermal optimum. We observed the greatest mortality and lowest feeding in juvenile Pisaster exposed to cool ocean temperatures ([~]15) and high aerial temperatures typical of extreme heat events ([~]30). Feeding rates increased with heat stress duration, indicating animals may be compensating for elevated metabolism. Metabolic rates did not differ between air temperatures, but oxygen consumption was higher in animals with access to mussels than for Pisaster that were fasted. The highest levels of experimental and field moribundity were observed in August, indicating Pisaster may have accumulated physiological stress damage following elevated air and ocean temperatures throughout the summer. Our research implicates shifts in community dynamics due to the loss of this keystone species as air temperatures warm. Summary StatementCooler ocean temperatures, rather than creating thermal refugia, may cause physiological stress for juvenile Pisaster ochraceus exposed to warm air during low tide.

ecology↗

bioRxiv2023

Widespread reductions in body size are paired with stable assemblage biomass.

Biotic responses to global change include directional shifts in organismal traits. Body size, an integrative trait that determines demographic rates and ecosystem functions, is often thought to be shrinking in the Anthropocene. Here, we assess the prevalence of body size change in six taxon groups across 5,032 assemblage time-series spanning 1960-2020. Using the Price equation to partition this change into within-species body size versus compositional changes, we detect prevailing decreases in body size through time. Change in assemblage composition contributes more to body size changes than within-species trends, but both components show substantial variation in magnitude and direction. The biomass of assemblages remains remarkably stable as decreases in body size trade-off with increases in abundance. One-Sentence SummaryVariable within-species and compositional trends combine into shrinking body size, abundance increases and stable biomass.

ecology↗

bioRxiv2022

Heating tolerance of ectotherms is explained by temperature's non-linear influence on biological rates

The capacity of ectotherms to adjust their thermal tolerance limits through evolution or acclimation seems relatively modest and highly variable, and we lack satisfying explanations for both findings given a limited understanding of what ultimately determines an organisms thermal tolerance. Here, we test if the amount of heating an ectotherm tolerates throughout a heating event until organismal failure scales with temperatures non-linear influence on biological rates. To account for the non-linear influence of temperature on biological rates on heating tolerance, we rescaled the duration of heating events of 316 ectothermic taxa acclimated to different temperatures and describe the biological rate-corrected heating duration. This rescaling reveals that the capacity of an organism to resist a heating event is in fact remarkably constant across any acclimation temperature, enabling high-precision estimates of how organismal thermal tolerance limits vary under different thermal regimes. We also find that faster heating consistently reduces biological rate-corrected heating durations, which helps further explain why thermal tolerance limits seem so variable on absolute temperature scales. Existing paradigms are that heating tolerances and thermal tolerance limits reflect incomplete metabolic compensatory responses, are constrained by evolutionary conservatism, or index failure of systems such as membrane function; our data provide a different perspective and show that an organisms thermal tolerance emerges from the interaction between the non-linear thermal dependence of biological rates and heating durations, which is an approximately-fixed property of a species.

ecology↗

bioRxiv2021

Species' traits and exposure as a future lens for quantifying seabird bycatch vulnerability in global fisheries

Fisheries bycatch, the incidental mortality of non-target species, is a global threat to seabirds and a major driver of their declines worldwide. Identifying the most vulnerable species is core to developing sustainable fisheries management strategies that aim to improve conservation outcomes. To advance this goal, we present a preliminary vulnerability framework that integrates dimensions of species exposure, sensitivity, and adaptive capacity to fisheries bycatch to classify species into five vulnerability classes. The framework combines species traits and distribution ranges for 341 seabirds, along with a spatially resolved fishing effort dataset. Overall, we find most species have high vulnerability scores for the sensitivity and adaptive capacity dimensions. By contrast, exposure is more variable across species, and thus the median scores calculated within seabird families is low. We further find 46 species have high exposure to fishing activities, but are not identified as vulnerable to bycatch, whilst 133 species have lower exposure, but are vulnerable to bycatch. Thus, the framework has been valuable for revealing patterns between and within the vulnerability dimensions. Still, further methodological development, additional traits, and greater availability of threat data are required to advance the framework and provide a new lens for quantifying seabird bycatch vulnerability that complements existing efforts, such as the International Union for Conservation of Nature (IUCN) Red List.

ecology↗

bioRxiv2021

Bycatch mitigation could prevent strong changes in the ecological strategies of seabird communities across the globe

Fisheries bycatch, the incidental mortality of non-target species, is a major threat to seabirds worldwide. Mitigating bycatch is an important factor to reduce seabird population declines and consequent changes in ocean trophic dynamics and ecosystem functioning. However, it remains an open question how and where mitigating bycatch at a global scale may conserve seabird traits and the ecological strategies that traits represent. Here we combine a dataset of species traits and distribution ranges for 341 seabirds with spatially resolved fishing effort data for gillnet, longline, trawl, and purse seine gears to: (1) understand spatial variation in seabird community traits; and (2) test whether mitigating fisheries bycatch may prevent shifts in traits of seabird communities and loss of ecological strategies. We find distinct spatial variation in the community weighted mean of five seabird traits (clutch size, body mass, generation length, foraging guild, and diet guild). Furthermore, our analysis suggests that successful bycatch mitigation could prevent strong shifts in the traits of seabird communities across the globe particularly in the North Atlantic and Southern Oceans. Specifically, changes in dominant foraging and diet guilds, and shifts towards communities with faster reproductive speeds (larger clutch sizes and shorter generation lengths) and smaller body masses could be avoided. Therefore, bycatch mitigation may have important indirect benefits for sustaining ecosystem functioning, as mediated by species traits. Incorporating species traits into management actions will provide valuable tools for marine spatial planning and when evaluating the success of conservation initiatives.

ecology↗

bioRxiv2020

Biological traits of seabirds predict extinction risk and vulnerability to anthropogenic threats

AimHere we aim to: 1) test whether globally-threatened vs non-threatened seabirds are separated in trait space; 2) quantify the redundancy and uniqueness of species trait combinations per IUCN Red List Category; and 3) identify traits that render species vulnerable to anthropogenic threats. LocationGlobal Time periodContemporary Major taxa studiedSeabirds MethodsWe compile and impute eight traits that relate to species vulnerabilities and ecosystem functioning across 341 seabird species. Using these traits, we build a mixed data PCA of species trait space. We further quantify trait redundancy with a unique trait combinations (UTCs) approach. Finally, we employ a similarity of percentages analysis (SIMPER) to identify which traits explain the greatest difference between threat groups. ResultsWe find seabirds segregate in trait space based on threat status, indicating anthropogenic impacts are selectively removing large, long-lived, pelagic surface feeders with narrow habitat breadths. We further find that globally threatened species have higher trait redundancy, while non-threatened species have relatively unique ecological strategies and limited redundancy. Finally, we find that species with narrow habitat breadths, fast reproductive speeds, and omnivorous diets are more likely to be threatened by habitat-modifying processes (e.g., pollution and natural system modifications); whereas pelagic specialists with slow reproductive speeds and omnivorous diets are vulnerable to threats that directly impact survival and fecundity (e.g., invasive species and biological resource use). Main conclusionsOur results suggest both globally threatened and non-threatened species contribute unique ecological strategies. Consequently, conserving both threat groups, but with contrasting approaches may avoid potential changes in ecosystem functioning and stability.

ecology↗

bioRxiv2019

Temperature-related biodiversity change across temperate marine and terrestrial systems

Climate change is reshaping global biodiversity as species respond to changing temperatures. However, the net effects of climate-driven species redistribution on local assemblage diversity remain unknown. Here, we relate trends in species richness and abundance from 21,500 terrestrial and marine assemblage time series across temperate regions (23.5-60.0{degrees}) to changes in air or sea surface temperature. We find a strong coupling between biodiversity and temperature changes in the marine realm, which is conditional on the baseline climate. We detect increases in species richness with increasing temperature that is twice as pronounced in warmer locations, while abundance declines with warming in the warmest marine locations. In contrast, we did not detect systematic temperature-related richness or abundance trends on land, despite a greater magnitude of warming. We also found no evidence for an interaction between biodiversity change and latitude, further emphasizing the importance of baseline climate in structuring assemblages. As the world is committed to further warming, significant challenges remain in maintaining local biodiversity amongst the non-uniform inflow and outflow of "climate migrants" across distinct regions, especially in the ocean.

ecology↗

bioRxiv2019

HIV-1 genome trafficking initiates APOBEC3G packaging in the cytosol

HIV-1 RNA genomes interact with diverse RNA binding proteins (RBPs) in the cytoplasm including antiviral factor APOBEC3G (A3G) that, in the absence of viral Vif proteins, is packaged into virions. Where and when HIV-1-A3G interactions are initiated for packaging inside the cell is unknown, and the relative contributions of genome vs. Gag capsid proteins to this process remains controversial. Here we visualized A3G responses to HIV-1 infection over an entire replication cycle using long-term (up to 72 h) live single cell imaging. We show that Vif-deficient HIV-1 dramatically shifts A3G and a second RNA surveillance factor, MOV10, from the cytoplasm to virus particle assembly sites with little to no net discernible effects on general markers of cytoplasmic processing bodies (DCP1A), stress granules (TIA-1), or a marker of the nonsense-mediated decay machinery (UPF1). Using a new live cell RNA-protein interaction assay based on RNA tethering (the in-cell RNA-protein interaction protocol, or IC-IP), we provide evidence that A3G- and MOV10- genome interactions are selective, strong, occur in presence or absence of Gag, and are initiated in the cytosol soon if not immediately after genome nuclear export. Finally, although Gag is sufficient to package A3G into virions even in the absence of genomes, single virion imaging indicates that selective A3G-genome interactions promote much more consistent per virion delivery of A3G to assembly sites. Collectively, these studies suggest a paradigm for early, strong, and persistent cytosolic detection of select HIV-1 RNA signatures by A3G, MOV10 and other host RBPs that are enriched in virions. IMPORTANCEHost-pathogen interactions determine the success of viral replication. While extensive work has identified many interactions between HIV-1 and cellular factors, our understanding of where these interactions in cells occur during the course of infection is incomplete. Here, we show that multiple RNA-binding proteins (including the antiviral restriction factor, APOBEC3G, and MOV10 helicase) bind HIV-1 RNA genomes in the cytoplasm and co-traffic with them into progeny virions. Furthermore, we show that these interactions with HIV-1 RNA occur in the absence of Gag and are sufficiently strong to recruit these to otherwise non-native subcellular locales. Together, these data begin to illuminate the intracellular trafficking pathways shared by host RNA binding proteins and the viral RNAs they preferentially bind.

cell biology↗