A recent theory of the vertical distribution of phytoplankton considers how interacting niche construction processes such as resource depletion, behavior, and population dynamics contribute to spatial heterogeneity in the aquatic environment. In poorly mixed water columns with opposing resource gradients of nutrients and light, theory predicts that a species should aggregate at a single depth. This depth of aggregation, or biomass maximum, should change through time due to depletion of available resources. In addition, the depth of the aggregation should be deeper under low amounts of nutrient loading and shallower under higher amounts of nutrient loading. Theory predicts total biomass to exhibit a saturating relationship with nutrient supply. A surface biomass maximum limited by light and a deep biomass maximum limited by nutrients or co-limited by nutrients and light is also predicted by theory. To test this theory, we used a motile phytoplankton species (Chlamydomonas reinhardtii) growing in cylindrical plankton towers. In our experiment, the resource environment was strongly modified by the movement, self-shading, nutrient uptake, and growth of the phytoplankton. Supporting predictions, we routinely observed a single biomass maximum at the surface throughout the course of the experiment and at equilibrium under higher nutrient loading. However, at equilibrium, low nutrient loading led to a non-distinct biomass maximum with the population distributed over most of the water column instead of the distinct subsurface peak predicted by theory. Also supporting predictions, total biomass across water columns was positively related to nutrient supply but saturating at high nutrient supply conditions. Further supporting predictions, we also found evidence of light limitation for a surface biomass maximum and nutrient limitation for the deep biomass when no surface maximum was present. In addition, the light level leaving the bottom of the water column declined through time as the phytoplankton grew and was negatively related to nutrient loading. Nutrients were strongly depleted where biomass was present by the end of the experiment. This experimental study shows that the vertical distribution of phytoplankton may be driven by intraspecific resource competition in space.

Ongoing climate change is shifting species distributions and increasing extinction risks globally. It is generally thought that large population sizes and short generation times of marine phytoplankton may allow them to adapt rapidly to global change, including warming, thus limiting losses of biodiversity and ecosystem function. Here, we show that a marine diatom survives high, previously lethal, temperatures after adapting to above-optimal temperatures under nitrogen (N)-replete conditions. N limitation, however, precludes thermal adaptation, leaving the diatom vulnerable to high temperatures. A trade-off between high-temperature tolerance and increased N requirements may explain why N limitation inhibited adaptation. Because oceanic N limitation is common and likely to intensify in the future, the assumption that phytoplankton will readily adapt to rising temperatures may need to be reevaluated.

C:N ratios of the two 34C‐tolerant populations of Chaetoceros simplex and control and ancestral populations, at different temperatures. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/778926 Copyright: https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0

Daily growth rates of 8 populations of Chaetoceros simplex grown at 31C and control population at 25C, in regular L1 medium (884 mum NO3) or nitrogen‐reduced L1 medium (5 mum NO3). For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/778869 Copyright: https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0

Daily growth rates for Thermal Performance Curve (TPC) of Chaetoceros simplex in nitrogen-replete evolved populations after about 200 generations of evolution at eight temperatures, 10-35 degrees C. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/778779 Copyright: https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0

Daily growth rates for Thermal Performance Curve (TPC) of Chaetoceros simplex after about 100 generations of evolution at seven temperatures, 12-34 degrees C. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/778749 Copyright: https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0

Current algal biomass research still focuses mainly on identifying and growing monocultures that produce high amounts of lipids or other target compounds. However, monocultures might have a lower efficiency of utilizing resources, due to their limited physiological resource use possibilities, compared to algal polycultures. Recent studies showed that species diversity enhances the lipid production of microalgae. To identify the general patterns of enhanced lipid production in diverse microalgal communities it is essential to investigate links between resource use complementarity and the corresponding lipid production.

Environments change, for both natural and anthropogenic reasons, which can threaten species persistence. Evolutionary adaptation is a potentially powerful mechanism to allow species to persist in these changing environments. To determine the conditions under which adaptation will prevent extinction (evolutionary rescue), classic quantitative genetics models have assumed a constantly changing environment. They predict that species traits will track a moving environmental optimum with a lag that approaches a constant. If fitness is negative at this lag, the species will go extinct. There have been many elaborations of these models incorporating increased genetic realism. Here, we review and explore the consequences of four ecological complications: non-quadratic fitness functions, interacting density- and trait-dependence, species interactions and fundamental limits to adaptation. We show that non-quadratic fitness functions can result in evolutionary tipping points and existential crises, as can the interaction between density- and trait-dependent mortality. We then review the literature on how interspecific interactions affect adaptation and persistence. Finally, we suggest an alternative theoretical framework that considers bounded environmental change and fundamental limits to adaptation. A research programme that combines theory and experiments and integrates across organizational scales will be needed to predict whether adaptation will prevent species extinction in changing environments. Copyright: CC BY 4.0

A synthesis of phenotypic and quantitative genomic traits is provided for bacteria and archaea, in the form of a scripted, reproducible workflow that standardizes and merges 26 sources. The resulting unified dataset covers 14 phenotypic traits, 5 quantitative genomic traits, and 4 environmental characteristics for approximately 170,000 strain-level and 15,000 species-aggregated records. It spans all habitats including soils, marine and fresh waters and sediments, host-associated and thermal. Trait data can find use in clarifying major dimensions of ecological strategy variation across species. They can also be used in conjunction with species and abundance sampling to characterize trait mixtures in communities and responses of traits along environmental gradients.

Environmental factors that interact with increasing temperature under the ongoing global warming are an urgent issue determining marine phytoplankton's performance. Previous studies showed that nutrient limitation alters phytoplankton responses to temperature and may lower their temperature optima (T-opt), making them more susceptible to high temperatures. The generality of this relationship is unknown, as very few species were tested. Here we investigated how growth rate depended on temperature at two contrasting nitrogen concentrations in six marine diatoms isolated from different thermal environments, including the tropics. Low nitrate had a significant effect on thermal performance in five of the six species. The effect size was larger around the optimum temperature for growth, resulting in flattened thermal performance curves but no shift in T-opt. While that trend is independent of the thermal regime from which each species was isolated, the implications for the phytoplankton response to global warming may be region dependent.