Global change drivers (e.g., warming, acidification, deoxygenation, harmful algal blooms, etc.) pose individual and combined challenges to the persistence of aquatic populations. There is growing recognition that evolutionary adaptation on contemporary time scales may rescue populations from these challenges. However, cases documenting costs of adaptation and maladaptation that constrain evolutionary rescue remain limited. This session invites contributions documenting processes of adaptation, evolutionary rescue, costs of adaptation, and maladaptation in aquatic populations. We welcome studies at the phenotypic level or genetic level, and particularly their combination using such approaches as experimental evolution, space-for-time substitution, time-series, and the fossil record. Studies that involve multi-stressor experiments and identify the types of interactions (additive, synergistic or antagonistic), or provide new conceptual and methodological perspective on the effects of global change drivers on adaptation are particularly welcome. Across all studies, we seek research that highlights if adaptation is constrained/limited or if populations experience trade-offs/costs (i.e. fitness penalties or decreases) after adapting to novel environments. We seek a diverse group of presentations from students, early career scientists, and well-established researchers working on a variety of organisms from microbial to top predator populations in marine and freshwater habitats.
Lead Organizer: Jimmy deMayo, University of Colorado Denver (jamesdemayo@gmail.com)
Co-organizers:
Hans Dam, University of Connecticut (hans.dam@uconn.edu)
Melissa Pespeni, University of Vermont (melissa.pespeni@uvm.edu)
Reid Brennan, GEOMAR Helmholtz Centre for Ocean Research (reid.brennan@gmail.com)
Cornelia Jaspers, Technical University of Denmark (coja@aqua.dtu.dk)
Presentations
03:00 PM
Plastic and evolutionary responses of a marine diatom to concurrent changes in temperature and nitrate (4785)
Tutorial/Invited: Tutorial
Primary Presenter: Sinéad Collins, University of Edinburgh (s.collins@ed.ac.uk)
Two hallmarks of environmental change in oceans is that first, many aspects of the environment change concurrently. For example, while oceans will warm, the nutrients available for phytoplankton growth in many regions will drop. Second, projections of future environments carry high uncertainty. For example, projections of global average sea surface temperature changes in the coming decades span ~4°C, with uncertainties in local projections being even higher. Because of these two characteristics of ocean change, our understanding of organismal responses to it must be applicable over a wide range of multidriver environments. I will present experimental results of the plastic (short term) and evolutionary (long term) growth of a model diatom in 20-25 different temperature x nitrate environments, with each driver present as a gradient at each level of the other driver, also known as a fully factorial experiment. We show that the ability to respond to warming on all time scales is a function of initial nitrate availability, with the optimum temperature for growth (Topt) being a saturating function of nitrate availability in the short term. In the longer term, the ability to adapt to high temperatures by increasing growth and shifting Topt upwards depends on nitrate availability, and we identify the critical concentration of nitrate needed for adaptation to warming in otherwise ideal environments. Finally, we demonstrate that adaptation is linked to changes in common markers of stress, such as internal pools of reactive oxygen. We also discuss trends in changes in ecologically-important traits such as cell size across the full range of multidriver environments. The resourcing and logistics of fully-factorial multidriver experiments can appear substantial, but we strongly advocate for doing them where possible. Because of this, I will go over the advantages and limitations of laboratory experiments with enough environments to generate response surfaces relative to experiments that use a smaller number of environmental scenarios.
03:15 PM
Adaptations to change in the pelagic: on seasonality, changing risks, and linkages between the annual- and life-cycle scales (6897)
Tutorial/Invited: Invited
Primary Presenter: Øystein Varpe, University of Bergen (oystein.varpe@uib.no)
Global warming and other human stressors are changing aquatic systems. These changes take place on a planet with seasonality, and many of the involved stressors and ecological interactions have some level of seasonality to them. Here I will focus on the interplay between the annual- and life-cycle scales. Much of our work is on behaviour and life history trade-offs in zooplankton species that are impacted by body-size dependent and seasonally varying predation risk caused by fish. Environmental changes are impacting these interactions and trade-offs in complex ways, including via changing duration and timing of the seasonal growth period. I present some of our findings and discuss the scope and constraints for adaptations (phenotypic plasticity as well as evolution) in traits such as body size, voltinism, energy storage, and seasonal timing. Responses are typically state-dependent and can depend on life history strategy, such as where on the gradient from income- to capital-breeding a species is placed. Reduced fecundity through capital breeding can then be one of the implications. New selection pressures have the power to restructure annual routines and life cycles. For instance, increasing size-specific predation risk selects for smaller body size and other characteristics of a faster life cycle, including shorter generation time. Our work illustrates how a range of life history trade-offs interact, are complicated by seasonality, and determine how organisms may adapt to environmental change.
03:30 PM
Prediction of heatwave selection pressure on ectotherm populations (6840)
Primary Presenter: Jahangir Vajedsamiei, GEOMAR (jvajedsamiei@geomar.de)
Extreme events, notably summer heatwaves, are exacerbated by global climate change. The susceptibility of a species to heatwaves likely depends on several variables, including the duration and intensity of thermal exposure. While heat survival time models (thermal tolerance landscapes) have a century-long history, their core assumptions still need to be tested under dynamic heatwave regimes. This study first examines whether the model based on log-linear regression of lethality buildup rates in response to constant temperatures can fairly predict the survival probability of a mussel population observed under heatwave regimes. Therefore, we conducted a protocol consisting of an indoor experiment of heat selection under constant temperatures, an outdoor experiment under dynamic heatwave regimes, and a Monte-Carlo simulation framed around the mathematically formulated assumptions. Second, we provide a Markov-Chain Monte-Carlo Approximate-Bayesian algorithm to separately predict posterior parameter distributions using the observed heatwave survival data for each experiment. We indicate that the new approach can inform regarding populations’ heat lethality buildup and sensitivity parameters and, therefore, it is applicable to test hypotheses about acclimation or adaptation effect on the parameters defining the population survival trajectory and to provide local prediction of future heatwave selection pressures on natural and aqua-cultured populations.
03:45 PM
Hybridization patterns and physiological performance in the invasive comb jelly Mnemiopsis leidyi along the US Atlantic coast (6311)
Primary Presenter: Marti Pujolar, DTU (martipujolar@gmail.com)
Natural hybridization between individuals from genetically distinct populations or species, resulting in gene flow and subsequent introgression, plays a major role in evolution, together with natural selection and genetic drift. Hybridization may contribute to speciation as a potential source of adaptive novelty by the introgression of selectively favored alleles in the recipient population. In our study, we use single-nucleotide polymorphisms (SNPs) arrays to study and monitor genetic diversity as well as population structure in the comb jelly Mnemiopsis leidyi along the US Atlantic coast from Cape Cod to Chesapeake Bay. In particular, focusing on investigating patterns, directionality and evolution of hybridization. While all individuals north off Chesapeake Bay along the US east- coast were suggested to be non-admixed, the majority of individuals from Chesapeake Bay were of admixed origin. Hybridization was not restricted to F1 hybrids and first and second generation backcrosses were observed and hence introgression, which points to hybrids having an evolutionary advantage to thrive in the particular conditions of Chesapeake Bay. However, common garden experiments investigating the performance of hybrids under controlled conditions do not suggest a superior performance in terms of egg production, pointing to other mechanisms driving hybridization events in extreme events in nature.
04:00 PM
WARMING ADAPTATION TRADE-OFFS IN CORAL SYMBIONT SYMBIODINIUM ADRIATICUM FROM THE RED SEA (5730)
Primary Presenter: Isabel Armelles Vicent, King Abdullah University of Science and Technology (KAUST) (isabel.armellesvicent@kaust.edu.sa)
Coral reefs are under threat by ocean warming leading to the death of the endosymbiotic Symbiodinium with consequent bleaching. Several experiments proved Symbiodinium capacity for warming adaptation. We assessed the cost of adaptation to warmer conditions in Red Sea isolated Symbiodinium adriaticum long-term adapted to ambient (26 ºC) and warming (32 ºC) temperatures. Temperature adaptation’s trade-offs were tested in population growth, photosynthetic performance and oxidative stress. Ambient adapted cultures reached higher growth rates, but warming adapted strain showed a higher optimum growth temperature. Production of intracellular reactive oxygen species (ROS) was similar in both strains at low and medium temperatures. However, at 32 ºC, warming adapted strain kept the same levels of reactive oxygen species as in lower temperature treatments, clearly showing a better capacity to cope with thermal stress. Photosynthetic performance was measured using the maximum photochemical quantum yield (Fv/Fm). Ambient adapted strain showed a significant decrease in photosynthetic performance in all treatments above 26 ºC along the experiment, whereas Fv/Fm values were more stable for warming strain. We demonstrated that warming adapted strain seems to cope better with thermal stress and its main consequence, ROS production, by keeping same production levels or not affecting its removal capacity, although reducing maximum growth rate. We also exposed the two adapted strains to UVB radiation to analyze whether warming adaptation could represent a cost facing multiple stressors.
04:15 PM
GENOMIC MECHANISMS OF PARALLEL ADAPTATION DURING HABITAT SHIFTS IN A COPEPOD (5079)
Tutorial/Invited: Invited
Primary Presenter: Carol Eunmi LEE, University of Wisconsin, Madison (carollee@wisc.edu)
Climate change is inducing rapid salinity and temperature change in coastal habitats. Thus, the ability of populations to expand their ranges presents among the most serious global problems today. However, fundamental mechanisms that enable certain populations to rapidly adapt to novel habitats remain poorly understood. Recently, populations of the copepod Eurytemora affinis complex have experienced drastic changes in habitat salinity and temperature. These copepods are dominant grazers in aquatic habitats throughout the Northern Hemisphere and support major fisheries. Intriguingly, we discovered that evolutionary changes during salinity transitions repeatedly involve the same loci (and SNPs) in wild populations and laboratory selection lines far beyond expectations. In both wild populations and laboratory lines, ion transporter genes dominate as the functional category undergoing natural selection. Using extensive simulations, we found that this degree of parallelism was consistent with positive synergistic epistasis among alleles, where selection on one allele promotes selection on other related alleles. Our results were consistent with mechanisms of ion uptake from dilute habitats, requiring the coordinated action of cooperating ion transporter proteins. Interestingly, temperature adaptation resulted in selection acting on an entirely different set of loci, indicating tradeoffs between salinity and temperature adaptation. Here, we find strong support for a novel and potentially widespread mechanism, namely positive epistasis, in promoting parallel polygenic adaptation.
SS082 Mechanisms and Costs of Adaptation to Global Change in Aquatic Systems
Description
Time: 3:00 PM
Date: 5/6/2023
Room: Sala Menorca A