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The abundance distribution and species richness of encysted plankton have been investigated in the bottom sediments of the Taranto Marine System (southern Italy) for contributing to the understanding of plankton dynamics in a confined coastal area. This confined area is characterized by four contiguous basins with different degrees of confinement. The investigation was carried out in the fall season with the aim to intercept a period of rich cyst production from the plankton before overwintering. From the analysis of a total of 36 sediment samples, from 12 sample sites, the highest abundance of cysts and species richness were registered in the confined part of the system. A total of 103 cyst morphotypes have been recognized in the whole area, with highest abundances and taxa richness in the most confined stations. These results, suggesting a benthic-pelagic exchange of living matter, more intense in confined environments than in the open sea, highlight the necessity of (i) including the analysis of sediment cyst banks in studies of plankton dynamics, and (ii) to consider the role of confined areas, where the variability of environmental conditions favours a higher planktonic biodiversity in the sediments than in the water column. [ABSTRACT FROM AUTHOR]

Predators can strongly influence prey populations not only through consumptive effects (CE) but also through non‐consumptive effects (NCE) imposed by predation risk. Yet, the impact of NCE on bioenergetic and stoichiometric body contents of prey, traits that are shaping life histories, population and food web dynamics, is largely unknown. Moreover, the degree to which NCE can evolve and can drive evolution in prey populations is rarely studied.A 6‐week outdoor mesocosm experiment with Caged‐Fish (NCE) and Free‐Ranging‐Fish (CE and NCE) treatments was conducted to quantify and compare the effects of CE and NCE on population densities, bioenergetic and stoichiometric body contents of Daphnia magna, a keystone species in freshwater ecosystems. We tested for evolution of CE and NCE by using experimental populations consisting of D. magna clones from two periods of a resurrected natural pond population: a pre‐fish period without fish and a high‐fish period with high predation pressure.Both Caged‐Fish and Free‐Ranging‐Fish treatments decreased the body size and population densities, especially in Daphnia from the high‐fish period. Only the Free‐Ranging‐Fish treatment affected bioenergetic variables, while both the Caged‐Fish and Free‐Ranging‐Fish treatments shaped body stoichiometry. The effects of CE and NCE were different between both periods indicating their rapid evolution in the natural resurrected population. Both the Caged‐Fish and Free‐Ranging‐Fish treatments changed the clonal frequencies of the experimental Daphnia populations of the pre‐fish as well as the high‐fish period, indicating that not only CE but also NCE induced clonal sorting, hence rapid evolution during the mesocosm experiment in both periods.Our results demonstrate that CE as well as NCE have the potential to change not only the body size and population density but also the bioenergetic and stoichiometric characteristics of prey populations. Moreover, we show that these responses not only evolved in the studied resurrected population, but that CE and NCE also caused differential rapid evolution in a time frame of 6 weeks (ca. four to six generations). As NCE can evolve as well as can drive evolution, they may play an important role in shaping eco‐evolutionary dynamics in predator–prey interactions. [ABSTRACT FROM AUTHOR]

Summary: Plant–pollinator interactions evolved early in the angiosperm radiation. Ongoing environmental changes are however leading to pollinator declines that may cause pollen limitation to plants and change the evolutionary pressures shaping plant mating systems.We used resurrection ecology methodology to contrast ancestors and contemporary descendants in four natural populations of the field pansy (Viola arvensis) in the Paris region (France), a depauperate pollinator environment. We combine population genetics analysis, phenotypic measurements and behavioural tests on a common garden experiment.Population genetics analysis reveals 27% increase in realized selfing rates in the field during this period. We documented trait evolution towards smaller and less conspicuous corollas, reduced nectar production and reduced attractiveness to bumblebees, with these trait shifts convergent across the four studied populations.We demonstrate the rapid evolution of a selfing syndrome in the four studied plant populations, associated with a weakening of the interactions with pollinators over the last three decades. This study demonstrates that plant mating systems can evolve rapidly in natural populations in the face of ongoing environmental changes. The rapid evolution towards a selfing syndrome may in turn further accelerate pollinator declines, in an eco‐evolutionary feedback loop with broader implications to natural ecosystems. See also the Commentary on this article by Kelly, 242: 331–332. [ABSTRACT FROM AUTHOR]

Premise: Increased aridity and drought associated with climate change are exerting unprecedented selection pressures on plant populations. Whether populations can rapidly adapt, and which life history traits might confer increased fitness under drought, remain outstanding questions. Methods: We utilized a resurrection ecology approach, leveraging dormant seeds from herbarium collections to assess whether populations of Plantago patagonica from the semi‐arid Colorado Plateau have rapidly evolved in response to approximately ten years of intense drought in the region. We quantified multiple traits associated with drought escape and drought resistance and assessed the survival of ancestors and descendants under simulated drought. Results: Descendant populations displayed a significant shift in resource allocation, in which they invested less in reproductive tissues and relatively more in both above‐ and below‐ground vegetative tissues. Plants with greater leaf biomass survived longer under terminal drought; moreover, even after accounting for the effect of increased leaf biomass, descendant seedlings survived drought longer than their ancestors. Conclusions: Our results document rapid adaptive evolution in response to climate change in a selfing annual and suggest that shifts in tissue allocation strategies may underlie adaptive responses to drought in arid or semi‐arid environments. This work also illustrates a novel approach, documenting that under specific circumstances, seeds from herbarium specimens may provide an untapped source of dormant propagules for future resurrection experiments. [ABSTRACT FROM AUTHOR]

Abstract The climate is currently warming fast, threatening biodiversity all over the globe. Populations often adapt rapidly to environmental change, but for climate warming very little evidence is available. Here, we investigate the pattern of adaptation to an extreme +10°C climate change in the wild, following the introduction of brine shrimp Artemia franciscana from San Francisco Bay, USA, to Vinh Chau saltern in Vietnam. We use a resurrection ecology approach, hatching diapause eggs from the ancestral population and the introduced population after 13 and 24 years (∼54 and ∼100 generations, respectively). In a series of coordinated experiments, we determined whether the introduced Artemia show increased tolerance to higher temperatures, and the extent to which genetic adaptation, developmental plasticity, transgenerational effects, and local microbiome differences contributed to this tolerance. We find that introduced brine shrimp do show increased phenotypic tolerance to warming. Yet strikingly, these changes do not have a detectable additive genetic component, are not caused by mitochondrial genetic variation, and do not seem to be caused by epigenetic marks set by adult parents exposed to warming. Further, we do not find any developmental plasticity that would help cope with warming, nor any protective effect of heat‐tolerant local microbiota. The evolved thermal tolerance might therefore be entirely due to transgenerational (great)grandparental effects, possibly epigenetic marks set by parents who were exposed to high temperatures as juveniles. This study is a striking example of “missing heritability,” where a large adaptive phenotypic change is not accompanied by additive genetic effects.

Abstract There has been a steady rise in the use of dormant propagules to study biotic responses to environmental change over time. This is particularly important for organisms that strongly mediate ecosystem processes, as changes in their traits over time can provide a unique snapshot into the structure and function of ecosystems from decades to millennia in the past. Understanding sources of bias and variation is a challenge in the field of resurrection ecology, including those that arise because often‐used measurements like seed germination success are imperfect indicators of propagule viability. Using a Bayesian statistical framework, we evaluated sources of variability and tested for zero‐inflation and overdispersion in data from 13 germination trials of soil‐stored seeds of Schoenoplectus americanus, an ecosystem engineer in coastal salt marshes in the Chesapeake Bay. We hypothesized that these two model structures align with an ecological understanding of dormancy and revival: zero‐inflation could arise due to failed germinations resulting from inviability or failed attempts to break dormancy, and overdispersion could arise by failing to measure important seed traits. A model that accounted for overdispersion, but not zero‐inflation, was the best fit to our data. Tetrazolium viability tests corroborated this result: most seeds that failed to germinate did so because they were inviable, not because experimental methods failed to break their dormancy. Seed viability declined exponentially with seed age and was mediated by seed provenance and experimental conditions. Our results provide a framework for accounting for and explaining variability when estimating propagule viability from soil‐stored natural archives which is a key aspect of using dormant propagules in eco‐evolutionary studies.

Premise: As part of global change, climate warming and pollinator decline are expected to affect plant phenology and plant–pollinator interactions. This paper aims at characterizing rapid evolution of life history traits and floral traits over two decades in the wild pansy (Viola arvensis), a common weed in agrosystems. Methods: We used a resurrection ecology approach with genotypes sampled in 1991 and 2012 from a population in Burgundy (France). The species has a mixed mating system (hereafter: mixed selfer) and presents a floral polymorphism. To correct for maternal effects, we measured plant traits in the second generation in a common garden (after a refreshing generation) to characterize plant evolution during the two decades. In addition, historical population selfing rates in 1991 and 2012 were inferred from microsatellites markers through heterozygote deficiency and identity disequilibrium. Results: Phenotypic data revealed a significant advance in flowering date, reduced flower sizes and a higher propensity of plants to set seed by autonomous selfing. Moreover, we detected a change in color morph frequency with an increase of the pale morph frequency. In accordance with phenotypic data, the neutral genetic data revealed an increase in historical selfing rates from 0.68 in 1991 to 0.86 in 2012. Conclusions: Taken together, such data suggest that the wild pansy, a mixed selfer, is evolving a selfing syndrome that may be the consequence of reduced pollinator activity in agrosystems. [ABSTRACT FROM AUTHOR]

Although it is becoming widely appreciated that microbes can enhance plant tolerance to environmental stress, the nature of microbial mediation of exposure responses is not well understood. We addressed this deficit by examining whether microbial mediation of plant responses to elevated salinity is contingent on the environment and factors intrinsic to the host. We evaluated the influence of contrasting environmental conditions relative to host genotype, provenance and evolution by conducting a common‐garden experiment utilizing ancestral and descendant cohorts of Schoenoplectus americanus genotypes recovered from two 100+ year coastal marsh seed banks. We compared S. americanus productivity and trait variation as well as associated endophytic microbial communities according to plant genotype, provenance, and age cohort under high and low salinity stress with and without native soil inoculation. The magnitude and direction of microbial mediation of S. americanus responses to elevated salinity varied according to individual genotype, provenance, as well as temporal shifts in genotypic variation and G × E (gene by environment) interactions. Relationships differed between plant traits and the structure of endosphere communities. Our findings indicate that plant‐microbe associations and microbial mediation of plant stress are not only context‐dependent but also dynamic. Our results additionally suggest that evolution can shape the fate of marsh ecosystems by altering how microbes confer plant tolerance to pressures linked to global change. [ABSTRACT FROM AUTHOR]

The climate is currently warming fast, threatening biodiversity all over the globe. Populations often adapt rapidly to environmental change, but for climate warming very little evidence is available. Here, we investigate the pattern of adaptation to an extreme +10°C climate change in the wild, following the introduction of brine shrimp Artemia franciscana from San Francisco Bay, USA, to Vinh Chau saltern in Vietnam. We use a resurrection ecology approach, hatching diapause eggs from the ancestral population and the introduced population after 13 and 24 years (∼54 and ∼100 generations, respectively). In a series of coordinated experiments, we determined whether the introduced Artemia show increased tolerance to higher temperatures, and the extent to which genetic adaptation, developmental plasticity, transgenerational effects, and local microbiome differences contributed to this tolerance. We find that introduced brine shrimp do show increased phenotypic tolerance to warming. Yet strikingly, these changes do not have a detectable additive genetic component, are not caused by mitochondrial genetic variation, and do not seem to be caused by epigenetic marks set by adult parents exposed to warming. Further, we do not find any developmental plasticity that would help cope with warming, nor any protective effect of heat‐tolerant local microbiota. The evolved thermal tolerance might therefore be entirely due to transgenerational (great)grandparental effects, possibly epigenetic marks set by parents who were exposed to high temperatures as juveniles. This study is a striking example of "missing heritability," where a large adaptive phenotypic change is not accompanied by additive genetic effects. [ABSTRACT FROM AUTHOR]

Abstract Evidence is mounting that climate‐driven shifts in environmental conditions can elicit organismal evolution, yet there are sparingly few long‐term records that document the tempo and progression of responses, particularly for plants capable of transforming ecosystems. In this study, we “resurrected” cohorts of a foundational coastal marsh sedge (Schoenoplectus americanus) from a time‐stratified seed bank to reconstruct a century‐long record of heritable variation in response to salinity exposure. Common‐garden experiments revealed that S. americanus exhibits heritable variation in phenotypic traits and biomass‐based measures of salinity tolerance. We found that responses to salinity exposure differed among the revived cohorts, with plants from the early 20th century exhibiting greater salinity tolerance than those from the mid to late 20th century. Fluctuations in salinity tolerance could reflect stochastic variation but a congruent record of genotypic variation points to the alternative possibility that the loss and gain in functionality are driven by selection, with comparisons to historical rainfall and paleosalinity records suggesting that selective pressures vary according to shifting estuarine conditions. Because salinity tolerance in S. americanus is tightly coupled to primary productivity and other vital ecosystem attributes, these findings indicate that organismal evolution merits further consideration as a factor shaping coastal marsh responses to climate change.

Predators can strongly influence prey populations through both consumptive and non-consumptive effects. Nevertheless, most studies have focused on the consumptive effects in driving evolutionary changes. By integrating experimental evolution and resurrection ecology, we tested the roles of non-consumptive and consumptive effects in driving evolution in a Daphnia magna population that experienced strong changes in fish predation pressure. All resurrected genotypes were pooled, inoculated in outdoor mesocosms, and exposed to free-fish or caged-fish treatments. Non-consumptive effects induced rapid, repeatable changes in the clonal composition and associated genotypic trait changes that were similar in magnitude and direction to those imposed by killing. Both non-consumptive and consumptive effects caused a shift towards a dominance of the high-fish period clones that can perform better under fish predation, and this may be explained by the higher intrinsic growth rate of the high-fish period clones under predation risk. The genotypic trait changes (e.g. reduced body sizes, earlier maturation, more and smaller offspring) of the Daphnia in the mesocosm experiments were in the same direction as the adaptive trait shifts observed in situ through resurrection ecology. Our results demonstrate that non-consumptive effects can induce rapid adaptive evolution and may represent an overlooked driver of eco-evolutionary dynamics. [ABSTRACT FROM AUTHOR]

Premise of the studyProject Baseline is a seed bank that offers an unprecedented opportunity to examine spatial and temporal dimensions of microevolution during an era of rapid environmental change. Over the upcoming 50 years, biologists will withdraw genetically representative samples of past populations from this time capsule of seeds and grow them contemporaneously with modern samples to detect any phenotypic and molecular evolution that has occurred during the intervening time.MethodsWe carefully developed this living genome bank using protocols to enhance its experimental value by collecting from multiple populations and species across a broad geographical range in sites that are likely to be preserved into the future. Seeds are accessioned with site and population data and are stored by maternal line under conditions that maximize seed longevity. This open-access resource will be available to researchers at regular intervals to evaluate contemporary evolution.Key resultsTo date, the Project Baseline collection includes 100-200 maternal lines of each of 61 species collected from over 831 populations on sites that are likely to be preserved into the future across the United States (∼78,000 maternal lines). Our strategically designed collection circumvents some problems that can cloud the results of "resurrection" studies involving naturally preserved or existing seed collections that are available fortuitously.ConclusionsThe resurrection approach can be coupled with long-established and newer techniques over the next five decades to elucidate genetic change and thereby vastly improve our understanding of temporal and spatial changes in phenotype and the evolutionary processes underlying it.

Historical herbarium collections have been proposed as a last resort for recovery of extinct plant species not represented in dedicated seed banks or other living conservation collections. For critically endangered plants at the brink of extinction, herbarium collections may also contain historical material from extinct subpopulations representing a species' former range and lost genetic diversity of high value for conservation management. We explored the potential for germination of 81 critically endangered seed plant taxa endemic to the Hawaiian island of Kaua'i from herbarium specimens in herbarium PTBG of the National Tropical Botanical Garden (NTBG). Of 1250‐recorded specimens of wild origin, 138 specimens representing 37 taxa contained mature seeds that could be subjected to germination testing. Seven of these taxa were not represented by any NTBG seed bank collections. Fresh embryos were observed in one seed of each of the three species Schiedea helleri, Schiedea kauaiensis, and Viola helena. While potential germination success may be low, we conclude that testing of seeds from herbarium collections should be extended from a focus on strictly extinct taxa to critically endangered taxa, which may not have sufficient representation in seed banks or other living collections of subpopulations and genetic diversity across their wild range. [ABSTRACT FROM AUTHOR]

Premise: Understanding the adaptive capacities of species over long timescales lies in examining the revived recent and millennia‐old resting spores buried in sediments. We show for the first time the revival, viability, and germination rate of resting spores of the diatom Chaetoceros deposited in sub‐seafloor sediments from three ages (recent: 0 to 80 years; ancient: ~1250 (Medieval Climate Anomaly) and ~6600 (Holocene Thermal Maximum) calendar year before present. Methods: Recent and ancient Chaetoceros spores were revived to examine their viability and germination rate. Light and scanning electron microscopy and Sanger sequencing was done to identify the species. Results: We show that ~6600 cal. year BP old Chaetoceros resting spores are still viable and that the vegetative reproduction in recent and ancient resting spores varies. The time taken to germinate is three hours to 2 to 3 days in both recent and ancient spores, but the germination rate of the spores decreased with increasing age. The germination rate of the recent spores was ~41% while that of the ancient spores were ~31% and ~12% for the ~1250 and ~6600 cal. year BP old resting spores, respectively. Based on the morphology of the germinated vegetative cells we identified the species as Chaetoceros muelleri var. subsalsum. Sanger sequences of nuclear and chloroplast markers identified the species as Chaetoceros muelleri. Conclusions: We identify a unique model system, Chaetoceros muelleri var. subsalsum and show that recent and ancient resting spores of the species buried in sediments in the Baltic Sea can be revived and used for long‐term evolutionary studies. [ABSTRACT FROM AUTHOR]

There has been a steady rise in the use of dormant propagules to study biotic responses to environmental change over time. This is particularly important for organisms that strongly mediate ecosystem processes, as changes in their traits over time can provide a unique snapshot into the structure and function of ecosystems from decades to millennia in the past. Understanding sources of bias and variation is a challenge in the field of resurrection ecology, including those that arise because often‐used measurements like seed germination success are imperfect indicators of propagule viability. Using a Bayesian statistical framework, we evaluated sources of variability and tested for zero‐inflation and overdispersion in data from 13 germination trials of soil‐stored seeds of Schoenoplectus americanus, an ecosystem engineer in coastal salt marshes in the Chesapeake Bay. We hypothesized that these two model structures align with an ecological understanding of dormancy and revival: zero‐inflation could arise due to failed germinations resulting from inviability or failed attempts to break dormancy, and overdispersion could arise by failing to measure important seed traits. A model that accounted for overdispersion, but not zero‐inflation, was the best fit to our data. Tetrazolium viability tests corroborated this result: most seeds that failed to germinate did so because they were inviable, not because experimental methods failed to break their dormancy. Seed viability declined exponentially with seed age and was mediated by seed provenance and experimental conditions. Our results provide a framework for accounting for and explaining variability when estimating propagule viability from soil‐stored natural archives which is a key aspect of using dormant propagules in eco‐evolutionary studies. [ABSTRACT FROM AUTHOR]

Abstract Historical herbarium collections have been proposed as a last resort for recovery of extinct plant species not represented in dedicated seed banks or other living conservation collections. For critically endangered plants at the brink of extinction, herbarium collections may also contain historical material from extinct subpopulations representing a species' former range and lost genetic diversity of high value for conservation management. We explored the potential for germination of 81 critically endangered seed plant taxa endemic to the Hawaiian island of Kaua'i from herbarium specimens in herbarium PTBG of the National Tropical Botanical Garden (NTBG). Of 1250‐recorded specimens of wild origin, 138 specimens representing 37 taxa contained mature seeds that could be subjected to germination testing. Seven of these taxa were not represented by any NTBG seed bank collections. Fresh embryos were observed in one seed of each of the three species Schiedea helleri, Schiedea kauaiensis, and Viola helena. While potential germination success may be low, we conclude that testing of seeds from herbarium collections should be extended from a focus on strictly extinct taxa to critically endangered taxa, which may not have sufficient representation in seed banks or other living collections of subpopulations and genetic diversity across their wild range.

Multiple stressors linked to anthropogenic activities can influence how organisms adapt and evolve. So far, a consensus on how multiple stressors drive adaptive trajectories in natural populations has not been reached. Some meta‐analysis reports show predominance of additive effects of stressors on ecological endpoints (e.g., fecundity, mortality), whereas others show synergistic effects more frequently. Moreover, it is unclear what mechanisms of adaptation underpin responses to complex environments. Here, we use populations of Daphnia magna resurrected from different times in the past to investigate mechanisms of adaptation to multiple stressors and to understand how historical exposure to environmental stress shapes adaptive responses of modern populations. Using common garden experiments on resurrected modern and historical populations, we investigate (1) whether exposure to one stress results in higher tolerance to a second stressor; (2) the mechanisms of adaptation underpinning long‐term evolution to multistress (genetic evolution, plasticity, evolution of plasticity); and (3) the interaction effects of multiple stressors on fitness (synergism, antagonism, additivity). We measure the combined impact of different levels of resource availability (algae) and biocides on fitness‐linked life‐history traits and interpret these results in light of historical environmental exposures. We show that exposure to one stressor can alter tolerance to second stressors and that the interaction effect depends on the severity of either stressor. We also show that mechanisms of adaptation underpinning phenotypic evolution significantly differ in single‐stress and multistress scenarios. These adaptive responses are driven largely by synergistic effects on fecundity and size at maturity, and additive effects on age at maturity. Exposure to multiple stressors shifts the trade‐offs among fitness‐linked life‐history traits, with a stronger effect on Daphnia populations when low‐resource availability and high biocide levels are experienced. Our study indicates that mitigation interventions based on single‐stress analysis may not capture realistic threats. [ABSTRACT FROM AUTHOR]

Evidence is mounting that climate‐driven shifts in environmental conditions can elicit organismal evolution, yet there are sparingly few long‐term records that document the tempo and progression of responses, particularly for plants capable of transforming ecosystems. In this study, we "resurrected" cohorts of a foundational coastal marsh sedge (Schoenoplectus americanus) from a time‐stratified seed bank to reconstruct a century‐long record of heritable variation in response to salinity exposure. Common‐garden experiments revealed that S. americanus exhibits heritable variation in phenotypic traits and biomass‐based measures of salinity tolerance. We found that responses to salinity exposure differed among the revived cohorts, with plants from the early 20th century exhibiting greater salinity tolerance than those from the mid to late 20th century. Fluctuations in salinity tolerance could reflect stochastic variation but a congruent record of genotypic variation points to the alternative possibility that the loss and gain in functionality are driven by selection, with comparisons to historical rainfall and paleosalinity records suggesting that selective pressures vary according to shifting estuarine conditions. Because salinity tolerance in S. americanus is tightly coupled to primary productivity and other vital ecosystem attributes, these findings indicate that organismal evolution merits further consideration as a factor shaping coastal marsh responses to climate change. [ABSTRACT FROM AUTHOR]

Populations rely on already present plastic responses (ancestral plasticity) and evolution (including both evolution of mean trait values, constitutive evolution, and evolution of plasticity) to adapt to novel environmental conditions. Because of the lack of evidence from natural populations, controversy remains regarding the interplay between ancestral plasticity and rapid evolution in driving responses to new stressors. We addressed this topic at the level of the metabolome utilizing a resurrected natural population of the water flea Daphnia magna that underwent a human‐caused increase followed by a reduction in predation pressure within ~16 years. Predation risk induced plastic changes in the metabolome which were mainly related to shifts in amino acid and sugar metabolism, suggesting predation risk affected protein and sugar utilization to increase energy supply. Both the constitutive and plastic components of the metabolic profiles showed rapid, probably adaptive evolution whereby ancestral plasticity and evolution contributed nearly equally to the total changes of the metabolomes. The subpopulation that experienced the strongest fish predation pressure and showed the strongest phenotypic response, also showed the strongest metabolomic response to fish kairomones, both in terms of the number of responsive metabolites and in the amplitude of the multivariate metabolomic reaction norm. More importantly, the metabolites with higher ancestral plasticity showed stronger evolution of plasticity when predation pressure increased, while this pattern reversed when predation pressure relaxed. Our results therefore highlight that the evolution in response to a novel pressure in a natural population magnified the metabolomic plasticity to this stressor. [ABSTRACT FROM AUTHOR]

The biological processes involved in the preservation, viability, and revival of long‐term dormant dinoflagellate cysts buried in sediments remain unknown. Based on studies of plant seed physiology, we tested whether the revival of ancient cysts preserved in century‐old sediments from the Bay of Brest (France) could be stimulated by melatonin and gibberellic acid, two molecules commonly used in seed priming. Dinoflagellates were revived from sediments dated to approximately 150 years ago (156 ± 27, 32 cm depth), extending the known record age of cyst viability previously established as around one century. A culture suspension of sediments mixed with melatonin and gibberellic acid solutions as biostimulants exhibited germination of 11 dinoflagellate taxa that could not be revived under controlled culture conditions. The biostimulants revived some dinoflagellates from century‐old sediments, including the potentially toxic species Alexandrium minutum. The biostimulants showed positive effects on germination on even more ancient cysts, showing dose‐dependent effects on the germination of Scrippsiella acuminata. Concentrations of 1, 10, and 100 µM melatonin and gibberellic acid promoted germination. In contrast, 1,000 µM solutions, particularly for melatonin, drastically decreased germination, suggesting a potential noxious effect of high doses of these molecules on dinoflagellate revival. Our findings suggest that melatonin and gibberellic acid are involved in the stimulation of germination of dinoflagellate cysts. These biostimulants can be used to germinate long‐term stored dinoflagellate cysts, which may promote studies of ancient strains in the resurrection ecology research field. [ABSTRACT FROM AUTHOR]

In rare circumstances, scientists have been able to revive dormant propagules from ancestral populations and rear them with their descendants to make inferences about evolutionary responses to environmental change. Although this is a powerful approach to directly assess microevolution, it has previously depended entirely upon fortuitous conditions to preserve ancestral material. We propose a coordinated effort to collect, preserve, and archive genetic materials today for future studies of evolutionary change - a "resurrection paradigm." The availability of ancestral material that is systematically collected and intentionally stored using best practices will greatly expand our ability to illuminate microevolutionary patterns and processes and to predict ongoing responses of species to global change. In the workshop "Project Baseline," evolutionary biologists and seed storage experts met to discuss establishing a coordinated effort to implement the resurrection paradigm. © 2008 American Institute of Biological Sciences.

Loss of native foundation tree species to introduced pests profoundly alters the structure and function of many forest ecosystems. Recent advances to resurrect or prevent the loss of species by developing resistant hybrids hold promise, but uncertainty remains about the potential impacts of introducing a novel genotype on ecological processes, such as fire. A classic example of a non-native, pathogen-caused loss of a foundation species is American chestnut (Castanea dentata), a species now functionally extinct from the eastern US but undergoing experimental trials to resurrect the species with a putatively disease-resistant genotype. We compared the litter flammability among American chestnut, Chinese chestnut (C. mollisima), and a population of first intercross, third-generation backcrossed hybrid (BC3F2) using laboratory burning experiments. Litter flammability of American chestnut was consistently greater than Chinese chestnut, whereas the hybrid had an intermediate flammability or more closely resembled Chinese chestnut flammability by some measures. Greater flammability in American chestnut was associated with a longer leaf structure with greater curling when dry. American chestnut had flammability properties consistent with other pyrophytic species present in contemporary fire-prone ecosystems. The loss of American chestnut may have altered litter flammability of some eastern US forest ecosystems, a result more commonly associated with compositional changes in conjunction with fire exclusion and other disturbances. Resurrecting American chestnut with a hybrid genotype may mitigate this change in areas where less flammable species have replaced American chestnut. Resurrection of lost foundation species through introduction of resistant genotypes may represent a resounding ecological success story, but unanticipated changes to ecological processes, such as fire, should be considered. [ABSTRACT FROM AUTHOR]

Understanding how populations adapt to rising temperatures has been a challenge in ecology. Research often evaluates multiple populations to test whether local adaptation to temperature regimes is occurring. Space-for-time substitutions are common, as temporal constraints limit our ability to observe evolutionary responses. We employed a resurrection ecology approach to understand how thermal tolerance has changed in a Daphnia pulicaria population over time. Temperatures experienced by the oldest genotypes were considerably lower than the youngest. We hypothesized clones were adapted to the thermal regimes of their respective time periods. We performed two thermal shock experiments that varied in length of heat exposure. Overall trends revealed that younger genotypes exhibited higher thermal tolerance than older genotypes; heat shock protein (hsp70) expression increased with temperature and varied among genotypes, but not across time periods. Our results indicate temperature may have been a selective factor on this population, although the observed responses may be a function of multifarious selection. Prior work found striking changes in population genetic structure, and in other traits that were strongly correlated with anthropogenic changes. Resurrection ecology approaches should help our understanding of interactive effects of anthropogenic alterations to temperature and other stressors on the evolutionary fate of natural populations.

Stratigraphic accretion of dormant propagules in soil can result in natural archives useful for studying ecological and evolutionary responses to environmental change. Few attempts have been made, however, to use soil‐stored seed banks as natural archives, in part because of concerns over nonrandom attrition and mixed stratification. Here, we examine the persistent seed bank of Schoenoplectus americanus, a foundational brackish marsh sedge, to determine whether it can serve as a resource for reconstructing historical records of demographic and population genetic variation. After assembling profiles of the seed bank from radionuclide‐dated soil cores, we germinated seeds to "resurrect" cohorts spanning the 20th century. Using microsatellite markers, we assessed genetic diversity and differentiation among depth cohorts, drawing comparisons to extant plants at the study site and in nearby and more distant marshes. We found that seed density peaked at intermediate soil depths. We also detected genotypic differences among cohorts as well as between cohorts and extant plants. Genetic diversity did not decline with depth, indicating that the observed pattern of differentiation is not due to attrition. Patterns of differentiation within and among extant marshes also suggest that local populations persist as aggregates of small clones, likely reflecting repeated seedling recruitment and low immigration from admixed regional gene pools. These findings indicate that persistent and stratified soil‐stored seed banks merit further consideration as resources for reconstructing decadal‐ to century‐long records that can lend insight into the tempo and nature of ecological and evolutionary processes that shape populations over time. [ABSTRACT FROM AUTHOR]

Abstract: Synergistic interactions between temperature and contaminants are a major challenge for ecological risk assessment, especially under global warming. While thermal evolution may increase the ability to deal with warming, it is unknown whether it may also affect the ability to deal with the many contaminants that are more toxic at higher temperatures. We investigated how evolution of genetic adaptation to warming affected the interactions between warming and a novel stressor: zinc oxide nanoparticles (nZnO) in a natural population of Daphnia magna using resurrection ecology. We hatched resting eggs from two D. magna subpopulations (old: 1955–1965, recent: 1995–2005) from the sediment of a lake that experienced an increase in average temperature and in recurrence of heat waves but was never exposed to industrial waste. In the old “ancestral” subpopulation, exposure to a sublethal concentration of nZnO decreased the intrinsic growth rate, metabolic activity, and energy reserves at 24°C but not at 20°C, indicating a synergism between warming and nZnO. In contrast, these synergistic effects disappeared in the recent “derived” subpopulation that evolved a lower sensitivity to nZnO at 24°C, which indicates that thermal evolution could offset the elevated toxicity of nZnO under warming. This evolution of reduced sensitivity to nZnO under warming could not be explained by changes in the total internal zinc accumulation but was partially associated with the evolution of the expression of a key metal detoxification gene under warming. Our results suggest that the increased sensitivity to the sublethal concentration of nZnO under the predicted 4°C warming by the end of this century may be counteracted by thermal evolution in this D. magna population. Our results illustrate the importance of evolution to warming in shaping the responses to another anthropogenic stressor, here a contaminant. More general, genetic adaptation to an environmental stressor may ensure that synergistic effects between contaminants and this environmental stressor will not be present anymore. [ABSTRACT FROM AUTHOR]

There is growing evidence of rapid genetic adaptation of natural populations to environmental change, opening the perspective that evolutionary trait change may subsequently impact ecological processes such as population dynamics, community composition, and ecosystem functioning. To study such eco-evolutionary feedbacks in natural populations, however, requires samples across time. Here, we capitalize on a resurrection ecology study that documented rapid and adaptive evolution in a natural population of the water flea Daphnia magna in response to strong changes in predation pressure by fish, and carry out a follow-up mesocosm experiment to test whether the observed genetic changes influence population dynamics and top-down control of phytoplankton. We inoculated populations of the water flea D. magna derived from three time periods of the same natural population known to have genetically adapted to changes in predation pressure in replicate mesocosms and monitored both Daphnia population densities and phytoplankton biomass in the presence and absence of fish. Our results revealed differences in population dynamics and top-down control of algae between mesocosms harboring populations from the time period before, during, and after a peak in fish predation pressure caused by human fish stocking. The differences, however, deviated from our a priori expectations. An S-map approach on time series revealed that the interactions between adults and juveniles strongly impacted the dynamics of populations and their top-down control on algae in the mesocosms, and that the strength of these interactions was modulated by rapid evolution as it occurred in nature. Our study provides an example of an evolutionary response that fundamentally alters the processes structuring population dynamics and impacts ecosystem features. [ABSTRACT FROM AUTHOR]

Abstract: Resting eggs banks are unique windows that allow us to directly observe shifts in population genetics, and phenotypes over time as natural populations evolve. Though a variety of planktonic organisms also produce resting stages, the keystone freshwater consumer, Daphnia, is a well‐known model for paleogenetics and resurrection ecology. Nevertheless, paleogenomic investigations are limited largely because resting eggs do not contain enough DNA for genomic sequencing. In fact, genomic studies even on extant populations include a laborious preparatory phase of batch culturing dozens of individuals to generate sufficient genomic DNA. Here, we furnish a protocol to generate whole genomes of single ephippial (resting) eggs and single daphniids. Whole genomes of single ephippial eggs and single adults were amplified using Qiagen REPLI‐g Single Cell kit reaction, followed by NEBNext Ultra DNA Library Prep Kit for library construction and Illumina sequencing. We compared the quality of the single‐egg and single‐individual amplified genomes to the standard batch genomic DNA extraction in the absence of genome amplification. At mean 20× depth, coverage was essentially identical for the amplified single individual relative to the unamplified batch extracted genome (>90% of the genome was covered and callable). Finally, while amplification resulted in the slight loss of heterozygosity for the amplified genomes, estimates were largely comparable and illustrate the utility and limitations of this approach in estimating population genetic parameters over long periods of time in natural populations of Daphnia and also other small species known to produce resting stages. [ABSTRACT FROM AUTHOR]

The evolution of tolerance to environmental contaminants in non-target taxa has been largely studied by comparing extant populations experiencing contrasting exposure. Previous research has demonstrated that “resurrected” genotypes from a population of Daphnia pulicaria express temporal variation in sensitivity to the insecticide chlorpyrifos. Ancient genotypes (1301–1646 AD.) were on average more sensitive to this chemical compared to the contemporary genotypes (1967–1977 AD.). To determine the physiological mechanisms of tolerance, a series of biochemical assays was performed on three ancient and three contemporary genotypes; these six genotypes exhibited the most sensitive and most tolerant phenotypes within the population, respectively. Metabolic tolerance mechanisms were evaluated using acute toxicity testing, while target-site tolerance was assessed via in vitro acetylcholinesterase (AChE) assays. Acute toxicity tests were conducted using i ) the toxic metabolite chlorpyrifos-oxon (CPF-oxon) and ii ) CPF-oxon co-applied with piperonyl butoxide (PBO), a known Phase-I metabolic inhibitor. Both series of toxicity tests reduced the mean variation in sensitivity between tolerant and sensitive genotypes. Exposure to CPF-O reduced the disparity from a 4.7-fold to 1.6-fold difference in sensitivity. The addition of PBO further reduced the variation to a 1.2-fold difference in sensitivity. In vitro acetylcholinesterase assays yielded no significant differences in constitutive activity or target-site sensitivity. These findings suggest that pathways involving Phase-I detoxification and/or bioactivation of chlorpyrifos play a significant role in dictating the microevolutionary trajectories of tolerance in this population. [ABSTRACT FROM AUTHOR]

Changes in food quality can play a substantial role in the vulnerability of hosts to infectious diseases. In this study, we focused on the genetic differentiation of the water flea Daphnia magna towards food of different quality (by manipulating C:N:P ratios) and its impact on the interaction with a virulent infectious disease, 'White Fat Cell Disease ( WFCD)'. Via a resurrection ecology approach, we isolated two Daphnia subpopulations from different depths in a sediment core, which were exposed to parasites and a nutrient ratio gradient in a common garden experiment. Our results showed a genetic basis for sensitivity towards food deprivation. Both fecundity and host survival was differently affected when fed with low-quality food. This strongly impacted the way both subpopulations interacted with this parasite. A historical reconstruction of nutrient changes in a sediment core reflected an increase in organic material and phosphorus concentration (more eutrophic conditions) over time in the studied pond. These results enable us to relate patterns of genetic differentiation in sensitivity towards food deprivation to an increasing level of eutrophication of the subpopulations, which ultimately impacts parasite virulence effects. This finding was confirmed via a dynamic energy budgets ( DEB), in which energy was partitioned for the host and the parasite. The model was tailored to our study by integrating (1) increased growth and a fecundity shift in the host upon parasitism and (2) differences of food assimilation in the subpopulations showing that a reduced nutrient assimilation resulted in increased parasite virulence. The combination of our experiment with the DEB model shows that it is important to consider genetic diversity when studying the impact of nutritional stress on species interactions, especially in the context of changing environments and emerging infectious diseases. [ABSTRACT FROM AUTHOR]

Life-history adaptations to environmental change can be studied retrospectively in organisms that produce dormant propagules using methods of resurrection ecology. Here, we investigated such responses in a planktonic freshwater rotifer, Brachionus calyciflorus. We resurrected 14 clonal lineages from resting eggs extracted from three distinct sediment layers-representing periods of high, medium and low copper pollution-of a previously contaminated lake (Lake Orta, Italy). We exposed the resurrected clones to four copper concentrations over 14 days and recorded population densities at 48 h intervals. If the original populations in Lake Orta had adapted to the changing pollution levels, we expected to find demographic evidence of this adaptation in the resurrected lineages. However, we found high clonal variation in population-growth dynamics, which was more pronounced within than between pollution periods. Moreover, intrinsic population growth rates ( r) increased chronologically. As such, the results did not reveal signs of adaptive evolution. Furthermore, we found that lineages from the period of medium copper pollution invested less into sexual reproduction than lineages from the other periods. By using this bio-demographic perspective, our analysis of resurrected rotifers provides insights into the life-history responses of an aquatic invertebrate in an ever-changing environment. [ABSTRACT FROM AUTHOR]

Paleoecologists have speculated that post-glacial migration of tree species could have been facilitated by mycorrhizal symbionts surviving glaciation as resistant propagules belowground. The general premise of this idea, which we call the 'paleosymbiosis hypothesis', is that host plants can access and be colonised by fungal root symbionts that have been inactive for millennia. Here, we explore the plausibility of this hypothesis by synthesising relevant findings from a diverse literature. For example, the paleoecology literature provided evidence of modern roots penetrating paleosols containing ancient (>6000 years) fungal propagules, though these were of unknown condition. With respect to propagule longevity, the available evidence is of mixed quality, but includes convincing examples consistent with the paleosymbiosis hypothesis (i.e. >1000 years viable propagules). We describe symbiont traits and environmental conditions that should favour the development and preservation of an ancient propagule bank, and discuss the implications for our understanding of soil symbiont diversity and ecosystem functioning. We conclude that the paleosymbiosis hypothesis is plausible in locations where propagule deposition and preservation conditions are favourable (e.g. permafrost regions). We encourage future belowground research to consider and explore the potential temporal origins of root symbioses. [ABSTRACT FROM AUTHOR]

Human environmental impacts have driven some of the strongest and fastest phenotypic changes recorded in wild animal populations. Across populations, this variation is often adaptive, because populations evolve fitness advantages in response to human-modified environments. Yet some populations fail to adapt to changing environments. Evidenced by declines in relative fitness, such seemingly maladaptive outcomes are less common but may be more likely in human-modified contexts. Further, our ability to investigate the dynamics of these adaptive and maladaptive responses over time is typically limited in natural systems. I combined resurrection ecology and paleolimnology approaches to examine evolutionary responses of the freshwater zooplankter Daphnia to exposure to heavy metal contamination over the past 50-75 years, using animals hatched from diapausing egg banks. In contrast to the predicted trend of adaptation to metal exposure over time, I observed an increase in sensitivity to both copper and cadmium exposure associated with increasing historic contamination. This potentially maladaptive trend occurred in Daphnia populations in three lakes. Given that the release of toxicants such as heavy metals is widespread and that other researchers have observed local maladaptation to toxicant exposure, it is important to understand the drivers and implications of this pattern. [ABSTRACT FROM AUTHOR]

Lake Orta experienced for a few decades a unique history of chronic pollution, with extreme changes in pH and copper concentration. Currently, the lake has recovered to its almost pristine oligotrophic conditions, but its sediments still preserve the record of all the changes that happened since the establishment of the first polluting factories in the 1920s, through to the liming activities in 1989-1990, and to the recovery phase that is still going on. Here we review the current knowledge for Lake Orta regarding rotifers, a diverse component of the zooplankton of the lake, through studies on living organisms and on their resting stages accumulated in the sediments. We also report a brief review of what is known in general on the effects of changes in pH and copper concentration on rotifers at the population, species and community level, providing expectations for such effects on the rotifers of Lake Orta. Then, we conclude our review with a perspective on the potential use of rotifers hatched from the resting stages in the sediment of Lake Orta with the description of experiments that can be performed in the future in the framework of resurrection ecology, in order to understand the mechanisms of past and future changes in the environment.

Natural populations can cope with rapid changes in stressors by relying on sets of physiological defence mechanisms. Little is known onto what extent these physiological responses reflect plasticity and/or genetic adaptation, evolve in the same direction and result in an increased defence ability. Using resurrection ecology, we studied how a natural Daphnia magna population adjusted its antioxidant defence to ultraviolet radiation ( UVR) during a period with increasing incident UVR reaching the water surface. We demonstrate a rapid evolution of the induction patterns of key antioxidant enzymes under UVR exposure in the laboratory. Notably, evolutionary changes strongly differed among enzymes and mainly involved the evolution of UV-induced plasticity. Whereas D. magna evolved a strong plastic up-regulation of glutathione peroxidase under UVR, it evolved a lower plastic up-regulation of glutathione S-transferase and superoxide dismutase and a plastic down-regulation of catalase. The differentially evolved antioxidant strategies were collectively equally effective in dealing with oxidative stress because they resulted in the same high levels of oxidative damage (to lipids, proteins and DNA) and lowered fitness (intrinsic growth rate) under UVR exposure. The lack of better protection against UVR may suggest that the UVR exposure did not increase between both periods. Predator-induced evolution to migrate to lower depths that occurred during the same period may have contributed to the evolved defence strategy. Our results highlight the need for a multiple trait approach when focusing on the evolution of defence mechanisms. [ABSTRACT FROM AUTHOR]

Lake Orta experienced for a few decades a unique history of chronic pollution, with extreme changes in pH and copper concentration. Currently, the lake has recovered to its almost pristine oligotrophic conditions, but its sediments still preserve the record of all the changes that happened since the establishment of the first polluting factories in the 1920s, through to the liming activities in 1989-1990, and to the recovery phase that is still going on. Here we review the current knowledge for Lake Orta regarding rotifers, a diverse component of the zooplankton of the lake, through studies on living organisms and on their resting stages accumulated in the sediments. We also report a brief review of what is known in general on the effects of changes in pH and copper concentration on rotifers at the population, species and community level, providing expectations for such effects on the rotifers of Lake Orta. Then, we conclude our review with a perspective on the potential use of rotifers hatched from the resting stages in the sediment of Lake Orta with the description of experiments that can be performed in the future in the framework of resurrection ecology, in order to understand the mechanisms of past and future changes in the environment. [ABSTRACT FROM AUTHOR]

In seasonal climates, dormancy is a common strategy that structures biodiversity and is necessary for the persistence of many species. Climate change will likely alter dormancy dynamics in zooplankton, the basis of aquatic food webs, by altering two important hatching cues: mean temperatures during the ice-free season, and mean day length when lakes become ice free. Theory suggests that these changes could alter diversity, hatchling abundances and phenology within lakes, and that these responses may diverge across latitudes due to differences in optimal hatching cues and strategies., To examine the role of temperature and day length on hatching dynamics, we collected sediment from 25 lakes across a 1800 km latitudinal gradient and exposed sediment samples to a factorial combination of two photoperiods (12 and 16 h) and two temperatures (8 and 12 °C) representative of historical southern (short photoperiod, warm) and northern (long photoperiod, cool) lake conditions. We tested whether sensitivity to these hatching cues varies by latitudinal origin and differs among taxa., Higher temperatures advanced phenology for all taxa, and these advances were greatest for cladocerans followed by copepods and rotifers. Although phenology differed among taxa, the effect of temperature did not vary with latitude. The latitudinal origin of the egg bank influenced egg abundance and hatchling abundance and diversity, with these latter effects varying with taxa, temperature and photoperiod., Copepod hatchling abundances peaked at mid-latitudes in the high temperature and long photoperiod treatments, whereas hatchling abundances of other zooplankton were greatest at low latitudes and high temperature. The overall diversity of crustacean zooplankton (copepods and cladocerans) also reflected distinct responses of each taxa to our treatments, with the greatest diversity occurring at mid-latitudes (~56 °N) in the shorter photoperiod treatment., Our results demonstrate that hatching cues differ for broad taxonomic groups that vary in developmental and life-history strategies. These differences are predicted to drive latitude-specific shifts in zooplankton emergence with climate change and could alter the base of aquatic food webs. [ABSTRACT FROM AUTHOR]

Climatic changes are projected to result in rapid adaptive events with considerable phenotypic shifts. In order to reconstruct the impact of increased mean water temperatures during past decades and to reveal possible thermal micro-evolution, we applied a resurrection ecology approach using dormant eggs of the freshwater keystone species Daphnia galeata. To this end, we compared the adaptive response of D. galeata clones from Lake Constance of two different time periods, 1965-1974 ('historical') versus 2000-2009 ('recent'), to experimentally increased temperature regimes. In order to distinguish between genetic versus environmentally induced effects, we performed a common garden experiment in a flow-through system and measured variation in life-history traits. Experimental thermal regimes were chosen according to natural temperature conditions during the reproductive period of D. galeata in Central European lakes, with one additional temperature regime exceeding the currently observable maximum (+2°C). Increased water temperatures were shown to significantly affect measured life-history traits, and significant 'temperature × clonal age' interactions were revealed. Compared to historical clones, recent clonal lineages exhibited a shorter time to first reproduction and a higher survival rate, which may suggest temperature-driven micro-evolution over time but does not allow an explicit conclusion on the adaptive nature of such responses. [ABSTRACT FROM AUTHOR]

A resurrection ecology reconstruction of 14 morphological, life history and behavioural traits revealed that a natural Daphnia magna population rapidly tracked changes in fish predation by integrating phenotypic plasticity and widespread evolutionary changes both in mean trait values and in trait plasticity. Increased fish predation mainly generated rapid adaptive evolution of plasticity (especially in the presence of maladaptive ancestral plasticity) resulting in an important change in the magnitude and direction of the multivariate reaction norm. Subsequent relaxation of the fish predation pressure resulted in reversed phenotypic plasticity and mainly caused evolution of the trait means towards the ancestral pre-fish means. Relaxation from fish predation did, however, not result in a complete reversal to the ancestral fishless multivariate phenotype. Our study emphasises that the study population rapidly tracked environmental changes through a mosaic of plasticity, evolution of trait means and evolution of plasticity to generate integrated phenotypic changes in multiple traits. [ABSTRACT FROM AUTHOR]