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Heterogeneity and seeming unpredictability in responses to environmental change is driving a push to understand the underlying organismal mechanisms. The 2024 Vice Presidential Symposium of the American Society of Naturalists aimed to catalyze a promising and underutilized approach to extend understanding: repeating historical experiments or otherwise quantifying organism function through time. Many physiological, behavioral, ecological, and evolutionary experiments or observations reported in journal articles and elsewhere offer the potential for repeating the data collection to detect responses to environmental change. The approach extends beyond resurrection studies, which revive organisms to compare function and performance of modern organisms to their historical counterparts but are severely taxonomically and logistically restricted. In this introductory article, we discuss the promise of functional resurveys and highlight exemplar research repeating physiological measurements, behavioral experiments or observations, selection and quantitative genetic experiments, and measurement of ecosystem function. We also feature novel approaches to infer function from both modern and historical specimens and data, including temporal genomics, quantifying composition or energy stores, and genomic reconstruction. The research reveals key organismal mechanisms that mediate responses to environmental changes and can be accounted for to improve ecological and evolutionary forecasts. 

ABSTRACT With novel ocean conditions rapidly appearing as the result of climate change, basing decisions about fisheries and other ocean activities on historical conditions is no longer tenable. There is instead a widespread need for shifting ecological baselines to more effectively guide decisions into the future. What has not been as widely recognised is that the relevant timescales differ substantially across ocean‐related decisions, from lead times of hours to decades depending on the decision being made, and that this range necessitates a matching range of ecological forecast products across similar timescales. At the moment, a predictability gap exists at intermediate timescales, from multi‐annual to multi‐decadal forecasts. Because most fisheries and many other ocean activities rely on biological conditions like fish abundance or distribution, the ecological inertia of organismal growth, generational turnover, movement, and food web dynamics can help push ecological forecasts further across this gap. To realise this potential for more effective and usable ecological forecasts, coordinated research and implementation at the intersection of biology, climate science, social science, and decision‐making is needed. These efforts will be critical for forecasting shifting ecosystem baselines and sustaining fisheries, ocean ecosystems, and the ocean economy in the coming decades of rapid change. 

Evaluating the evolutionary impacts of anthropogenic activity on populations is key to understanding species resiliency and to designing effective conservation strategies. Sequencing DNA from historical specimens provides the opportunity to establish a his torical baseline and empirically assess changes in genetic diversity, changes in effective population size, and selection over time. Here, we sequenced historical and contemporary samples of the cardinalfish Taeniamia zosterophora collected in 1908 and in 2021–2022 across two sites with differing human impact in the Philippines. At both sites, genetic diversity increased over time, with contemporary samples hav ing significantly higher Watterson’s v than historical samples. This di versity increase was primarily attributable to positive selection on low-frequency alleles such that they increased toward intermediate fre quencies through time. For the putatively neutral fraction of the ge nome, in contrast, there was a slight but significant decline in Watterson’s v at both low and high human impact sites, suggesting that drift strength ened and effective population sizes declined through time. There was more evidence for selection and greater loss of neutral diversity at the site with higher human impact. Our results provide empirical evi dence for the surprising preservation of genetic diversity through the action of natural selection in the face of anthropogenic impacts. 

Abstract Genetic diversity is a fundamental component of biodiversity. Examination of global patterns of genetic diversity can help highlight mechanisms underlying species diversity, though a recurring challenge has been that patterns may vary by molecular marker. Here, we compiled 6862 observations of genetic diversity from 492 species of marine fish and tested among hypotheses for diversity gradients: the founder effect hypothesis, the kinetic energy hypothesis, and the productivity‐diversity hypothesis. We fit generalized linear mixed effect models (GLMMs) and explored the extent to which various macroecological drivers (latitude, longitude, temperature (SST), and chlorophyll‐a concentration) explained variation in genetic diversity. We found that mitochondrial genetic diversity followed geographic gradients similar to those of species diversity, being highest near the Equator, particularly in the Coral Triangle, while nuclear genetic diversity did not follow clear geographic patterns. Despite these differences, all genetic diversity metrics were correlated with chlorophyll‐a concentration, while mitochondrial diversity was also positively associated with SST. Our results provide support for the kinetic energy hypothesis, which predicts that elevated mutation rates at higher temperatures increase mitochondrial but not necessarily nuclear diversity, and the productivity‐diversity hypothesis, which posits that resource‐rich regions support larger populations with greater genetic diversity. Overall, these findings reveal how environmental variables can influence mutation rates and genetic drift in the ocean, caution against using mitochondrial macrogenetic patterns as proxies for whole‐genome diversity, and aid in defining global gradients of genetic diversity. 

Abstract Global change is impacting biodiversity across all habitats on earth. New selection pressures from changing climatic conditions and other anthropogenic activities are creating heterogeneous ecological and evolutionary responses across many species' geographic ranges. Yet we currently lack standardised and reproducible tools to effectively predict the resulting patterns in species vulnerability to declines or range changes.We developed an informatic toolbox that integrates ecological, environmental and genomic data and analyses (environmental dissimilarity, species distribution models, landscape connectivity, neutral and adaptive genetic diversity, genotype‐environment associations and genomic offset) to estimate population vulnerability. In our toolbox, functions and data structures are coded in a standardised way so that it is applicable to any species or geographic region where appropriate data are available, for example individual or population sampling and genomic datasets (e.g. RAD‐seq, ddRAD‐seq, whole genome sequencing data) representing environmental variation across the species geographic range.To demonstrate multi‐species applicability, we apply our toolbox to three georeferenced genomic datasets for co‐occurring East African spiny reed frogs (Afrixalus fornasini, A. delicatusandA. sylvaticus) to predict their population vulnerability, as well as demonstrating that range loss projections based on adaptive variation can be accurately reproduced from a previous study using data for two European bat species (Myotis escaleraiandM. crypticus).Our framework sets the stage for large scale, multi‐species genomic datasets to be leveraged in a novel climate change vulnerability framework to quantify intraspecific differences in genetic diversity, local adaptation, range shifts and population vulnerability based on exposure, sensitivity and landscape barriers. 

Anticipating how species distributions will shift with climate change is key for biodiversity conservation and management. Commonly, species’ range shifts are observed by analyzing changes in occurrence or abundance data through time, or predicted across different climate change scenarios by modeling species’ climatic niches. However, it remains unclear how well these climate-based forecasts align with empirically documented range shifts from monitoring efforts. Here, we tested the congruence between modeled range shifts, predicted using climatic niche models, and documented range shifts, derived from empirical observations collected over recent decades, for more than 9,500 range shifts across over 3,500 marine and terrestrial species. We found that documented and modeled range shifts tend to align in latitudinal direction, with greater alignment for marine (76%) than terrestrial (56%) cases. However, even when the directions aligned, documented shifts exceeded modeled shifts in 62% of cases, nearly twice as often as they lagged behind (38%), and their median rates were four times faster than those of the modeled shifts. Our findings suggest that climate-based models can approximate observed range dynamics under specific conditions, particularly over long time periods and restricted spatial areas, when habitats remain well connected and under low climate fluctuations over time. These insights provide valuable guidance for both improving predictions and informing responses to climate-driven biodiversity redistribution. 

Abstract Patterns of population connectivity shape ecological and evolutionary phenomena from population persistence to local adaptation and can inform conservation strategy. Connectivity patterns emerge from the interaction of individual behavior with a complex and heterogeneous environment. Despite ample observation that dispersal patterns vary through time, the extent to which variation in the physical environment can explain emergent connectivity variation is not clear. Empirical studies of its contribution promise to illuminate a potential source of variability that shapes the dynamics of natural populations. We leveraged simultaneous direct dispersal observations and oceanographic transport simulations of the clownfishAmphiprion clarkiiin the Camotes Sea, Philippines, to assess the contribution of oceanographic variability to emergent variation in connectivity. We found that time‐varying oceanographic simulations on both annual and monsoonal timescales partly explained the observed dispersal patterns, suggesting that temporal variation in oceanographic transport shapes connectivity variation on these timescales. However, interannual variation in observed mean dispersal distance was nearly 10 times the expected variation from biophysical simulations, revealing that additional biotic and abiotic factors contribute to interannual connectivity variation. Simulated dispersal kernels also predicted a smaller scale of dispersal than the observations, supporting the hypothesis that undocumented abiotic factors and behaviors such as swimming and navigation enhance the probability of successful dispersal away from, as opposed to retention near, natal sites. Our findings highlight the potential for coincident observations and biophysical simulations to test dispersal hypotheses and the influence of temporal variability on metapopulation persistence, local adaptation, and other population processes. 

Genetic diversity is a crucial component of biodiversity, and as such, its maintenance and preservation is of high conservation concern. Tropical environments are undergoing intense rates of environmental change, and these changes may be driving large declines in genetic diversity. However, data on genetic diversity are highly skewed towards temperate regions. The degree to which diversity loss has occurred in tropical species, particularly marine species, remains an open and important question. Here, we directly compare genomic data from modern and museum collections of two commercially harvested nearshore marine fishes (Equulites laterofenestraandGazza minuta) gathered from a single location in the Philippines, spanning a century of intense environmental change. These data reveal a marked loss in genetic diversity and evidence for multiple orders of magnitude reductions in effective population size (N_e) in both species, indicating substantial genomic erosion. Such a decline highlights the long-lasting genomic consequences of anthropogenic activity and sheds light on an, until-now, invisible loss of diversity from the most biodiverse ocean region. 

Abstract Large‐scale shifts in marine species biogeography have been a notable impact of climate change. An effective explanation of what drives these species shifts, as well as accurate predictions of where they might move, is crucial to effectively managing these natural resources and conserving biodiversity. While temperature has been implicated as a major driver of these shifts, physiological processes suggest that oxygen, prey, and other factors should also play important roles. We expanded upon previous temperature‐based distribution models by testing whether oxygen, food web productivity, salinity, and scope for metabolic activity (the Metabolic Index) better explained the changing biogeography of Black Sea Bass (Centropristis striata) in the Northeast US. This species has been expanding further north over the past 15 years. We found that oxygen improved model performance beyond a simple consideration of temperature (ΔAIC = 799, ΔTSS = 0.015), with additional contributions from prey and salinity. However, the Metabolic Index did not substantially increase model performance relative to temperature and oxygen (ΔAIC = 0.63, ΔTSS = 0.0002). Marine species are sensitive to oxygen, and we encourage researchers to use ocean biogeochemical hindcast and forecast products to better understand marine biogeographic changes.