Climate Change Ecology最新文献

Predicting how species respond to changes in climate is critical to conserving biodiversity. Modeling efforts to date have largely centered on predicting the effects of warming temperatures on temperate species phenology. In and near the tropics, the effects of a warming planet on species phenology are more likely to be driven by changes in the seasonal precipitation cycle rather than temperature. To demonstrate the importance of considering precipitation-driven phenology in ecological studies, we present a case study wherein we construct a mechanistic population model for a rare subtropical butterfly (Miami blue butterfly, Cyclargus thomasi bethunebakeri) and use a suite of global climate models to project butterfly populations into the future. Across all iterations of the model, the trajectory of Miami blue populations is uncertain. We identify both biological uncertainty (unknown diapause survival rate) and climate uncertainty (ambiguity in the sign of precipitation change across climate models), and their interaction as key factors that determine persistence vs. extinction. Despite uncertainty, the most optimistic iteration of the model predicts that Miami blue butterfly populations will decline under the higher emissions scenario (RCP 8.5). The lack of climate model agreement across the projection ensemble suggests that investigations into the effect of climate change on precipitation-driven phenology require a higher level of rigor in the uncertainty analysis compared to analogous studies of temperature. For tropical species, a mechanistic approach that incorporates both biological and climate uncertainty is the best path forward to understand the effect shifting precipitation regimes have on phenology and population dynamics.

Community ecology is driven by the patterns and drivers of species assemblages. Montane communities, in particular, are extremely vulnerable to climate change and are one of the first ecosystems to experience climate-induced biological responses. Loss of natural areas driven by human alteration of land use in montane areas may further alter the reorganization of regional assemblages. Several studies have shown latitudinal shifts in individual species as a result of climate change in the twenty-first century, however, the effects of these shifts on assemblages are yet unknown. Therefore, in the current study, we aim to examine the impacts of projected climate and Land Use Land Cover (LULC) changes on dominant species assemblages in western Himalaya. We investigated the spatio-temporal variations in species distribution and composition within the assemblages under climate and LULC changes in two sub-regions- temperate and alpine using ensemble bioclimatic envelope modelling and logistic regression models. While the climate change impacts were found to be more profound in the alpine region, the footprints of LULCC are more significant in temperate areas. The key findings of the study reveal- 1) Number of associated species within assemblages may reduce under climate change (CC) as an outcome of the declining extent of species bioclimatic envelopes; 2) climate change-induced emergence of novel assemblages especially in the alpine region, and 3) significant unfavourable impacts on species assemblages in the temperate region owing to the intersection of climate and LULC changes.

Location

Western Himalayan region, India

Time period

1975 – 2015; projected year- 2070

Major Taxa

Vascular plants

We consider the current evidence of climate change effects on marine mammals that occur in U.S. waters relative to past predictions. Compelling cases of such effects have been documented, though few studies have confirmed population-level impacts on abundance or vital rates. While many of the observed effects had been predicted, some unforeseen and relatively acute consequences have also been documented. Effects often occur when climate-induced alterations are superimposed upon marine mammals’ ecological (e.g., predator-prey) relationships or coincident human activities. As they were unanticipated, some of the unpredicted effects of climate change have strained the ability of existing conservation and management systems to respond effectively. The literature is replete with cases suggestive of climate change impacts on marine mammals, but which remain unconfirmed. This uncertainty is partially explained by insufficient research and monitoring designed to reveal the connections. Detecting and mitigating the impacts of climate change will require some realignment of research and monitoring priorities, coupled with rapid and flexible management that includes both conventional and novel conservation interventions.

This study uses radiometric dating, palynological, loss-on-ignition, and X-ray fluorescence analyses to reconstruct the vegetation history and coastal morphological changes at the boreal mangrove range limit along the Gulf of Mexico, based on three sediment cores taken from St. George Island, Apalachicola, Florida, USA. The multi-proxy record indicates that the mangrove stands in the vicinity of St. George Island were formed in the recent decades, and no signs of mangroves were found for the last 1500 years during the Late-Holocene in the sedimentary record. The current mangrove expansion at St. George Island is caused by the recent climate warming instead of a recurring phenomenon tied with cyclical global climate variability. Further analysis based on decadal-scale climatic and environmental records reveal that the accelerated sea-level rise and warmer winters, especially the decrease of winter freeze events in the 21st century, are the most plausible causes for mangrove expansion at their boreal range limit during the recent decades. Under the predicted warming trend and accelerating sea-level rise in the 21st century, it is reasonable to believe that mangrove encroachment into coastal marshes will accelerate at Apalachicola and other areas near their poleward range limits.

Climate change threatens to alter the processes of ecological interactions in addition to the composition and function of communities. Traditional ecological paradigms typically do not account for strong differences in the impacts of environmental stressors by trophic level, focusing instead on differential effects on competitors or functional types. Massive cyanobacterial blooms now represent a common phenomenon across most freshwater and marine communities. Here, we present a perspective considering marine cyanobacterial mats as an extreme but accessible system in which traditional ecological trophic paradigms may be tested, and make recommendations for future research on this topic.

Four drivers of global change are acting in concert to speed up the ecology of our coastal and open ocean ecosystems. Ocean warming, nutrient pollution, disturbance, and species additions increase biological and ecological rates, favoring weedy communities and causing pervasive human impacts. Ocean warming via greenhouse gas emissions is accelerating metabolic processes, with effects scaling up to populations and ecosystems. Likewise, supercharging primary production via increased resources (e.g., nutrients and light) is leading to faster, weedier communities in estuarine and coastal ecosystems. Disturbances like ocean heat waves are becoming more frequent, resetting succession, and creating permanently young assemblages, while species additions are transporting the quick-growing and the fecund. The speeding up of marine ecosystems will necessitate changes in the ways we do science, attempt conservation, and use ecosystem services.

The response of biotic interactions to changes in temperature will play a large role in determining the impact of climate change on ecological communities. In particular, how warming alters predator-prey interactions will influence population stability, food web connectivity, and the movement of energy across trophic levels. The functional response relates predator foraging rates to prey availability, and it is often predicted to increase monotonically with temperature, at least within the limits of predator function. However, some studies suggest that functional responses peak and then decline, and such a difference has critical implications for the effect of warming on ecological communities. Here we investigate the effect of temperature on the functional response of wolf spiders (Schizocosa saltatrix) foraging on midges. Our results clearly support a unimodal response of the functional response, with peak foraging occurring at normal daytime temperatures for the area. Thus, daytime active spiders might experience a decline in foraging with warming, while night active spiders might experience an increase in foraging. Together with previous work, our study strongly suggests that the widespread assumption of a monotonic increase in foraging with warming is not warranted.

Understanding species responses to climatic change over extended timescales helps elucidate past and future extinction events. Amphibians are one of the most environmentally sensitive groups and yet showed high resilience to the Cretaceous-Paleogene (KPg) mass extinction, an event marked by sudden cooling and drought. To understand this past resilience and the associated filter mechanisms, we investigated the evolutionary history of key survival traits (body size and lifestyle) and explored climate-driven body-size selectivity of modern anuran assemblages. We found clear environment constraints on present-day anurans, where extreme temperatures and high seasonality filter against extreme-sized species. Our fossil-extant phylogenetic reconstruction reveals that anuran assemblages surrounding the KPg were mostly medium-sized species but large anuran species went extinct at the KPg, which is consistent with the uneven size-resilience to climate across modern anurans. Additionally, we found that cooling periods were marked by accelerated body-size diversification in anurans, and we inferred a close association between the evolution of arboreal frogs and angiosperms. Using the climate resilience of modern species as baselines, we estimate that future climate change will impact tropical anurans the most, where up to ∼500 species may face increased climate-related extinction pressure by 2100. Here we show that size-extinction selectivity in anurans is consistent over time and space, with extreme climate conditions filtering out larger and smaller species, conditions of which are likely to become increasingly prevalent in the future.

Climate change is altering the distribution of wildlife across the globe. These distributional changes, paired with the environmental and vegetative shifts that spurred them, are likely to change co-occurrence patterns and interspecific interactions of native and invasive wildlife. A mesocosm of global change, we worked on Sanibel Island; a low-lying ∼4,900 ha barrier island in southwestern Florida, USA. Sanibel Island possessed a freshwater interior lined with mangrove forests to the north. Sanibel was ∼50% developed, ∼50% conserved, hydrologically degraded, shrub-encroached, and susceptible to inundation by sea-level rise. We used a Bayesian multispecies occupancy modeling approach to investigate how the effects of climate change might change co-occurrence patterns of 2 native island-endemic species (Sanibel Island rice rat [Oryzomys palustris sanibeli]; insular hispid cotton rat [Sigmodon hispidus insulicola]) and 1 exotic invasive species (black rat [Rattus rattus]). We found that co-occurrence is likely to increase between cotton rats and black rats with unknown impacts on interspecific interactions. We also found that climate change may threaten the persistence of cotton rats and black rats on Sanibel Island, but not rice rats so long as mangrove forests persist. Broadly our research demonstrates the importance of investigating interactions between climate change and co-occurrence when assessing contemporary and future wildlife distributions.