Genetic and plastic responses of a northern mammal to climate change

Climate change is predicted to be most severe in northern regions and there has been much interest in to what extent organisms can cope with these changes through phenotypic plasticity or microevolutionary processes. A red squirrel population in the southwest Yukon, Canada, faced with increasing spring temperatures and food supply has advanced the timing of breeding by 18 days over the last 10 years (6 days per generation). Longitudinal analysis of females breeding in multiple years suggests that much of this change in parturition date can be explained by a plastic response to increased food abundance (3.7 days per generation). Significant changes in breeding values (0.8 days per generation), were in concordance with predictions from the breeder's equation (0.6 days per generation), and indicated that an evolutionary response to strong selection favouring earlier breeders also contributed to the observed advancement of this heritable trait. The timing of breeding in this population of squirrels, therefore, has advanced as a result of both phenotypic changes within generations, and genetic changes among generations in response to a rapidly changing environment.     

The microevolutionary consequences of climate change

Species may respond to climate change by shifting in abundance and distribution, by going extinct, or by evolving. Predicting which will occur is difficult. Climate change may lead to alterations in both abiotic and biotic components of selection. Although there is evidence that abundant genetic variation exists in some species which can respond to such selection, other species seem to have little genetic variation for key characters determining distribution and abundance. Moreover, climate change can affect nonselective components of microevolution, such as genetic variances and covariances, and the magnitudes of drift, mutation and gene flow. There is almost no species for which we know enough relevant ecology, physiology and genetics to predict its evolutionary response to climate change.     

The changing solar ultraviolet climate and the ecological consequences for higher plants

There is compelling evidence that a general erosion of the global ozone layer is occurring. Since ozone in the stratosphere absorbs much of the shortwave solar ultraviolet radiation (UV-B), diminished ozone means that more UV-B of a very specific wavelength composition will be received at the earth's surface. Evaluating the implications for vegetation involves consideration of the wavelength specificity of biological photochemical reactions and their sensitivity to the extant and future solar spectrum. Recent research suggests the occurrence of direct damaging reactions and of indirect morphological and chemical responses with implications at the community and ecosystem levels.     

Bioenergetic prediction of climate change impacts on northern mammals

Climate change will likely alter the distribution and abundanceof northern mammals through a combination of direct, abioticeffects (e.g., changes in temperature and precipitation) andindirect, biotic effects (e.g., changes in the abundance ofresources, competitors, and predators). Bioenergetic approachesare ideally suited to predicting the impacts of climate changebecause individual energy budgets integrate biotic and abioticinfluences, and translate individual function into populationand community outcomes. In this review, we illustrate how bioenergeticscan be used to predict the regional biodiversity, species rangelimits, and community trophic organization of mammals underfuture climate scenarios. Although reliable prediction of climatechange impacts for particular species requires better data andtheory on the physiological ecology of northern mammals, tworobust hypotheses emerge from the bioenergetic approaches presentedhere. First, the impacts of climate change in northern regionswill be shaped by the appearance of new species at least asmuch as by the disappearance of current species. Second, seasonallyinactive mammal species (e.g., hibernators), which are largelyabsent from the Canadian arctic at present, should undergo substantialincreases in abundance and distribution in response to climatechange, probably at the expense of continuously active mammalsalready present in the arctic.     

Hydrologic refugia,plants, and climate change

Climate, physical landscapes, and biota interact to generate heterogeneous hydrologic conditions in space and over time, which are reflected in spatial patterns of species distributions. As these species distributions respond to rapid climate change, microrefugia may support local species persistence in the face of deteriorating climatic suitability. Recent focus on temperature as a determinant of microrefugia insufficiently accounts for the importance of hydrologic processes and changing water availability with changing climate. Where water scarcity is a major limitation now or under future climates, hydrologic microrefugia are likely to prove essential for species persistence, particularly for sessile species and plants. Zones of high relative water availability – mesic microenvironments – are generated by a wide array of hydrologic processes, and may be loosely coupled to climatic processes and therefore buffered from climate change. Here, we review the mechanisms that generate mesic microenvironments and their likely robustness in the face of climate change. We argue that mesic microenvironments will act as species‐specific refugia only if the nature and space/time variability in water availability are compatible with the ecological requirements of a target species. We illustrate this argument with case studies drawn from California oak woodland ecosystems. We posit that identification of hydrologic refugia could form a cornerstone of climate‐cognizant conservation strategies, but that this would require improved understanding of climate change effects on key hydrologic processes, including frequently cryptic processes such as groundwater flow.     

Testing for the effects and consequences of mid paleogene climate change on insect herbivory

Background

The Eocene, a time of fluctuating environmental change and biome evolution, was generally driven by exceptionally warm temperatures. The Messel (47.8 Ma) and Eckfeld (44.3 Ma) deposits offer a rare opportunity to take a census of two, deep-time ecosystems occurring during a greenhouse system. An understanding of the long-term consequences of extreme warming and cooling events during this interval, particularly on angiosperms and insects that dominate terrestrial biodiversity, can provide insights into the biotic consequences of current global climatic warming.

Methodology/Principal Findings

We compare insect-feeding damage within two middle Eocene fossil floras, Messel and Eckfeld, in Germany. From these small lake deposits, we studied 16,082 angiosperm leaves and scored each specimen for the presence or absence of 89 distinctive and diagnosable insect damage types (DTs), each of which was allocated to a major functional feeding group, including four varieties of external foliage feeding, piercing- and-sucking, leaf mining, galling, seed predation, and oviposition. Methods used for treatment of presence–absence data included general linear models and standard univariate, bivariate and multivariate statistical techniques.

Conclusions/Significance

Our results show an unexpectedly high diversity and level of insect feeding than comparable, penecontemporaneous floras from North and South America. In addition, we found a higher level of herbivory on evergreen, rather than deciduous taxa at Messel. This pattern is explained by a ca. 2.5-fold increase in atmospheric CO₂ that overwhelmed evergreen antiherbivore defenses, subsequently lessened during the more ameliorated levels of Eckfeld times. These patterns reveal important, previously undocumented features of plant-host and insect-herbivore diversification during the European mid Eocene.     

Shifting global invasive potential of European plants with climate change

Global climate change and invasions by nonnative species rank among the top concerns for agents of biological loss in coming decades. Although each of these themes has seen considerable attention in the modeling and forecasting communities, their joint effects remain little explored and poorly understood. We developed ecological niche models for 1804 species from the European flora, which we projected globally to identify areas of potential distribution, both at present and across 4 scenarios of future (2055) climates. As expected from previous studies, projections based on the CGCM1 climate model were more extreme than those based on the HadCM3 model, and projections based on the a2 emissions scenario were more extreme than those based on the b2 emissions scenario. However, less expected were the highly nonlinear and contrasting projected changes in distributional areas among continents: increases in distributional potential in Europe often corresponded with decreases on other continents, and species seeing expanding potential on one continent often saw contracting potential on others. In conclusion, global climate change will have complex effects on invasive potential of plant species. The shifts and changes identified in this study suggest strongly that biological communities will see dramatic reorganizations in coming decades owing to shifting invasive potential by nonnative species.     

Allowing for human socioeconomic impacts in the conservation of plants under climate change

Abstract

The impact of climate change on conservation planning is affected by the availability of data (especially in data-sparse countries) and socioeconomic impacts. We build models using MaxEnt for Egyptian medicinal plants as a model system, projecting them to different future times under two IPCC 4th assessment emission scenarios (A2a and B2a) assuming unlimited and no dispersal. We compare the effect of two indices of socioeconomic activity [Human Influence Index (HII) and human population density/km²] as cost layers in spatial prioritization for conservation using zonation. We assess the efficacy of Egypt's network of Protected Areas (PAs) by comparing the predicted conservation value inside and outside each PA under the various scenarios. The results show that there are many locations in Egypt (the main cities, agricultural land, coastal areas) that are highly ranked for conservation before human socioeconomic impacts are included. The HII had a stronger impact than using human population density. The PA value excess (inside–outside) varied significantly with the type of cost and dispersal, but not with climate-change scenario or Zonation settings. We conclude that human socioeconomic impacts add new scope and insights for future conservation; and conservation planning without consideration of such impacts cannot be complete.     

Extinction of water plants in the Hula Valley: Evidence for climate change

We describe two events of water plant extinction in the Hula Valley, northern Israel: the ancient, natural extinction of 3 out of 14 extinct species at Gesher Benot Ya‘aqov, which occurred some 800-700 k.yr., and an anthropogenic, near contemporary extinction of seven species in the artificial drainage of the Hula Lake in the 1950s. We conclude that the considerable fraction of water plants that disappeared from the Hula Valley in the Early-Middle Pleistocene was the result of habitat desiccation and not global warming. Thus, there is evidence that the hominins who lived in the Hula Valley inhabited a comparatively dry place. The disappearance of water plant species was partially the result of reduced seed dispersal by birds (ornitochory) as a result of the shrinkage of water bodies and their number along the Rift Valley. We suggest that the disappearance of a group of rare, local water plants can be used as an indicator of climate drying and impacts on the local vegetation.     

Adapting streams for climate change using riparian broadleaf trees and its consequences for stream salmonids

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Avian population consequences of climate change are most severe for long-distance migrants in seasonal habitats

One consequence of climate change is an increasing mismatch between timing of food requirements and food availability. Such a mismatch is primarily expected in avian long-distance migrants because of their complex annual cycle, and in habitats with a seasonal food peak. Here we show that insectivorous long-distance migrant species in The Netherlands declined strongly (1984–2004) in forests, a habitat characterized by a short spring food peak, but that they did not decline in less seasonal marshes. Also, within generalist long-distance migrant species, populations declined more strongly in forests than in marshes. Forest-inhabiting migrant species arriving latest in spring declined most sharply, probably because their mismatch with the peak in food supply is greatest. Residents and short-distance migrants had non-declining populations in both habitats, suggesting that habitat quality did not deteriorate. Habitat-related differences in trends were most probably caused by climate change because at a European scale, long-distance migrants in forests declined more severely in western Europe, where springs have become considerably warmer, when compared with northern Europe, where temperatures during spring arrival and breeding have increased less. Our results suggest that trophic mismatches may have become a major cause for population declines in long-distance migrants in highly seasonal habitats.     

Potential consequences of climate change for primary production and fish production in large marine ecosystems

Existing methods to predict the effects of climate change on the biomass and production of marine communities are predicated on modelling the interactions and dynamics of individual species, a very challenging approach when interactions and distributions are changing and little is known about the ecological mechanisms driving the responses of many species. An informative parallel approach is to develop size-based methods. These capture the properties of food webs that describe energy flux and production at a particular size, independent of species'' ecology. We couple a physical–biogeochemical model with a dynamic, size-based food web model to predict the future effects of climate change on fish biomass and production in 11 large regional shelf seas, with and without fishing effects. Changes in potential fish production are shown to most strongly mirror changes in phytoplankton production. We project declines of 30–60% in potential fish production across some important areas of tropical shelf and upwelling seas, most notably in the eastern Indo-Pacific, the northern Humboldt and the North Canary Current. Conversely, in some areas of the high latitude shelf seas, the production of pelagic predators was projected to increase by 28–89%.     

气候变化对野生植物的影响及保护对策

以温室气体浓度持续上升、全球气候变暖为主要特征的全球气候变化对野生植物及生物多样性造成的潜在影响, 已经引起了国际学者的高度关注。本文总结了全球气候变化的现状与未来趋势, 概述了中国野生植物的保护及管理现状, 从不同侧面综述了国内外关于全球气候变暖对野生植物影响的研究进展和动态, 包括气候带北移、两极冰山退缩、高海拔山地变暖、海平面上升、早春温度提前升高、荒漠草原土壤增温、旱涝急转弯等对野生植物造成的影响以及气候变暖对种间关系和敏感植物类群的影响, 并从气候变化背景下全球生态系统敏感度、植物多样性、物种迁移与气候槽(sink areas)、物种适应与灭绝以及物候节律5个方面分析了未来全球变暖影响野生植物的总体趋势。在以后的野生植物保护与管理中, 应确定全球气候变化的植物多样性敏感区, 重点关注对气候变化敏感的植物类群以及气候要素改变植物-动物互作关系中的野生植物, 自然保护区的建设要重点考虑全球气候变化的影响, 通过在全球范围内对野生植物分布和种群变化进行长期、系统的追踪监测, 建立有效的数据库, 发展野生植物迁地保护的保育技术及信息网络, 发展有关野生植物对全球气候变化响应的量化指标及相应的模型。最后提出应将全球气候变化下野生植物保护与管理列入相关基金会的研究重点。     

Phenological responses of plants to climate change in an urban environment

Global climate change is likely to alter the phenological patterns of plants due to the controlling effects of climate on plant ontogeny, especially in an urbanized environment. We studied relationships between various phenophases (i.e., seasonal biological events) and interannual variations of air temperature in three woody plant species (Prunus davidiana, Hibiscus syriacus, and Cercis chinensis) in the Beijing Metropolis, China, based on phenological data for the period 1962–2004 and meteorological data for the period 1951–2004. Analysis of phenology and climate data indicated significant changes in spring and autumn phenophases and temperatures. Changes in phenophases were observed for all the three species, consistent with patterns of rising air temperatures in the Beijing Metropolis. The changing phenology in the three plant species was reflected mainly as advances of the spring phenophases and delays in the autumn phenophases, but with strong variations among species and phenophases in response to different temperature indices. Most phenophases (both spring and autumn phenophases) had significant relationships with temperatures of the preceding months. There existed large inter- and intra-specific variations, however, in the responses of phenology to climate change. It is clear that the urban heat island effect from 1978 onwards is a dominant cause of the observed phenological changes. Differences in phenological responses to climate change may cause uncertain ecological consequences, with implications for ecosystem stability and function in urban environments.