Can changes in the distributions of resident birds in China over the past 50?years be attributed to climate change?

The distributions of bird species have changed over the past 50 years in China. To evaluate whether the changes can be attributed to the changing climate, we analyzed the distributions of 20 subspecies of resident birds in relation to climate change. Long‐term records of bird distributions, gray relational analysis, fuzzy‐set classification techniques, and attribution methods were used. Among the 20 subspecies of resident birds, the northern limits of over half of the subspecies have shifted northward since the 1960s, and most changes have been related to the thermal index. Driven by climate change over the past 50 years, the suitable range and latitude or longitude of the distribution centers of certain birds have exhibited increased fluctuations. The northern boundaries of over half of the subspecies have shifted northward compared with those in the 1960s. The consistency between the observed and predicted changes in the range limits was quite high for some subspecies. The changes in the northern boundaries or the latitudes of the centers of distribution of nearly half of the subspecies can be attributed to climate change. The results suggest that climate change has affected the distributions of particular birds. The method used to attribute changes in bird distributions to climate change may also be effective for other animals.     

Does cadmium pollution affect reproduction in the clam Ruditapes decussatus? A one-year case study

The effect of cadmium (Cd) on the reproduction of Ruditapes decussatus was monitored over a period of 12 months, from June 2001 to June 2002. Two sites "Bordj d'Ungha" and "El Hofra" differing by their degree of cadmium contamination were chosen in the Gulf of Gabès area (Tunisia). Annual mean concentrations of Cd in the whole soft tissues of clams from the site El Hofra were more than 4 times higher than those from the site Bordj d'Ungha (reference site). The gametogenic cycle of the clam R. decussatus was also investigated by histological examination and monthly observations of gonadal sections in a population of clams from both sites. The results show that gametogenesis occurred from March to December in clams from both sites. Nevertheless, spawning and emission of gametes were synchronized in both sexes from only the clams of the reference site. Although this species is considered as gonochoristic, 6.6% of hermaphroditic cases were observed in clams from both sites in which gametes of both males and females were in ripe stage. Moreover, the period of ripening of sexual products led to an increase of condition index and to a decrease of Cd concentrations in the whole soft tissues of clams from both sites, hence reflecting the phenomenon of "biological dilution".     

Does local habitat fragmentation affect large‐scale distributions? The case of a specialist grassland bird

Aim

Although the negative effects of habitat fragmentation have been widely documented at the landscape scale, much less is known about its impacts on species distributions at the biogeographical scale. We hypothesize that fragmentation influences the large‐scale distribution of area‐ and edge‐sensitive species by limiting their occurrence in regions with fragmented habitats , despite otherwise favourable environmental conditions. We test this hypothesis by assessing the interplay of climate and landscape factors influencing the distribution of the calandra lark, a grassland specialist that is highly sensitive to habitat fragmentation.

Location

Iberia Peninsula, Europe.

Methods

Ecological niche modelling was used to investigate the relative influence of climate/topography, landscape fragmentation and spatial structure on calandra lark distribution. Modelling assumed explicitly a hierarchically structured effect among explanatory variables, with climate/topography operating at broader spatial scales than landscape variables. An eigenvector‐based spatial filtering approach was used to cancel bias introduced by spatial autocorrelation. The information theoretic approach was used in model selection, and variation partitioning was used to isolate the unique and shared effects of sets of explanatory variables.

Results

Climate and topography were the most influential variables shaping the distribution of calandra lark, but incorporating landscape metrics contributed significantly to model improvement. The probability of calandra lark occurrence increased with total habitat area and declined with the number of patches and edge density. Variation partitioning showed a strong overlap between variation explained by climate/topography and landscape variables. After accounting for spatial structure in species distribution, the explanatory power of environmental variables remained largely unchanged.

Main conclusions

We have shown here that landscape fragmentation can influence species distributions at the biogeographical scale. Incorporating fragmentation metrics into large‐scale ecological niche models may contribute for a better understanding of mechanism driving species distributions and for improving predictive modelling of range shifts associated with land use and climate changes.

     

Does iron overload in metabolic syndrome affect macrophage profile? A case control study

AimsDysmetabolic iron overload syndrome (DIOS) is common but the clinical relevance of iron overload is not understood. Macrophages are central cells in iron homeostasis and inflammation. We hypothesized that iron overload in DIOS could affect the phenotype of monocytes and impair macrophage gene expression.MethodsThis study compared 20 subjects with DIOS to 20 subjects with metabolic syndrome (MetS) without iron overload, and 20 healthy controls. Monocytes were phenotyped by Fluorescence-Activated Cell Sorting (FACS) and differentiated into anti-inflammatory M2 macrophages in the presence of IL-4. The expression of 38 genes related to inflammation, iron metabolism and M2 phenotype was assessed by real-time PCR.ResultsFACS showed no difference between monocytes across the three groups. The macrophagic response to IL-4-driven differentiation was altered in four of the five genes of M2 phenotype (MRC1, F13A1, ABCA1, TGM2 but not FABP4), in DIOS vs Mets and controls demonstrating an impaired M2 polarization. The expression profile of inflammatory genes was not different in DIOS vs MetS. Several genes of iron metabolism presented a higher expression in DIOS vs MetS: SCL11A2 (a free iron transporter, +76 %, p = 0.04), SOD1 (an antioxidant enzyme, +27 %, p = 0.02), and TFRC (the receptor 1 of transferrin, +59 %, p = 0.003).ConclusionsIn DIOS, macrophage polarization toward the M2 alternative phenotype is impaired but not associated with a pro-inflammatory profile. The up regulation of transferrin receptor 1 (TFRC) in DIOS macrophages suggests an adaptive role that may limit iron toxicity in DIOS.     

To what extent does land-use affect relationships between the distribution of woody species and climatic change? A case study along an aridity gradient in western Burkina Faso

The study aims at evaluating how land-use modifies the link between the observed distribution of species and the climatic variability and at detecting species involved in that modification. The area studied covers the phytogeographical transition between the South-Sudanian sector and the North-Sudanian sector in western Burkina Faso. It lies along an aridity gradient, of which the aridity index (UNESCO-MAB) ranges from 0.363 to 0.533. The data studied were derived from observations performed on 192 woody species in 603 vegetation survey plots inside and outside protected areas. The species turn-over (β diversity) and the mutual information were assessed along the aridity gradient inside protected areas on one hand and outside protected areas on the other. Our study shows that the statistical links between the geographical distributions of species and the aridity gradient differ according to whether the observations are performed inside or outside the protected areas. Anthropogenic disturbances, mainly agricultural in the region of study, result in a decrease in the β diversity and in the average mutual information between the distribution of all the woody species and the climatic gradient. Moreover, the variation in mutual information differs according to the species: it diversely decreases with agricultural land-use for most of them, but increases for some. Thus, land-use leads to species-specific changes in the realised climatic niches.     

Vegetation dynamics in western Uganda during the last 1000 years: climate change or human induced environmental degradation?

A multi-proxy analysis of microfossils from sedimentary records, together with evidence from historical and archaeological data, has provided evidence of vegetation dynamics and human environment interactions in western Uganda for the last 1000 years. Pollen, fungal spores and phytoliths extracted from sediment cores obtained from a papyrus swamp at Munsa archaeological site indicate a relatively wet and forested environment in western Uganda prior to ca 1000 yr bp (cal 977–1159 ad ). A subsequent decline in forest vegetation occurred from ca 920 yr bp (cal 1027–1207 ad ). However, the deforestation period occurred during a wet period as registered in the River Nile water records, suggesting a human induced deforestation at Munsa rather than reduced precipitation. Increased numbers of herbivores, presumably domesticated cattle, postdeforestation are evidenced by the presence of dung fungal spores and broad accord with the archaeological evidence for initial occupation of the site at Munsa and the establishment of a mixed economy based on crops, cattle and iron working between 1000 and 1200 ad . From ca 200 yr bp (cal 1647–1952 ad ), forest recovery occurred at Munsa site and appears to reflect abandonment of the site, as suggested by archaeological evidence, possibly following a period of prolonged drought and famine between 1600 and 1800 ad , as recounted in the oral rich traditions of western Uganda and also reflected by low water levels of River Nile.     

Does a top predator suppress the abundance of an invasive mesopredator at a continental scale?

Aim We examined evidence for the mesopredator release hypothesis at a subcontinental scale by investigating the relationship between indices of abundance of the dingo Canis lupus dingo (top‐order predator) and the invasive red fox Vulpes vulpes (mesopredator) in three large regions across mainland Australia. The red fox is known to be one of the major threats to the persistence of small and medium‐sized native vertebrates across the continent. Location Australia. Methods Indices of abundance were calculated from three independently collected datasets derived from bounty returns and field surveys. Data were analysed using univariate parametric, semi‐parametric and nonparametric techniques. Results Predator abundance indices did not conform to a normal distribution and the relationships between dingo and fox abundance indices were not well described by linear functions. Semi‐parametric and nonparametric techniques revealed consistently negative associations between indices of dingo and fox abundance. Main conclusions The results provide evidence that mesopredator suppression by a top predator can be exerted at very large geographical scales and suggest that relationships between the abundances of top predators and mesopredators are not linear. Our results have broad implications for the management of canid predators. First, they suggest that dingoes function ecologically to reduce the activity or abundance of red foxes and thus are likely to dampen the predatory impacts of foxes. More generally, they provide support for the notion that the mesopredator‐suppressive effects of top predators could be incorporated into broad‐scale biodiversity conservation programmes in many parts of the world by actively maintaining populations of top predators or restoring them in areas where they are now rare. Determining the population densities at which the interactions of top predators become ecologically effective will be a critical goal for conservation managers who aim to maintain or restore ecosystems using the ecological interactions of top predators.     

Does the number of sons born affect long-term mortality of parents? A cohort study in rural Bangladesh

It has been suggested that bearing sons increases long-term mortality in women, because sons may be more physiologically demanding to produce than daughters. In this historical cohort study in rural Bangladesh, no association between the number of sons born and mortality was seen in women in the unadjusted analyses. However, a significant reduction in mortality with the number of surviving sons was seen. In addition, after adjusting for the number of surviving sons, there was evidence of increasing mortality with the number of sons born, in women. In men, mortality also depended strongly on the number of surviving sons, but not on the number born. These data provide support for negative long-term costs of bearing sons in mothers in rural Bangladesh, and suggest that there are context-specific factors that mask the true effects of sons in some populations.     

What can cetacean stranding records tell us? A study of UK and Irish cetacean diversity over the past 100 years

There are many factors that may explain why cetaceans (whales, dolphins, and porpoises) strand. Around the UK and Ireland, over 20,000 stranding records have been collected since 1913, resulting in one of the longest, continuous, systematic stranding data sets in the world. We use this data set to investigate temporal and spatial trends in cetacean strandings and use generalized additive models (GAMs) to investigate correlates of strandings. We find a dramatic increase in strandings since the 1980s, most likely due to increases in recording effort, and the formation of formal strandings networks. We found no correlation between the numbers of cetaceans stranding each year and several potential environmental and anthropogenic predictors: storms, geomagnetic activity, North Atlantic Oscillations, sea‐surface temperature, and fishing catch. We suggest that this is because the scale of change in the variables is too coarse to detect any potential correlations. It may also highlight the idiosyncratic nature of species’ responses to external pressures, and further the need to investigate other potential correlates of strandings, such as bycatch and military sonar. Long‐term cetacean stranding data provide vital information on past and present diversity for common, rare, and inconspicuous species. This study underlines the importance of continued support for stranding networks.     

Does spatial scale affect the pattern of mangrove change under different rainfall regimes? An example in southeast Queensland,Australia

The aim of this study was to investigate the interactions of natural and anthropogenic variables at different spatial scales related to changes in mangrove distribution during a relatively wet period (1972–1990) and a dry period (1991–2004) in subtropical eastern Australia. Previous research has demonstrated that mangroves are encroaching into salt marsh. Mangrove spatial change in southeast Queensland is related generally to landscape variables especially during the relatively wet period. What has not been explored is the spatial scale of the influence under the two rainfall regimes (wet and dry) and that is the aim of this paper. Ten sites were examined at different levels of resolution including catchment, sub‐catchment and two buffer zones (1000 and 500 m), under the period of relatively higher and lower rainfall. Land use was ascertained from Landsat satellite imagery using Maximum Likelihood Classification techniques. Partial least squares regression analysis was used to study the relationships between the predictor variables and the rate of change in the mangrove distribution. The research has found that the impact of land use/cover on the encroachment of mangrove into saltmarsh can vary and appears to be related to rainfall patterns, which in turn affect hydrological connectivity. A major finding of this research was that the changing spatial patterns of mangroves during the wet period was more a function of land use/cover pattern and population density at the sub‐catchment level, whereas during drier periods it was more affected by the local effects of nearby land use/cover in buffer zones.     

How do different aspects of biodiversity change through time? A case study on an Australian bird community

The study of ecological communities through time can reveal fundamental ecological processes and is key to understanding how natural and human pressures will affect biodiversity. Most studies of ecological communities through time consider only one or a few summary measures (e.g. species richness, total abundance), which might neglect important aspects of community structure or function. We studied temporal variation in several measures of species diversity, size diversity, and species composition in an intensively sampled bird community to determine whether different biodiversity measures change synchronously. We used a novel function regression model, which supports the study of diversity measures that are distributions (e.g. species abundance distributions) alongside measures that are scalar values (e.g. species richness). Most diversity measures changed predictably within years, but inter‐annual changes in size diversity and species composition were not reflected in species diversity. Within and among years, there was considerable variation in distributional measures that was not captured in scalar measures. Predictable variation within years probably was related to seasonal variation in weather patterns or food availability, but variation in size diversity among years probably resulted from stochastic changes in species composition. These results suggest that species and size diversity may be decoupled, and that inferences on scalar diversity measures might not reflect fundamental changes to community structure or function. Our method supports the inclusion of size‐based measures and distributional measures in ecological analyses, and broader uptake of our approach is likely to provide new insight into the processes structuring ecological communities, and inform the links between structure and function in ecological communities.     

Resilience and regime change in a southern Rocky Mountain ecosystem during the past 17?000 years

Paleoecological records indicate that subalpine forests in western North America have been resilient in response to multiple influences, including severe droughts, insect outbreaks, and widely varying fire regimes, over many millennia. One hypothesis for explaining this ecosystem resilience centers on the disruption of forest dynamics by frequent disturbance and climatic variability, and the resulting development of non-steady-state regimes dominated by early-successional conifers with broad climatic tolerances, such as lodgepole pine (Pinus contorta var. latifolia Engelm. ex Wats.). To evaluate this hypothesis, we independently reconstructed the vegetation, fire, and effective-moisture histories of a small, forested watershed at 2890 m elevation in southeastern Wyoming, USA, using sedimentary pollen and charcoal counts in conjunction with sedimentary lake-level indicators. The data indicate that prominent vegetation shifts (from sagebrush steppe to spruce–fir parkland at ca. 10.7 ka and spruce–fir parkland to pine-dominated forest at ca. 8.5 ka [ka stands for thousands of years before the present, defined as AD 1950]) coincided with changes in effective moisture. However, after lodgepole pine forests established at ca. 8.5 ka, similar hydroclimatic changes did not produce detectable vegetation responses. Fire history data show that other aspects of the ecosystem were responsive to changes in effective moisture at centennial timescales with prolonged fire-free episodes coinciding with periods of low effective moisture ca. 7.2–5.6 and 3.7–1.6 ka. Throughout our record, the ratio of ecosystem perturbation time (i.e., fire frequency and changes in effective moisture) to recovery time (assuming 200–600-year successional processes) falls within estimates of the ratio for non-steady state ecosystems. Frequent perturbations, therefore, may have prevented this ecosystem from reaching compositional equilibrium with the varied climatic conditions over the past 8.5 ka. Equilibrium states could have included more abundant spruce (Picea spp.) and fir (Abies spp.) than presently observed based on brief increases in pollen abundances of these taxa during prolonged dry, fire-free intervals. Our results show that, although current climate changes favor widespread disturbance in Rocky Mountain forests, the composition of these ecosystems could be highly resilient and recover through successional dynamics over the next few decades to centuries.     

Can we disentangle predator–prey interactions from species distributions at a macro‐scale? A case study with a raptor species

There is a debate on whether an influence of biotic interactions on species distributions can be reflected at macro‐scale levels. Whereas the influence of biotic interactions on spatial arrangements is beginning to be studied at local scales, similar studies at macro‐scale levels are scarce. There is no example disentangling, from other similarities with related species, the influence of predator–prey interactions on species distributions at macro‐scale levels. In this study we aimed to disentangle predator–prey interactions from species distribution data following an experimental approach including a factorial design. As a case of study we selected the short‐toed eagle because of its known specialization on certain prey reptiles. We used presence–absence data at a 100 km2 spatial resolution to extract the explanatory capacity of different environmental predictors (five abiotic and two biotic predictors) on the short‐toed eagle species distribution in peninsular Spain. Abiotic predictors were relevant climatic and topographic variables, and relevant biotic predictors were prey richness and forest density. In addition to the short‐toed eagle, we also obtained the predictor's explanatory capacities for 1) species of the same family Accipitridae (as a reference), 2) for other birds of different families (as controls) and 3) artificial species with randomly selected presences (as null models). We run 650 models to test for similarities of the short‐toed eagle, controls and null models with reference species, assessed by regressions of explanatory capacities. We found higher similarities between the short‐toed eagle and other species of the family Accipitridae than for the other two groups. Once corrected by the family effect, our analyses revealed a signal of predator–prey interaction embedded in species distribution data. This result was corroborated with additional analyses testing for differences in the concordance between the distributions of different bird categories and the distributions of either prey or non‐prey species of the short‐toed eagle. Our analyses were useful to disentangle a signal of predator–prey interactions from species distribution data at a macro‐scale. This study highlights the importance of disentangling specific features from the variation shared with a given taxonomic level.     

Do asynchronies in extinction debt affect the structure of trophic networks? A case study of antagonistic butterfly larvae–plant networks

Habitat loss and fragmentation affect species richness in fragmented habitats and can lead to immediate or time‐delayed species extinctions. Asynchronies in extinction and extinction debt between interacting species may have severe effects on ecological networks. However, these effects remain largely unknown. We evaluated the effects of habitat patch and landscape changes on antagonistic butterfly larvae–plant trophic networks in Mediterranean grasslands in which previous studies had shown the existence of extinction debt in plants but not in butterflies. We sampled current species richness of habitat‐specialist and generalist butterflies and vascular plants in 26 grasslands. We assessed the direct effects of historical and current patch and landscape characteristics on species richness and on butterfly larvae–plant trophic network metrics and robustness. Although positive species‐ and interactions–area relationships were found in all networks, structure and robustness was only affected by patch and landscape changes in networks involving the subset of butterfly specialists. Larger patches had more species (butterflies and host plants) and interactions but also more compartments, which decreased network connectance but increased network stability. Moreover, most likely due to the rescue effect, patch connectivity increased host‐plant species (but not butterfly) richness and total links, and network robustness in specialist networks. On the other hand, patch area loss decreased robustness in specialist butterfly larvae–plant networks and made them more prone to collapse against host plant extinctions. Finally, in all butterfly larvae–plant networks we also detected a past patch and landscape effect on network asymmetry, which indicates that there were different extinction rates and extinction debts for butterflies and host plants. We conclude that asynchronies in extinction and extinction debt in butterfly–plant networks provoked by patch and landscape changes caused changes in species richness and network links in all networks, as well as changes in network structure and robustness in specialist networks.     

Does a favourable change in the living conditions of young Kenyans affect their body (morphological) structure?

The aim of this study is to describe changes in the body structure of young Kenyans as a result of an upturn in the living conditions. The analyzed changes in their body build were caused by regular lifestyle and nutrition. The research material was male youth aged between 18 and 26. All those young men were students of a basic vocational school in Nairobi (Kenya). The first research was carried out in 1999 (n=121), the second one (n=302) exactly 12 months later and at the same institution. Changes in the body structure were studied on 31 individuals, who were examined twice. The examined parameters included: body height, body weight, chest circumference, waist circumference and thigh circumference. Information was also collected on the period a given student had stayed at that institution, his tribal membership, the number of children in his household and his number in the sequence of births in his family. Also the date of birth (at least the year) was of significance. All the examined men, whose body structure changes were analyzed, belonged to the Bantu language group. The studied individuals were at an age when growth had already finished. A more significant increase was observed in body weight, waist and thigh circumference. A regular schedule of activities and meals served in the dormitory resulted in body weight changes in 87% of those individuals, who were reexamined. As the basic reason for the observed changes one can regard the improvement in the level of nutrition, which was described by the examined individuals as "good".