Wheat or barley?: Feeding preferences affect distribution of three rodent species in agricultural landscape

Spatial distribution of voles and mice and their abundances in agricultural landscape are largely influenced by their food preferences and the distribution of preferred crops. Here we examined the correspondence between food preferences of dominant rodent species (two mice and one vole) for two cereals (wheat and barley) estimated in the lab and the long-term field abundances observed at the harvest time in southern Moravia, Czech Republic. In the first laboratory trial, harvested culms of wheat and barley were offered. The pygmy field mouse preferred (100%) the seed head of wheat, also the wood mouse (87%) and common vole (60%) showed low preference for wheat. In the second trial, we observed similar preferences in consuming the offered grains of both cereals, the wheat being preferred by the pygmy field mouse, and the wood mouse, while with the common vole showing no preference. Laboratory analysis of the harvested grains indicated a lower fibre content in wheat compared with barley. In the field, rodent abundances in wheat were higher than those in barley, especially in mice. This suggests that food preferences in the laboratory correspond closely to field distribution of these rodents and their abundances. Therefore, studying diet preferences may be of essential in predicting small rodent abundances in changing agricultural landscape.     

Climate and landscape explain richness patterns depending on the type of species’ distribution data

Understanding the patterns of species richness and their environmental drivers, remains a central theme in ecological research and especially in the continental scales where many conservation decisions are made. Here, we analyzed the patterns of species richness from amphibians, reptiles and mammals at the EU level. We used two different data sources for each taxon: expert-drawn species range maps, and presence/absence atlases. As environmental drivers, we considered climate and land cover. Land cover is increasingly the focus of research, but there still is no consensus on how to classify land cover to distinct habitat classes, so we analyzed the CORINE land cover data with three different levels of thematic resolution (resolution of classification scheme ˗ less to more detailed). We found that the two types of species richness data explored in this study yielded different richness maps. Although, we expected expert-drawn range based estimates of species richness to exceed those from atlas data (due to the assumption that species are present in all locations throughout their region), we found that in many cases the opposite is true (the extreme case is the reptiles where more than half of the atlas based estimates were greater than the expert-drawn range based estimates). Also, we detected contrasting information on the richness drivers of biodiversity patterns depending on the dataset used. For atlas based richness estimates, landscape attributes played more important role than climate while for expert-drawn range based richness estimates climatic variables were more important (for the ectothermic amphibians and reptiles). Finally we found that the thematic resolution of the land cover classification scheme, also played a role in quantifying the effect of land cover diversity, with more detailed thematic resolution increasing the relative contribution of landscape attributes in predicting species richness.     

What determines Orthoptera species distribution and richness in temperate semi-natural dry grassland remnants?

Wide-spread fragmentation and isolation of habitats with high nature conservation value lends increasing importance to a better understanding of the factors which determine species richness in isolated habitat patches. Using data of one of the most abundant invertebrate groups in grasslands, Orthoptera, we analysed how species richness and distribution in 60 isolated semi-natural grassland remnants in Austria were affected by five environmental variables (altitude, habitat and land use diversity within each patch, habitat diversity of areas adjacent to each patch, patch size), and related to diversity of their main food source, i.e. vascular plants. We found a significant positive correlation between Orthoptera and vascular plant species richness, with threatened Orthoptera species having the lowest correlation coefficients. Life form diversity of plants was only moderately positively correlated with Orthoptera species richness. Habitat diversity within and adjacent to the grassland patch had by far the highest loadings on the first two axes of the principal component analysis, which jointly explained 99?% of the variance, and proved to be significant for total, threatened and not threatened Orthoptera, as well as for the two Orthoptera orders occurring in Central Europe (Caelifera, Ensifera). Additionally, the distribution of the majority of those 14 Orthoptera species analysed individually was mainly correlated with habitat diversity within and adjacent to the grassland patch. However, the distribution of a significant proportion of species was associated with other factors: five species were closely related to on-site land use diversity and patch size, and the distribution of three Ensifera species was not significantly correlated to any of the explanatory variables. We conclude that a surrogate taxa approach, i.e. the use of well-known taxonomic groups (e.g. vascular plants), may indeed deliver good results for capturing total, but less so for threatened, Orthoptera species richness in semi-natural grassland remnants. Small scale habitat diversity may be crucial to allow for the co-existence of a large number of Orthoptera species and has to be taken equally into account as patch size in nature conservation.     

How can we preserve and restore species richness of pollinating insects on agricultural land?

During recent decades, concern about the loss of biodiversity on agricultural land has increased, and semi‐natural grasslands have been highlighted as critical habitats. Temperate European agricultural landscapes require distinct and appropriate management to prevent further impoverishment of the flora and fauna. This is especially urgent for pollinating insects that provide important ecosystem services. Our aim was to examine how species richness of three important groups of pollinating insects; solitary bees, butterflies and burnet moths are related to different farm characteristics, and if there are any differences between these three groups. A further aim was to test if red‐listed species are related to any farm characteristics. Species richness of solitary bees, butterflies and burnets was measured on all semi‐natural grasslands at 16 farms in a forest‐dominated area of 50 km² in southern Sweden, using systematic transect walks in April to September 2003 (only butterflies and burnets) and 2005. Species richness of solitary bees and butterflies was intercorrelated, both before and after controlling for the area of semi‐natural grassland. Species richness of solitary bees increased with the area of semi‐natural grassland. After controlling for the effect of the area of semi‐natural grassland species richness was strongly positively related with the density of the plant Knautia arvensis and negatively related with the proportion of grazed grassland. The results were similar for solitary bees and butterflies. The number of red‐listed solitary bees was positively related to the proportion of meadows with late harvest (after mid‐July) and decreased with increased farm isolation. The number of burnet species (all red‐listed) was positively related to vegetation height, flower density and the proportion of meadows with late harvest on a farm. Areas with a high density of K. arvensis and with traditional hay‐meadow with late harvest present, harbour most species. Promoting traditional hay‐meadows, late extensive grazing and the herb K. arvensis, people managing agricultural biodiversity can encompass high species richness of pollinating insects and support red‐listed species. Further, we suggest that the density of K. arvensis at a farm can be used as a biodiversity indicator, at least for pollinating insects.     

How wide to cast the net? Cross‐taxon congruence of species richness,community similarity and indicator taxa in ponds

1. Broad‐scale assessments of biodiversity often rely on the use of surrogate taxa, whose reliability has rarely been tested, particularly in freshwater systems. Here we use data from 46 ponds in two regions of the U.K. to explore the performance of macroinvertebrate taxa as surrogates for the rapid assessment of pond biodiversity. For the four dominant taxonomic groups in these ponds (Chironomidae, Coleoptera, Gastropoda and Trichoptera) we explore cross‐taxon species richness relationships in each of the two regions, and also determine the degree of concordance between the different taxa in accurately representing the similarity relationships between pond assemblages. 2. Patterns of cross‐taxon congruence in species richness were highly variable among taxa and study sites, making the use of a single taxon as a predictor of overall macroinvertebrate species richness problematic. In contrast, all four taxa show >70% congruence with the pattern of community similarity between sites resulting from the entire macroinvertebrate dataset, this result being consistent within and between regions. Canonical correspondence analysis demonstrated that all taxa were related in a similar manner to measured environmental parameters, meaning that limited additional ecological information is gained by including a wider range of pond taxa in rapid site assessment. 3. Single taxonomic groups can, therefore, perform consistently as indicators of community similarity between ponds, and no one taxon dramatically outperforms any other in this respect. The relative merits of the four focal taxa as surrogates for pond invertebrate assemblage composition are discussed with reference to ease of survey, ease of identification and ecological range occupied. 4. It is suggested that Coleoptera have a number of advantages as a surrogate taxon, being diverse, easily sampled, readily identified, taxonomically stable, ecologically well understood and occurring across a wide spectrum of pond types. They are therefore recommended for use as a focal group in rapid pond biodiversity assessments, employing an approach such as ours, which examines patterns of assemblage similarity, rather than species richness alone.     

Do species population parameters and landscape characteristics affect the relationship between local population abundance and surrounding habitat amount?

In landscape ecology, correlational approaches are typically used to analyse links between local population abundance, and the surrounding habitat amount to estimate biologically-relevant landscape size (extent) for managing endangered or pest populations. The direction, strength, and spatial extent of the correlations are then sometimes interpreted in terms of species population parameters. Here we simulated the population dynamics of generalized species across spatially explicit landscapes that included two distinct habitat types. We investigated how characteristics of a landscape (structure), including the variation in habitat quality and spatial aggregation of the habitat, and the precise population-dynamic properties of the simulated species (dispersal and growth rates) affect the correlation between population abundance and amount of surrounding favourable habitat in the landscape. To evaluate these spatial extents of correlation, proportions of favourable habitat were calculated within several circles of increasing diameter centred on sampling patches of favourable habitat where population abundance was recorded.We found that the value of the correlation coefficients between population abundance and amount of surrounding favourable habitat depended on both population dynamic parameters and landscape characteristics. Coefficients of correlation increased with the variation in habitat quality and the aggregation of favourable habitat in the landscape, but decreased with the dispersal distance. The distance at which the correlation was maximized was sensitive to an interaction between the level of aggregation of the habitat and the dispersal distance; whereas the greatest distance at which a significant correlation occurred was more sensitive to the variation in habitat quality. Our results corroborate the view that correlational analyses do provide information on the local population dynamics of a species in a given habitat type and on its dispersal rate parameters. However, even in simplified, model frameworks, direct relationships are often difficult to disentangle and global landscape characteristics should be reported in any studies intended to derive population-dynamic parameters from correlations. Where possible, replicated landscapes should be examined in order to control for the interaction between population dynamics and landscape structure. Finally, we recommend using species-specific, population-dynamic modelling in order to interpret correctly the observed patterns of correlation in the landscape.     

Effects of habitat fragmentation on foraging behaviour of tits and related species: does niche space vary in relation to size and degree of isolation of forest fragments?

We studied the winter foraging niches of tits and related species in deciduous forest fragments varying in size between 1 and 30 ha (plus one forest of 200 ha) in order to investigate the influence of forest fragmentation on foraging niches Very few correlations between niche structure (foraging niche, width and overlap) and forest size or isolation turned out to be significant This implies that either the species that disappear in small fragments are those that suffer most from competition (making the effect unmeasurable), or that competition is relatively unimportant for niche structure In any case we find no evidence that foraging niches are strongly affected by the changes (in habitat and/or community structure) associated with fragmentation     

Do seasonal temperatures,species traits and nearby timber harvest predict variation in moth species richness and abundance in unlogged deciduous forests?

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Can tree species richness attenuate the effect of drought on organic matter decomposition and stabilization in young plantation forests?

Changes in precipitation due to climate change are likely to influence soil organic matter (SOM) decomposition and stabilization. In forests, increased tree species diversity could modulate the effects of drought on SOM decomposition and stabilization. We addressed this issue by a decomposition study under simulated drought (through precipitation reduction at Zedelgem, Belgium) and natural drought (ORPHEE, southern France) in young experimental plantations (tree species richness 1 to 5). In Zedelgem, the study focused on tree species richness around oak and beech trees. Two tea bag indices (TBI) – decomposition rate (k) and stabilization factor (S) – were calculated by measuring the decay of green and rooibos tea in soils. Overall, TBI's were higher in Zedelgem than at ORPHEE. In Zedelgem, k increased with tree species richness under drought around oak, indicating that tree species richness modulated the effects of drought on decomposition. Under beech, k decreased with drought while no effect of tree species richness was detected. S increased with drought under both oak and beech, without any effect of tree species richness. In ORPHEE, we did not detect any tree species richness effect on both TBIs. S decreased significantly, while k was marginally reduced under drought. The higher S under drought in Zedelgem and under control in OPRHEE suggests that the carbon sequestration potential under climate change would be dependent on the environmental context. Further, in young plantations, high species richness may modulate the drought effect on SOM decomposition, but not on stabilization.     

Contrasting effects of biotic interactions on richness and distribution of vascular plants,bryophytes and lichens in an arctic–alpine landscape

Biotic interactions may strongly affect the distribution of individual species and the resulting patterns of species richness. However, the impacts can vary depending on the species or taxa examined, suggesting that the influences of interactions on species distributions and diversity are not always straightforward and can be taxon-contingent. The aim of this study was therefore to examine how the importance of biotic interactions varies within a community. We incorporated three biotic predictors (cover of the dominant vascular species) into two correlative species richness modelling frameworks to predict spatial variation in the number of vascular plants, bryophytes and lichens in arctic–alpine Fennoscandia, in N Europe. In addition, predictions based on single-species distribution models were used to determine the nature of the impact (negative vs. positive outcome) of the three dominant species on individual vascular plant, bryophyte and lichen species. Our results suggest that biotic variables can be as important as abiotic variables, but their relative contributions in explaining the richness of sub-dominant species vary among dominant species, species group and the modelling framework implemented. Similarly, the impacts of biotic interactions on individual species varied among the three species groups and dominant species, with the observed patterns partly reflecting species’ biogeographic range. Our study provides additional support for the importance of biotic interactions in modifying arctic–alpine biodiversity patterns and highlights that the impacts of interactions are not constant across taxa or biotic drivers. The influence of biotic interactions, including the taxon contingency and range-based impacts, should therefore be accounted for when developing biodiversity forecasts.     

Co-variation and indicators of species diversity: Can richness of forest-dwelling species be predicted in northern boreal forests?

Design and establishment of ecologically good networks of conservation areas often requires quick assessments of their biodiversity. Reliable indicators would be useful when doing such assessments. In order to explore the potential indicators for species richness in boreal forests, we studied (1) the co-variation of species richness and composition of species assemblages among beetles, polypores, birds and vascular plants, (2) the relationships between species richness and four boreal forest site types, (3) the relationship between species richness and forest physical structure and (4) the suitability of potential indicator groups within the four taxa to predict the species richness generally. The data show that there are probably not a single taxonomic or forest structural characteristic to be used as a general biodiversity indicator or surrogate for all the species. The correlations in species richness among the four taxa studied were low. However, group-specific indicators were obvious: forest site type was a good surrogate for vascular plant richness, and quantity and quality of dead wood predicted the species richness of polypores. The results support the view that different indicators shall be used for different forest types and taxonomic groups. These indicators should facilitate relatively rapid methods to assess biodiversity patterns at the forest stand level.     

Is orchid species richness and abundance related to the conservation status of oak forest?

The response of organisms to anthropogenic or natural modification of the environment is one of the most important questions in conservation biology and ecological theory. In spite of the fact that orchids are one of the most studied groups of plants, little information exists regarding their response to habitat alteration. The few existing studies are biased toward European orchid species and no consensus exists with regard to the response of orchids to human and natural disturbance. In this study, we sampled 30 transects (0.1 ha each) of oak forest located in Morelos, Central Mexico, and measured 13 variables related to forest aging and stump abundance, and six variables of orchid species richness and abundance. Neither abundance nor the richness and specific abundance of orchid genus or species were related to timber extraction. The abundance of dead standing trees in the forest, a surrogate variable of forest age, was positively related to abundance of orchids of the genus Malaxis, orchid richness and orchid abundance. This finding suggests that the conservation of all facets of the studied forest orchid community is dependent on natural processes (such as self-thinning) and the maintenance of older areas of the forest, and concurs with previous studies that suggest that natural disturbance is a key process for orchid survival.     

On the brink of extinction? How climate change may affect global chelonian species richness and distribution

Anthropogenic global climate change has already led to alterations in biodiversity patterns by directly and indirectly affecting species distributions. It has been suggested that poikilothermic animals, including reptiles, will be particularly affected by global change and large‐scale reptile declines have already been observed. Currently, half of the world's freshwater turtles and tortoises are considered threatened with extinction, and climate change may exacerbate these declines. In this study, we assess how global chelonian species richness will change in the near future. We use species distribution models developed under current climate conditions for 78% of all extant species and project them onto different Intergovernmental Panel on Climate Change (IPCC) scenarios for 2080. We detect a strong dependence of temperature shaping most species ranges, which coincide with their general temperature‐related physiological traits (i.e., temperature‐dependent sex determination). Furthermore, the extent and distribution of the current bioclimatic niches of most chelonians may change remarkably in the near future, likely leading to a substantial decrease of local species abundance and ultimately a reduction in species richness. Future climatic changes may cause the ranges of 86% of the species to contract, and of these ranges, nearly 12% are predicted to be situated completely outside their currently realized niches. Hence, the interplay of increasing habitat fragmentation and loss due to climatic stress may result in a serious threat for several chelonian species.     

Leaf photosynthesis and respiration of three bioenergy crops in relation to temperature and leaf nitrogen: how conserved are biochemical model parameters among crop species?

Given the need for parallel increases in food and energy production from crops in the context of global change, crop simulation models and data sets to feed these models with photosynthesis and respiration parameters are increasingly important. This study provides information on photosynthesis and respiration for three energy crops (sunflower, kenaf, and cynara), reviews relevant information for five other crops (wheat, barley, cotton, tobacco, and grape), and assesses how conserved photosynthesis parameters are among crops. Using large data sets and optimization techniques, the C(3) leaf photosynthesis model of Farquhar, von Caemmerer, and Berry (FvCB) and an empirical night respiration model for tested energy crops accounting for effects of temperature and leaf nitrogen were parameterized. Instead of the common approach of using information on net photosynthesis response to CO(2) at the stomatal cavity (A(n)-C(i)), the model was parameterized by analysing the photosynthesis response to incident light intensity (A(n)-I(inc)). Convincing evidence is provided that the maximum Rubisco carboxylation rate or the maximum electron transport rate was very similar whether derived from A(n)-C(i) or from A(n)-I(inc) data sets. Parameters characterizing Rubisco limitation, electron transport limitation, the degree to which light inhibits leaf respiration, night respiration, and the minimum leaf nitrogen required for photosynthesis were then determined. Model predictions were validated against independent sets. Only a few FvCB parameters were conserved among crop species, thus species-specific FvCB model parameters are needed for crop modelling. Therefore, information from readily available but underexplored A(n)-I(inc) data should be re-analysed, thereby expanding the potential of combining classical photosynthetic data and the biochemical model.     

Fox defecation behaviour in relation to spatial distribution of voles in an urbanised area: An increasing risk of transmission of Echinococcus multilocularis?

Urbanisation of alveolar echinococcosis is a new phenomenon that has been highlighted during the last few decades. It has thus become necessary to understand the dynamics of transmission of Echinococcus multilocularis in urbanised areas. Spatial heterogeneity of infection by E. multilocularis has been explained as the result of a multifactorial dependence of the transmission in which the factors depend on the scale of the investigation. The aim of this study was to assess, in an urbanised area, the effect of such environmental factors as season, habitat type and the level of urbanisation, on the availability of two major intermediate hosts (Microtus spp. and Arvicola terrestris), the distribution of red fox faeces and the distribution of E. multilocularis as determined by detection of coproantigens in faeces. Results of the study revealed higher densities of Microtus spp. in rural than in peri-urban areas. Moreover this species was highly aggregated in urban wasteland. Arvicola terrestris densities did not appear to be linked to the level of urbanisation or to the type of habitat studied. Distribution of faeces was positively linked to distance walked and to Microtus spp. and A. terrestris distributions whatever the level of urbanisation. Such a distribution pattern could enhance the transmission cycle in urban areas. The Copro-ELISA test results on faeces collected in the field revealed that ODs were significantly negatively correlated with the abundance of A. terrestris. The larger population densities of Microtus spp. found in urban wastelands and the well known predominance of Microtus spp. in the red fox diet in the region suggest that Microtus spp. may play a key role in urban transmission of the parasite in the study area.     

Do changes in gene expression contribute to sexual isolation and reinforcement in the house mouse?

Expression divergence, rather than sequence divergence, has been shown to be important in speciation, particularly in the early stages of divergence of traits involved in reproductive isolation. In the two European subspecies of house mice, Mus musculus musculus and Mus musculus domesticus, earlier studies have demonstrated olfactory‐based assortative mate preference in populations close to their hybrid zone. It has been suggested that this behaviour evolved following the recent secondary contact between the two taxa (~3,000 years ago) in response to selection against hybridization. To test for a role of changes in gene expression in the observed behavioural shift, we conducted a RNA sequencing experiment on mouse vomeronasal organs. Key candidate genes for pheromone‐based subspecies recognition, the vomeronasal receptors, are expressed in these organs. Overall patterns of gene expression varied significantly between samples from the two subspecies, with a large number of differentially expressed genes between the two taxa. In contrast, only ~200 genes were found repeatedly differentially expressed between populations within M. m. musculus that did or did not display assortative mate preferences (close to or more distant from the hybrid zone, respectively), with an overrepresentation of genes belonging to vomeronasal receptor family 2. These receptors are known to play a key role in recognition of chemical cues that handle information about genetic identity. Interestingly, four of five of these differentially expressed receptors belong to the same phylogenetic cluster, suggesting specialization of a group of closely related receptors in the recognition of odorant signals that may allow subspecies recognition and assortative mating.