Find research datasets worth reusing

Data from: Root elemental composition in Chinese forests: implications for biogeochemical niche differentiation

1. Trait-based community analysis provides a new approach to integrate functional ecology with community ecology. However, our understanding of the linkages between root chemical traits and community chemical diversity and assembly is still in its infancy. 2. Environmental filtering and niche differentiation are two opposite driving forces of community assembly based on deterministic niche processes. We hypothesize that environmental filtering is a strong driver of root chemical assembly at a large spatial scale, whereas biogeochemical niche differentiation drives root chemical traits divergence among co-occurring species at site scale. 3. We analyzed the concentrations of 15 elements in the fine roots of 281 species across five forest types of China. Discriminant analysis was used to measure the degree of similarity of root chemical traits at the community level and biogeochemical niche differentiation at the species level. 4. Root chemical traits at the community level showed a systematic shift along environmental gradients. The growth rate-related dimension represented by root P and Ca was the most important niche dimension associated with community root chemical assembly, driven by large-scale environmental filters, particularly soils and climate. Biogeochemical niche differentiation of co-occurring species could be a consequence of reducing nutrient competition, especially the competition for nitrogen. 5. Root chemical traits provide a new dimension for assessing the functional niche and may help improve our understanding of the underlying mechanisms of root chemical assembly from the local to the biome scale.

Data from: Configurational landscape heterogeneity shapes functional community composition of grassland butterflies

1. Landscape heterogeneity represents two aspects of landscape simplification: (i) compositional heterogeneity (diversity of habitat types) and (ii) configurational heterogeneity (number, size and arrangement of habitat patches); both with different ecological implications for community composition. 2. We examined how independent gradients of compositional and configurational landscape heterogeneity, at eight spatial scales, shape taxonomic and functional composition of butterfly communities in 91 managed grasslands across Germany. We used landscape metrics that were calculated from functional maps based on habitat preferences of individual species during different life stages. The relative effects of compositional and configurational landscape heterogeneity were compared with those of local land use intensity on butterfly taxonomic diversity, community composition and functional diversity of traits related to body size, feeding breadth and migratory tendency. 3. As expected, compositional heterogeneity had strong positive effects on taxonomic diversity while configurational heterogeneity had strong positive effects on trait dominance within the community. When landscapes had smaller mean patch size and greater boundary area, communities were dominated by species with more specialized larval feeding, decreased forewing length and limited migratory tendency. 4. The positive effects of increased configurational landscape heterogeneity outweighed the negative effects of local land use intensity on larval feeding specialization, at all spatial scales, highlighting its importance for specialists of all dispersal capabilities. 5. Synthesis and applications. We show that landscapes with high compositional heterogeneity support communities with greater taxonomic diversity, while landscapes with high configurational heterogeneity support communities that include vulnerable species (feeding specialists with larger body size, sedentary nature and more negatively affected by local management intensity). A decline in functional community composition can lead to functional homogenization, affecting the viability of the ecosystems by decreasing the variability in their responses to disturbance and altering their functioning. A landscape management for grasslands that promotes the maintenance of small patch sizes and a diversity of land-uses in the surrounding landscape (within 250–1000 m) is recommended for the conservation of diverse butterfly communities. These strategies could also benefit Government programs such as the EU 2020 Biodiversity Strategy in their efforts to reduce the loss of biodiversity in agricultural landscapes.

Data from: Massive structural redundancies in species composition patterns of floodplain forest moths

Terrestrial arthropod communities usually consist of very large species numbers. Data from experiments or long time-series would be required to ascertain the functional significance of individual species. Both are largely unavailable for species-rich natural communities. Recognising structural redundancies in species composition allows for an alternative approach to address how strong functional redundancy might be in natural assemblages, if structural and functional redundancies are related to each other. Determining structural redundancies is a regular topic in aquatic ecology, but has rarely been applied to terrestrial communities. We explored the extent of structural redundancy in species-rich terrestrial insect assemblages and whether structural redundancies are contingent to species abundances or functional group affiliations. We used the BVSTEP algorithm to determine structural redundancies in a large data set of moth species (32 181 individuals; 448 species) that had been sampled with light-traps in three different floodplain forests in eastern Austria. We partitioned the moth species into 12 functional types based on larval host-plant affiliations to test if moth species included in reduced subsets represent functional groups in the same proportions as they occur in the entire fauna. We observed far more massive structural redundancies in moth assemblages than previously found in aquatic communities. Subsets containing only 8–15 species (1.8–3.3% of all recorded species) were still highly representative for the overall data. Subsets selected by the BVSTEP procedure performed better than equally small subsets that were defined solely by species abundances or by functional group affiliations. Effective 'surrogate' subsets contained only 6–9 of the 12 functional moth types. High abundance only loosely corresponded with the frequency at which a moth species was included in the subsets. Thus, certain uncommon species contribute importantly to species composition patterns. Our results show unexpectedly extensive structural redundancies in complex floodplain forest moth communities, which may also indicate strong functional redundancies.

Data from: Modeling the impact of Plasmodium falciparum sexual stage immunity on the composition and dynamics of the human infectious reservoir for malaria in natural settings

Malaria transmission remains high in Sub-Saharan Africa despite large-scale implementation of malaria control interventions. A comprehensive understanding of the transmissibility of infections to mosquitoes may guide the design of more effective transmission reducing strategies. The impact of P. falciparum sexual stage immunity on the infectious reservoir for malaria has never been studied in natural settings. Repeated measurements were carried out at start-wet, peak-wet and dry season, and provided data on antibody responses against gametocyte/gamete antigens Pfs48/45 and Pfs230 as anti-gametocyte immunity. Data on high and low-density infections and their infectiousness to anopheline mosquitoes were obtained using quantitative molecular methods and mosquito feeding assays, respectively. An event-driven model for P. falciparum sexual stage immunity was developed and fit to data using an agent based malaria model infrastructure. We found that Pfs48/45 and Pfs230 antibody densities increased with increasing concurrent gametocyte densities; associated with 55–70% reduction in oocyst intensity and achieved up to 44% reduction in proportions of infected mosquitoes. We showed that P. falciparum sexual stage immunity significantly reduces transmission of microscopic (p < 0.001) but not submicroscopic (p = 0.937) gametocyte infections to mosquitoes and that incorporating sexual stage immunity into mathematical models had a considerable impact on the contribution of different age groups to the infectious reservoir of malaria. Human antibody responses to gametocyte antigens are likely to be dependent on recent and concurrent high-density gametocyte exposure and have a pronounced impact on the likelihood of onward transmission of microscopic gametocyte densities compared to low density infections. Our mathematical simulations indicate that anti-gametocyte immunity is an important factor for predicting and understanding the composition and dynamics of the human infectious reservoir for malaria.

Data from: Patterns of local community composition are linked to large-scale diversification and dispersal of clades

At any location, a group of organisms may be represented by several clades. What determines which clades will dominate local communities in terms of their species richness? Here, this relatively neglected question is addressed by analyzing 166 local assemblages of snakes distributed globally. For most regions, local assemblages are dominated by clades with higher global-scale diversification rates and more frequent dispersal into each region, and not by clades that have been present in that region longer. This result contrasts with many other studies of local richness (in other organisms), which show strong impacts of regional colonization time on overall local species richness of clades. Furthermore, even though local assemblages are assembled independently on different continents, most regions have converged on similar patterns of proportional richness. Specifically, a few rapidly diversifying clades dominate most communities around the world. The high diversification rates of these clades are then linked to their high dispersal rates. Similar patterns may occur in many groups, such as plants, frogs, salamanders, birds, and mammals.

Data from: Genetic diversity, breed composition and admixture of Kenyan domestic pigs

The genetic diversity of African pigs, whether domestic or wild has not been widely studied and there is very limited published information available. Available data suggests that African domestic pigs originate from different domestication centers as opposed to international commercial breeds. We evaluated two domestic pig populations in Western Kenya, in order to characterize the genetic diversity, breed composition and admixture of the pigs in an area known to be endemic for African swine fever (ASF). One of the reasons for characterizing these specific populations is the fact that a proportion of indigenous pigs have tested ASF virus (ASFv) positive but do not present with clinical symptoms of disease indicating some form of tolerance to infection. Pigs were genotyped using either the porcine SNP60 or SNP80 chip. Village pigs were sourced from Busia and Homabay counties in Kenya. Because bush pigs (Potamochoerus larvatus) and warthogs (Phacochoerus spp.) are known to be tolerant to ASFv infection (exhibiting no clinical symptoms despite infection), they were included in the study to assess whether domestic pigs have similar genomic signatures. Additionally, samples representing European wild boar and international commercial breeds were included as references, given their potential contribution to the genetic make-up of the target domestic populations. The data indicate that village pigs in Busia are a non-homogenous admixed population with significant introgression of genes from international commercial breeds. Pigs from Homabay by contrast, represent a homogenous population with a "local indigenous' composition that is distinct from the international breeds, and clusters more closely with the European wild boar than African wild pigs. Interestingly, village pigs from Busia that tested negative by PCR for ASFv genotype IX, had significantly higher local ancestry (>54%) compared to those testing positive, which contained more commercial breed gene introgression. This may have implication for breed selection and utilization in ASF endemic areas. A genome wide scan detected several regions under preferential selection with signatures for pigs from Busia and Homabay being very distinct. Additionally, there was no similarity in specific genes under selection between the wild pigs and domestic pigs despite having some broad areas under similar selection signatures. These results provide a basis to explore possible genetic determinants underlying tolerance to infection by ASFv genotypes and suggests multiple pathways for genetically mediated ASFv tolerance given the diversity of selection signatures observed among the populations studied.

Data from: Genotyping-by-sequencing of genome-wide microsatellite loci reveals fine-scale harvest composition in a coastal Atlantic salmon fishery

Individual assignment and genetic mixture analysis are commonly utilized in contemporary wildlife and fisheries management. Although microsatellite loci provide unparalleled numbers of alleles per locus, their use in assignment applications is increasingly limited. However, next-generation sequencing, in conjunction with novel bioinformatic tools allows large numbers of microsatellite loci to be simultaneously genotyped, presenting new opportunities for individual assignment and genetic mixture analysis. Here we scanned the published Atlantic salmon genome to identify 706 microsatellite loci, from which we developed a final panel of 101 microsatellites distributed across the genome (average 3.4 loci per chromosome). Using samples from 35 Atlantic salmon populations (n=1485 individuals) from coastal Labrador, Canada, a region characterized by low levels of differentiation in this species, this panel identified 844 alleles (average of 8.4 alleles per locus). Simulation-based evaluations of assignment and mixture identification accuracy revealed unprecedented resolution, clearly identifying 26 rivers or groups of rivers spanning 500 km of coastline. This baseline was used to examine the stock composition of 696 individuals harvested in the Labrador Atlantic salmon fishery and revealed that coastal fisheries largely targeted regional groups (<300km). This work suggests that the development and application of large sequenced microsatellite panels presents great potential for stock resolution in Atlantic salmon and more broadly in other exploited anadromous and marine species.

opencc-zeroFeb 2020View details →

Extinction-immigration dynamics lag behind environmental filtering in shaping the composition of tropical dry forests within a changing landscape

The impact of rapid habitat loss and fragmentation on biodiversity is a major issue. However, we still lack an integrative understanding of how these changes influence biodiversity dynamics over time. In this study, we investigate the effects of these changes in terms of both niche-based and neutral dynamics. We hypothesize that habitat loss has delayed effects on neutral immigration-extinction dynamics, while edge effects and environmental heterogeneity in habitat patches have rapid effects on niche-based dynamics. We analyzed taxonomic and functional composition of 100 tree communities in a tropical dry forest landscape of New-Caledonia subject to habitat loss and fragmentation. We designed an original, process-based simulation framework, and performed Approximate Bayesian Computation to infer the influence of niche-based and neutral processes. Then, we performed partial regressions to evaluate the relationships between inferred parameter values of communities and landscape metrics (distance to edge, patch area, and habitat amount around communities), derived from either recent or past (65 yrs ago) aerial photographs, while controlling for the effect of soil and topography. We found that landscape structure influences both environmental filtering and immigration. Immigration rate was positively related to past habitat amount surrounding communities. In contrast, environmental filtering was mostly affected by present landscape structure and mainly influenced by edge vicinity and topography. Our results highlight that landscape changes have contrasting spatio-temporal influences on niche-based and neutral assembly dynamics. First, landscape-level habitat loss and community isolation reduce immigration and increase demographic stochasticity, resulting in slow decline of local species diversity and extinction debt. Second, recent edge creation affects environmental filtering, incurring rapid changes in community composition by favoring species with edge-adapted strategies. Our study brings new insights about temporal impacts of landscape changes on biodiversity dynamics. We stress that landscape history critically influences these dynamics and should be taken into account in conservation policies.

opencc-zeroDec 2013View details →

Data from: Long-term experimental warming alters community composition of ascomycetes in Alaskan moist and dry arctic tundra

Arctic tundra regions have been responding to global warming with visible changes in plant community composition, including expansion of shrubs and declines in lichens and bryophytes. Even though it is well-known that the majority of arctic plants are associated with their symbiotic fungi, how fungal community composition will be different with climate warming remains largely unknown. In this study, we addressed the effects of long-term (18 years) experimental warming on the community composition and taxonomic richness of soil ascomycetes in dry and moist tundra types. Using deep Ion Torrent sequencing we quantified how OTU assemblage and richness of different orders of Ascomycota changed in response to summer warming. Experimental warming significantly altered ascomycete communities with stronger responses observed in the moist tundra compared to dry tundra. The proportion of several lichenized and moss-associated fungi decreased with warming, while the proportion of several plant and insect pathogens and saprotrophic species was higher in the warming treatment. The observed alterations in both taxonomic and ecological groups of ascomycetes are discussed in relation to previously reported warming-induced shifts in arctic plant communities, including decline in lichens and bryophytes and increase in coverage and biomass of shrubs.

Data from: Bryophyte abundance, diversity and composition after retention harvest in boreal mixedwood forest

1. Variable-retention harvest is widely recognised as an alternative to more intensive methods such as clear-cutting. However, present information is inadequate to judge impact of variable-retention on biodiversity of indigenous forest organisms intolerant of canopy removal, such as forest-inhabiting bryophytes. 2. We examined how bryophyte species cover, richness, diversity and composition change with time in response to a broad range of dispersed retention harvest treatments (2% (clear-cut), 10%, 20%, 50%, 75% retention of original basal area) contrasted with uncut controls (100% retention)) in broadleaf deciduous, mixedwood and conifer-dominated boreal forests in NW Alberta, Canada. Bryophytes were studied in 432 permanent sample plots within 72 compartments before harvest and at three, six and eleven years after harvest. 3. Clear-cut and lower (10% and 20%) retention levels resulted in lower cover and richness of bryophytes than in unharvested control compartments in mixed and conifer-dominated forests, but less so in deciduous-dominated forests, which generally supported low cover and richness. Species composition in each forest type varied along the gradient of harvesting intensity; clear-cuts and lower levels of retention supported similar composition, as did control plots and those representing higher retention levels. Over time the retention harvest treatments became more similar to uncut controls. 4. Synthesis and applications. Increased retention moderated the negative impacts of harvesting on bryophyte assemblages across all forest types, and our results suggest that even 10% retention will facilitate faster post-harvest recovery of bryophytes.02-Aug-2017

Data from: The impact of conservation management on the community composition of multiple organism groups in eutrophic interconnected man-made ponds

Ponds throughout the world are subjected to a variety of management measures for purposes of biodiversity conservation. Current conservation efforts typically comprise a combination of multiple measures that directly and indirectly impact a wide range of organism groups. Knowledge of the relative impact of individual measures on different taxonomic groups is important for the development of effective conservation programs. We conducted a field study of 28 man-made ponds, representing four management types differing in the frequency of periodic pond drainage and the intensity of fish stock management. We disentangled the relative importance of direct and indirect effects of pond management measures on the community composition of phytoplankton, zooplankton, aquatic macro-invertebrates, submerged and emergent vascular plants. With the exception of phytoplankton, pond management had strong effects on the community composition of all investigated biota. Whether management affected communities directly or indirectly through its impact on fish communities or local environmental conditions in the pond varied between organism groups. Overall, the impact of pond drainage regime and fish community characteristics on the community composition of target organism groups were more important than local environmental conditions. The majority of taxa were negatively associated with fish density, whereas multiple emergent plant species and several taxa of aquatic macro-invertebrates were positively affected by increased drainage frequency. The effects of fish community and drainage tended to be largely independent. The present study indicates that pond drainage is an important element for biodiversity conservation in eutrophicated shallow and interconnected man-made ponds.

opencc-zeroDec 2013View details →

Data from: Smooth brome invasion increases rare soil bacterial species prevalence and alters soil bacterial community composition

Plant and soil communities are tightly linked, but the mechanisms by which the invasion of an exotic plant and the resulting shifts in plant diversity and productivity influence soil bacterial community structure remain poorly understood. We investigated the effects of invasive smooth brome (Bromus inermis) on grassland soil bacterial community structure using massively-parallel sequencing of the 16S rRNA gene to determine bacterial community richness, evenness, composition, and beta diversity (UniFrac indices) of soils collected along a gradient of smooth brome abundance. We evaluated several hypotheses including: a) that the declines in native plant diversity associated with smooth brome invasion would cause declines in bacterial community diversity, and b) that mechanisms driving smooth brome effects on bacterial community structure involved altered soil edaphic properties rather than preferential invasion in areas of high soil nitrogen and distinct soil microbial communities. Smooth brome invasion led to increased soil nitrogen, soil carbon and root biomass. Bacterial evenness and bacterial richness increased with increasing smooth brome cover, while bacterial beta diversity declined. We found no evidence of a dominant direct link between the alteration of soil edaphic properties by brome and the changes in the soil bacterial community. Rather, the main controls on the soil bacterial community were direct effects of pH and smooth brome that could not be linked to the edaphic changes. The most important effect of brome on the bacterial community was the selective suppression of dominant bacterial species, which allowed rarer bacteria to increase in relative abundance. Synthesis: Here we show that plant community composition influences bacterial community structure at a very fine scale, but that these changes are not due to altered soil total nitrogen or carbon content. The dominant direct effect of smooth brome invasion on soil communities suggests non-edaphic, i.e. inter and intra-trophic, interactions among smooth brome and non-bacterial components of the soil ecosystem are key drivers of soil community structure. Some of the data in this repository were also reported in the following paper: Piper, C.L., Lamb, E.G. & Siciliano, S.D. (In Press) Smooth brome changes gross soil nitrogen cycling processes during invasion of a rough fescue grassland. Plant Ecology. doi:10.1007/s11258-014-0431-y

Data from: Species composition of First Nation whaling hunts in the Clayoquot Sound region of Vancouver Island as estimated through genetic analyses

Deepening our understanding of whale hunting practices is important from both cultural and biological perspectives. Many cultures practice whaling activities, including the Nuu-cha-nulth Nations of the Pacific Northwest. Nuu-cha-nulth cultural lifeways and laws include great care and respect for these animals that provide so much wealth to their communities. The disruption of this culture by colonial governments, combined with the decimation of whale populations through industrial whaling, led to the loss of traditional whaling activities and a gap between contemporary and historical knowledge and practices. From a scientific perspective, knowledge of current whale populations is compromised by lack of data with regards to abundance and distribution of these populations prior to colonial industrial whaling. Analysis of whale bones from First Nation whaling sites are valuable for addressing both these issues by identifying the species landed by communities in traditional hunts, and by providing a sample of the presence and distribution of whale species before colonial industrial whaling. Genetic analyses of 95 bones collected from 7 traditional whaling sites of Nuu-chah-nulth First Nations in the Pacific Northwest were conducted, as well as 11 bones from a colonial industrial whaling site in the area that operated from 1905 to 1918. Specifically, we sequenced a portion of the mitochondrial control region and cytochrome-b gene to identify what species were taken, and in what proportions. We found that 45.4% of the bones were from grey whales (Eschrictius robustus), 43.0% were from humpback whales (Megaptera novaeangliae), 8.1% were from North Pacific right whales (Eubalaena japonica), and the remaining 3.5% were from fin whales (Balaenoptera physalus). These results reveal catch compositions of historical hunts, and therefore help to inform our understanding of historic practices and preferences, and provide information on which species were present in these areas.

opencc-zeroDec 2015View details →

Data from: Vertebrate community composition and diversity declines along a defaunation gradient radiating from rural villages in Gabon

Anthropocene defaunation is the global phenomenon of human-induced animal biodiversity loss. Understanding the patterns and process of defaunation is critical to predict outcomes for wildlife populations and cascading consequences for ecosystem function and human welfare. We investigated a defaunation gradient in northeastern Gabon by establishing 24 transects at varying distances (2–30 km) to rural villages and surveying the abundance and composition of vertebrate communities. Distance from village was positively correlated with observations of hunting (shotgun shells, campfires, hunters), making it a good proxy for hunting pressure. Species diversity declined significantly with proximity to village, with mammal richness increasing by roughly 1.5 species every 10 km travelled away from a village. Compared to forest far from villages, the wildlife community near villages consisted of higher abundances of large birds and rodents and lower abundances of large mammals like monkeys and ungulates. Distance to nearest village emerged as a key driver of the relative abundance of five of the six taxonomic guilds, indicating that the top–down force of hunting strongly influences large vertebrate community composition and structure. Several measures of vegetation structure also explained animal abundance, but these varied across taxonomic guilds. Forest elephants were the exception: no measured variable or combination of variables explained variation in elephant abundances. Synthesis and applications. Hunting is concentrated within 10 km around villages, creating a hunting halo characterized by heavily altered animal communities composed of relatively small-bodied species. Although the strongest anthropogenic effects are relatively distance-limited, the linear increase in species richness shown here even at distances 30 km from villages suggests that hunting may have altered vertebrate abundances across the entire landscape. Central African forests store >25% of the carbon in tropical forests and are home to 3000 endemic species, but roughly 53% of the region lies within the village hunting halo. Resource management strategies should take into account this hunting-induced spatial variation in animal communities. Near villages, resource management should focus on sustainable community-led hunting programs that provide long-term supplies of wild meat to rural people. Resource management far from villages should focus on law enforcement and promoting industry practices that maintain remote tracts of land to preserve ecosystem services like carbon storage and biodiversity.

opencc-zeroJul 2019View details →

Data from: The influence of fire frequency on the structure and botanical composition of savanna ecosystems

Savannas cover 60% of the land surface in Southern Africa, with fires and herbivory playing a key role in their ecology. The Limpopo National Park (LNP) is a 10,000 km2 conservation area in southern Mozambique and key to protecting savannas in the region. Fire is an important factor in LNP's landscapes, but little is known about its role in the park's ecology. In this study, we explored the interaction between fire frequency (FF), landscape and vegetation. To assess the FF, we analysed ten years of the MODerate resolution Imaging Spectroradiometer (MODIS) burned area product (2003-2013). A stratified-random sampling approach was used to assess biodiversity across three dominant landscapes (Nwambia Sandveld-NS, Lebombo North-LN and Shrubveld Mopane on Calcrete-C) and two FF levels (low - twice or less; and high - 3 times or more, during 10 years). Six ha were sampled in each stratum, except for the LN vs High FF in which low accessibility allowed only 3 ha sampling. FF was higher in NS and LN landscapes, where 25% and 34% of the area, respectively burned more than three times in 10 years. The landscape type was the main determinant of grass composition and biomass. However, in the sandy NS biomass was higher under high FF. The three landscapes supported three different tree/shrub communities, but FF resulted in compositional variations in NS and LN. Fire frequency had no marked influence on woody structural parameters (height, density and phytomass). We concluded that the savannas in LNP are mainly driven by landscape (geology), but FF may impose specific modifications. We recommend a fire laissez-faire management system for most of the park and a long-term monitoring system of vegetation to address vegetation changes related to fire. Fire management should be coordinated with the neighboring Kruger National Park, given its long history of fire management.

Data from: Can ecosystem functioning be maintained despite climate-driven shifts in species composition? Insights from novel marine forests

1. Climate change is driving a redistribution of species and reconfiguration of ecological communities at a global scale. Persistent warming in many regions has caused species to extend their geographical ranges into new habitats, with thermally-tolerant species often becoming competitively dominant over species with colder affinities. Although these climate-driven changes in species abundance and diversity are well documented, their ecosystem-level implications are poorly understood, and resolving whether reconfigured communities can maintain fundamental ecosystem functions represents a pressing challenge in an increasingly warmer world. 2. Here, we investigated how climate-driven substitutions of foundation species influence processes associated with carbon and nutrient cycling (biomass production, detritus flow, herbivory, decomposition) by comparing two habitat-forming kelp species with contrasting thermal affinities. We examined the wider consequences of the observed (and predicted) emergence of novel marine forests in the NE Atlantic, which are expected to become more dominated by range-expanding, warm-temperate kelps. 3. Warm-temperate kelps both accumulated and released 80% more biomass than the cold-temperate species despite being taxonomically closely-related and morphologically similar. Furthermore, the warm-temperate species accumulated biomass and released detritus year-round, whereas the cold-temperate species did so during short, discrete periods. The warm-temperate kelps supported higher densities of invertebrate grazers and were a preferred food source. Finally, their detritus decomposed 6.5 times faster, despite supporting comparable numbers of detritivores. Overall, our results indicate an important shift in the cycling of organic matter in kelp forests along parts of the NE Atlantic coastline following climate-driven expansion of a warm-affinity kelp, with novel forests supplying large amounts of temporally-continuous—yet highly labile—organic matter. 4. Synthesis. Collectively, our results show that, like species invasions, climate-driven range expansions and consequent shifts in the identity of dominant species can modify a wide range of important ecosystem processes. However, alterations in overall ecosystem functioning may be relatively limited where foundation species share similar ecological and functional traits.

opencc-zeroDec 2015View details →

Data from: Effects of experimental warming on biodiversity depend on ecosystem type and local species composition

Climatic warming is a primary driver of change in ecosystems worldwide. Here, we synthesize responses of species richness and evenness from 187 experimental warming studies in a quantitative meta-analysis. We asked 1) whether effects of warming on diversity were detectable and consistent across terrestrial, freshwater and marine ecosystems, 2) if effects on diversity correlated with intensity, duration, and experimental unit size of temperature change manipulations, and 3) whether these experimental effects on diversity interacted with ecosystem types. Using multilevel mixed linear models and model averaging, we also tested the relative importance of variables that described uncontrolled environmental variation and attributes of experimental units. Overall, experimental warming reduced richness across ecosystems (mean log-response ratio = –0.091, 95% bootstrapped CI: –0.13, –0.05) representing an 8.9% decline relative to ambient temperature treatments. Richness did not change in response to warming in freshwater systems, but was more strongly negative in terrestrial (–11.8%) and marine (–10.5%) experiments. In contrast, warming impacts on evenness were neutral overall and in aquatic systems, but weakly negative on land (7.6%). Intensity and duration of experimental warming did not explain variation in diversity responses, but negative effects on richness were stronger in smaller experimental units, particularly in marine systems. Model-averaged parameter estimation confirmed these main effects while accounting for variation in latitude, ambient temperature at the sites of manipulations, venue (field versus lab), community trophic type, and whether experiments were open or closed to colonization. These analyses synthesize extensive experimental evidence showing declines in local richness with increased temperature, particularly in terrestrial and marine communities. However, the more variable effects of warming on evenness were better explained by the random effect of site identity, suggesting that effects on species' relative abundances were contingent on local species composition.

Data from: Metabolic programming mediated by an essential fatty acid alters body composition and survival skills of a marine fish

Metabolic programming occurs when variations in nutrition during a specific developmental window result in long-term metabolic effects. It has been studied almost exclusively in humans and other mammals but never in an ecological context. Here, we report metabolic programming and its functional consequences in a marine fish, red drum. We demonstrate that maternal provisioning of eggs with an essential fatty acid, docosahexaenoic acid (DHA), varies with DHA content of the maternal diet. When offspring are reared on a DHA-replete diet, whole-body DHA content of offspring depends upon the amount of DHA that was in the egg. We further demonstrate that whole-body DHA content is correlated with traits related to offspring fitness (escape responses, routine swimming, growth, and survival). DHA content of red drum eggs produced in nature is in the range where the effects of metabolic programming are most pronounced. Our findings indicate that during a brief developmental window DHA plays a role in establishing the pathways for its own uptake or storage, with protracted and possibly permanent effects on ecologically important survival skills of individuals and important implications for dynamics of populations and food webs.

opencc-zeroDec 2012View details →

Data from: Substantial compositional turnover of fungal communities in an alpine ridge-to-snowbed gradient

The main gradient in vascular plant, bryophyte and lichen species composition in alpine areas, structured by the topographic gradient from wind-exposed ridges to snowbeds, has been extensively studied. Tolerance to environmental stress, resulting from wind abrasion and desiccation towards windswept ridges or reduced growing season due to prolonged snow cover towards snowbeds, is an important ecological mechanism in this gradient. The extent to which belowground fungal communities are structured by the same topographic gradient, and the eventual mechanisms involved, are less well known. In this study, we analyzed variation in fungal diversity and community composition associated with roots of the ectomycorrhizal plant Bistorta vivipara along the ridge-to-snowbed gradient. We collected root samples from fifty B. vivipara plants in ten plots in an alpine area in central Norway. The fungal communities were analyzed using 454 pyrosequencing analyses of tag encoded ITS1 amplicons. A distinct gradient in the fungal community composition was found that coincided with variation from ridge to snowbeds. This gradient was paralleled by change in soil content of carbon, nitrogen and phosphorus. A large proportion (66%) of the detected 801 non-singleton operational taxonomic units (OTUs) were ascomycetes, while basidiomycetes dominated quantitatively (i.e., with respect to number of reads). Numerous fungal OTUs, many with taxonomic affinity to Sebacinales, Cortinarius and Meliniomyces, showed distinct affinities either to ridge or to snowbed plots, indicating habitat specialization. The compositional turnover of fungal communities along the gradient was not paralleled by a gradient in species richness.