Find research datasets worth reusing

Data from: Assessing feeding preferences of a consumer guild: partitioning variation among versus within species

Interspecific variation in resource use is critical to understanding species diversity, coexistence, and ecosystem functioning. A growing body of research describes analogous intraspecific variation and its potential importance for population dynamics and community outcomes. However, the magnitude of intraspecific variation relative to interspecific variation in key dimensions of consumer-resource interactions remains unknown, and is critical for understanding the importance of this variation for population and community processes. In this study, we examine feeding preference through repeated laboratory choice feeding assays of 444 wild-caught individuals of eight invertebrate grazer species on rocky reefs in northern California, USA. Between-species variation accounted for 25-33% of the total variation in preference for the preferred resource, while between-individual variation accounted for 4-5% of total variation. For two of the eight species, between-individual variation was significantly different from zero and contributed on-average 14% and 17% of the total diet variation, even after accounting for differences due to size and sex. Therefore, even with clearly distinguishable between-species differences in mean preference, diet variation between and within individuals can contribute to the dietary niche width of species and guilds, which may be overlooked by focusing solely on species' mean resource use patterns.

Data from: Habitat partitioning during character displacement between the sexes

Ecological differences between the sexes are often interpreted as evidence of within-species ecological character displacement (ECD), a hypothesis with almost no direct tests. Here we experimentally-test two predictions, that are direct corollaries of ECD between the sexes, in a salamander. First, we find support for the prediction that each sex has a growth rate advantage in the aquatic microhabitat where it is most commonly found. Second, we test the prediction that selection for ECD in the breeding environment may affect partial migration out of this environment. We found that phenotype-dependent migration resulted in a shift in the phenotypic distribution across treatments, with the highest sexual dimorphism occurring among residents at high founding density, suggesting migration and ECD can both be driven by competition. Our work illustrates how complex patterns of habitat partitioning evolve during ECD between the sexes and suggest ECD and partial migration can interact to effect both ecological dynamics and evolution of sexual dimorphism.

opencc-zeroDec 2015View details →

Data from: Experimental evidence for fundamental, and not realised, niche partitioning in a plant-herbivore community interaction network

Patterns of niche partitioning can result from local ecological interactions (e.g. interspecific competition) occurring within a contemporary time frame (realised niche partitioning). Alternatively they may represent the end-product of historical processes acting over long time frames (fundamental niche partitioning). Niche partitioning is often detected by analysing patterns of resource use within communities, but experiments are rarely conducted to test whether patterns of non-overlapping resource use reflect realised or fundamental niche partitioning. We studied a community of restio leafhoppers from the genus Cephalelus, and their host plants, the Restionaceae (restios). We used network and experimental approaches to determine whether network modularity (a measure of niche partitioning within local communities) reflects fundamental or realised niche partitioning. Using a weighted modularity index for two party networks (e.g. insect - plant) we determined whether the network of this community is modular (i.e. consists of groups of species interacting strongly, with weak interactions between groups). We also aimed to identify specific Cephalelus - restio modules (groups). Using knowledge of module membership to design experiments, we tested whether Cephalelus species from two different modules, C. uncinatus and C. pickeri, prefer and perform better on restios from their own modules versus restios from other modules. These experiments were performed under controlled conditions, eliminating the influences of competition and predation on host choices. The Cephalelus – restio community was modular, implying niche partitioning. Cephalelus also preferred and performed better on restios from their own modules in the absence of local contemporary factors. Most niche partitioning in the investigated Cephalelus community, is not caused by local interactions, and thus host use patterns represent fundamental niches. Our findings highlight the importance of understanding local community structure in the light of processes extrinsic to the local community context.

opencc-zeroDec 2011View details →

Data from: Diversity partitioning confirms the importance of beta components in tropical rainforest Lepidoptera

Tropical beta diversity, and particularly that of herbivorous insects in rainforests, is often considered enormous, but this notion has recently been challenged. As tropical beta diversity is highly relevant to our view on biodiversity, it is important to gain more insights and resolve methodological problems that may lead to the contradictions in different studies. We used data on two ecologically distinct moth families from Southeast-Asia and analyzed separately the contribution of beta components to overall species richness at three spatial scales. Observed diversity partitions were compared under different types of null models. We found that alpha diversity was lower than expected from null models, whereas hierarchical beta components were larger than expected. Beta components played a significant role in shaping gamma diversity, and their contribution can be high (multiplicative beta >5). We found a reduction of beta components when comparing primary forests and agricultural sites (cf. "biotic homogenization"), but even in these habitats beta components were still substantial. Our analyses show that beta components do play an important role in our data on tropical herbivorous insects, and that these results are not due to lumping different habitats when sampling environmental gradients.

opencc-zeroDec 2014View details →

Data from: Rehabilitating the cyanobacteria – niche partitioning, resource use efficiency, and phytoplankton community structure during diazotrophic cyanobacterial blooms

1. Blooms of nitrogen-fixing cyanobacteria are recurrent phenomena in marine and freshwater habitats, and their supplying role in aquatic biogeochemical cycles is generally considered vital. The objective of this study is to analyze if an increasing proportion of nitrogen-fixing cyanobacteria affects (i) the composition of the non-diazotrophic component of ambient phytoplankton communities, and (ii) resource use efficiency (RUE; ratio of chl a to total nutrients) – an important ecosystem function. We hypothesize that diazotrophs increase community P use, and decrease N use efficiencies, as new N is brought into the system, relaxing N, and concomitantly aggravating P limitation. We test this by analyzing an extensive dataset from the Baltic Sea (> 3700 quantitative phytoplankton samples), known to harbor conspicuous and recurrent blooms of Nodularia spumigena and Aphanizomenon sp. 2. System-level phosphorus use efficiency (RUEP) was positively related with high proportion of diazotrophic cyanobacteria, suggesting aggravation of phosphorus limitation. However, concomitant decrease of nitrogen use efficiency (RUEN) was not observed. Nodularia spumigena, a dominant diazotroph and a notorious toxin producer, had a significantly stronger relationship with RUEP, compared to the competing non-toxic Aphanizomenon sp., confirming niche differentiation in P acquisition strategies between the major bloom-forming cyanobacterial species in the Baltic Sea. Nodularia occurrences were associated with stronger temperature stratification in more offshore environments, indicating higher reliance on in situ P regeneration. 3. By using constrained and unconstrained ordination, permutational multivariate analysis of variance, and local similarity analysis, we show that diazotrophic cyanobacteria explained no more than a few percent of the ambient phytoplankton community variation. The analyses furthermore yielded rather evenly distributed negative and positive effects on individual co-occurring phytoplankton taxa, with no obvious phylogenetic or functional trait-based patterns. 4. Synthesis. Our study reveals that despite the widely acknowledged noxious impacts of cyanobacterial blooms, the overall effect on phytoplankton community structure is minor. There are no predominantly positive or negative associations with ambient phytoplankton species. Species-specific niche differences in cyanobacterial resource acquisition affect important ecosystem functions, like biomass production per unit limiting resource.

opencc-zeroDec 2016View details →

Data from: Temporal and spatial activity-associated energy partitioning in free-swimming sea snakes

1. Partitioning energy between critical basal functions and activity-associated behaviours is a primary determinant of animal survival. Consequently, habitat selection is likely to be driven by the efficiency with which resources can be acquired from a heterogeneous energy landscape. 2. Determining how energy partitioning is achieved across temporal and spatial scales is particularly challenging in aquatic animals due to the logistical limitations in estimating field metabolic rates (FMR) while simultaneously examining habitat choice. 3. Here, accelerometry telemetry and bimodal respirometry were used to correlate vectorial dynamic body acceleration (VeDBA) with oxygen consumption rates (V̇o2) of sea snakes (Hydrophis curtus and H. elegans) across an ecologically-relevant temperature range. Subsequently, VeDBA of free-roaming snakes was used to estimate activity-associated FMR within a near-shore environment over diel, seasonal and spatial scales. 4. Diel changes in activity explained short-term patterns in FMR, whereas seasonal changes in water temperature drove long-term patterns. Spatial analyses demonstrated that activity-associated FMR was elevated in productive seagrass and mudflat habitats, indicative of a concentration of foraging efforts. 5. Our findings illustrate for the first time how sea snakes partition activity-associated FMR across time and space, providing an approach by which we can monitor the impacts of, and vulnerabilities to, natural and anthropogenic disturbances like warming and trawl fisheries.

opencc-zeroDec 2016View details →

Data from: Space partitioning in wild, non-territorial mountain gorillas: the impact of food and neighbours

In territorial species, the distribution of neighbours and food abundance play a crucial role in space use patterns but less is known about how and when neighbours use shared areas in non-territorial species. We investigated space partitioning in 10 groups of wild, non-territorial mountain gorillas (Gorilla beringei beringei). Using location data, we examined factors influencing daily movement decisions and calculated the per cent overlap of annual kernel home ranges and core areas among neighbours. We found that the probability that a group chose an area was positively influenced by both food availability and the previous use of that area by the group. Additionally, groups reduced their overall utilization of areas previously used by neighbouring groups. Lastly, groups used their core areas more exclusively than their home ranges. In sum, our results show that both foraging needs and avoidance of competition with neighbours determined the gorillas' daily movement decisions, which presumably lead to largely mutually exclusive core areas. Our research suggests that non-territorial species actively avoid neighbours to maintain core area exclusivity. Together, these findings contribute to our understanding of the costs and benefits of non-territoriality.

opencc-zeroDec 2016View details →

Data from: Isotopic niche partitioning between two apex predators over time

1. Stable isotope analyses have become an important tool in reconstructing diets, analyzing resource use patterns, elucidating trophic relations among predators and understanding the structure of food webs. 2. Here, we use stable carbon and nitrogen isotope ratios in bone collagen to reconstruct and compare the isotopic niches of adult South American fur seals (Arctocephalus australis); n = 86) and sea lions (Otaria flavescens); n = 49) –two otariid species with marked morphological differences– in the Río de la Plata estuary (Argentina - Uruguay) and the adjacent Atlantic Ocean during the second half of the 20th century and the beginning of the 21st century. Samples from the middle Holocene (n = 7 fur seals and n = 5 sea lions) are also included in order to provide a reference point for characterizing resource partitioning before major anthropogenic modifications of the environment. 3. We found that the South American fur seals and South American sea lions had distinct isotopic niches during the middle Holocene. Isotopic niche segregation was similar at the beginning of the second half of the 20th century, but has diminished over time. 4. The progressive convergence of the isotopic niches of these two otariids during the second half of the 20th century and the beginning of the 21st century is most likely due to the increased reliance of South American fur seals on demersal prey. 5. This recent dietary change of South American fur seals can be explained by at least two non-mutually exclusive mechanisms: (i) the decrease in the abundance of sympatric South American sea lions as a consequence of small colony size and high pup mortality resulting from commercial sealing; and (ii) the decrease in the average size of demersal fishes due to intense fishing of the larger class sizes, which may have increased their accessibility to those eared seals with a smaller mouth gape, i.e., South American fur seals of both sexes and female South American sea lions.

opencc-zeroDec 2015View details →

Data from: Fine partitioning of epiphyte habitat within Johansson zones in tropical Australian rainforest trees

For over three decades, the Johansson zones have been widely used in epiphyte studies as a way of stratifying the host tree into habitat zones, however, the usefulness of this system has been questioned. We test the effectiveness of the Johansson zones by grouping epiphyte species by the substrate and microclimatic attributes of their individual occurrences and assessing the fidelity of these groups to the Johansson zones. Habitat characteristics were recorded for every individual epiphyte on 30 trees in the lower montane rainforests of north-eastern Australia. Twenty-four epiphyte species were agglomerated into four groups using Ward's method. Group 4 was highly distinct and included shade loving species and nomadic vines from the lower zones of the host trees. Group 3 contained species from the most exposed habitats. Group 1 had higher light levels and lower substrate thickness than Group 2, yet both groups had close to identical distributions over the Johansson zones. This suggests that groups of epiphyte species may utilise different micro-sites within the same zone. While the Johansson zones are a useful tool in epiphyte studies, finer partitioning of habitat within the host tree may be missed.

opencc-zeroDec 2012View details →

Data from: Increasing zooplankton size diversity enhances the strength of top-down control on phytoplankton through diet niche partitioning

1. The biodiversity-ecosystem functioning debate is a central topic in ecology. Recently, there has been a growing interest in size diversity because body size is sensitive to environmental changes and is one of the fundamental characteristics of organisms linking many ecosystem properties. However, how size diversity affects ecosystem functioning is an important yet unclear issue. 2. To fill the gap, with large-scale field data from the East China Sea, we tested the novel hypothesis that increasing zooplankton size diversity enhances top-down control on phytoplankton (H1) and compared it with five conventional hypotheses explaining the top-down control: flatter zooplankton size spectrum enhances the strength of top-down control (H2); nutrient enrichment lessens the strength of top-down control (H3); increasing zooplankton taxonomic diversity enhances the strength of top-down control (H4); increasing fish predation decreases the strength of top-down control of zooplankton on phytoplankton through trophic cascade (H5); increasing temperature intensifies the strength of top-down control (H6). 3. The results of univariate analyses support the hypotheses based on zooplankton size diversity (H1), zooplankton size spectrum (H2), nutrient (H3), and zooplankton taxonomic diversity (H4), but not the hypotheses based on fish predation (H5) and temperature (H6). More in depth analyses indicate that zooplankton size diversity is the most important factor in determining the strength of top-down control on phytoplankton in the East China Sea. 4. Our results suggest a new potential mechanism, that increasing predator size diversity enhances the strength of top-down control on prey through diet niche partitioning. This mechanism can be explained by the optimal predator-prey body-mass ratio concept. Suppose each size group of zooplankton predators has its own optimal phytoplankton prey size, increasing size diversity of zooplankton would promote diet niche partitioning of predators and thus elevates the strength of top-down control.

opencc-zeroMar 2024View details →

Data and code for: Partitioning variance in a signaling trade-off under sexual selection reveals among-individual covariance in trait allocation

Understanding the evolution of traits subject to trade-offs is challenging because phenotypes can (co)vary at both the among- and within-individual levels. Among-individual covariation indicates consistent, possibly genetic, differences in how individuals resolve the trade-off, while within-individual covariation indicates trait plasticity. There is also the potential for consistent among-individual differences in behavioral plasticity, although this has rarely been investigated. We studied the sources of (co)variance in two characteristics of an acoustic advertisement signal that trade off with one another and are under sexual selection in the gray treefrog, Hyla chrysoscelis: call duration and call rate. We recorded males on multiple nights calling spontaneously and in response to playbacks simulating different competition levels. Call duration, call rate, and their product, call effort, were all repeatable both within and across social contexts. Call duration and call rate covaried negatively, and the largest covariance was at the among-individual level. There was extensive plasticity in calling with changes in social competition, and we found some evidence for among-individual variance in call rate plasticity. The significant negative among-individual covariance in trait values is perpendicular to the primary direction of sexual selection in this species, indicating potential limits on the response to selection.

opencc-zeroFeb 2022View details →

Data from: Partitioning the effects of plant diversity on ecosystem functions at different trophic levels

Biodiversity effects on ecosystem functioning can be partitioned into complementarity effects, driven by many species, and selection effects, driven by few. Selection effects occur through interspecific abundance shifts (dominance) and intraspecific shifts in functioning. Complementarity and selection effects are often calculated for biomass, but very rarely for secondary productivity, i.e. energy transfer to higher trophic levels. We calculated diversity effects for three functions: aboveground biomass, insect herbivory and pathogen infection, the latter two as proxies for energy transfer to higher trophic levels, in a grassland experiment (PaNDiv) manipulating species richness, functional composition, nitrogen enrichment and fungicide treatment. Complementarity effects were on average positive and selection effects negative for biomass production and pathogen infection and multiple species contributed to diversity effects in mixtures. Diversity effects were on average less pronounced for herbivory. Diversity effects for the three functions were not correlated, because different species drove the different diversity effects. Benefits (and costs) from growing in diverse communities, be it reduced herbivore or pathogen damage or increased productivity either due to abundance increases or increased productivity per area were distributed across different plant species, leading to highly variable contributions of single species to diversity effects on different functions. These results show that different underlying ecological mechanisms can result in similar overall diversity effects across functions.

opencc-by-4.0Mar 2019View details →

Experimental data from the paper "Subset-Saturated Cost Partitioning for Optimal Classical Planning"

The data set contains the raw experiment data, parsed values and basic reports for the experiments in the paper. For each experiment there are two directories. The first directory contains the raw data of all experiment runs. The code directories and benchmark files have been removed to avoid duplication and save space. The second directory (*-eval) contains a "properties" file with all parsed values and an HTML report.

opencc-by-4.0May 2019View details →

Trophic niche partitioning of seven skate species (Rajidae), in the Northern and Central Patagonia, Argentina-Raw data

Skate´s content stomach information and statistics information

opencc-by-4.0May 2019View details →

Experimental data from the IJCAI 2019 paper "Pattern Selection for Optimal Classical Planning with Saturated Cost Partitioning"

This data set contains the raw experiment data, parsed values and basic reports for the experiments in the paper. For each experiment there are two directories. The first directory contains the raw data of all experiment runs. The code directories and benchmark files have been removed to avoid duplication and to save space. The second directory (*-eval) contains a "properties" file with all parsed values and an HTML report.

opencc-by-4.0Oct 2019View details →

Experimental data from the JAIR 2020 paper "Saturated Cost Partitioning for Optimal Classical Planning"

Data from: Isotopic and dietary niches as indicators for resource partitioning in the gleaner bats M. bechsteinii, M. nattereri, and P. auritus

The n-dimensional ecological niche summarizes all living requirements of a species. According to the competition and niche theory, co-occurring species have to differ in at least one dimension to live in stable coexistence. Measuring the overall ecological niche within natural ecosystems is probably impossible but methods that describe several dimensions at once like the isotopic niche are good approximations. However, the impact of each factor contributing to the isotopic niche might be difficult to estimate. The dietary niche, as one part of the isotopic niche, can be examined with high resolution using molecular techniques. In this study we aimed to improve our understanding of species coexistence. We outlined the importance of the isotopic and dietary niches in the context of resource partitioning using the bat species M. bechsteinii, M. nattereri, and P. auritus of the gleaner guild as examples. The dietary and isotopic niches were estimated with stable isotope analysis and molecular fecal analysis. We tested (i) how distinct the occupied dietary niches of members of the same guild are and (ii) how similar the dietary and isotopic niches are to each other. While the inter-specific overlap was high for the dietary niche, no overlap could be observed for the isotopic niche. In general, the isotopic niche can describe a more complete picture of the ecological niche, while the dietary niche provides highly detailed information. The combination of both niches might advance our understanding of stable species coexistences.

Data from: Sex-specific prey partitioning in breeding piscivorous birds examined via a novel, non-invasive approach

Piscivorous birds frequently display sex-specific differences in their hunting and feeding behaviour, which lead to diverging impacts on prey populations. Cormorants (Phalacrocoracidae), for example, were previously studied to examine dietary differences between the sexes and males were found to consume larger fish in coastal areas during autumn and winter. However, information on prey partitioning during breeding and generally on sex-specific foraging in inland waters is missing. Here, we assess sex-specific prey choice of Great Cormorants (Phalacrocorax carbo) during two subsequent breeding seasons in the Central European Alpine foreland, an area characterized by numerous stagnant and flowing waters in close proximity to each other. We developed a unique, non-invasive approach and applied it to regurgitated pellets: molecular cormorant sexing combined with molecular fish identification and fish-length regression analysis performed on prey hard parts. Altogether, 364 pellets delivered information on both, bird sex and consumed prey. The sexes differed significantly in their overall prey composition, even though Perca fluviatilis, Rutilus rutilus and Coregonus spp. represented the main food source for both. Albeit prey composition did not indicate the use of different water bodies by the sexes, male diet was characterized by higher prey diversity within a pellet and the consumption of larger fish. The current findings show that female and male cormorants to some extent target the available prey spectrum at different levels. Finally, the comprehensive and non-invasive approach has great potential for application in studies of other piscivorous bird species.

opencc-zeroDec 2014View details →

Data from: Genome-wide association and genome partitioning reveal novel genomic regions underlying variation in gastrointestinal nematode burden in a wild bird

Identifying the genetic architecture underlying complex phenotypes is a notoriously difficult problem that often impedes progress in understanding adaptive eco-evolutionary processes in natural populations. Host–parasite interactions are fundamentally important drivers of evolutionary processes, but a lack of understanding of the genes involved in the host's response to chronic parasite insult makes it particularly difficult to understand the mechanisms of host life history trade-offs and the adaptive dynamics involved. Here, we examine the genetic basis of gastrointestinal nematode (Trichostrongylus tenuis) burden in 695 red grouse (Lagopus lagopus scotica) individuals genotyped at 384 genome-wide SNPs. We first use genome-wide association to identify individual SNPs associated with nematode burden. We then partition genome-wide heritability to identify chromosomes with greater heritability than expected from gene content, due to harbouring a multitude of additive SNPs with individually undetectable effects. We identified five SNPs on five chromosomes that accounted for differences of up to 556 worms per bird, but together explained at best 4.9% of the phenotypic variance. These SNPs were closely linked to genes representing a range of physiological processes including the immune system, protein degradation and energy metabolism. Genome partitioning indicated genome-wide heritability of up to 29% and three chromosomes with excess heritability of up to 4.3% (total 8.9%). These results implicate SNPs and novel genomic regions underlying nematode burden in this system and suggest that this phenotype is somewhere between being based on few large-effect genes (oligogenic) and based on a large number of genes with small individual but large combined effects (polygenic).