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opencc-zeroNov 2020View details →

Generalised host-plant feeding can hide sterol specialised foraging behaviours in bee-plant interactions

Host-plant selection is a key factor driving the ecology and evolution of insects. While the majority of phytophagous insects are highly host specific, generalist behaviour is quite widespread among bees and presumably involves physiological adaptations that remain largely unexplored. However floral visitation patterns suggest that generalist bees do not forage randomly on all available resources. While resource availability and accessibility as well as nectar composition have been widely explored, pollen chemistry could also have an impact on the range of suitable host-plants. This study focuses on particular pollen nutrients that cannot be synthesised de novo by insects but are key compounds of cell membranes and the precursor for moulting process: the sterols. We compared the sterol composition of pollen from the main host-plants of three generalist bees: Anthophora plumipes,Colletes cuniculariusand Osmia cornuta, as well as one specialist bee Andrena vaga. We also analysed the sterols of their brood cell provisions, the tissues of larvae and non-emerged females to determine which sterols are used by the different species. Our results show that sterols are not used accordingly to foraging strategy: Both the specialist species Andrena vagaand the generalist species Colletes cuniculariusmight metabolise a rare C27sterol, while the two generalist species Anthophora plumipesand Osmiacornutamight rather use a very common C28sterol. Our results suggest that shared sterolic compounds among plant species could facilitate the exploitation of multiple host-plants by A. plumipesand O. cornutawhereas the generalist C. cuniculariusmight be more constrained due to its physiological requirements of a more uncommon dietary sterol. Our findings suggest that a bee displaying a generalist foraging behaviour may sometimes hide a sterol-specialised species. This evidence challenges the hypothesis that all generalist free-living bee species are all able to develop on a wide range of different pollen types.

opencc-zeroDec 2016View details →

Data from: Environmental stability increases relative individual specialisation across populations of an aquatic top predator

The concept of the niche has long been a central pillar in ecological theory, with a traditional focus on quantifying niches at the species or population level. However, the importance of individual-level niche variation is increasingly being recognised, with a strong focus on individual specialisation. While examples illustrating the contribution of the individual niche to whole population niche structure are accumulating rapidly, surprisingly little is known about the conditions that shape the differences between these two potentially divergent components. Though theory predicts that stability should influence the extent of such intra-specific specialisation, we know of no previous study that has investigated its role in individual specialisation, and the differentiation between individual- and population niches. Here, we studied the diet of individuals from multiple populations of an aquatic top-predator, Salmo trutta, inhabiting contrasting stable, groundwater fed and unstable, surface water fed pre-alpine streams. Based on stomach content analysis, we found that individuals living in stable environments displayed a higher degree of specialisation than those in unstable environments, with the between-individual component of niche width being approximately twice as high in the former. We subsequently validated these results by evidence gained from stable isotope analysis of muscle tissue. As such, we reveal that environmental stability can significantly influence individual niches within populations, leading to increased specialisation.

opencc-zeroDec 2013View details →

Data from: Consistency pays: sex differences and fitness consequences of behavioural specialisation in a wide ranging seabird

Specialists and generalists often coexist within a single population, but the biological drivers of individual strategies are not fully resolved. When sexes differ in their foraging strategy, this can lead them to different environmental conditions and stability across their habitat range. As such, sexual segregation, combined with dominance, may lead to varying levels of specialization between the sexes. Here, we examine spatial and temporal niche width (intraindividual variability in aspects of foraging behaviour) of male and female black-browed albatrosses (Thalassarche melanophrys), and its consequences for fitness. We show that females, where maximum foraging range is under fluctuating selection, exhibit more variable behaviours and appear more generalist than males, who are under directional selection to forage close to the colony. However within each sex, successful birds had a much narrower niche width across most behaviours, suggesting some specialization is adaptive in both sexes. These results demonstrate that while there are sex differences in niche width, the fitness benefit of specialization in spatial distribution is strong in this wide-ranging seabird.

opencc-zeroAug 2019View details →

Data from: Evolution of resource specialisation in competitive metacommunities

Spatial environmental heterogeneity coupled with dispersal can promote ecological persistence of diverse metacommunities. Does this premise hold when metacommunities evolve? Using a 2-resource competition model, we studied the evolution of resource-uptake specialization as a function of resource type (substitutable to essential) and shape of the trade-off between resource uptake affinities (generalist- to specialist-favoring). In spatially homogeneous environments, evolutionarily stable coexistence of consumers is only possible for sufficiently substitutable resources and specialist-favoring trade-offs. Remarkably, these same conditions yield comparatively low diversity in heterogeneous environments, because they promote sympatric evolution of two opposite resource specialists that, together, monopolize the two resources everywhere. Consumer diversity is instead maximized for intermediate trade-offs and clearly substitutable or clearly essential resources, where evolved metacommunities are characterized by contrasting selection regimes. Taken together, our results present new insights on resource-competition-mediated evolutionarily-stable diversity in homogeneous and heterogeneous environments, which should be applicable to a wide range of systems.

opencc-zeroDec 2016View details →

Data from: Reproductive success is driven by local site fidelity despite stronger specialisation by individuals for large scale habitat preference

1. There is widespread evidence that within populations, specialists and generalists can coexist and this is particularly prevalent in marine ecosystems, where foraging specialisations are evident. 2. While individuals may limit niche overlap by consistently foraging in specific areas, site fidelity may also emerge as an artefact of habitat choice but both drivers and fitness consequences of site fidelity are poorly understood. 3. Here we examine an individual metric of site and habitat fidelity, using tracking data collected over 11 years for black-browed albatrosses (Thalassarche melanophris). Fidelity was calculated as the similarity between pairs of foraging zones, quantifying measures for within and between years. Foraging areas were identified using area restricted search, defined as periods during which birds decrease speed and increase turning. 4. Our results demonstrate that birds were considerably more specialised in the habitat in which they forage than the exact location they use within years, and there was a similar pattern between years. However, despite this, it was site fidelity that explained reproductive success. Within a single year, females which were more faithful to a specific location had higher reproductive success than non-specialists and between years there was tendency for both sexes. 5. Our results suggest that black-browed albatrosses are highly faithful in their foraging habitat but it is rather site fidelity that is more clearly associated with reproductive success.

opencc-zeroDec 2017View details →

Data from: Venom of prey-specialised spiders is more toxic to their preferred prey: a result of prey-specific toxins

1. In specialised predators a variety of adaptations have evolved to such a level of specificity that they allow very effective exploitation of focal prey. Venom is an essential adaptive trait of predatory venomous species, such as spiders, yet our knowledge of spider venom is incomplete. 2. In agreement with the prey preference hypothesis, we expected that the venom of spider specialists should be more toxic to focal than to alternative prey, because it is composed of prey-specific toxins. 3. Here we used spiders with three types of trophic specialisations: specialists that were ant-eating, termite-eating, and spider-eating. We compared the efficacy of prey capture of preferred and alternative prey (measured as paralysis latency) with that of related generalists and profiled the venom of the studied species using proteomic methods. We used 22 spider species: six myrmecophagous, two termitophagous, three araneophagous, and 11 euryphagous generalist species belonging to different families. 4. We found that ten of the eleven specialist species induced significantly shorter paralysis latency in preferred prey than in alternative prey. Generalists exhibited either similar efficiency on both prey types or slightly higher efficiency on preferred prey. 5. Multivariate analysis of proteomic profiles (peptides and proteins) revealed significant differences between trophic specialisations, particularly in peptides. Specialists appear to have venom composed of unique specific compounds as revealed by the multivariate ordination and indicator analysis. These components are likely prey-specific toxins.

opencc-zeroMay 2022View details →

Ecological specialisation and range size determine intraspecific body size variation in a speciose clade of insect herbivores

The body size of an adult insect is strongly determined by the environmental factors to which it is exposed during growth and development. Insect species confronted with a high environmental variability across their geographical range (i.e., wide ecological niche breadth) may therefore reveal broader variation in body size than those species which are more specialised (i.e., narrow ecological niche). In this study, we aim to investigate whether characteristics related to the ecological niche breadth of a holometabolous insect species (i.e., its ecological specialisation) affect its intraspecific variation in adult body size. By using European geometrid moths as a model group, we specifically tested whether latitudinal range size, larval resource use, and voltinism affect intraspecific body size variation. We hypothesised that plasticity will increase along with latitudinal range and larval diet breadth. We further expected that univoltine species reveal a lower body size variation compared to those with multiple generations per year. To test these hypotheses, we compiled a comprehensive trait database for 631 species of European geometrid moths from literature, including information on adult body size, life history, and distribution. We further reconstructed a molecular phylogeny including all analysed geometrid species and applied phylogenetic comparative methods in order to test our predictions. In support of our hypotheses, we found that intraspecific size variation is positively related to latitudinal range size and larval diet breadth, and that multivoltine species reveal a higher heterogeneity in body size than taxa with a strictly univoltine life style. Based on our results, we demonstrated that intraspecific body size variation in geometrid moths is negatively related to ecological specialisation. We further suggest that increased variation in body size with increasing niche breadth is a general pattern, which likely applies to many other insect groups as well. This assumption, however, demands further empirical scrutiny.

opencc-zeroAug 2021View details →

Seasonality affects specialisation of a temperate forest herbivore community

Understanding spatiotemporal trends on insect-plant interaction networks is essential to unveil the ecological and evolutionary processes driving herbivore specialisation. However, community studies accounting for temporal dynamics in host-plant specialisation of herbivorous insects are surprisingly scarce. Here, we provide the background data which were used to investigate how seasonality affects specialisation of a temperate forest herbivore community. This dataset results from a comprehensive sampling of more than 4,700 folivorous caterpillars associated with 16 deciduous tree species in eastern North America. Specifically, we provide three abundance-based plant-caterpillar interaction matrices. Each interaction matrix represents a six-week period of the growing season. These time periods are defined as follow: early season, midseason, and late season. We observed a significantly less specialised herbivore fauna in the early season than in the two subsequent summer seasons. We further found that the seasonal increase in specialisation was driven by a remarkable turnover in species composition rather than by shifts in guild structure or intraspecific changes in diet breadth of the herbivores.

opencc-zeroOct 2021View details →

Supplemental data for: Three-dimensional kinematics of euchelicerate limbs uncover functional specialisation in eurypterid appendages

Sea scorpions (Eurypterida; Euchelicerata) explored the extreme limits of the aquatic euchelicerate body plan. Indeed, the group contains the largest known marine euarthropods. Inferences on eurypterid life modes—in particular walking and eating—are commonly made by comparing the group to horseshoe crabs (Xiphosura; Euchelicerata). However, no models have been presented to test these hypotheses. Here, we reconstruct prosomal appendages of two exceptionally well-preserved eurypterids Eurypterus tetragonophthalmus and Pentecopterus decorahensis and kinematically model the flexure and extension of these appendages in 3D. We compare these models to 3D kinematic models of Limulus polyphemus prosomal appendages. This comparison highlights that the examined eurypterid prosomal appendages could not have effectively moved prey items to the gnathal edges, and therefore would not have emulated the motion of a L. polyphemus walking leg. It seems that these eurypterid appendages were primarily used to walk or grab prey and other appendages would have moved prey for mastication. Such 3D kinematic modelling highlights how eurypterid appendage morphologies placed substantial limits on their function, suggesting a high degree of specialisation, especially when compared to horseshoe crabs. 3D kinematic modelling of these extinct groups also presents an innovative approach to understanding the position of these animals within their respective paleoecosystems.

opennotspecifiedMar 2022View details →

Fig. 2. Key 1 H– 1 H in Anti-inflammatory and cytotoxic specialised metabolites from the leaves of Glandularia × hybrida

Fig. 2. Key 1 H– 1 H COSY and HMBC correlations in compound 1.

opennotspecifiedMar 2022View details →

Fig. 1 in Anti-inflammatory and cytotoxic specialised metabolites from the leaves of Glandularia × hybrida

Fig. 1. List of isolated compounds (1-5).

opennotspecifiedMar 2022View details →

Fig. 3 in Anti-inflammatory and cytotoxic specialised metabolites from the leaves of Glandularia × hybrida

Fig. 3. Stereochemical structure of compound 1.

Fig. 5 in Bioactive specialised metabolites from the endophytic fungus Xylaria sp. of Cudrania tricuspidata

Fig. 5. Calculated ECD or experimental ECD curves of 11.

Fig. 3 in Bioactive specialised metabolites from the endophytic fungus Xylaria sp. of Cudrania tricuspidata

Fig. 3. Calculated ECD or experimental ECD curves of 1a, 1b, 1c, 2a and 2b.

Fig. 4 in Bioactive specialised metabolites from the endophytic fungus Xylaria sp. of Cudrania tricuspidata

Fig. 4. Key NOESY correlations of compound 1c.

Fig. 1 in Bioactive specialised metabolites from the endophytic fungus Xylaria sp. of Cudrania tricuspidata

Fig. 1. Structures of compounds 1–13.

opennotspecifiedOct 2022View details →

Fig. 2. 1H–1H in Undescribed specialised metabolites from the endophytic fungus Emericella sp. XL029 and their antimicrobial activities

Fig. 2. 1H–1H COSY and key HMBC correlations of compounds 1–7.