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991.
Pollination networks are usually constructed and assessed by direct field observations which commonly assume that all flower visitors are true pollinators. However, this assumption is often invalid and the use of data based on mere visitors to flowers may lead to a misunderstanding of intrinsic pollination networks. Here, using a large dataset by both sampling floral visitors and analyzing their pollen loads, we constructed 32 networks pairs (visitation versus pollen transport) across one flowering season at four elevation sites in the Himalaya–Hengduan Mountains region. Pollen analysis was conducted to determine which flower visitors acted as potential pollinators (pollen vectors) or as cheaters (those not carrying pollen of the visited plants). We tested whether there were topological differences between visitation and pollen transport networks and whether different taxonomic groups of insect visitors differed in their ability to carry pollen of the visited plants. Our results indicated that there was a significantly higher degree of specialization at both the network and species levels in the pollen transport networks in contrast to the visitation networks. Modularity was lower but nestedness was higher in the visitation networks compared to the pollen transport networks. All the cheaters were identified as peripheral species and most of them contributed positively to the nested structure. This may explain in part the differences in modularity and nestedness between the two network types. Bees carried the highest proportion of pollen of the visited plants. This was followed by Coleoptera, other Hymenoptera and Diptera. Lepidoptera carried the lowest proportion of pollen of the visited plants. Our study shows that the construction of pollen transport networks could provide a more in‐depth understanding of plant–pollinator interactions. Moreover, it suggests that detecting and removing cheater interactions when studying the topology of other mutualistic networks might be also important.  相似文献   
992.
The assessment of genetic differentiation in functional traits is fundamental towards understanding the adaptive characteristics of forest species. While traditional phenotyping techniques are costly and time‐consuming, remote sensing data derived from cameras mounted on unmanned aerial vehicles (UAVs) provide potentially valid high‐throughput information for assessing morphophysiological differences among tree populations. In this work, we test for genetic variation in vegetation indices (VIs) and canopy temperature among populations of Pinus halepensis as proxies for canopy architecture, leaf area, photosynthetic pigments, photosynthetic efficiency and water use. The interpopulation associations between vegetation properties and above‐ground growth (stem volume) were also assessed. Three flights (July 2016, November 2016 and May 2017) were performed in a genetic trial consisting of 56 populations covering a large part of the species range. Multispectral (visible and near infrared wavelengths), RGB (red, green, blue) and thermal images were used to estimate canopy temperature and vegetation cover (VC) and derive several VIs. Differences among populations emerged consistently across flights for VC and VIs related to leaf area, indicating genetic divergence in crown architecture. Population differences in indices related to photosynthetic pigments emerged only in May 2017 and were probably related to a contrasting phenology of needle development. Conversely, the low population differentiation for the same indices in July 2016 and November 2016 suggested weak interpopulation variation in the photosynthetic machinery of mature needles of P. halepensis. Population differences in canopy temperature found in July 2016 were indicative of variation in stomatal regulation under drought stress. Stem volume correlated with indices related to leaf area (positively) and with canopy temperature (negatively), indicating a strong influence of canopy properties and stomatal conductance on above‐ground growth at the population level. Specifically, a combination of VIs and canopy temperature accounted for about 60% of population variability in stem volume of adult trees. This is the first study to propose UAV remote sensing as an effective tool for screening genetic variation in morphophysiological traits of adult forest trees.  相似文献   
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A key point of protein stability engineering is to identify specific target residues whose mutations can stabilize the protein structure without negatively affecting the function or activity of the protein. Here, we propose a method called RiSLnet (Rapid i dentification of Smart mutant Library using residue network) to identify such residues by combining network analysis for protein residue interactions, identification of conserved residues, and evaluation of relative solvent accessibility. To validate its performance, the method was applied to four proteins, that is, T4 lysozyme, ribonuclease H, barnase, and cold shock protein B. Our method predicted beneficial mutations in thermal stability with ~62% average accuracy when the thermal stability of the mutants was compared with the ones in the Protherm database. It was further applied to lysine decarboxylase (CadA) to experimentally confirm its accuracy and effectiveness. RiSLnet identified mutations increasing the thermal stability of CadA with the accuracy of ~60% and significantly reduced the number of candidate residues (~99%) for mutation. Finally, combinatorial mutations designed by RiSLnet and in silico saturation mutagenesis yielded a thermally stable triple mutant with the half-life (T 1/2) of 114.9 min at 58°C, which is approximately twofold higher than that of the wild-type.  相似文献   
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Chuan Yan  Zhibin Zhang 《Oikos》2019,128(8):1147-1157
Despite the prevalence of context‐dependent interaction transitions in ecological systems, their impacts on persistence and interaction diversity have scarcely been explored in complex ecological networks. By using multispecies bi‐directional and unidirectional consumer–resource models, representing a continuum of interaction transitions (sign change of interaction outcomes), we investigated the effects of structural interaction transitions on persistence (the fraction of remaining species) and long‐term interaction outcomes in random ecological networks. We found that high interaction strength of exploiting resources generally decreased persistence, and high strength of providing resources increased persistence when the strength of exploiting resources was low in more complex networks; also, the networks with high persistence had a high proportion of mutualistic interactions relative to antagonistic interactions present initially and over the long term. The shifting of interaction strengths shaped the long‐term interaction compositions. Meanwhile, population dynamics, especially species extinction, affected the difference between initial and long‐term interactions. Based on classical consumer–resource theory, these results establish a transitional continuum of interaction outcomes in ecological networks and imply a theoretical association among interaction transition, community persistence and interaction diversity.  相似文献   
999.
Biodiversity–ecosystem functioning (BEF) studies typically show that species richness enhances community biomass, but the underlying mechanisms remain debated. Here, we combine metrics from BEF research that distinguish the contribution of dominant species (selection effects, SE) from those due to positive interactions such as resource partitioning (complementarity effects, CE) with a functional trait approach in an attempt to reveal the functional characteristics of species that drive community biomass in species mixtures. In a biodiversity experiment with 16 plant species in monocultures, 4‐species and 16‐species mixtures, we used aboveground biomass to determine the relative contributions of CE and SE to biomass production in mixtures in the second, dry year of the experiment. We also measured root traits (specific root length, root length density, root tissue density and the deep root fraction) of each species in monocultures and linked the calculated community weighted mean (CWM) trait values and trait diversity of mixtures to CE and SE. In the second year of the experiment, community biomass, CE and SE increased compared to the first year. The contribution of SE to this positive effect was greater than that of CE. The increased contribution of SE was associated with root traits: SE increased most in communities with high abundance of species with deep, thick and dense roots. In contrast, changes in CE were not related to trait diversity or CWM trait values. Together, these results suggest that increased positive effects of species richness on community biomass in a dry year were mainly driven by increased dominance of deep‐rooting species, supporting the insurance hypothesis of biodiversity. Positive CE indicates that other positive interactions did occur, but we could not find evidence that belowground resource partitioning or facilitation via root trait diversity was important for community productivity in our biodiversity experiment.  相似文献   
1000.
Modularity and integration are variational properties expressed at various levels of the biological hierarchy. Mismatches among these levels, for example developmental modules that are integrated in a functional unit, could be informative of how evolutionary processes and trade‐offs have shaped organismal morphologies as well as clade diversification. In the present study, we explored the full, integrated and modular spaces of two developmental modules in phacopid trilobites, the cephalon and the pygidium, and highlight some differences among them. Such contrasts reveal firstly that evolutionary processes operating in the modular spaces are stronger in the cephalon, probably due to a complex regime of selection related to the numerous functions ensured by this module. Secondly, we demonstrate that the same pattern of covariation is shared among species, which also differentiate along this common functional integration. This common pattern might be the result of stabilizing selection acting on the enrolment and implying a coordinate variation between the cephalon and the pygidium in a certain direction of the morphospace. Finally, we noticed that Austerops legrandi differs slightly from other species in that its integration is partly restructured in the way the two modules interact. Such a divergence can result from the involvement of the cephalon in several vital functions that may have constrained the response of the features involved in enrolment and reorganized the covariation of the pygidium with the cephalon. Therefore, it is possible that important evolutionary trade‐offs between enrolment and other functions on the cephalon might have partly shaped the diversification of trilobites.  相似文献   
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