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462 results for “Mutualisms”
Data from: Functional mismatch in a bumble bee pollination mutualism under climate change
Ecological partnerships, or mutualisms, are globally widespread, sustaining agriculture and biodiversity. Mutualisms evolve through the matching of functional traits between partners, such as tongue length of pollinators and flower tube depth of plants. Long-tongued pollinators specialize on flowers with deep corolla tubes, whereas shorter-tongued pollinators generalize across tube lengths. Losses of functional guilds because of shifts in global climate may disrupt mutualisms and threaten partner species. We found that in two alpine bumble bee species, decreases in tongue length have evolved over 40 years. Co-occurring flowers have not become shallower, nor are small-flowered plants more prolific. We argue that declining floral resources because of warmer summers have favored generalist foraging, leading to a mismatch between shorter-tongued bees and the longer-tubed plants they once pollinated.
Data from: Horizontal partner exchange does not preclude stable mutualism in fungus-growing ants
Vertical symbiont transmission tends to stabilize mutualisms by aligning the reproductive interests of cooperating species. The attine ants conform well to this principle, because all species are nutritionally dependent on vertically transmitted and clonally propagated fungal cultivars. Multiple mechanisms expressed by both partners constrain cultivar transmission between established colonies, but these appear not to preclude horizontal transfer during colony founding, consistent with multiple phylogenetic analyses indicating at least occasional horizontal transfer. The ecological and evolutionary impact of transfers is unknown because, although they can be induced in laboratory experiments, they remain undocumented in natural colonies. In a large-scale field study, we manipulated clusters of newly founded nests and their still portable gardens in two sympatric species of Acromyrmex leaf-cutting ants. This created mosaics of intact nests, queens without a cultivar, and cultivars without a tending queen. We tracked the movements of queens and cultivars through direct observation and microsatellite analysis, respectively. This showed that horizontal acquisition of incipient gardens is surprisingly common, because queens actively searched for replacement cultivars and often adopted orphaned gardens. However, these horizontal cultivar exchanges are unlikely to destabilize obligate farming mutualisms when they are restricted to the founding stage, as colonies eventually commit to a single cultivar clone, irreversibly aligning the partners' fitness interests before colonies reproduce.
Data from: Divergence in an obligate mutualism is not explained by divergent climatic factors
Adaptation to divergent environments creates and maintains biological diversity, but we know little about the importance of different agents of ecological divergence. Coevolution in obligate mutualisms has been hypothesized to drive divergence, but this contention has rarely been tested against alternative ecological explanations. Here, we use a well-established example of coevolution in an obligate pollination mutualism, Yucca brevifolia and its two pollinating yucca moths, to test the hypothesis that divergence in this system is the result of mutualists adapting to different abiotic environments as opposed to coevolution between mutualists. We used a combination of principal component analyses and ecological niche modeling to determine whether varieties of Y. brevifolia associated with different pollinators specialize on different environments. Yucca brevifolia occupies a diverse range of climates. When the two varieties can disperse to similar environments, they occupy similar habitats.This suggests that the two varieties have not specialized on distinct habitats. In turn, this suggests that nonclimatic factors, such as the biotic interaction between Y. brevifolia and its pollinators, are responsible for evolutionary divergence in this system.
Data from: Scale-dependent responses of pollination and seed dispersal mutualisms in a habitat transformation scenario
Transformed habitats are the result of deliberate replacement of native species by an exotic monoculture, involving changes in biotic and abiotic conditions. Despite this, transformed habitats are becoming more common and constitute a major biodiversity change driver, little is known about the scale-dependent responses of plant-animal mutualisms. Aiming to test the multi-scale responses of pollination and seed dispersal in a habitat transformation scenario, we examined a gradient of native and transformed habitats at three spatial scales (0-50, 50-100, and 100-250 m), focused on a highly-specialized mutualistic system composed of a hemiparasitic mistletoe (Tristerix corymbosus) that is almost exclusively pollinated by a hummingbird (Sephanoides sephaniodes) and dispersed by an arboreal marsupial (Dromiciops gliroides). Even though mistletoes were found along the gradient, they were more abundant and more densely aggregated when the transformed habitat was dominant. Disperser and pollinator activity also increased as the transformed habitat become dominant, at the scale of 0-50 m and 50-100 m, respectively. Furthermore, crop size and disperser activity co-varied at broad and intermediate scales, whereas recruitment co-varied at intermediate and fine scales. Moreover, disperser activity and the number of seedlings were spatially associated, stressing D. gliroides' role in the recruitment of the mistletoe. Synthesis: This highly specialized mutualistic system seems to be responding positively to the habitat structure modifications associated with Eucalyptus plantations. However, the actual costs (e.g., reduced gene flow, increased herbivory) in these transformed habitats are yet to be assessed.
Data from: Large mammal declines and the incipient loss of mammal-bird mutualisms in an African savanna ecosystem
Over the past half-century, large mammal populations have declined substantially throughout East Africa, mainly due to habitat loss and unsustainable direct exploitation. While it has been acknowledged that the loss of large mammals can have direct and cascading effects on community composition and ecosystem characteristics, limited quantitative work has been done on how declines of large herbivore populations impacts the abundance of mutualistic symbionts. Using a space-for-time observational approach, we quantified the large mammal community alongside the densities, host preferences and behaviors of mutualistic red-billed oxpeckers (Buphagus erythrorhynchus), and yellow-billed oxpeckers (Buphagus africanus) in northern Tanzania. At the landscape scale, mammal community composition was substantially less diverse in highly human-dominated areas when compared with more protected areas, with an observed complete loss of large wild mammal species in two study areas. Mirroring this trend, oxpecker densities were lowest in the least protected areas, and highest in fully protected areas. Using resource selection functions implemented via generalized linear models at different scales, we found that oxpeckers (1) were predominantly (67% of red-billed oxpeckers; 70% of yellow-billed oxpeckers) feeding on larger (between 500kg and 1500kg) ungulate host species within the mammal community, (2) usually preferred feeding on larger individuals (adults and males) within a specific host species population, and (3) preferred hosts that were more tolerant of their presence. In particular, cattle were especially intolerant of oxpecker presence and were relatively effective in displacing oxpeckers. We found little evidence that oxpecker feeding was parasitic across all host species; wound feeding was only observed on giraffe, comprising 6% and 4% of feeding behavior in red-billed and yellow-billed oxpeckers respectively. Thus, a loss of large-bodied and oxpecker tolerant host species is a likely explanation for declines of oxpecker populations in human dominated landscapes, which may have further cascading effects.
Data from: Density-dependent fitness effects stabilize parasitic hitchhiking within a mutualism
1. Mutualisms are often subject to perturbations by parasitism arising from third-party interactions. How third-party perturbations are dampened is a fundamental question pertaining to mutualism stability. Phoretic organisms that turn parasitic within a mutualism may destabilise it. If the fitness cost of such phoresy is high, then density-dependent effects could be one mechanism to stabilize these interactions. 2. We experimentally examined the fitness effects of a phoretic nematode community on a brood-site pollination mutualism involving a pollinating fig wasp (the vehicle) and its associated fig species (the host for wasp and nematode development). 3. We comprehensively investigated fitness impacts of phoresy on wasp lifespan, lifetime reproductive success, dispersal ability and predation risk as well as on host brood-site volume and seed number. We employed a range of hitchhiker densities that encompassed natural and overloading levels for two nematode taxa (one plant- and one animal-parasitic type). 4. None of the plant host and vehicle fitness parameters were affected by wasps with low nematode transportation loads for either type of nematode. Furthermore, wasps arriving at their destinations carried lower densities of both animal- and plant-parasitic nematodes compared to dispersing wasps suggesting that there is selection on hitchhiker numbers during the dispersal process, and that wasps loaded with a greater density of nematodes do not successfully disperse. Overloaded wasps had shorter flight durations, suggesting limited dispersal ability; on arrival at their destination they suffered greater predation risk. Such overloaded wasps delivered impaired pollination services and produced fewer offspring resulting in lower lifetime fitness. Therefore, the direct and indirect effects of nematodes on their vehicles are strong. These effects also translated into impacts on host plant fitness, with the overloaded pollinators promoting the development of smaller brood-sites with fewer seeds, thus reducing fig tree reproductive success. The effects of the animal parasites were greater than that of the plant parasite in this study. 5. The third-party interaction is therefore self-limited and exhibits density dependence. The strong negative effects of overloading likely explain the low number of nematodes found in nature on dispersing and arriving fig wasps. Consequently, parasitic hitchhikers do not destabilise the mutualism.
Data from: Heterogeneity in plant-soil feedbacks and resident population dynamics affect mutual invasibility
1. Understanding the mechanisms governing coexistence is a central goal in ecology and has implications for conserving and restoring communities, yet the high diversity in many plant communities is difficult to explain. Theory suggests that plant-soil feedbacks (PSF) can lead to frequency-dependent coexistence by suppressing conspecifics more than heterospecifics, potentially helping to explain high-diversity plant communities. In addition, species-specific population dynamics, including the rate at which individuals are replaced in a population, or population turnover rate, may influence coexistence outcomes. 2. We have created a rigorous test of the coexistence predictions of theory by generating a soil heterogeneity experiment in the field and testing for mutual invasibility by establishing resident populations, then experimentally invading them. Experimental tests of mutual invasibility can demonstrate coexistence because, if species are able to invade one another's populations when at low density, they should exhibit long-term coexistence. We use pairs of congeners in this experiment that coexist at small spatial scales, sometimes within cm, at our field site. 3. We demonstrate that invader individuals established better in congener's soils than in conspecific soils, consistent with plant-soil feedback mediated coexistence. This effect was often mediated by competition with established resident plants. 4. Further, we show that soil heterogeneity interacted with the population turnover rate of the resident population to influence invasibility (P < 0.10), consistent with the theoretical prediction that a plant's population dynamics will interact with heterogeneity to influence coexistence. 5. Synthesis - Plant-soil feedbacks can in theory lead to frequency-dependent coexistence, and reciprocally negative feedback effects in greenhouse experiments are often consistent with this prediction. We provide the first field test of mutual invasibility structured by PSF, demonstrating that PSF can lead to coexistence when they create a patchy, or heterogeneous, soil environment. This work suggests that understanding the influence of PSF on diversity necessitates understanding the spatial scale at which soil heterogeneity emerges in the field. Thus high diversity might be maintained in plant communities by heterogeneity created by plants' influence on the soil, and this outcome depends strongly on population dynamics.
Data from: Network reorganization and breakdown of an ant–plant protection mutualism with elevation
Both the abiotic environment and the composition of animal and plant communities change with elevation. For mutualistic species, these changes are expected to result in altered partner availability, and shifts in context-dependent benefits for partners. To test these predictions, we assessed the network structure of terrestrial ant-plant mutualists and how the benefits to plants of ant inhabitation changed with elevation in tropical forest in Papua New Guinea. At higher elevations, ant-plants were rarer, species richness of both ants and plants decreased, and the average ant or plant species interacted with fewer partners. However, networks became increasingly connected and less specialized, more than could be accounted for by reductions in ant-plant abundance. On the most common ant-plant, ants recruited less and spent less time attacking a surrogate herbivore at higher elevations, and herbivory damage increased. These changes were driven by turnover of ant species rather than by within-species shifts in protective behaviour. We speculate that reduced partner availability at higher elevations results in less specialized networks, while lower temperatures mean that even for ant-inhabited plants, benefits are reduced. Under increased abiotic stress, mutualistic networks can break down, owing to a combination of lower population sizes, and a reduction in context-dependent mutualistic benefits.
Data from: Forest disturbance and seasonal food availability influence a conditional seed dispersal mutualism
The interaction between granivorous scatter-hoarding mammals and plants is a conditional mutualism: scatter-hoarders consume seeds (acting as predators), but the movement of seed by scatter-hoarders may contribute to dispersal (acting as mutualists). Understanding the ecological factors that shape this relationship is highly relevant in anthropogenically disturbed tropical forests where large-bodied frugivores are extirpated. In such forests, large-seeded trees that once depended on these frugivores for dispersal may now only have scatter-hoarders as prospective dispersers. We studied Carapa oreophila (Meliaceae) in an Afromontane forest, to test the hypotheses that the proportion of seeds immediately consumed or hoarded (dispersed) would vary over a disturbance gradient. Temporal replication also afforded exploration of how habitat effects might vary with food availability. Using a Bayesian framework, we demonstrate that seeds were more likely to be hoarded in less disturbed forest, irrespective of temporal variation in food abundance. In contrast, forest disturbance only appeared to increase seed predation in temporal replicates that coincided with sustained food availability. These results highlight the potential variability in the dynamics between plants and scatter-hoarders over fine temporal scales, elucidating possible ecological scenarios where scatter-hoarders might act as mutualists (contributing positively to plant recruitment). Our study also fills important knowledge gaps about the importance of scatter-hoarders as dispersers in tropical forests depleted of large-bodied frugivores, particularly in Africa where scatter-hoarding mutualisms have not been extensively studied.
Data from: Water stress strengthens mutualism among ants, trees, and scale insects
Abiotic environmental variables strongly affect the outcomes of species interactions. For example, mutualistic interactions between species are often stronger when resources are limited. The effect might be indirect: water stress on plants can lead to carbon stress, which could alter carbon-mediated plant mutualisms. In mutualistic ant–plant symbioses, plants host ant colonies that defend them against herbivores. Here we show that the partners' investments in a widespread ant–plant symbiosis increase with water stress across 26 sites along a Mesoamerican precipitation gradient. At lower precipitation levels, Cordia alliodora trees invest more carbon in Azteca ants via phloem-feeding scale insects that provide the ants with sugars, and the ants provide better defense of the carbon-producing leaves. Under water stress, the trees have smaller carbon pools. A model of the carbon trade-offs for the mutualistic partners shows that the observed strategies can arise from the carbon costs of rare but extreme events of herbivory in the rainy season. Thus, water limitation, together with the risk of herbivory, increases the strength of a carbon-based mutualism.
Data from: Transcriptomic basis of genome by genome variation in a legume-rhizobia mutualism
In the legume-rhizobia mutualism, the benefit each partner derives from the other depends on the genetic identity of both host and rhizobial symbiont. To gain insight into the extent of genome x genome interactions on hosts at the molecular level and to identify potential mechanisms responsible for the variation, we examined host gene expression within nodules (the plant organ where the symbiosis occurs) of four genotypes of Medicago truncatula grown with either Ensifer meliloti or E. medicae symbionts. These host x symbiont combinations show significant variation in nodule and biomass phenotypes. Likewise, combinations differ in their transcriptomes: host, symbiont, and host x symbiont affected the expression of 70%, 27% and 21%, respectively, of the approximately 27,000 host genes expressed in nodules. Genes with the highest levels of expression often varied between hosts and/or symbiont strain and include leghemoglobins that modulate oxygen availability and hundreds of Nodule Cysteine-Rich (NCR) peptides involved in symbiont differentiation and viability in nodules. Genes with host x symbiont dependent expression were enriched for functions related to resource exchange between partners (sugar/sulfate/iron/amino acid transport and dicarboxylate/amino acid synthesis). These enrichments suggest mechanisms for host control of the currencies of the mutualism. The transcriptome of M. truncatula accession HM101 (A17), the reference genome used for most molecular research, was less affected by symbiont identity than the other hosts. These findings underscore the importance of assessing the molecular basis of variation in ecologically important traits, particularly those involved in biotic interactions, in multiple genetic contexts.
First field-based evidence that the seagrass-lucinid mutualism can mitigate sulfide stress in seagrasses
<p>Seagrass meadows form vital ecological components of coastal zones worldwide, but are rapidly declining. Large-scale seagrass diebacks have been related to accumulation of toxic sulfide in the sediment, a phenomenon predicted to occur more frequently in the near future due to ongoing global warming and increasing organic loading of coastal systems worldwide. Recently, a facultative mutualism between seagrasses and lucinid bivalves with endosymbiotic sulfide-consuming gill bacteria was discovered that may prevent toxic sulfide accumulation in seagrass sediments. Yet, direct field-based evidence for the importance of this mutualism in alleviating sulfide stress in seagrasses is currently lacking, as well as how its role may change when sediment sulfide levels increase due to environmental change. Here, we investigated the sulfide detoxification function of this seagrass-lucinid mutualism and its resilience to organic-loading induced sulfide stress in a temperate lagoon system (Thau lagoon, France), using a correlative field survey and a full factorial field experiment. The field survey revealed a strong positive correlation between seagrass above-ground biomass and lucinid densities, and pore water sulfide concentrations close to zero at all sites. Furthermore, the field experiment revealed that addition of organic matter (starch mixed with sucrose) increased sedimentary sulfide intrusion into seagrass (<em>Zostera noltei</em>) leaves (a proxy for sulfide stress), while experimentally enhanced lucinid densities reduced sulfide intrusion, regardless of addition of organic matter. Moreover, addition of organic matter reduced seagrass rhizome biomass and increased pore water sulfide levels, lucinid tissue sulfur content, lucinid condition (expressed as flesh/shell dry weight ratio), and total lucinid biomass, while enhancement of lucinid densities reduced lucinid condition. These results provide the first field-based evidence that lucinid bivalves and their sulfide-oxidizing gill symbionts mitigate sulfide stress in seagrasses, and suggests that the dependence of seagrass on this seagrass-lucinid mutualism will increase under conditions of enhanced sediment sulfide production, as predicted for the near future. Therefore, we suggest that awareness of the ecological importance of the seagrass-lucinid mutualism may be instrumental for designing new measures for improving long-term restoration success and seagrass resilience to global change.</p>
Data from: Sanctions, partner recognition, and variation in mutualism
Mutualistic interactions can be stabilized against invasion by noncooperative individuals by putting such "cheaters" at a selective disadvantage. Selection against cheaters should eliminate genetic variation in partner quality—yet such variation is often found in natural populations. One explanation for this paradox is that mutualism outcomes are determined not only by responses to partner performance but also by partner signals. Here, we build a model of coevolution in a symbiotic mutualism, in which hosts' ability to sanction noncooperative symbionts and recognition of symbiont signals are determined by separate loci, as are symbionts' cooperation and expression of signals. In the model, variation persists without destabilizing the interaction, in part because coevolution of symbiont signals and host recognition is altered by the coevolution of sanctions and cooperation, and vice versa. Individual-based simulations incorporating population structure strongly corroborate these results. The dual systems of sanctions and partner recognition converge toward conditions similar to some economic models of mutualistic symbiosis, in which hosts offering the right incentives to potential symbionts can initiate symbiosis without screening for partner quality. These results predict that mutualists can maintain variation in recognition of partner signals or in the ability to sanction noncooperators without destabilizing mutualism, and they reinforce the notion that studies of mutualism should consider communication between partners as well as the exchange of benefits.
Data from: The role of abiotic and biotic factors in determining coexistence of multiple pollinators in the yucca-yucca moth mutualism
The determinants of a species' geographic distribution are a combination of both abiotic and biotic factors. Environmental niche modeling of climatic factors has been instrumental in documenting the role of abiotic factors in a species' niche. Integrating this approach with data from species interactions provides a means to assess the relative roles of abiotic and biotic components. Here, we examine whether the high host specificity typically exhibited in the active pollination mutualism between yuccas and yucca moths is the result of differences in climatic niche requirements that limit yucca moth distributions or the result of competition among mutualistic moths that would co-occur on the same yucca species. We compared the species distribution models of two Tegeticula pollinator moths that use the geographically widespread plant Yucca filamentosa. Tegeticula yuccasella occurs throughout eastern North America whereas T. cassandra is restricted to the southeastern portion of the range, primarily occurring in Florida. Species distribution models demonstrate that T. cassandra is restricted climatically to the southeastern United States and T. yuccasella is predicted to be able to live across all of eastern North America. Data on moth abundances in Florida demonstrate that both moth species are present on Y. filamentosa; however, T. cassandra is numerically dominant. Taken together, the results suggest that moth geographic distributions are heavily influenced by climate, but competition among pollinating congeners will act to restrict populations of moth species that co-occur.
Data from: Fishing-down within populations harms seed dispersal mutualism
Large fish are often the most effective seed dispersers, but they are also the preferred target for fisheries. We recently started to comprehend the detrimental impacts of the extirpation of large frugivorous fish species on natural forest regeneration, but we lack a general understanding of how intraspecific size-selective harvest affects fish–fruit mutualism. Our literature review demonstrated that large individuals within populations positively affect diverse aspects of seed dispersal, from consuming a higher diversity of seeds to enhancing germination. Furthermore, we filled a research gap by studying how individual size variations within two small frugivorous fish species (<16 cm) affect seed dispersal in flooded savannas. Even within small-bodied species, large individuals swallow a higher number of intact seeds, but not necessarily a higher proportion. Overall, our results demonstrate the disproportional role of large-bodied individuals as key seed dispersers in flooded habitats. Consequently, fishing-down within both large- and small-bodied species can negatively affect seed dispersal and natural regeneration in overfished wetlands.
Data from: Reduced sexual dichromatism, mutual ornamentation, and individual quality in the monogamous Zenaida dove, Zenaida aurita
Although variation in plumage coloration is known to occur both between and within sexes, its study remains limited to a few bird families. The Zenaida dove, Zenaida aurita, is a socially monogamous tropical columbid bird species, characterized by an overall cinnamon-brownish plumage and structural colorations on the head and neck. The species has been described as sexually dichromatic for plumage, although color differences between males and females are not obvious in the field. We investigated variation in the presumably melanin-based color of the crown, mantle, breast, and belly, in the iridescent dark-blue streaks on the head, and in the symmetric iridescent patches on the neck, over the whole spectrum visible to birds. Further, unlike most previous studies, we assessed covariation between plumage color and phenotypic traits in both males and females in relation to the putative signaling function of ornaments. Zenaida doves appeared to be slightly sexually dichromatic for the hue of pigment-based colored areas, with males being on average more reddish than females. However, this difference was not discernible when considering the avian visual system. Conversely, although the reflectance spectra of iridescent plumage did not significantly differ between sexes in brightness, chroma or spectral position of the peaks, color discrimination analyses showed that individuals should be able to perceive between- or within-sex differences in the color of the iridescent patch. In addition, several color parameters of brown and iridescent feathers were significantly related to territorial status, body condition, wing chord, and, albeit weakly, to individual multilocus heterozygosity. Overall, our results thus suggest that plumage color might be a reliable signal of quality in individuals of both sexes in this species. Further studies are needed to test the potential implication of plumage coloration in mate choice and mating patterns in the Zenaida Dove.
Data from: Trade-offs in an ant–plant–fungus mutualism
Species engaged in multiple, simultaneous mutualisms are subject to trade-offs in their mutualistic investment if the traits involved in each interaction are overlapping, which can lead to conflicts and affect the longevity of these associations. We investigate this issue via a tripartite mutualism involving an ant plant, two competing ant species and a fungus the ants cultivate to build galleries under the stems of their host plant to capture insect prey. The use of the galleries represents an innovative prey capture strategy compared with the more typical strategy of foraging on leaves. However, because of a limited worker force in their colonies, the prey capture behaviour of the ants results in a trade-off between plant protection (i.e. the ants patrol the foliage and attack intruders including herbivores) and ambushing prey in the galleries, which has a cascading effect on the fitness of all of the partners. The quantification of partners' traits and effects showed that the two ant species differed in their mutualistic investment. Less investment in the galleries (i.e. in fungal cultivation) translated into more benefits for the plant in terms of less herbivory and higher growth rates and vice versa. However, the greater vegetative growth of the plants did not produce a positive fitness effect for the better mutualistic ant species in terms of colony size and production of sexuals nor was the mutualist compensated by the wider dispersal of its queens. As a consequence, although the better ant mutualist is the one that provides more benefits to its host plant, its lower host–plant exploitation does not give this ant species a competitive advantage. The local coexistence of the ant species is thus fleeting and should eventually lead to the exclusion of the less competitive species.
Data from: Recurrent mutualism breakdown events in a legume rhizobia metapopulation
<p><span>Bacterial mutualists generate major fitness benefits for eukaryotes, reshaping the host phenotype and its interactions with the environment. Yet microbial mutualist populations are predicted to generate mutants that defect from providing costly services to hosts while maintaining the capacity to exploit host resources. Here, we examined the mutualist service of symbiotic nitrogen fixation in a metapopulation of root-nodulating <i>Bradyrhizobium spp.</i> that associate with the native legume <i>Acmispon strigosus</i>. We quantified mutualism traits of 85 <i>Bradyrhizobium</i> isolates gathered from a 700km transect in California spanning ten sampled <i>A. strigosus</i> populations. We clonally inoculated each <i>Bradyrhizobium </i>isolate onto <i>Acmispon strigosus</i> hosts and quantified nodulation capacity and net effects of infection, including host growth and isotopic nitrogen concentration. Six <i>Bradyrhizobium</i> isolates from five populations were categorized as ineffective because they formed nodules but did not enhance host growth via nitrogen fixation. Six additional isolates from three populations failed to form root nodules. Phylogenetic reconstruction inferred two types of mutualism breakdown, including three to four independent losses of effectiveness and five losses of nodulation capacity on <i>Acmispon strigosus</i>. The evolutionary and genomic drivers of these mutualism breakdown events remain poorly understood. </span></p>
Data from: Ant mutualism increases long-term growth and survival of a common Amazonian tree
How ecological context shapes mutualistic relationships remains poorly understood. We combined long-term tree census data with ant censuses in a permanent 25-ha Amazonian forest dynamics plot to evaluate the effect of the mutualistic ant Myrmelachista schumanni (Formicinae) on the growth and survival of the common Amazonian tree Duroia hirsuta (Rubiaceae), considering its interactions with tree growth, population structure, and habitat. We found that the mutualist ant more than doubled tree relative growth rates and increased odds of survival. However, host tree size and density of conspecific neighbors modified the effect of the ant. Smaller trees hosting the mutualist ant consistently grew faster when surrounded by higher densities of conspecifics, suggesting that the benefit to the tree outweighs any negative effects of high conspecific densities. Moreover, our findings suggest that the benefit afforded by the ant diminishes with plant age and also depends on the density of conspecific neighbors. We provide the first long-term large-scale evidence of how mutualism affects the population biology of an Amazonian tree species.
An effective mutualism? The role of theoretical studies in ecology and evolution
<p>Theoretical models often have fundamentally different goals than do empirical studies of the same topic. Models can test the logic of existing hypotheses, explore the plausibility of new hypotheses, provide expectations that can be tested with data, and address aspects of topics that are currently inaccessible empirically. Theoretical models are common in ecology and evolution, and are generally well-cited, but I show that many citations appearing in non-theoretical studies are general to topic and a substantial proportion are incorrect. One potential cause of this pattern is that some functions of models are rather abstract, leading to miscommunication between theoreticians and empiricists. Such misunderstandings are often triggered by simplifying, logistical assumptions that modelers make. The 2018 Vice Presidential Symposium of the American Society of Naturalists included a variety of mathematical models in ecology and evolution from across several topics. Common threads that appear in the use of the models are identified, highlighting the power of a theoretical approach and the role of the assumptions that such models make.</p>
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Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
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The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
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