Temperature and nutrients are two of the most important drivers of global change. Both can modify the elemental composition (i.e. stoichiometry) of primary producers and consumers. Yet their combined effect on the stoichiometry, dynamics and stability of ecological communities remains largely unexplored. To fill this gap, we extended the Rosenzweig-MacArthur consumer-resource model by including thermal dependencies, nutrient dynamics and stoichiometric constraints on both the primary producer and the consumer. We found that stoichiometric and nutrient conservation constraints dampen the paradox of enrichment and increased persistence at high nutrient levels. Nevertheless, stoichiometric constraints also reduced consumer persistence at extreme temperatures. Finally, we also found that stoichiometric constraints and nutrient dynamics can strongly influence biomass distribution across trophic levels by modulating consumer assimilation efficiency and resource growth rates along the environmental gradients. In the Rosenzweig-MacArthur model, consumer biomass exceeded resource biomass for most parameter values whereas, in the stoichiometric model, consumer biomass was strongly reduced and sometimes lower than resource biomass. Our findings highlight the importance of accounting for stoichiometric constraints as they can mediate the temperature and nutrient impact on the dynamics and functioning of ecological communities.

Phenological shifts, changes in the seasonal timing of life cycle events, are among the best documented responses of species to climate change. However, the consequences of these phenological shifts for population dynamics remain unclear. Population growth could be enhanced if species that advance their phenology benefit from longer growing seasons and gain a pre-emptive advantage in resource competition. However, it might also be reduced if phenological advances increase exposure to stresses, such as herbivores and, in colder climates, harsh abiotic conditions early in the growing season. We exposed subalpine grasslands to ~ 3 K of warming by transplanting intact turfs from 2000 m to 1400 m elevation in the eastern Swiss Alps, with turfs transplanted within the 2000 m site acting as a control. In the first growing season after transplantation, we recorded species' flowering phenology at both elevations. We also measured species' cover change for three consecutive years as a measure of plant performance. We used models to estimate species' phenological plasticity (the response of flowering time to the change in climate) and analysed its relationship with cover changes following climate change. The phenological plasticity of the 18 species in our study varied widely but was unrelated to their changes in cover. Moreover, early- and late-flowering species did not differ in their cover response to warming, nor in the relationship between cover changes and phenological plasticity. These results were replicated in a similar transplant experiment within the same subalpine community, established one year earlier and using larger turfs. We discuss the various ecological processes that can be affected by phenological shifts, and argue why the population-level consequences of these shifts are likely to be species- and context-specific. Our results highlight the importance of testing assumptions about how warming-induced changes in phenotypic traits, like phenology, impact population dynamics.

Accurately characterizing spatial patterns on landscapes is necessary to understand the processes that generate biodiversity, a problem that has applications in ecological theory, conservation planning, ecosystem restoration, and ecosystem management. However, the measurement of biodiversity patterns and the ecological and evolutionary processes that underlie those patterns is highly dependent on the study unit size, boundary placement, and number of observations. These issues, together known as the modifiable areal unit problem, are well known in geography. These factors limit the degree to which results from different metacommunity and macro-ecological studies can be compared to draw new inferences, and yet these types of comparisons are widespread in community ecology. Using aquatic community datasets, we demonstrate that spatial context drives analytical results when landscapes are sub-divided. Next, we present a framework for using resampling and neighborhood smoothing to standardize datasets to allow for inferential comparisons. We then provide examples for how addressing these issues enhances our ability to understand the processes shaping ecological communities at landscape scales and allows for informative meta-analytical synthesis. We conclude by calling for greater recognition of issues derived from the modifiable areal unit problem in community ecology, discuss implications of the problem for interpreting the existing literature, and identify tools and approaches for future research.

Many plants produce structural defenses to deter feeding by herbivores. However, many previous studies testing whether spines are effective at defending against mammalian herbivores have produced equivocal results. These ambiguous results are hypothesized to be due to herbivore counter-adaptations. We investigated potential counter-adaptations in a population of white-throated woodrats that specialize on cactus by investigating feeding behavior and preference for cacti varying in spinescence. exhibited a unique behavior of clipping cactus spines, which renders these defenses ineffective. Strikingly, these woodrats chose to collect spiny cacti over experimentally de-spined cacti, demonstrating that spines act as a proximal cue that attracts woodrats. This attraction is likely due to the higher protein and lower fiber content of spiny cacti compared to naturally non-spiny cacti. Thus, the 'defensive' spines of cacti are ineffective against a specialist herbivore and instead serve as an indicator of nutritional quality that promotes herbivory. Our results support the 'rule-of-thumb' hypothesis of foraging, which states that herbivores forage according to obvious visual cues that are indicative of nutritional content, rather than sampling nutrient composition of plants. We propose that specialist herbivores are unique systems in which to study other counter-adaptations to structural defenses and 'rule-of-thumb' foraging strategies.

Compensatory or catch-up growth following growth impairment caused by transient environmental stress, due to adverse abiotic factors or food, is widespread in animals. Such growth strategies commonly balance retarded development and reduced growth. They depend on the type of stressor but are unknown for predation risk, a prime selective force shaping life history. Anti-predator behaviours by immature prey typically come at the cost of reduced growth rates with potential negative consequences on age and size at maturity. Here, we investigated the hypothesis that transient intraguild predation (IGP) risk induces compensatory or catch-up growth in the plant-inhabiting predatory mite . Immature were exposed in the larval stage to no, low or high IGP risk, and kept under benign conditions in the next developmental stage, the protonymph. High but not low IGP risk prolonged development of larvae, which was compensated in the protonymphal stage by increased foraging activity and accelerated development, resulting in optimal age and size at maturity. Our study provides the first experimental evidence that prey may balance developmental costs accruing from anti-predator behaviour by compensatory growth.

Climate change is altering the timing of life history events in a wide array of species, many of which are involved in mutualistic interactions. Because many mutualisms can form only if partner species are able to locate each other in time, differential phenological shifts are likely to influence their strength, duration and outcome. At the extreme, climate change-driven shifts in phenology may result in phenological mismatch: the partial or complete loss of temporal overlap of mutualistic species. We have a growing understanding of how, when, and why phenological change can alter one type of mutualism-pollination. However, as we show here, there has been a surprising lack of attention to other types of mutualism. We generate a set of predictions about the characteristics that may predispose mutualisms in general to phenological mismatches. We focus not on the consequences of such mismatches but rather on the likelihood that mismatches will develop. We explore the influence of three key characteristics of mutualism: 1) intimacy, 2) seasonality and duration, and 3) obligacy and specificity. We predict that the following characteristics of mutualism may increase the likelihood of phenological mismatch: 1) a non-symbiotic life history in which co-dispersal is absent; 2) brief, seasonal interactions; and 3) facultative, generalized interactions. We then review the limited available data in light of our a priori predictions and point to mutualisms that are more and less likely to be at risk of becoming phenologically mismatched, emphasizing the need for research on mutualisms other than plant-pollinator interactions. Future studies should explicitly focus on mutualism characteristics to determine whether and how changing phenologies will affect mutualistic interactions.

Ecological interaction networks, such as those describing the mutualistic interactions between plants and their pollinators or between plants and their frugivores, exhibit non-random structural properties that cannot be explained by simple models of network formation. One factor affecting the formation and eventual structure of such a network is its evolutionary history. We argue that this, in many cases, is closely linked to the evolutionary histories of the species involved in the interactions. Indeed, empirical studies of interaction networks along with the phylogenies of the interacting species have demonstrated significant associations between phylogeny and network structure. To date, however, no generative model explaining the way in which the evolution of individual species affects the evolution of interaction networks has been proposed. We present a model describing the evolution of pairwise interactions as a branching Markov process, drawing on phylogenetic models of molecular evolution. Using knowledge of the phylogenies of the interacting species, our model yielded a significantly better fit to 21% of a set of plant - pollinator and plant - frugivore mutualistic networks. This highlights the importance, in a substantial minority of cases, of inheritance of interaction patterns without excluding the potential role of ecological novelties in forming the current network architecture. We suggest that our model can be used as a null model for controlling evolutionary signals when evaluating the role of other factors in shaping the emergence of ecological networks.

Assessing the relative importance of intransitive competition networks in nature has been difficult because it requires a large number of pairwise competition experiments linked to observed field abundances of interacting species. Here we introduce metrics and statistical tests for evaluating the contribution of intransitivity to community structure using two kinds of data: competition matrices derived from the outcomes of pairwise experimental studies ( matrices) and species abundance matrices. We use C matrices to develop patch transition matrices () that predict community structure in a simple Markov chain model. We propose a randomization test to evaluate the degree of intransitivity from these matrices in combination with empirical or simulated matrices. Benchmark tests revealed that the methods could correctly detect intransitive competition networks, even in the absence of direct measures of pairwise competitive strength. These tests represent the first tools for estimating the degree of intransitivity in competitive networks from observational datasets. They can be applied to both spatio-temporal data sampled in homogeneous environments or across environmental gradients, and to experimental measures of pairwise interactions. To illustrate the methods, we analyzed empirical data matrices on the colonization of slug carrion by necrophagous flies and their parasitoids.

In many group-living animals, within-group associations are determined by familiarity, i.e. familiar individuals, independent of genetic relatedness, preferentially associate with each other. The ultimate causes of this behaviour are poorly understood and rigorous documentation of its adaptive significance is scarce. Limited attention theory states that focusing on a given task has interrelated cognitive, behavioural and physiological costs with respect to the attention paid to other tasks. In multiple signal environments attention has thus to be shared among signals. Assuming that familiar neighbours require less attention than unfamiliar ones, associating with familiar individuals should increase the efficiency in other tasks and ultimately increase fitness. We tested this prediction in adult females of the group-living, plant-inhabiting predatory mite We evaluated the influence of social familiarity on within-group association behaviour, activity, predation and reproduction. In mixed groups (familiar and unfamiliar), familiar predator females preferentially associated with each other. In pure groups (either familiar or unfamiliar), familiar predator females produced more eggs than unfamiliar females at similar predation rates. Higher egg production was correlated with lower activity levels, indicating decreased restlessness. In light of limited attention theory, we argue that the ability to discriminate between familiar and unfamiliar individuals and preferential association with familiar individuals confers a selective advantage because familiar social environments are cognitively and physiologically less taxing than unfamiliar social environments.

Positive and negative plant-plant interactions are major processes shaping plant communities. They are affected by environmental conditions and evolutionary relationships among the interacting plants. However, the generality of these factors as drivers of pairwise plant interactions and their combined effects remain virtually unknown. We conducted an observational study to assess how environmental conditions (altitude, temperature, irradiance and rainfall), the dispersal mechanism of beneficiary species and evolutionary relationships affected the co-occurrence of pairwise interactions in 11 steppes located along an environmental gradient in Spain. We studied 197 pairwise plant-plant interactions involving the two major nurse plants (the resprouting shrub and the tussock grass ) found in these communities. The relative importance of the studied factors varied with the nurse species considered. None of the factors studied were good predictors of the co-ocurrence between and its neighbours. However, both the dispersal mechanism of the beneficiary species and the phylogenetic distance between interacting species were crucial factors affecting the co-occurrence between and its neighbours, while climatic conditions (irradiance) played a secondary role. Values of phylogenetic distance between 207-272.8 Myr led to competition, while values outside this range or fleshy-fruitness in the beneficiary species led to positive interactions. The low importance of environmental conditions as a general driver of pairwise interactions was caused by the species-specific response to changes in either rainfall or radiation. This result suggests that factors other than climatic conditions must be included in theoretical models aimed to generally predict the outcome of plant-plant interactions. Our study helps to improve current theory on plant-plant interactions and to understand how these interactions can respond to expected modifications in species composition and climate associated to ongoing global environmental change.

Understanding the static and dynamic expression of life history traits is a prerequisite for the development of a causal theory of the evolution of aging and of life histories. We analyzed the statics and dynamics of reproduction and survival in a wild population of the Northern Fulmar, (Procellaridae). Survival rate is most influenced by year as compared to age and cohort. When temporal variation is ignored, survival rate increases slowly with age and then declines more rapidly at late ages. Survival rate contingent upon reproductive "stratum" (producing an egg, hatching an egg, fledging a hatchling) also exhibits this pattern. Survival and reproduction have a positive static association in that survival rate increases as the apparent energy allocated to reproduction increases (as indexed by stratum). There is a broad distribution of realized lifetime reproductive success, which could be due to "fixed" heterogeneity, with some individuals always having low survival and reproduction and others always having high survival and reproduction, or be due to "dynamic" heterogeneity, with all individuals having the same expected reproductive and survival rates. Analysis of stochastic stratum dynamics indicates that individuals do not remain long in any given stratum and suggest that the variation among individuals with respect to lifetime reproductive success is due to dynamic heterogeneity. The probability of producing an egg increases with age for both sexes, whereas the probability of producing a fledgling initially declines with age and then increases. These results underscore the necessity of understanding the static and dynamic expression of demographic traits when making a causal claim about their evolution.

Body size of animals often increases with increasing latitude. These latitudinal clines in body size have interested biologists for over 150 years. However, the mechanisms that generate these clines in size are still unclear, though latitudinal gradients in temperature appear to play an important role. More importantly, many studies that examine latitudinal clines in body size and the mechanisms responsible for these clines use phenotypic data, confounding genetic (adaptive) and non-genetic (plasticity) sources of variation. Yet, most of these studies make adaptive conclusions based on phenotypic measures of size. Here I show the dangers of making adaptive inferences from phenotypic measures of size. In addition, I use a specific form of plasticity in body size of ectotherms, called the temperature - size rule, to illustrate how confusion about genetic and non-genetic contributions to phenotypic variation has hampered progress in understanding the evolution of latitudinal clines in size. Field-based measurements of body size can no doubt be influenced by plasticity, but demonstrating that latitudinal clines have a genetic basis is necessary to show that these patterns are adaptive.

Communication and information are central concepts in evolutionary biology. In fact, it is hard to find an area of biology where these concepts are not used. However, quantifying the information transferred in biological interactions has been difficult. How much information is transferred when the first spring rainfall hits a dormant seed, or when a chick begs for food from its parent? One measure that is commonly used in such cases is fitness value: by how much, on average, an individual's fitness would increase if it behaved optimally with the new information, compared to its average fitness without the information. Another measure, often used to describe neural responses to sensory stimuli, is the mutual information-a measure of reduction in uncertainty, as introduced by Shannon in communication theory. However, mutual information has generally not been considered to be an appropriate measure for describing developmental or behavioral responses at the organismal level, because it is blind to function; it does not distinguish between relevant and irrelevant information. In this paper we show that there is in fact a surprisingly tight connection between these two measures in the important context of evolution in an uncertain environment. In this case, a useful measure of fitness benefit is the increase in the long-term growth rate, or the fold increase in number of surviving lineages. We show that in many cases the fitness value of a developmental cue, when measured this way, is exactly equal to the reduction in uncertainty about the environment, as described by the mutual information.

Environmental change is not likely to act on biodiversity in a random manner, but rather according to species traits that affect assembly processes, thus, having potentially serious consequences on ecological functions. We investigated the effects of anthropogenic land use on functional richness of local hoverfly communities of 24 agricultural landscapes across temperate Europe. A multivariate ordination separated seven functional groups based on resource use, niche characteristics and response type. Intensive land use reduced functional richness, but each functional group responded in a unique way. Species richness of generalist groups was nearly unaffected. Local habitat quality mainly affected specialist groups, while land use affected intermediate groups of rather common species. We infer that high species richness within functional groups alone is no guarantee for maintaining functional richness. Thus, it is not species richness per se that improves insurance of functional diversity against environmental pressures but the degree of dissimilarity within each functional group.