Stem diameter is one of the most commonly measured attributes of trees, forming the foundation of forest censuses and monitoring. Changes in tree stem circumference include both irreversible woody stem growth and reversible circumference changes related to water status, yet these fine-scale dynamics are rarely leveraged to understand forest ecophysiology and typically ignored in plot- or stand-scale estimates of tree growth and forest productivity. Here, we deployed automated dendrometer bands on 12–40 trees at four...

Chemically mediated plant–herbivore interactions contribute to the diversity of terrestrial communities and the diversification of plants and insects. While our understanding of the processes affecting community structure and evolutionary diversification has grown, few studies have investigated how trait variation shapes genetic and species diversity simultaneously in a tropical ecosystem. We investigated secondary metabolite variation among subpopulations of a single plant species, Piper kelleyi (Piperaceae), using high-performance liquid chromatography (HPLC), to understand associations between plant phytochemistry...

Phenotypic variability in horn characteristics, such as their size, number and shape, offers the opportunity to elucidate the molecular basis of horn development. The objective of this study was to map the genetic determinant controlling the production of four horns in two breeds, Jacob sheep and Navajo-Churro, and examine whether an eyelid abnormality occurring in the same populations is related. Genome-wide association mapping was performed using 125 animals from the two breeds that contain two-...

Glucocorticoids are important mediators of energy utilization for key physiological processes, including immune function. Much work has focused on the effects of energy limitation and stress for key physiological processes such as reproduction and immunity. However, it is unclear how stress alters energy use across different energy states, and the physiological ramifications of such effects are even less clear. In this study, we altered energy and stress states of an infrequent feeder, the Terrestrial Gartersnake...

1. Oxidative stress is a potential cost of reproduction, but conclusive evidence for this relationship is lacking. The goal of this study was to serially assess across a seasonal gradient the relationship between reproduction, circulating plasma energy metabolites, and oxidative state. 2. Here we examine a study animal ideally suited to test for the oxidative costs of reproduction: The Allen Cays Rock Iguana. Female rock iguanas reproduce at varying frequencies, often skipping years, allowing for...

Serum biochemical parameters can be utilized to evaluate the physiological status of an animal, and relate it to the animal’s health. In order to accurately interpret individual animal biochemical results, species-specific reference intervals (RI) must be established. Reference intervals for biochemical parameters differ between species, and physiological differences including reproductive status, nutritional resource availability, disease status, and age affect parameters within the same species. The objectives of this study were to (1) establish RI for...

Complex systems can be conceptualized and studied as networks of nodes with varying connectivity between nodes. In well-connected systems, local disturbance of individual nodes can be countered by input from neighbouring nodes, buffering the system against local change. Thus, pronounced change in a well-connected system may not occur until the system hits a threshold or ‘tipping point’ that drives a shift to an alternative, system-wide state. In contrast, poorly connected systems are more prone to...

The origins of evolutionary radiations are often traced to the colonization of novel adaptive zones, including unoccupied habitats or unutilized resources. For herbivorous insects, the predominant mechanism of diversification is typically assumed to be a shift onto a novel lineage of host plants. However, other drivers of diversification are important in shaping evolutionary history, especially for groups residing in regions with complex geological histories. We evaluated the contributions of shifts in host plant clade, bioregion,...

Patterns of phenotypic variation within and among species can be shaped and constrained by trait genetic architecture. This is particularly true for complex traits, such as butterfly wing patterns, that consist of multiple elements. Understanding the genetics of complex trait variation across species boundaries is difficult, as it necessitates mapping in structured populations and can involve many loci with small or variable phenotypic effects. Here, we investigate the genetic architecture of complex wing pattern variation...

Consensus has emerged in the literature that increased biodiversity enhances the capacity of ecosystems to perform multiple functions. However, most biodiversity/ecosystem function studies focus on a single ecosystem, or on landscapes of homogenous ecosystems. Here we investigate how increased landscape-level environmental dissimilarity may affect the relationship between different metrics of diversity (α, β, or γ) and ecosystem function. We produced a suite of simulated landscapes, each of which contained four experimental outdoor aquatic mesocosms. Differences...

Organisms are frequently coinfected by multiple parasite strains and species, and interactions between parasites within hosts are known to influence parasite prevalence and diversity, as well as epidemic timing. Importantly, interactions between coinfecting parasites can be affected by the order in which they infect hosts (i.e. within-host priority effects). In this study, we use a single-host, two-pathogen, SI model with environmental transmission to explore how within-host priority effects scale up to alter host population-scale infection...

Evidence shows the important role biota play in the carbon cycle, and strategic management of plant and animal populations could enhance CO2 uptake in aquatic ecosystems. However, it is currently unknown how management-driven changes to community structure may interact with climate warming and other anthropogenic perturbations to alter CO2 fluxes. Here we showed that under ambient water temperatures, predators (three-spined stickleback) and nutrient enrichment synergistically increased primary producer biomass, resulting in increased CO2 uptake by...

An intriguing aspect of social foraging behaviour is that large groups are often no better at capturing prey than are small groups, a pattern that has been attributed to diminished cooperation (i.e., free riding) in large groups. Although this suggests the formation of large groups is unrelated to prey capture, little is known about cooperation in large groups that hunt hard-to-catch prey. Here, we used direct observations of Yellowstone wolves (Canis lupus) hunting their most...

1. Adapting to a low-quality plant may require modification of an insect's digestive physiology, oviposition behaviour, or other host-use traits. If colonising a marginal host entails a cost, a decay in adaptation would be expected after selection is relaxed, i.e. if populations on a novel host are reverted to their high-quality ancestral host. 2. Replicate lines of the seed beetle Callosobruchus maculatus (F.) rapidly adapted to lentil seeds; larval survival rose from approximately 1 to...

Species interactions, and their fitness consequences, vary across the geographic range of a coevolutionary relationship. This spatial heterogeneity in reciprocal selection is predicted to generate a geographic mosaic of local adaptation, wherein coevolutionary traits are phenotypically variable from one location to the next. Under this framework, allopatric populations should lack variation in coevolutionary traits due to the absence of reciprocal selection. We examine phenotypic variation in tetrodotoxin (TTX) toxicity of the Rough-Skinned Newt (Taricha granulosa)...

Cosmopolitan pests can consist of geographic populations that differ in their current host ranges or in their ability to colonize a novel host. We compared the responses of cowpea-adapted seed-beetle populations (Callosobruchus maculatus [F.]) from Africa, North America, and South America to four novel legumes: chickpea, lentil, mung bean, and pea. We also qualitatively compared these results to those obtained earlier for an Asian population. For each host, we measured larval survival to adult emergence,...

Hybridization is a potent evolutionary process that can affect the origin, maintenance, and loss of biodiversity. Because of its ecological and evolutionary consequences, an understanding of hybridization is important for basic and applied sciences, including conservation biology and agriculture. Herein, we review and discuss ideas that are relevant to the recognition of hybrids and hybridization. We supplement this discussion with simulations. The ideas we present have a long history, particularly in botany, and clarifying them...

Extreme environmental events (EEE) are likely to exert deleterious effects on populations. From 1996-2012 we studied the nesting dynamics of a riverine population of painted turtles (Chrysemys picta) that experienced seven years with significantly definable spring floods. We used capture-mark-recapture methods to estimate the relationships between >5-m and >6-m flood events and population parameters. Contrary to expectations, flooding was not associated with annual differences in survival, recruitment, or annual population growth rates of the adult...

Convergent phenotypes often result from similar underlying genetics, but recent work suggests convergence may also occur in the historical order of substitutions en route to an adaptive outcome. We characterized convergence in the mutational steps to two independent outcomes of tetrodotoxin (TTX) resistance in separate geographic lineages of the common garter snake (Thamnophis sirtalis) that coevolved with toxic newts. Resistance is largely conferred by amino acid changes in the skeletal muscle sodium channel (NaV1.4) that...

1. Understanding the population dynamics of top predators is essential to assess their impact on ecosystems and to guide their management. Key to this understanding is identifying the mechanisms regulating vital rates. 2. Determining the influence of density on survival is necessary to understand the extent to which human-caused mortality is compensatory or additive. In wolves (Canis lupus), empirical evidence for density-dependent survival is lacking. Dispersal is considered the principal way in which wolves adjust...

The extinction vortex is a theoretical model describing the process by which extinction risk is elevated in small, isolated populations owing to interactions between environmental, demographic, and genetic factors. However, empirical demonstrations of these interactions have been elusive. We modelled the dynamics of a small mountain lion population isolated by anthropogenic barriers in greater Los Angeles, California, to evaluate the influence of demographic, genetic, and landscape factors on extinction probability. The population exhibited strong survival...

Identifying how sympatric species belonging to the same guild coexist is a major question of community ecology and conservation. Habitat segregation between two species might help reduce the effects of interspecific competition and apex predators are of special interest in this context, because their interactions can have consequences for lower trophic levels. However, habitat segregation between sympatric large carnivores has seldom been studied. Based on monitoring of 53 brown bears (Ursus arctos) and 7 sympatric...

Theory predicts that intraspecific competition should be stronger than interspecific competition for any pair of stably coexisting species, yet previous literature reviews found little support for this pattern. We screened over 5400 publications and identified 39 studies that quantified phenomenological intraspecific and interspecific interactions in terrestrial plant communities. Of the 67% of species pairs in which both intra- and interspecific effects were negative (competition), intraspecific competition was, on average, four to five-fold stronger than interspecific...

Ecological patterns arise from the interplay of many different processes, and yet the emergence of consistent phenomena across a diverse range of ecological systems suggests that many patterns may in part be determined by statistical or numerical constraints. Differentiating the extent to which patterns in a given system are determined statistically, and where it requires explicit ecological processes, has been difficult. We tackled this challenge by directly comparing models from a constraint-based theory, the Maximum...

Despite growing concerns regarding increasing frequency of extreme climate events and declining population sizes, the influence of environmental stochasticity on the relationship between population carrying capacity and time-to-extinction has received little empirical attention. While time-to-extinction increases exponentially with carrying capacity in constant environments, theoretical models suggest increasing environmental stochasticity causes asymptotic scaling, thus making minimum viable carrying capacity vastly uncertain in variable environments. Using empirical estimates of environmental stochasticity in fish metapopulations, we showed that...