Annual Review of Ecology, Evolution, and Systematics - Early Publication

The idea that species interactions are more ecologically and evolutionarily important toward lower latitudes underpins seminal theories in ecology and evolution. Recent global studies have found the predicted latitudinal gradients in interactions, particularly predation. However, latitudinal patterns alone do not reveal why interactions vary geographically and so do not provide strong predictions in space (e.g., for specific ecosystems) or time (e.g., forecasting responses to global change). Here, I review theory to identify a clearer, mechanistic, and testable framework for predicting geographic variation in the importance of species interactions. I review competing metrics of importance, proximate mechanisms that can increase interaction importance, and environmental gradients that could generate predictable geographic patterns (climate extremes and stability, warmth, productivity, and biodiversity). Strong empirical tests are accumulating thanks to the rise of global experiments and datasets; renewed focus on testing why interactions vary spatially will help move the field from identifying latitudinal patterns to understanding broader mechanisms.

As the Anthropocene proceeds, the matrix in which remaining habitats are embedded is an increasingly dominant component of altered landscapes. The matrix appears to have diverse and far-reaching effects, yet our understanding of the causes and consequences of these effects remains limited. We first synthesize the broad range of perspectives on the matrix, provide a generalized framing that captures these perspectives, and propose hypotheses for how and why the matrix matters for ecological and evolutionary processes. We then summarize evidence for these hypotheses from experiments in which the matrix was manipulated. Nearly all experiments revealed matrix effects, including changes in local spillover, individual movement and dispersal, and use of resources in the matrix. Finally, we discuss how the matrix has been, and should be, incorporated into conservation and management and suggest future issues to advance research on and applications of the matrix in ecology, evolution, and conservation.

Early studies in coral reefs showed that simple measurements of ecosystem metabolism (primary production and ecosystem respiration) were useful for understanding complex reef dynamics at an ecosystem scale. These studies also helped establish the field of ecosystem ecology, but contemporary coral reef ecology has shifted away from these origins. In this manuscript, I describe the historical development of a theory of ecosystem metabolism that was foundational for the discipline of ecosystem ecology, and I update this theory to fully incorporate dynamics on coral reefs (and all ecosystems). I use this updated theory to (a) identify important controls on coral reef processes and (b) provide a rationale for patterns of coral reef carbon dynamics that allow me to generate hypotheses of coral reef ecosystem production. I then use existing data to broadly evaluate these hypotheses. My findings emphasize the importance of integrating measurements of ecosystem metabolism with current approaches to improve the development of theory and the efficacy of conservation and management of coral reefs.

Phylogenetic comparative methods are important tools in biology, providing insights into the way traits evolve. There are many technical resources describing how these methods work. Our aim here is to complement these with an overview of the types of biological questions that can be addressed by different methods and to outline potential pitfalls and considerations when embarking on comparative studies. First, we introduce what comparative methods are and why they are important. Second, we outline how they can be used to understand when, where, and how frequently traits evolve. Third, we examine how the coevolution of traits within and between species can be studied, along with patterns of causality. Finally, we discuss how to approach comparative analyses and the ways in which different types of data, such as published relationships, omic, and remote sensing data, can be integrated.

Arctic ecosystems have long been thought to be minimal sources of volatile organic compounds (VOCs) to the atmosphere because of their low plant biomass and cold temperatures. However, these ecosystems experience rapid climatic warming that alters vegetation composition. Tundra vegetation VOC emissions have stronger temperature dependency than current emission models estimate. Thus, warming, both directly and indirectly (via vegetation changes) likely increases the release and alters the blend of emitted plant volatiles, such as isoprene, monoterpenes, and sesquiterpenes, from Arctic ecosystems. Climate change also increases the pressure of both background herbivory and insect outbreaks. The resulting leaf damage induces the production of volatile defense compounds, and warming amplifies this response. Soils function as both sources and sinks of VOCs, and thawing permafrost is a hotspot for soil VOC emissions, contributing to ecosystem emissions if the VOCs bypass microbial uptake. Overall, Arctic VOC emissions are likely to increase in the future with implications for ecological interactions and atmospheric composition.

Deadwood represents a significant carbon pool and unique biodiversity reservoir in forests and savannas but has been largely overlooked until recently. Storage and release of carbon from deadwood is controlled by interacting decomposition drivers including biotic consumers (animals and microbes) and abiotic factors (water, fire, sunlight, and freeze–thaw). Although previous research has focused mainly on forests, we synthesize deadwood studies across diverse ecosystems with woody vegetation. As changing climates and land-use practices alter the landscape, we expect accelerating but variable rates of inputs and outputs from deadwood pools. Currently, Earth system models implicitly represent only microbial consumers as drivers of wood decomposition; we show that many other factors influence deadwood pools. Forest management practices increasingly recognize deadwood as an important contributor to forest dynamics, biodiversity, and carbon budgets. Together, emerging knowledge from modeling and management suggests a growing need for additional research on deadwood contributions to carbon storage and greenhouse gas emissions.

Successful invasive species commonly depend on the establishment of mutualistic interactions with native and nonnative biota. In turn, invasive species can affect native mutualisms and community stability. Here, we examine different forms of mutualist acquisition by invasive species and the causes and consequences of mutualism abandonment for invasion processes. Additionally, we delve into the quantitative and qualitative effects of invaders on native biota via mutualism disruption that can occur through direct and diverse indirect pathways. These effects of invasive species on native biota via mutualistic interactions can often be a consequence of the invaders’ abundance, which should be considered a prime predictor when evaluating the impact of invasive species on native mutualisms and community stability. We propose that the ecological as well as the evolutionary consequences of mutualism disruption and switches caused by invasive species can play crucial roles in determining future biodiversity.

There is broad concern that the range shifts of global flora and fauna will not keep up with climate change, increasing the likelihood of population declines and extinctions. Many populations of nonnative species already have advantages over native species, including widespread human-aided dispersal and release from natural enemies. But do nonnative species also have an advantage with climate change? Here, we review observed and potential range shifts for native and nonnative species globally. We show that nonnative species are expanding their ranges 100 times faster than native species, reflecting both traits that enable rapid spread and ongoing human-mediated introduction. We further show that nonnative species have large potential ranges and range expansions with climate change, likely due to a combination of widespread introduction and broader climatic tolerances. With faster spread rates and larger potential to persist or expand, nonnative populations have a decided advantage in a changing climate.