The process of adaptive radiation—the proliferation of species from a single ancestor and diversification into many ecologically different forms—has been of great interest to evolutionary biologists since Darwin. Since the middle of the last century, ecological opportunity has been invoked as a potential key to understanding when and how adaptive radiation occurs. Interest in the topic of ecological opportunity has accelerated as research on adaptive radiation has experienced a resurgence, fueled in part by advances in phylogenetic approaches to studying evolutionary diversification. Nonetheless, what the term actually means, much less how it mechanistically leads to adaptive diversification, is currently debated; whether the term has any predictive value or is a heuristic useful only for post hoc explanation also remains unclear. Recent recognition that evolutionary change can occur rapidly and on a timescale commensurate with ecological processes suggests that it is time to synthesize ecological and evolutionary approaches to the study of community assembly and evolutionary diversification.

Adaptive radiation plays a fundamental role in our understanding of the evolutionary process. However, the concept has provoked strong and differing opinions concerning its definition and nature among researchers studying a wide diversity of systems. Here, we take a broad view of what constitutes an adaptive radiation, and seek to find commonalities among disparate examples, ranging from plants to invertebrate and vertebrate animals, and remote islands to lakes and continents, to better understand processes shared across adaptive radiations. We surveyed many groups to evaluate factors considered important in a large variety of species radiations. In each of these studies, ecological opportunity of some form is identified as a prerequisite for adaptive radiation. However, evolvability, which can be enhanced by hybridization between distantly related species, may play a role in seeding entire radiations. Within radiations, the processes that lead to speciation depend largely on (1) whether the primary drivers of ecological shifts are (a) external to the membership of the radiation itself (mostly divergent or disruptive ecological selection) or (b) due to competition within the radiation membership (interactions among members) subsequent to reproductive isolation in similar environments, and (2) the extent and timing of admixture. These differences translate into different patterns of species accumulation and subsequent patterns of diversity across an adaptive radiation. Adaptive radiations occur in an extraordinary diversity of different ways, and continue to provide rich data for a better understanding of the diversification of life.

Populations occurring at species' range edges can be locally adapted to unique environmental conditions. From a species' perspective, range‐edge environments generally have higher severity and frequency of extreme climatic events relative to the range core. Under future climates, extreme climatic events are predicted to become increasingly important in defining species' distributions. Therefore, range‐edge genotypes that are better adapted to extreme climates relative to core populations may be essential to species' persistence during periods of rapid climate change. We use relatively simple conceptual models to highlight the importance of locally adapted range‐edge populations (leading and trailing edges) for determining the ability of species to persist under future climates. Using trees as an example, we show how locally adapted populations at species' range edges may expand under future climate change and become more common relative to range‐core populations. We also highlight how large‐scale habitat destruction occurring in some geographic areas where many species range edge converge, such as biome boundaries and ecotones (e.g., the arc of deforestation along the rainforest‐cerrado ecotone in the southern Amazonia), can have major implications for global biodiversity. As climate changes, range‐edge populations will play key roles in helping species to maintain or expand their geographic distributions. The loss of these locally adapted range‐edge populations through anthropogenic disturbance is therefore hypothesized to reduce the ability of species to persist in the face of rapid future climate change.

It is critical that we understand the effects of climate change on natural systems if we ever hope to predict or mitigate consequent changes in diversity and ecosystem function. In order to identify coherent 'fingerprints' of climate change across Earth's terrestrial and marine ecosystems, various reviews have been conducted to synthesize studies of climate change impacts on individual species, assemblages and systems. These reviews help to make information about climate change impacts accessible for researchers as well as for the general public and policymakers. As such, these reviews can be highly influential in setting the direction of policy and research. Unfortunately, due to limited data availability, the majority of reviews of climate change impacts suffer from severe taxonomic and geographic biases. In particular, tropical and marine systems are grossly underrepresented, as are plants and endothermic animals. These biases may preclude a comprehensive understanding of how climate change is affecting Earth's natural systems at a global scale. In order to advance our understanding of climate change impacts on species and ecosystems, we need to first assess the types of data that are and are not available and then correct these biases through directed studies and initiatives.

1392 25 MARCH 2016 • VOL 351 ISSUE 6280 sciencemag.org SCIENCE PHOTO: © BLACK CAT IMAGING/ALAMY STOCK PHOTOThe knowledge that large-scale rearrangements in two key proteins in the spliceosome likely play key roles in the cycling of the spliceosome provide a new perspective on prior genetic and biochemical data, and should provide opportunities to further explore the functional consequences of these arrangements. Cryo-EM reconstructions of other steps in the splicing pathway, previously imaged at much lower resolution (2 to 4 nm) (8)-too low for accurate docking of the new modelsare now primed to be imaged at resolutions better than 1 nm, given the rapid advances in cryo-EM in the past 3 years (10). Higherresolution structures of the spliceosome in these other steps are likely to reveal additional conformational changes required for splicing to occur.The recent structural models of the spliceosome in dif erent steps of the splicing reaction represent a turning point for the fi eld, reminiscent of the change that occurred when structures of the proteinsynthesizing machine-the ribosome-were resolved in 2000 (11). Now, dozens of ribosome and ribosomal subunit structures are determined every year. With the advent of high-resolution cryo-EM, the same is likely to be true for the spliceosome over the next decade. New structures will be needed to understand the catalytic cycle and the process by which pre-mRNAs can be alternatively spliced to form many dif erent mature mRNAs encoding dif erent proteins. Model organisms such as fungi, which were needed for the fi rst high-resolution cryo-EM structures (2-5), will likely continue to provide important insights into alternative splicing-for example, into exon skipping (12) (see the fi gure, panel B). In the meantime, it will be exciting to see how the present burst of spliceosome structural knowledge permeates through the fi eld to inspire new genetic, biochemical, and biophysical experiments aimed at unraveling the fundamental properties of this ancient regulator of gene expression. ■

Community ecology is an inherently complicated field, confounded by the conflicting use of fundamental terms. Nearly two decades ago, Fauth et al. (1996) demonstrated that imprecise language led to the virtual synonymy of important terms and so attempted to clearly define four keywords in community ecology; “community,” “assemblage,” “guild,” and “ensemble”. We revisit Fauth et al.'s conclusion and discuss how the use of these terms has changed over time since their review. An updated analysis of term definition from a selection of popular ecological textbooks suggests that definitions have drifted away from those encountered pre‐1996, and slightly disagreed with results from a survey of 100 ecology professionals (comprising of academic professors, nonacademic PhDs, graduate and undergraduate biology students). Results suggest that confusion about these terms is still widespread in ecology. We conclude with clear suggestions for definitions of each term to be adopted hereafter to provide greater cohesion among research groups.

Across the globe terrestrial ectotherms-amphibians and non-avian reptiles-are facing a range of emerging challenges. Increasing global temperatures, in particular, are affecting all aspects of ectotherm biology and life history. Embryonic development is a thermally sensitive period of the organismal lifecycle, yet the impacts of thermal stress on the early development of ectotherms have significantly lagged behind studies of later stages and adult thermal physiology. Morphogenesis, the stage where the major anatomical systems are actively forming, is particularly sensitive to thermal stress, yet is not studied as often as later stages where growth is the primary process happening within the egg. Here, we focus on the effects of thermal stress on the first 12 days of development, the stages of morphogenesis, in the lizard Anolis sagrei. We examine the resiliency of the early developmental stages to heat stress by incubating eggs at temperatures that parallel conditions observed today and predicted over the next 50-100 years of projected climate change. Our results suggest that some anole nests are currently at the thermal limits for which the early embryonic stages can properly develop. Our results emphasize the importance of studying early embryonic stages of development and the importance of studying stage-specific effects of thermal stress on squamate development.

Extreme climate events such as droughts, cold snaps, and hurricanes can be powerful agents of natural selection, producing acute selective pressures very different from the everyday pressures acting on organisms. However, it remains unknown whether these infrequent but severe disruptions are quickly erased by quotidian selective forces, or whether they have the potential to durably shape biodiversity patterns across regions and clades. Here, we show that hurricanes have enduring evolutionary impacts on the morphology of anoles, a diverse Neotropical lizard clade. We first demonstrate a transgenerational effect of extreme selection on toepad area for two populations struck by hurricanes in 2017. Given this short-term effect of hurricanes, we then asked whether populations and species that more frequently experienced hurricanes have larger toepads. Using 70 y of historical hurricane data, we demonstrate that, indeed, toepad area positively correlates with hurricane activity for both 12 island populations of Anolis sagrei and 188 Anolis species throughout the Neotropics. Extreme climate events are intensifying due to climate change and may represent overlooked drivers of biogeographic and large-scale biodiversity patterns.