Assisted migration (AM) is the translocation of species beyond their historical range to locations that are expected to be more suitable under future climate change. However, a relocated population may fail to establish in its donor community if there is high uncertainty in decision-making, climate, and interactions with the recipient ecological community. To quantify the benefit to persistence and risk of establishment failure of AM under different management scenarios (e.g., choosing target species, proportion of population to relocate, and optimal location to relocate), we built a stochastic metacommunity model to simulate several species reproducing, dispersing, and competing on a temperature gradient as temperature increases over time. Without AM, the species were vulnerable to climate change when they had low population sizes, short dispersal, and strong poleward competition. When relocating species that exemplified these traits, AM increased the long-term persistence of the species most when relocating a fraction of the donor population, even if the remaining population was very small or rapidly declining. This suggests that leaving behind a fraction of the population could be a robust approach, allowing managers to repeat AM in case they move the species to the wrong place and at the wrong time, especially when it is difficult to identify a species' optimal climate. We found that AM most benefitted species with low dispersal ability and least benefited species with narrow thermal tolerances, for which AM increased extinction risk on average. Although relocation did not affect the persistence of nontarget species in our simple competitive model, researchers will need to consider a more complete set of community interactions to comprehensively understand invasion potential.

Many species are shifting their ranges to keep pace with climate change, but habitat fragmentation and limited dispersal could impede these range shifts. In the case of climate-vulnerable foundation species such as tropical reef corals and temperate forest trees, such limitations might put entire communities at risk of extinction. Restoring connectivity through corridors, stepping-stones or enhanced quality of existing patches could prevent the extinction of several species, but dispersal-limited species might not benefit if other species block their dispersal. Alternatively, managers might relocate vulnerable species between habitats through assisted migration, but this is generally a species-by-species approach. To evaluate the relative efficacy of these strategies, we simulated the climate-tracking of species in randomized competitive metacommunities with alternative management interventions. We found that corridors and assisted migration were the most effective strategies at reducing extinction. Assisted migration was especially effective at reducing the extinction likelihood for short-dispersing species, but it often required moving several species repeatedly. Assisted migration was more effective at reducing extinction in environments with higher stochasticity, and corridors were more effective at reducing extinction in environments with lower stochasticity. We discuss the application of these approaches to an array of systems ranging from tropical corals to temperate forests. This article is part of the theme issue 'Ecological complexity and the biosphere: the next 30 years'.

Aim: Many tree species may be threatened with declines in range and biomass, or even extinction, if they cannot disperse or adapt quickly enough to keep pace with climate change. One potential, and potentially risky, strategy to mitigate this threat is assisted migration (AM), the intentional movement of species to facilitate population range shifts to more climatically suitable locations under climate change. The ability for AM to minimise risk and maximise conservation and forestry outcomes depends on a multi-faceted decision process for determining, what, where and how much to move. We provide an assessment on how the benefits and risks of AM could affect the decision-making process. Location: Mountainous coastal western United States. Taxon: Trees. Methods: We used a dynamic vegetation model parameterised with 23 tree species. Results: We found that most of the modelled species are likely to experience a substantial decline in biomass, with many potentially facing regional extinction by 2100 under the high-emission SSP5-85 climate-change scenario. Though simulations show AM had little effect on the forestry goal of total biomass across all species, its effects on the conservation goal of promoting individual species' persistence were far more substantial. Among eight AM strategies (differing in the life cycle stage of movement and target destination selection criteria), the approach that conserved the highest biomass for individual species involved relocating target seedlings to areas that recently experienced fire. Although this strategy significantly reduced extinction risk for six at-risk species compared with no action, it also slightly reduced biomass of four species, due to increasing competition. Species with relatively weak tolerance to drought, fire or high temperature were the most likely candidate groups for AM. Main Conclusions: Our simulations indicate that AM can aid conservation by reducing extinction risks for species vulnerable to climate change, but it has limited impact on forestry-specific goals, affecting overall biomass minimally. This model framework could be applied to other forest ecosystems to evaluate the efficacy of AM globally.

Animal acoustic communication often takes the form of complex sequences, made up of multiple distinct acoustic units. Apart from the well-known example of birdsong, other animals such as insects, amphibians, and mammals (including bats, rodents, primates, and cetaceans) also generate complex acoustic sequences. Occasionally, such as with birdsong, the adaptive role of these sequences seems clear (e.g. mate attraction and territorial defence). More often however, researchers have only begun to characterise - let alone understand - the significance and meaning of acoustic sequences. Hypotheses abound, but there is little agreement as to how sequences should be defined and analysed. Our review aims to outline suitable methods for testing these hypotheses, and to describe the major limitations to our current and near-future knowledge on questions of acoustic sequences. This review and prospectus is the result of a collaborative effort between 43 scientists from the fields of animal behaviour, ecology and evolution, signal processing, machine learning, quantitative linguistics, and information theory, who gathered for a 2013 workshop entitled, 'Analysing vocal sequences in animals'. Our goal is to present not just a review of the state of the art, but to propose a methodological framework that summarises what we suggest are the best practices for research in this field, across taxa and across disciplines. We also provide a tutorial-style introduction to some of the most promising algorithmic approaches for analysing sequences. We divide our review into three sections: identifying the distinct units of an acoustic sequence, describing the different ways that information can be contained within a sequence, and analysing the structure of that sequence. Each of these sections is further subdivided to address the key questions and approaches in that area. We propose a uniform, systematic, and comprehensive approach to studying sequences, with the goal of clarifying research terms used in different fields, and facilitating collaboration and comparative studies. Allowing greater interdisciplinary collaboration will facilitate the investigation of many important questions in the evolution of communication and sociality.