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A major goal of evolutionary science is to understand how biological diversity is generated and altered. Despite considerable advances, we still have limited insight into how phenotypic variation arises and is sorted by natural selection. Here we argue that an integrated view, which merges ecology, evolution and developmental biology (eco evo devo) on an equal footing, is needed to understand the multifaceted role of the environment in simultaneously determining the development of the phenotype and the nature of the selective environment, and how organisms in turn affect the environment through eco evo and eco devo feedbacks. To illustrate the usefulness of an integrated eco evo devo perspective, we connect it with the theory of resource polymorphism (i.e. the phenotypic and genetic diversification that occurs in response to variation in available resources). In so doing, we highlight fishes from recently glaciated freshwater systems as exceptionally well‐suited model systems for testing predictions of an eco evo devo framework in studies of diversification. Studies on these fishes show that intraspecific diversity can evolve rapidly, and that this process is jointly facilitated by (i) the availability of diverse environments promoting divergent natural selection; (ii) dynamic developmental processes sensitive to environmental and genetic signals; and (iii) eco evo and eco devo feedbacks influencing the selective and developmental environments of the phenotype. We highlight empirical examples and present a conceptual model for the generation of resource polymorphism – emphasizing eco evo devo, and identify current gaps in knowledge.

In an artificial stream environment, established wild brown trout initiated 44% of the mean aggressive acts whilst hatchery-reared trout initiated 34% and introduced wild trout initiated 22%. Established wild fish maintained home stations closer to a point source of feed than did both hatchery-reared and introduced wild conspecifics. Established wild fish were the only group to show a positive mean specific growth rate during the trials. Introduced wild fish showed a slightly negative mean specific growth rate, whilst introduced hatchery-reared fish exhibited a considerable negative mean specific growth rate. These results suggest that established wild brown trout in a semi-natural stream environment display a prior-resident effect over late introductions of hatchery-reared and wild conspecifics. Introduced hatcheryreared fish were more aggressive and exhibited a lower mean specific growth rate than simultaneously stocked wild fish, suggesting that excessive expenditure of energy for unnecessary aggression may contribute to the poor survival of hatchery-reared fish after they are stocked into streams. 1999 The Fisheries Society of the British Isles

Invasive alien species (IAS) are one of the major drivers of change that can negatively affect biodiversity, ecosystem functions and services and human health; islands are particularly vulnerable to biological invasions. Horizon scanning can lead to Electronic supplementary material The online version of this article (

1. The white-clawed crayfish, Austropotamobius pallipes (Lereboullet), is the only freshwater crayfish indigenous to Great Britain and Ireland. It has a widespread, though declining distribution in England and parts of Wales but does not occur naturally in Scotland. 2. The North American signal crayfish, Pacifastacus leniusculus (Dana), is not native to Europe and was introduced to Britain in the 1970s. The signal crayfish out-competes the native white-clawed crayfish as it is larger and more aggressive. It is also responsible for the introduction and spread of crayfish plague, which has devastated white-clawed crayfish populations in Europe. 3. Signal crayfish populations are causing significant changes to the equilibrium of native flora and fauna through increased grazing and predation pressures; they also contribute to habitat degradation through burrowing. 4. Manual removal of crayfish using traps and pond trials with biocides have met with moderate success in reducing crayfish numbers and containing populations. However, with new populations of signal crayfish being reported each year within the UK, there is now an urgent need to develop a strategy with which to eradicate or contain their spread. 5. Signal crayfish have populated many habitat types in the UK, each of which may require a different control strategy; hence no single strategy or universal solution is likely to be attainable. 6. Signal crayfish are susceptible to various biocides and microbial pathogens but significant scientific research will be required to develop safe biological control methods and integrated pest management (IPM) strategies to control these invasive organisms