In recent years, the concept of evolvability has been gaining in prominence both within evolutionary developmental biology (Evodevo) and the broader field of evolutionary biology. Despite this, there remains considerable disagreement about what evolvability is. is paper offers a solution to this problem. I argue that, in focusing too closely on the role played by evolvability as an explanandum in Evodevo, existing philosophical attempts to clarify the evolvability concept have been too narrow. Within evolutionary biology more broadly, evolvability offers a robust explanation for the evolutionary trajectories of populations. Evolvability is an abstract, robust, dispositional property of populations, which captures the joint causal influence of their internal features upon the outcomes of evolution (as opposed to the causal influence of selection, which is oen characterised as external). When considering the nature of the physical basis of this disposition, it becomes clear that the many existing definitions of evolvability at play within Evo-devo should be understood as capturing only aspects of a much broader phenomenon.

1. Although polyphagy is widespread among Drosophila, some specialist species have evolved in response to resource competition and other selection factors favouring niche separation. The small fruit specialist Drosophila suzukii Matsumura has evolved a unique serrated ovipositor that allows it to access ripening fruit, a niche unavailable to most Drosophila. However, it is unclear whether ancestral traits (the use of non‐fruit resources) are maintained in this specialist species. 2. In this study, maternal preferences and offspring fitness in response to novel apple, mushroom, and bird manure‐based diets were investigated by comparing oviposition and offspring survival and development on various diets. The effect of those diets on survival at cool temperatures and the effect of natal environment/previous exposure on adult preferences were evaluated. 3. Female D. suzukii accepted non‐fruit diets such as mushroom and bird manure, and offspring completed their larval development on all diets tested. However, D. suzukii did not perform well on diets that included bird manure. By contrast, combinational apple/mushroom diets were associated with greater oviposition, lower mortality, faster development, and larger offspring than other diets. These diets were also associated with increased resistance to cold stress, and preference for these diets was positively affected by previous feeding experience. 4. These data suggest that D. suzukii may use non‐fruit resources when preferred resources are scarce. Given that this pest is adapted to temperate climates, alternative resources might provide seasonal nutritional support when fruit resources are not temporally available, although field data are needed to support this hypothesis.

Traditional accounts of the role of learning in evolution have concentrated upon its capacity as a source of fitness to individuals. In this paper I use a case study from invasive species biology-the role of conditioned taste aversion in mitigating the impact of cane toads on the native species of Northern Australia-to highlight a role for learning beyond this-as a source of evolvability to populations. This has two benefits. First, it highlights an otherwise under-appreciated role for learning in evolution that does not rely on social learning as an inheritance channel nor ''special'' evolutionary processes such as genetic accommodation (both of which many are skeptical about). Second, and more significantly, it makes clear important and interesting parallels between learning and exploratory behaviour in development. These parallels motivate the applicability of results from existing research to learning and learning evolution and to our understanding the evolution of evolvability more generally.

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