Sozos Michaelides

1 Introduction Ecological and evolutionary processes influence the amount and structuring of genetic and phenotypic variability in natural populations and, while the determinants of such variation are part of species' evolutionary history, recent human activities have been shown to induce rapid phenotypic and genetic changes leading to major threats for biodiversity (Ceballos et al. 2020; Pelletier and Coltman 2018; Tilman et al. 2017).

1 Introduction Intraspecific variation, among and within populations, is key to supporting the ecosystem and the services it provides to people (Des Roches et al. 2021). This is especially true for species that are regularly harvested and thus at a greater risk of decline due to diversity loss (Des Roches et al. 2021). As an example, fisheries harbouring a larger number of populations have been shown to be more sustainable and productive over time (Hilborn et al. 2003).