Indirect genetic effects: an evolutionary mechanism linking feedbacks, genotypic diversity and coadaptation in a climate change context

1Predicting the response of communities and ecosystems to range shifts as a consequence of global climate change is a critical challenge confronting modern evolutionary ecologists. Indirect genetic effects (IGEs) occur when the expression of genes in a conspecific neighbouring species affects the phenotype of a focal species, and the same concept applies for interspecific indirect genetic effects (IIGEs) except that the neighbouring species is then required to be heterospecific. Theory and empirical data indicate that indirect genetic effects and interspecific indirect genetic effects have fundamental roles in understanding the consequences of genotypic diversity, evolutionary feedbacks, the co-evolutionary process and coadaptation and are a primary mechanism for the broad ecological and evolutionary dynamics that are likely to be a consequence of climate change. When indirect genetic effects and interspecific indirect genetic effects occur along environmental gradients, both positive and negative feedbacks can evolve, resulting in regions of strong local adaptation and competition as well as regions of complementarity and facilitation. Such evolutionary dynamics have direct consequences for how individuals interact and evolve in mixture and drive the services ecosystems provide. Integrating indirect genetic effects and interspecific indirect genetic effects, feedbacks and diversity effects along environmental gradients represents a major conceptual, theoretical and empirical frontier that must be considered to understand the whole-system consequences of climate change on biodiversity and the services ecosystems provide.