The consequences of environmental heterogeneity for fitness, selection, and inheritance.

The environment influences two key drivers of adaptive evolution: the relationship between phenotype and fitness (selection) and the translation of genotype to phenotype (inheritance). The same environmental conditions may simultaneously affect both of these components in natural populations, thereby shaping evolutionary trajectories in heterogeneous landscapes, although such concurrent environmental effects remain largely neglected by evolutionary ecologists. I employed empirical, meta-analytical, and conceptual approaches to address the evolutionary consequences of separate and simultaneous environmental effects on selection and inheritance. I explored the direct and indirect fitness consequences of multiple resource use in Bolitotherus cornutus, a mycophagous beetle that exploits three sympatric species of host fungus. My results demonstrate that the focal B. cornutus metapopulation does not exhibit resource specialization, in spite of the extreme and complex fitness consequences of the host fungi at multiple life stages. Cannibalism, which accelerates larval growth and is most common in a high-quality fungus, exacerbates phenotypic and fitness differences among larvae developing in the three host fungi. The heterogeneous host community therefore generates substantial fitness variation in B. cornutus through a combination of direct and indirect effects throughout the life cycle. I reached beyond the B. cornutus system to investigate environmental effects on inheritance. In a meta-analysis of published studies, I found that the environment is a potentially pervasive source of change in multivariate genetic architecture, suggesting that labile genetic constraints shape evolutionary trajectories in changing environments. Finally, I developed a conceptual framework to examine the evolutionary implications of an environmentally driven correlation between selection and inheritance. I found that a correlation between the strength of selection and the availability of genetic variation considerably impacts the rate of the evolutionary response. I demonstrate that concurrent environmental effects on the central components of adaptive evolution have the potential to alter evolutionary dynamics in heterogeneous landscapes.