Appendix 5—figure 1. A framework for integrating existing knowledge.

Tinbergen’s four levels of analysis (blue boxes) organized along dimensions that reflect Mayr’s distinction between proximal and distal mechanisms. Arrows denote interactions (pressures or constraints) between individual levels. Laland et al., 2011, Bateson and Laland, 2013, Krakauer et al., 2017, and Mobbs et al., 2018 provide additional discussions of this framework.