What are a source and a sink under ecological and evolutionary perspectives?

Source-sink dynamics investigates species dispersal, mainly at the landscape scale, providing outcomes for conservation problem-solving. Designing conservation plans requires accurately identifying a source or a sink habitat within the landscape. However, this practical use demands a theoretical background and a clear definition of source and sink for its successful implementation. This study investigates the application of the terms source and sink, examining how biological features affect their use, and if they have been consistently applied in published studies. We conducted a systematic review focused on source-sink dynamics and performed descriptive and textual analysis to understand their application. Most research did not expressly state what a source or sink was, leaving a knowledge gap that prevents complete understanding and practical application. The concept of source has different uses and is better detailed than the term sink. The application of source and sink concepts was taxon-dependent; animal requirements are needed to indicate if a population/habitat can play a role as a source or sink. Because these concepts were being used differently, the source-sink terminology hinders fundamental theory, evolutionary perspectives, and applicability for species research and conservation, especially in the tropics, where a significant information gap was found.