Biomarker Studies in Stress Biology: From the Gene to Population, from the Organism to the Application

SIMPLE SUMMARY: Ecosystems have been increasingly subject to stressful conditions and thus the need to develop tools capable of assessing their impacts on populations and communities. These effects assessed at higher levels of biological organization tend to reflect the sum of effects on individuals, arising from the effects at the cellular and molecular levels. These lower biological organization levels are more responsive at an early stage, allowing them to be used as early warning endpoints to address environmental stress—biomarkers. In this work, the need to link low to high levels of biological organization is addressed and the challenges and usefulness of biomarkers in a myriad of fields discussed. ABSTRACT: Endpoints assessed at the population or community level are most often the result of the sum of effects on individuals, arising from the effects at the cellular and molecular levels. Within this framework, these lower biological level endpoints are more responsive at an early stage of exposure, making them potential toolboxes to be used as early-warning markers to address stress. Given this, by linking responses and understanding organisms’ metabolism and physiology, the possibilities for the use of biomarkers in stress biology are vast. Here, biomarker comprehensive examples are given to enlighten the need to link levels of biological organization, and their usefulness for a myriad of fields and applications is presented and discussed.