👉 Fitness-infection is a concept that describes how pathogens, or infectious agents like viruses and bacteria, can affect the fitness of their hosts. Fitness refers to an organism's ability to survive and reproduce in its environment. When a pathogen infects a host, it can alter the host's physiological processes, potentially reducing its overall fitness by diverting resources to combat the infection, causing tissue damage, or impairing normal functions. However, some pathogens have evolved mechanisms to enhance their own fitness at the expense of the host, such as increasing transmission rates or evading immune responses. This dynamic can lead to a co-evolutionary arms race, where hosts develop defenses and pathogens adapt to overcome them, influencing both the pathogen's and host's evolutionary trajectories.
