How do pathogens affect population dynamics?

Pathogens play a significant role in population dynamics by impacting the health and survival of organisms within an ecosystem. When a pathogen infects a population, it can lead to a decrease in size as affected individuals may succumb to disease, reducing reproductive success and increasing mortality rates. This process can create shifts in community structures as certain species that are more susceptible to diseases may decline, allowing more resilient species to thrive. Additionally, the interactions between pathogens and host populations can influence evolutionary pressures, as hosts may develop resistance over time.

The option that states pathogens have no effect on population sizes neglects the well-documented influence of diseases on wildlife and human populations alike. The assertion that pathogens only affect plant species is incorrect, as pathogens can target both animals and humans, drastically altering population dynamics across a wide range of organisms. Lastly, while pathogens may inadvertently lead to increased genetic diversity through selection pressures, stating that they increase genetic diversity doesn’t accurately capture their primary role in population dynamics, which is more often associated with declines in numbers due to disease outbreaks rather than fostering diversity.