Live Stream Notes: In this live stream, we discuss community ecology. We learn that community ecology is the relationship among different species in the same environment. We start by discussing energy and how it flows through the trophic levels. Trophic levels consist of the producers (like plants and algae), primary consumers (like deer and rabbits), secondary consumers (like snakes), and tertiary consumers (like hawks and sharks). As we move up the trophic levels, we see that 90% energy is “lost” as heat per a level so the next level up only gets 10% of the previous trophic level’s energy. This is why tertiary consumers eat so much than secondary consumers. On the other hand, producers make up the largest portion of the food web and the energy pyramid. When a secondary consumer species is removed from an environment, the food source may be decreased for the tertiary consumers leading to a decrease in population while there would be overpopulation of the primary consumers and maybe even depletion of the producers. This species, usually near the top of the food web, would be a keystone species because it has a drastic impact on the food chain. We also learned that there are 3 relationships species can have other than predator and prey, parasitism (one benefits, one hurts), commensalism (one benefits, one does not have effects), and mutualism (both benefit). After doing 2 FRQ questions, we end the session by discussing the difference between commensalism and mutualism.