Chapter 10 Summary

• Interspecific interactions shape community structure: Species within a community interact in diverse ways—such as competition, predation, herbivory, parasitism, mutualism, and commensalism—which influence population dynamics, biodiversity, and evolutionary adaptations.
• Species evolve to reduce competition and survive environmental pressures: Through niche differentiation and the competitive exclusion principle, species adapt to avoid direct competition. Coevolution further drives reciprocal adaptations between interacting species, from predators and prey to mutualistic partners.
• Energy flows through trophic levels but is inefficiently transferred: Energy enters ecosystems via producers through photosynthesis and flows to herbivores, carnivores, and decomposers. Due to the 10% rule, only a small fraction of energy is passed on at each level, limiting food chain length and top predator populations.
• Food webs better represent complex ecological relationships than food chains: While food chains show linear feeding relationships, food webs reveal how species often occupy multiple trophic levels, emphasizing the interconnectedness and resilience or vulnerability of ecosystems.
• Biogeochemical cycles recycle essential nutrients: The carbon, nitrogen, phosphorus, and water cycles move matter through living and non-living components of ecosystems. These cycles sustain life by replenishing nutrients that organisms need to grow, reproduce, and function.
• Human activities disrupt ecosystem balance: Practices like burning fossil fuels, deforestation, and overuse of fertilizers introduce excess nutrients or pollutants, leading to ecosystem imbalances such as climate change, eutrophication, and biodiversity loss.

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OpenAI. (2025). ChatGPT. [Large language model]. https://chat.openai.com/chat
Prompt: Summarize the following content into six key takeaways.

Assimilation – The process by which plants absorb nitrates or ammonium from the soil and incorporate them into organic molecules such as proteins and DNA.

Behavioral defenses – Actions or behaviors that help prey avoid predators, such as fleeing, hiding, living in groups, or startling predators.

Biogeochemical cycles – Natural processes that recycle elements like carbon, nitrogen, phosphorus, and water through the living and non-living parts of ecosystems.

Camouflage – A defense mechanism that allows organisms to blend into their surroundings to avoid detection by predators.

Chemical defenses – The use of toxic, distasteful, or harmful chemical compounds by organisms to deter predators or herbivores.

Coevolution – The process by which two or more species influence each other’s evolutionary pathways over time through close ecological interactions.

Commensalism – An interspecific interaction in which one species benefits while the other is neither helped nor harmed (+/0).

Community – All the different populations of species that live together and interact in a particular area.

Competitive exclusion principle – The idea that two species competing for the exact same resources cannot stably coexist; one will outcompete the other.

Consumers – Organisms that obtain energy by feeding on other organisms (producers or other consumers).

Decomposers – Organisms, such as fungi and bacteria, that break down dead matter and waste into simpler substances, recycling nutrients into the ecosystem.

Decomposition – The breakdown of dead organisms and waste by decomposers, returning nutrients to the environment.

Denitrification – The conversion of nitrates in the soil back into nitrogen gas by bacteria, releasing it into the atmosphere.

Detritivores – Organisms that consume dead organic matter, especially in early stages of decomposition (e.g., earthworms, millipedes).

Detritus – Dead organic matter including the remains of organisms and waste products.

Ecological pyramid – A graphical representation that shows the amount of energy or organisms at each trophic level in an ecosystem.

Ectoparasites – Parasites that live on the surface of the host, such as ticks or lice.

Endoparasites – Parasites that live inside the host’s body, such as tapeworms or roundworms.

Energy flow – The one-way movement of energy through an ecosystem from the sun to producers and then to various levels of consumers.

Food chain – A linear sequence of organisms through which energy and nutrients flow as one organism eats another.

Food web – A complex network of interconnected food chains that shows the feeding relationships in an ecosystem.

Herbivory – An interaction where an animal feeds on a plant or algae, benefiting the herbivore and harming the plant (+/−).

Host – The organism that a parasite lives on or in and from which it obtains nourishment.

Interspecific interactions – Relationships between individuals of different species in a community, such as predation, competition, and mutualism.

Mechanical defenses – Physical features of an organism, like thorns or shells, that deter predators or herbivores.

Mimicry – An adaptation in which one species evolves to resemble another, often harmful or distasteful, species.

Mutualism – An interspecific interaction in which both species benefit (+/+).

Niche – The role an organism plays in its ecosystem, including how it uses resources and interacts with other organisms.

Niche differentiation – The process by which competing species use the environment differently to minimize competition.

Nitrogen fixation – A process by which certain bacteria convert atmospheric nitrogen gas (N₂) into forms (like ammonium) that plants can absorb.

Nutrient cycling – The continuous movement of nutrients such as nitrogen, phosphorus, and carbon through the environment and organisms.

Parasite – An organism that lives in or on another organism (host) and benefits by deriving nutrients at the host’s expense.

Parasitism – An interspecific interaction where one organism benefits (the parasite) and the other is harmed (the host) (+/−).

Phytoplankton – Microscopic photosynthetic organisms found in aquatic environments that serve as producers.

Photosynthesis – The process by which producers use sunlight, carbon dioxide, and water to create glucose and oxygen.

Positive/negative interaction – An interaction in which one species benefits while the other is harmed, such as predation or parasitism.

Predation – An interaction where one organism (the predator) kills and eats another (the prey) (+/−).

Prey – An organism that is hunted and consumed by a predator.

Primary consumers – Herbivores that feed directly on producers.

Primary production – The creation of organic compounds from carbon dioxide through photosynthesis, forming the base of the food web.

Primary productivity – The rate at which producers create usable energy through photosynthesis in an ecosystem.

Producers – Organisms, typically plants or algae, that make their own food using sunlight through photosynthesis.

Quaternary consumers – Top-level predators in a food chain that feed on tertiary consumers.

Secondary consumers – Carnivores that eat herbivores (primary consumers).

Species diversity – The variety and relative abundance of different species in a community.

Tertiary consumers – Carnivores that eat other carnivores (secondary consumers).

Trophic structure – The feeding relationships in an ecosystem, organized by trophic levels.

Warning coloration – Bright colors or patterns that signal to predators that an organism is toxic or unpalatable.

Zooplankton – Microscopic aquatic animals or heterotrophic protists that feed on phytoplankton and other small organisms.

Click on the flashcards to review key terms discussed in this chapter.

 

Text Description

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OpenAI. (2025). ChatGPT. [Large language model]. https://chat.openai.com/chat
Prompt: Provide definitions for all the bolded terms in the shared content and list all the terms in alphabetical order.