Symbiosis: Mutualism, Commensalism, Parasitism — Resource Availability

Definition: close long-term interaction between two species in an ecosystem.
Etymology: from Greek sim = together, bio = living; symbiosis = living together.
Big idea: ecosystems arise from both biotic and abiotic interactions; symbiosis is a key biotic interaction shaping communities.

Mutualism: both species receive a benefit that increases survival and reproduction; long-term and co-evolved traits.
Common examples: ants and acacia trees; bee and flower (pollination); clownfish and sea anemone.
Resource framing: identify which resources are gained and whether they are biotic or abiotic.

Commensalism: one species benefits, the other is unaffected; long-term relationship with co-evolution.
Examples: black-backed jackals scavenging; owls nesting in tree hollows; cattle and egrets; hermit crabs using discarded snail shells.
Resource framing: focus on the benefiting resource and note the other species is neither helped nor harmed.

Parasitism: one organism (parasite) benefits; the other (host) is harmed; host is rarely killed, unlike predation.
Examples: fleas or ticks on mammals; intestinal tapeworms; mosquitoes biting hosts; malaria.
Important distinction: parasitism harms without typically killing the host.

For each interaction, classify resources as biotic (living) or abiotic (non-living).
Examples: pest insects (biotic) as a food resource for a parasite or mutualist; shelter or safety as a resource often biotic (partner’s actions).

Oxpeckers on large mammals ( buffalo, giraffe, etc. )
- They eat ticks, flies, fleas (biotic resources) -> food for the oxpecker.
- They remove pests from the mammal (benefits host) -> host health benefit.
- They provide a loud warning call (communication) -> herd safety (additional benefit to host).
- Overall: mutualism with multiple benefits; assess each resource type (biological/biotic vs other effects).

Scenario: Rhizobacteria in plant root nodules convert atmospheric nitrogen into usable forms; plants provide carbon-containing molecules to nodules.
Task: identify the most likely ecological relationship and describe one mutual benefit to the rhizobacteria.
Likely relationship: mutualism.
Benefit to rhizobacteria (one): carbon-containing molecules from the plant.
Another possible benefit to rhizobacteria: a protected, nutrient-rich nodule environment with regulated oxygen for nitrogen fixation.
Suggested answer structure: full sentences describing relationship, one benefit to bacteria, and a second benefit or mechanism.

Mutualism: both benefit; co-evolution.
Commensalism: one benefits, other unaffected.
Parasitism: parasite benefits, host harmed; usually not lethal.
Resource framing: always identify biotic vs abiotic resources in each interaction.
Practice prompts and FRQ prep mirror AP-style questioning: describe relationships, benefits, and provide concise reasoning.