Big Idea 4

4. Climax Community: A climax community is an ecological community in which all the organisms exist in a state of equilibrium at the final stage of succession. A climax community remains relatively unchanged until it is disrupted by a disaster or some sort of interference. The American River Parkway is an example of a climax community with an abundance of plants and animals that live in harmony with each other. The parkway will remain at this stage until destroyed by a natural event such as flooding or even by human disruption.

5. Commensalism: Commensalism is a symbiotic relationship in which one organism benefits and the other neither benefits nor is harmed. Hermit crabs, like the one here, take over the discarded shells of sea snails for shelter and protection. The hermit crab benefits from the shell, while the sea snail is unaffected because the shell was discarded anyways. 

6. Competition: Competition refers to a relationship between organisms in which the presence of one adversely affects the other because they have similar living requirements, such as with regards to food or space. Competition can be between members of two different species (interspecific) or between members of the same species (infraspecific). Interspecific competition for food, space, and other resources exists between these two species of barnacles that reside in the intertidal zone. 

8. Endosperm: An endosperm is a nutritive tissue for a developing plant embryo that is produced around the time of fertilization. It provides nourishment usually in the form of starch, protein, and other nutrients. Flowering plants produce seeds with endosperms, and thus these honeysuckles must reproduce with seeds containing these food stores.   

11. K-strategist: K-strategists are relatively large organisms that have long lifespans, few offspring per each reproductive episode, and invest extensive parental care into their offspring. K-selected organisms are adapted to thrive at the carrying capacity of their population. This eastern bongo is an example of a K-selected organism that bears a small number of large offspring for each of the many reproductive events throughout its life. 

12. Mutualism: Mutualism refers to a relationship between two organisms in which both benefit. Lichens are mutualistic associations between fungi and a partner that can carry out photosynthesis. This sac fungus is growing on a branch of a tree, which is also inhabited by green algae, a photosynthetic organism. The fungus offers protection to the algae, while the algae gives nutrients to the fungus in return, making the relationship mutualistic. 

13. Niche: A niche is a role that an organism plays in its community. More specifically, it refers to all the ways an organism uses the resources of its environment. These mussels are adapted to the extremes of the intertidal niche that they occupy, feeding on plankton and other microscopic organisms and clustering together to reduce individual exposure. 

17. Pioneer Species: Pioneer species are the species that are the first to inhabit an area that has been destroyed or altered. They pave the way for a chain of ecological succession that will eventually lead to a stable environment. Mosses are examples of weedy species that first inhabit barren areas because they are tolerant to the harsh conditions. 

19. Predation: Predation refers to the consumption of an organism (prey) by another (predator). The leaves of this privet hedge are obviously being preyed upon by some sort of herbivore, such as a caterpillar or another leaf-eating insect, causing the holes that are evident in the picture above.

20. R-Strategist: R-strategists are organisms that are characterized by short lifespans and many small offspring that receive no or little parental care per each reproductive event. Ladybugs, like the one pictured, are r-strategists that live up to three years in perfect conditions and produce up to fifty offspring per each of their few reproductive events.