Lecture 14: Communities: Species Interactions III - Mutualism, Commensalism, and Ecosystem Engineering

Practice vocabulary flashcards covering ecological interactions including mutualisms (trophic, defense, dispersive), parasitism trade-offs, cheating dynamics, and ecosystem engineering from Lecture 14.

Mutualism

An ecological interaction characterized by reciprocal adaptations in two or more species that benefit all involved species, resulting in a net $+/+$ relationship.

Symbiosis

Any ecological interaction where members of different species live in intimately connected interactions, with outcomes that can be highly variable rather than strictly beneficial.

Trophic Mutualism

A category of mutualism in which partner species possess complementary adaptations and functions for obtaining energy and nutrients.

Defense Mutualism

A mutualistic interaction where one partner provides food or shelter and the other provides protection against natural enemies or herbivores, such as the relationship between Acacia plants and resident ants.

Dispersive Mutualism

A mutualistic interaction, such as pollination or seed dispersal, in which plants receive reproductive transport services while animals obtain food rewards.

Ectoparasite

A parasite that lives on the exterior of its host; it experiences high exposure to natural enemies and the external environment, low ease of feeding, but low difficulty moving between hosts and low exposure to the host's immune system.

Endoparasite

A parasite that lives inside its host; it experiences low exposure to the external environment and natural enemies, high ease of feeding, but high difficulty moving between hosts and high exposure to the host's immune system.

Endomycorrhizal Fungi

Fungi forming a trophic mutualism with plant roots where fungal hyphae penetrate root cells and grow between the plant cell wall and cell membrane.

Ectomycorrhizal Fungi

Fungi forming a trophic mutualism with plant roots where hyphae grow between root cells without penetrating cell membranes and construct an external fungal sheath around the root.

Metapleural Gland

A specialized gland found in ants, such as leaf-cutting ants, associated with maintaining antibiotic-producing defensive bacteria that protect their fungal garden against parasitic fungal invaders.

Context-Dependent Mutualism

A relationship where the net benefit of an interaction shifts based on ecological conditions, such as mycorrhizal fungi enhancing growth when soil nutrients are scarce but reducing plant growth in highly fertile soils.

Coevolutionary Stable State (Host-Pathogen)

A balanced evolutionary outcome where the host population evolves natural resistance to survive infection while the pathogen population simultaneously evolves less lethal strains to facilitate transmission.

Cheating (in Mutualisms)

A behavior where an individual in a mutualism exploits the benefits provided by its partner without reciprocating, such as a cleaner wrasse consuming host mucus and scales instead of ectoparasites.

Ecosystem Engineer

An organism that causes state changes in the environment that subsequently serve as vital resources or habitats for other species.

Bioturbation

A form of ecosystem engineering in which burrowing and digging organisms (such as worms, ants, pocket gophers, or prairie dogs) cause nutrient turnover and create disturbed habitat patches.

Structural Ecosystem Engineering

Environmental modification in which organisms alter physical surroundings by building or creating physical structures, such as beavers constructing dams or wood-boring beetles carving galleries in wood.

Lotic Habitat

A fast-moving freshwater ecosystem, such as a free-flowing stream, characterized by organisms like mayflies, stoneflies, caddisflies, anadromous fish, and stream salamanders.

Lentic Habitat

A slow-moving or standing freshwater ecosystem, such as a beaver pond or lake, characterized by organisms like blackflies, midges, dragonflies, leeches, mussels, lake fish, turtles, and waterfowl.