Ecology Lecture Review

Flashcards for vocabulary review based on lecture notes.

Food Web

A complex network of interactions showing the feeding relationships between organisms in an ecosystem.

Trophic Level

The position an organism occupies in a food web or food chain.

Detritivore

A heterotrophic organism that obtains its nutrients from detritus.

Biomass

The total mass of organisms in a given area or volume.

Gross Primary Productivity (GPP)

The rate at which an ecosystem's producers convert solar energy into chemical energy as biomass.

Net Primary Productivity (NPP)

The rate at which energy for use by consumers is stored in new biomass; NPP = GPP – R (Respiration).

Top-down Control

Occurs when a predator or herbivore controls the trophic levels below it.

Bottom-up Control

Occurs when herbivores and predators are limited by prey and not vice versa.

Keystone Species

A species whose removal from an ecosystem will have a significant cascading effect on the ecosystem structure.

Ecosystem Stability

A result of resistance and resilience; interactions are dynamic, indicating the food web is not static.

Resilience

The ability of a system to bounce back to its stable state after it changed as a result of a disturbance.

Resistance

The ability of a system to withstand disturbances.

Biome

A terrestrial ecosystem which extend across a large geographic area, such as tundra.

Biodiversity

The number and types of plants and animals that exist in a particular area or in the world generally.

Species Diversity

The number of different species in a particular area or ecosystem.

Genetic Diversity

Differences in the genome of individuals of the same species.

Ecosystem Diversity

The variety of ecosystems present in a region.

Functional Diversity

The number of different ecological roles in an ecosystem.

Intrinsic rate of natural increase (r)

The rate at which a population increases in size if there are no density-dependent forces regulating the population.

Carrying capacity (K)

The maximum population size of a biological species that can be sustained by that specific environment, given the food, habitat, water, and other necessities available in the environment

Unimodular Organisms

Individuals are discrete units with a definite form that remains largely unaltered until death, e.g. mammals.

Modular Organisms

Organisms composed of an indeterminate combination of modules, e.g. higher plants: leaves, axillary buds, stem.

Annuals

Plants that complete their life cycle in 12 months or less; discrete, non-overlapping generations.

Perennials

Organisms that persist for many growing seasons; one part dies/gets absorbed and regrows in the following season.

Semelparous

Individuals with one single reproductive event during its life, then dies.

Iteroparous

Individuals that may have many reproductive events during a season or life.

Life History Traits

Measurable characteristics or attributes that affect survival and reproduction.

Assembly Rules

Determinants of species combinations in ecosystems.

Community

Interacting species populations coexisting in a habitat over a particular time.

Assemblage

Taxonomically related group of species populations that occur together in a habitat.

Guild

A group of species populations that exploit the same class of resources in a similar way.

Functional Group

A group of species populations which share similar ecological roles in the ecosystem (e.g. pollinators).

Limiting Similarity

Coexisting species must differ in certain aspects, enabling them to exploit different resources; their similarity cannot exceed a certain limit.

Character Displacement

Increased differences between closely‐related or similar species in sympatry; an adaptive process leading to resource partitioning.

Habitat-filtering

Morphological differences between spp smaller than expected by chance.

Phylogenetic Signal

Closely related species have similar traits.

Ecological Equilibria

Stable equilibrium between predator and prey populations. Cycle is a stable equilibrium. Community structure is predictable.

Gap Dynamics

A prominent means of forest replacement. Another form of priority effect - whatever species has seeds at that time will fill the gap.

Storage Effect

Mechanism of species coexistence in variable environments BUT the changes are random and occur infrequent.

Lottery Models

Openings are filled at random by recruits from a large pool of potential colonists.

Intermediate Disturbance Hypothesis

High levels of diversity at intermediate levels of disturbance.

Ecosystem Services

Conditions and processes through which natural ecosystems help sustain and fulfill human life.

Resilience

The capacity of an ecosystem to respond to a perturbation.

Resistance/Stability

A stable system has low variability.

Functionality

Refers to processes like decomposition, production, nutrient cycling, and fluxes of nutrients and energy.

Productivity

The rate of production i.e. the amount of organic matter accumulated in any unit time.

Insurance Hypothesis

Functional Diversity -> Buffer-effect by functionally redundant species. Higher species(=functional) diversity favoured.

Latitudinal Gradients

Patterns of biodiversity and productivity.

Species-Area Relationships

One of the few general “laws” of ecology. Large areas (islands) support more species than smaller areas (islands).

Darlingtons Rule

10- fold increase in island area results in doubling of species no.

Island Biogeography Theory (IBT)

No. of spp. on an island represents a balance between recurrent immigration of new spp. onto island and recurrent extinction of resident spp.

Area Effect

Smaller islands will have greater extinction than large islands.

Distance Effect

Islands far from the mainland will have fewer species than close islands

Target Effect

Island area (size) might also affect the immigration rate

Rescue Effect

Extinction and distance