Biology Unit 3 Ecology (QCAA - from quizlet)

Biodiversity

The full range of different living things in a particular area/region. Can be described at the ecosystem, species and genetic level.

Species Diversity

Level of diversity related to the number and relative abundance of species in a biological community.

Ecosystem Diversity

Level of diversity related to the variety of habitats, living communities, and ecological processes in the living world.

Photosynthesis

The source of energy in ecosystems: a process that converts light energy and carbon dioxide into glucose and oxygen.

Ecosystem

A system formed by living organisms

interacting with one another and with their

physical environment.

Abiotic Factors

Non-living components (factors) in an ecosystem. Examples include air and water temperature, rainfall, altitude, light intensity, soil composition, pH, salinity, etc.

Biotic Factors

The living components (factors) that have an effect on an ecosystem or other organisms living in that ecosystem. Examples include plants, animals, pathogens, food availability, competitors, predators, etc.

Quadrat

A 1m x 1m square frame used in ecological sampling

Percentage Cover

An estimate of the percentage of each quadrat covered by a particular species. Can be basal cover, ground cover, leaf cover or canopy cover.

Percentage Frequency

Measure of how often a plant species appears within sample quadrats.

Species Richness

A simple tally of the number of different species within a particular area.

Abundance

The number of individuals of a particular species.

Species Evenness (relative species abundance)

A measure of the number of individuals of a particular species in relation to the total number of individuals of all species in the area. (often expressed as a %).

Simpson's Diversity Index

A measure of species diversity that considers both richness and evenness.

SDI = 1- (n(n-1)/N(N-1))

Spatial scale

This type of scale refers to how much area is covered by the ecosystem

Temporal scale

This type of scale refers to the time period over which an ecosystem is studied

Macro-level

This ecosystem level includes whole oceans or continents

Micro-level

This ecosystem level refers to specific local areas such as a warm temperate rainforest within a national park.

Meso-level

This ecosystem level refers to areas within oceans or continents with similar climatic conditions, eg. a large desert or national park.

Distribution

The geographic area/range over which the individuals in a population are found.

Limiting Factor

A factor that acts on a population to restrict its growth (biotic or abiotic).

Tolerance Limit (range)

Range of environmental conditions in which an organism can survive.

Taxonomy

The scientific study of how living things are classified.

Linnaean Classification

In this system of classification, organisms are classified based on their physical traits. Consists of a hierarchy of groupings, called taxa (singular, taxon), ie. domain, kingdom, phylum, class, order, family, genus and species.

Taxon

A level of a hierarchical classification system, eg. kingdom, family or species

Binomial nomenclature

A naming system in which organisms are given a two part name such as genus and species, eg. Homo sapien

asexual reproduction

Type of reproduction that involves only one parent and produces offspring that are identical to the parent.

sexual reproduction

Type of reproduction that involves two parents that combine their genetic material to produce a new organism, which differs from both parents

r-strategist (r-selected species)

Species that have a high growth rate but low survivability. Reproductive strategies include reproducing early, bearing many small, unprotected offspring (eg. insects, fish).

K-strategist (K-selected species)

Species that have a low growth rate but high survivability. Reproductive strategies include reproducing later, bearing fewer, nurtured offspring (eg. humans, elephants).

Common Ancestor

A species of organism whose offspring diverged over time

Phylogenetic tree

Diagram showing evolutionary relationships of organisms with a common ancestor; resembles a tree (branch length indicates genetic change).

Cladograms

A branching tree diagram in which organisms are grouped based on their most likely evolutionary relationships (cladistics). NB: branch length is unscaled.

Clade

A group of organisms that consists of a common ancestor and all its lineal descendants.

Node

A branching point in a cladogram which represents a common ancestor

Bifurcation

Two-way splitting of a branch, ie. as in cladograms

Molecular clock

This type of 'clock' measures the number of mutations which accumulate in the gene sequences of different species over time. Evolutionary biologists use this information to deduce how species evolve, and to estimate how long ago two species diverged.

Species

(biological species concept)

A group of organisms that can potentially interbreed with each other and produce fertile offspring.

Hybrid

An organism resulting from the interbreeding of two different species, eg. a mule

Predation

A species interaction in which one organism kills and eats another.

Competition

A species interaction in which two or more individuals compete for the same resources in the same area, eg. mates, nest sites, food or space. Can be intraspecific (within a species) or interspecific (between species).

Intraspecific

This type of competition occurs within a species, ie. individuals of the same species compete for resources, mates, etc.

Interspecific

This type of competition occurs between members of different species

Symbiosis

A close species interaction in which at least one species benefits from the relationship. Examples include parasitism, commensalism and mutualism.

Mutualism

A relationship in which two species provide resources or services to each other; both species benefit.

Commensalism

A relationship in which one organism receives resources or services from another; one organism benefits and the other is unaffected. eg. Cattle + egret

Parasitism

A relationship in which one species lives on or in another organism and feeds on them; one benefits and the other is harmed. e.g. tick on a dog

Pathogen

A disease-causing organism or agent such as a bacterium, virus or parasite

Terrestrial

Relating to the land

Aquatic

Relating to water; either marine or freshwater

Eutrophication

A process by which nutrients, particularly phosphorus and nitrogen, become highly concentrated in a body of water, leading to increased growth of organisms such as algae or cyanobacteria.

Biome

A large area classified based on its soil, climate and the species that live there. Five major types: aquatic, grassland, forest, desert, and tundra.

Habitat

The environment/area where an organism or species lives. Provides resources such as food, water, shelter, protection, mates, etc

Microhabitat

A small, particular part of a habitat in which particular organisms live; for example, beneath the bark of a tree within a forest habitat.

Stratified Sampling

Sampling technique where the study area or population is divided into strata or subgroups for separate sampling (can be vertical or horizontal).

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Systematic Sampling

Sampling technique in which researchers begin at a random point and systematically take samples at regular intervals, eg. along a transect.

Random Sampling

Sampling technique which every part of the area has an equal chance of being sampled (unbiased). This technique does not take into account habitat-based strata.

Capture-mark-recapture

Sampling technique where organisms are captured and marked, then recaptured to count how many are marked.

Autotroph (producer)

A organism that can produce its own organic compounds from sunlight, carbon dioxide and water.

Heterotroph (consumer)

An organism that obtains their nutritional and energy requirements by consuming other living things or their products.

Detritivore

An organism that consumes detritus (dead tissues and organic waste), e.g. earth worms

Decomposers

Microscopic organisms that secrete digestive enzymes which break down wastes and dead tissues and recycle raw materials in the environment.

Biomass

Measure of the total quantity of biological matter (dry weight) of a group of organisms in a given area. Can be expressed as the average mass per unit area (eg. g/m2 or kg/ha).

Productivity

The rate at which energy is added to the bodies of organisms in the form of biomass. It may be expressed in the units of energy (kJ/m2/year) or biomass (g/m2 or kg/m2).

Food Chain

A series of events in which one organism eats another and obtains energy.

Food Web

A system of interlocking and interdependent food chains.

Trophic Level

A level in the food chain of an ecosystem based on feeding relationships.

Biomass Pyramid

A pyramid diagram that shows the relative proportions of each trophic level in an ecosystem.

Gross Productivity

The overall rate of energy entering a trophic level, expressed as kJ/m2/year

Net Productivity

Gross productivity less the energy lost to heat/respiration

Gross Primary Productivity (GPP)

The rate at which energy is captured by plants or other primary producers during photosynthesis. They will use some of this energy for cellular work and some for growth (building biomass). Use of the term primary relates to producers only.

Net Primary Productivity (NPP)

The rate at which energy is stored as biomass by plants or other primary producers. Use of the term primary relates to producers only.

Ecological Niche

The role and space an organism fills in an ecosystem, including all its interactions with the biotic and abiotic factors of its environment. The part where the species is most likely to survive, reproduce and persist indefinitely.

Fundamental Niche

The widest potential niche a species could occupy in the absence of competitors, predators or parasites

Realised Niche

The actual niche a species occupies due to restrictions placed on it by interactions with other species.

Resource Partitioning

The use of space and time that reduces competition between species and allows many unique niches to exist in the same area

Competitive exclusion principle

This principle states that no two species can occupy exactly the same niche at the same time. If they do, one species will outcompete the other to extinction.

Keystone Species

A plant or animal that plays a unique and crucial role in the way an ecosystem functions. eg. cassowary, wolves, whales

Carrying Capacity

The size of population that can be supported indefinitely on the available resources and services of that ecosystem.

Density-dependent Factors

A factor that influences population size and density, but magnitude of effect depends on the existing population density (eg. predation, crowding, parasitism, disease.)

Density-independent Factors

A factor that impacts a population regardless of population size or density (environmental temperature, intensity of sunlight, pH of soil and water, salinity, natural disasters).

Population growth rate

= (birth rate + immigration rate) - (death rate + emigration rate)

Immigration

Movement of individuals into a population.

Emigration

The movement of individuals out of a population.

Lincoln Index

A method for determining population size by marking and recapturing portions of a population.

N= M x n/m

Exponential Growth (J curve)

Growth pattern which occurs when environmental conditions are favourable and resources are not limiting. If favourable conditions continue (no limiting factors) can result in population explosion.

Logistic Growth (S curve)

Growth pattern in which a population's growth rate grows exponentially initially before flattening out as growth is affected by density-dependent factors. Growth may decline until birth and death rates are balanced.

Ecological Succession

The process of gradual changes in an ecological community over time, with one community being replaced by the next. Usually classified as primary or secondary.

Primary Succession

An ecological succession that begins in an area where no biotic community previously existed, eg. newly made volcanic rock.

Sere

The plant and animal communities that occur successively from pioneer to a climax community during succession.

Pioneer species

Name given to the first species to colonise an area undergoing primary succession; they are effective colonisers due to their ability to fixate nitrogen, tolerance to extreme conditions, rapid germination of seeds and ability to photosynthesise.

Pioneer community

The first community of plants, animals and decomposers to colonise an area undergoing primary ecological succession; first sere.

Secondary Succession

The process of recolonising an area after a significant disturbance, such as fire, flood or tree clearing.

Climax Community

A stable, mature community that undergoes little or no change in species over time, eg. old-growth forests and rainforests. The "end point" of ecological succession.

Habitat Fragmentation

Breakup of a large area of habitat into smaller isolated habitats, usually as a result of human activities such as tree clearing and road building.