Water moves to the atmosphere by evapotranspiration (loss of water from plants and soil), evaporation from surface water and precipitation as well as industrial uses. The atmosphere cycles water back to earth via precipitation (rain and snow). Precipitation may be converted to ground water or surface runoff to lakes, streams, and oceans. Water in the form of ice or aquifers may cycle very infrequently.

A producer is a member of the trophic level which supports all others in the food web. These organisms are the autotrophs (or "self-feeders") which are capable of harnessing light or chemical energy in order to fix carbon dioxide into organic forms.  Photosynthesis is the most common type of producer and may be used by plants, algae and some bacteria.

The necessary energy is usually from light (photosynthesis) but chemical energy (chemisynthesis) is used in some specialized environments such as deep ocean vents.

A food web is the interconnected feeding relationships of who eats whom in an ecosystem.

A herbivore is an organism which feeds on plant tissue (including algae).

A carnivore is an organism which feeds on animal tissue.

A decomposer is an organism which obtains energy from the breakdown of dead organic matter into simpler substances.  This group is usually made up of bacteria and fungi. Their activities are crucial to nutrient cycling throughout the ecosystem.

A niche is the sum total of an organism's utilization of the biotic and abiotic resources of an environment.  It may also be considered as the functional role of a species in a community including all its activities and relationships. Either definition is accurate depending on the point of view of the researcher or reader.

No, while there may be considerable overlap between niches and competition for resources between populations, there must be some differences or competitive exclusion will eventually cause the localized extinction of the less competitive population.

A trophic level is a feeding level within an ecosystem. This is a functional rather than taxonomic classification. For example, an organism may be an autotroph, herbivore or various levels of a carnivore within an ecosystem.

Note: most of the available energy at any given level is used for maintenance activities (respiration, heat production, waste removal, growth, etc). Thus most food chains are only three or four links long above the primary producer level.

A predator is an organism that kills and consumes another - this may include herbivore-plant interactions. The predator is usually large, and actively seeks out its prey. A parasite is an organism (usually small) which lives on/in another organism from which it obtains food.  For a parasite, the host is both food and habitat, so ideally the parasite does not want to kill the host with too high a parasite load (need mechanism to disperse to new hosts).

Biogeochemical cycles are the movement of elements or compounds through living organisms and the nonliving environment to allow use of a limited resource.

Elements which are cycled include carbon, nitrogen, oxygen, phosphorus, sulphur, and calcium.

These cycles are important because they allow the reuse of a limited resource in various chemical forms throughout the environment.

The phenotype is the expressed traits of an organism as determined by genetics and environment.

The genotype is the genetic makeup of the organism.

A mutant is an organism which has a change in its genotype as compared to the "wild type" or the most common genotypic form found in nature. A mutation is an alteration in a gene. Thus, a mutant is an organism which has a mutation in its genes.

A change in an organism's genotype will not necessarily change its phenotype. The mutation may be silent - that is, it does not result in a change to a protein (e.g. the change does not alter which amino acid is specified by a codon).

Changes in an organism's phenotype may not be reflected in its genotype.

Example 1: hormone induced changes in form to prepare for breeding.
Example 2: developmental changes during maturation.
Example 3: scars resulting from healing injuries.
Example 4: changes due to illness or infection.
Example 5: changes due to chronic exposure to toxins

Natural selection is the differential success in survival and reproduction of individuals with different phenotypes resulting from interactions between organisms and their environment.  Evolution occurs when natural selection results in the changes in the relative frequencies of alleles for various phenotypes within the gene pool of a population.

Macroevolution is evolution on a very large scale - it includes origin of novel designs, evolutionary trends, adaptive radiation and mass extinctions. For example: it would include the development of wings for birds, development of upright posture for humans, trends such as increasing brain size for mammals, and the disappearance of the dinosaurs.  These are changes which occur on the geological time scale.  Tools to study macroevolution include paleontology, taxonomy, genetics (phylogeny), etc.

Microevolution is changes which occur in a gene pool of a population over a succession of generations. It is the smallest possible scale upon which to study evolution. The classic example is the change in the colour of peppered moths in England in response to the changes in the colour of the bark of trees caused by industrialization (soot deposition on the bark). Prior to industrialization, most pepper moths were white with black spots - they could rest on the light coloured trees and hide more effectively than the occasional black moth with white spots present in the population. Following industrialization, the soot deposits on the trees made the bark dark in colour. Over many moth generations, the black moths with the light spots were more likely to survive to breed.  In many areas of England, the black moths now make up most of the population of peppered moths.

Succession is the transition in the species composition of a biological community, often following an ecological disturbance, or establishing a community in an area virtually barren of life. This replacement of one community by another over time often progresses to a stable climax community e.g. forest.

Yes, early in succession processes diversity is increased due to the overlap of various communities from different stages due to colonization.  As succession proceeds towards the climax community, diversity decreases or levels off as members of earlier stages are out competed for resources.

Biodiversity is the abundance of different species in a given location.

Taxonomy is the naming and classification of life forms.

The correct order is: Kingdom, phylum, class, order, family, genus, species.

Homo sapiens.  Note: genus and species names should be underlined if you are handwriting the names and in italics if you are word processing the genus names are capitalized, while species names are lower case.

Organisms in the same genus are more closely related. For example: Mammalia is a class which includes all mammals including humans, whales, dogs, and the duck billed platypus, while Canis is the genus which refers to wolves and dogs only.

The plural of genus is genera.

A community is a group of interacting plants and animals that live in a given area.

A biome is a major regional ecological community of plants and animals.  They are classified by the predominant vegetation and characterized by adaptations of the organisms that live there to that particular environment.

Examples of biomes include: grasslands, tropical savannas, shrubland, deserts, tundras, tiagas, coniferous forests, temperate forests, tropical rain forests, lentic freshwater, lotic freshwater, wetlands, open sea, rocky shore, sandy shore and mudflats, coral reefs, estuaries, tidal marshes, mangrove swamps, etc.

An ecosystem is the interactions between the biotic community and the abiotic environment.

A population is a group of individuals of the same species living in a given area at a given time.

The Hardy-Weinberg Law proposes that the genotypic ratios resulting from random mating will remain unchanged form one generation to the next provided that natural selection, genetic drift and mutation are absent.  In other words, that the sexual shuffling of genes on its own is incapable of changing the overall genetic makeup of a population.

If there are two possible alleles for a trait, one dominant (A) and one recessive (a), then the frequency of A can be represented by p, and the frequency of a can be represented by q. Within a population, p + q =1.  This relationship can be used to determine the relative frequencies of homozygous dominants (AA), heterozygous individuals (Aa) and homozygous recessives (aa), using the formula:

p² + 2pq +q² = 1

For example, if the frequency for an allele B is 0.6 and for allele b is 0.4, then you can determine the genotypic frequencies for the various groups.

Number of homozygous BB = (0.6)² = 0.36 or 36%
Number of heterozygous Bb = 2(0.6)(0.4) = 0.48 or 48%
Number of homozygous bb = (0.4)² = 0.16 or 16 %

The genotypic frequency of XX is represented by p² in the Hardy-Weinberg equilibrium. Therefore, p² = 0.64, and the square root of 0.64 is 0.8. Thus the frequency of the X allele is 0.8. The frequency of the x allele is q² or 1-p, both of which give an allele frequency for x of 0.2

Genetic drift is random fluctuations in allele frequency over time due to chance occurrences alone without any influence by natural selection. It is an important factor in small populations.  For example: say that three individuals in a population of 10 carry a certain rare allele. If two of those individuals are killed prior to mating due to an accident of some kind, then the frequency of that rare allele will be considerably reduced in the following generation.

Types of interaction between organisms that only become apparent at the community level are competition, predation, parasitism, disease, mutualism.

Succession refers to the gradual change occurring in an ecosystem of a given area on which populations succeed each Succession is the transition in the species composition of a biological community, often following an ecological disturbance, or establishing a community in an area virtually barren of life. This replacement of one community by another over time often progresses to a stable climax community e.g. forest.

Succession generally is a plant-driven or plant-dominated process in which animal communities change as the plant community change.

Primary succession usually involves colonization of bare ground where no previous ecosystem was present; examples include sand dunes, volcanic flows, mud flats, glacial till, and dystrophic lakes and ponds.  Secondary succession is characterized by replacement of a community after some disturbance where a previous community existed on the site; examples include old abandoned fields, wind-blown gaps in forests, and areas after fire.

Succession is considered autogenic when directed from within the ecosystem, where changes in habitat are brought about by actions of the biota. Terrestrial ecosystems are thought to be largely autogenic. Succession is considered allogenic when driven by forces or factors external to the ecosystem. Aquatic systems are thought to be largely allogenic.

Submerged plants; floating plants; emergent plants; shrubs; mature forest.  lakes and ponds receive drainage and runoff from the surrounding landscape.  Soil accumulates, terrestrial plants invade, and a mature forest eventually develops

According to this theory, the number of species on an island will reach an equilibrium when rates of immigration and extinction are balanced.

It can also be applied to patches of habitat on mainland continents, such as mountaintops, ponds, dunes, nature reserves, and highly disturbed areas such as strip-mine tailing or clear-cut forest areas.

Disturbance is any relatively discrete event that comes from the outside and causes changes in ecosystems, communities, populations, substrates, or resources and thereby creates opportunities for individuals or groups of individuals to become established.

Spatial characteristics include the size of the area disturbed, the location of the disturbance and its severity.

Natural disturbances include wind, fire, moving water (storm runoff and wave action), drought, and actions of animals.  Winds associated with storm events can cause large openings in the forest canopy; fires cause major changes in species composition and diversity; storm runoff and flooding can alter the course of rivers and alter terrestrial ecosystems of the floodplain; storm waves and tides alter beach and dune structures, disturbing shore and island communities; drought can alter vegetation, which, in turn will have a major influence on animal populations in an area; overgrazing of vegetation by animals can have impact on an ecosystem; insect infestations can result in tree death or reduced growth; flooding of forested areas caused by beaver activity disturbs streams and adjacent terrestrial habitats.