BIOB50 glossary

ad hoc fallacy

A story or narrative that explains an observed pattern or process without any proof and that is believed to be correct because it seems logical. Also known as a “just-so-story.”

alternative hypothesis

A statement proposing that the focal explanatory factor or factors in an experiment do have an effect on the system of interest.

analytical model

A model that can be solved mathematically or for which the relationships among the variables can be interpreted through mathematics.

Anthropocene

The current geological epoch that is characterized by the large and influential effect humans have on the planet.

anthropogenic effect

An impact on Earth’s ecology that is caused by human actions.

conceptual model

A theoretical construct that specifies how various components of a system fit in relation to each other.

control

An unmanipulated unit of an experiment; generally used for comparison to detect the effect of a treatment in a manipulated unit of an experiment.

data

Individual facts, statistical results, or items of information that are often (but not always) numerical.

ecology

The study of the interactions that determine the distribution and abundance of organisms.

ecosystem

A group of interacting organisms (biotic components) along with their physical environment (abiotic components).

extraneous factor

An aspect of an ecological system that is not of interest or of importance to the researcher designing an experiment.

focal factor

An important or critical aspect at play in an ecological system that scientists focus on (alter or manipulate) when designing an experiment or constructing a model.

hypothesis

A tentative or proposed explanation about the world, made on the basis of limited evidence, that is a starting point for further, typically scientific, investigation

hypothesis testing

A method of statistical or scientific inquiry used to determine whether an assumption or explanation applies to a group or sample.

manipulative experiment

A scientific experiment in which the researcher intentionally alters one or more conditions in order to examine hypotheses.

mathematical model

A conceptual model that is translated into the language of mathematics.

naturalist

A person who studies or observes natural organisms or phenomena in detail.

null hypothesis

A statement proposing that the focal explanatory factor or factors in an experiment do not have an effect on the system of interest.

organism

A single individual of any type of living creature on the planet, including all plants, animals, and microbes.

simulation model

A mathematical or conceptual model that is run multiple times to explore outcomes with different parameters or configurations.

treatment

An aspect of an ecological system that has been manipulated by an experimenter in the design of a scientific experiment.

aphotic zone

The depths of lakes and ocean waters that receive too little light for photosynthesis. The actual depth of this zone varies among water bodies, depending on conditions in the water.

aquatic biological zone

An ecological zone in a water-based environment; similar to a biome but defined by the characteristics of physical features such as light, salinity, and temperature.

benthic zone

An ocean or lake bottom.

biome

A large geographic area affected by similar climatic and physical factors that lead to distinctive associations of plants and animals.

biosphere

All the living organisms on Earth, including the environments in which they live.

boreal forest

A terrestrial biome at a high latitude that is characterized by coniferous forests and long winters during which temperatures drop below freezing, leading to permafrost.

climate

An expected pattern in the physical factors that make up the world (e.g., precipitation, heat, wind).

climate diagram

A type of graph that combines data on a region’s annual patterns of precipitation and environmental temperature.

continental effect

An increase in the range of seasonal average temperatures with distance from the regulating climatic effects of any large body of water. Continental effects lead to much hotter summers and colder winters inland than along a coast.

coral reef

An aquatic biological zone found in warm, shallow, tropical waters that is dominated by coral animals, other invertebrates, and fishes.

Coriolis effect

The deflection of air and wind patterns in bands around the globe caused by the Earth’s daily rotation on its axis

desert

A terrestrial biome that receives very little precipitation year-round, has low primary productivity, and where evaporation exceeds precipitation.

estuary

An aquatic biological zone that sits at the juncture of a river (or rivers) and an ocean and that has a distinct salinity gradient from fresh to salt water.

Ferrel cell

A cyclic atmospheric pattern of airflow between 30° and 60° latitude with one Ferrel cell in the northern hemisphere and one in the south.

greenhouse effect

The retention of heat by the Earth’s atmosphere. The atmosphere allows sunlight energy to enter and then retains the longer-wavelength heat energy, thereby warming the planet. This effect is responsible for a climate that supports life on Earth; however, the tons of anthropogenically produced gases, such as carbon dioxide and methane, contribute to accelerating global warming, which is altering global ecological systems.

Hadley cell

A cyclic atmospheric pattern of airflow caused by the solar heating of air at the equator and the cooling and descending of air at 30° latitude. There are two Hadley cells; one from the equator to 30° north latitude and the other from the equator to 30° south latitude.

mangrove forest

An aquatic biological zone that is found at the terrestrial and marine interface in the tropics and subtropics and is dominated by mangrove trees.

Mediterranean scrubland

A terrestrial biome in which rainfall occurs in the cool winters, while the summers tend to be very warm and dry. Found on the west coasts of continents, next to cool oceanic currents.

oceanic zone

An aquatic biological zone that consists of open ocean.

pelagic zone

The open water of an ocean or lake.

photic zone

The portion of lakes and ocean waters where light is sufficient for photosynthesis. The actual depth of this zone varies among water bodies, depending on conditions in the water.

Polar cell

A cyclic atmospheric pattern of airflow between 60° and 90° latitude; one cell is in the northern hemisphere and a second in the southern hemisphere.

primary productivity

The synthesis of organic material through the process of photosynthesis or chemosynthesis; this term refers most commonly to production of biomass by plants through photosynthesis.

rain shadow

A climatic pattern whereby mountain ranges affect air movement, causing air masses to lose or deposit moisture on the “front” side (windward side) of mountains and create very dry conditions on the “back” side (leeward side) of mountains.

rocky substrate

An aquatic biological zone that is found along the rocky shoreline of terrestrial systems with cool to cold water.

sandy bottom

An aquatic biological zone dominated by a sandy substrate that is extremely dynamic and is constantly moving due to tides and wave action.

seagrass bed

An aquatic biological zone that spans the terrestrial and marine interface and is dominated by aquatic herbaceous plants called seagrasses.

taiga

An alternative name for the boreal forest biome.

temperate forest

A terrestrial biome that is dominated by deciduous trees and winter temperatures that drop below freezing.

temperate grassland

A terrestrial biome that occurs between 30° and 55° north and south latitudes and where the predominant vegetation is grasses or small shrubs.

transpiration

The release of water vapor by plants.

tropical dry forest

A terrestrial biome that is warm to hot year-round and has substantial precipitation that is concentrated in a few months.

tropical rainforest

A terrestrial biome found at or near the equator, where the temperature is uniformly warm year-round and large amounts of precipitation fall year-round.

tropical savanna

A terrestrial biome near the equator that is characterized by large, open grasslands, seasonal rainfall, and frequent fires.

tundra

A terrestrial biome at very high latitudes (higher than 65° north or south) in which the cold winters are so extreme and the summers so short that a portion of the soil remains frozen year-round. Most vegetation consists of shrubs, mosses, and lichens.

weather

The observed day-to-day variation in physical factors that make up the world.

adaptation

(1) A trait that has changed over time due to natural selection; the current phenotype helps an organism to survive and reproduce in a particular environment. (2) The process of evolution that leads to an adaptive trait becoming more common or fixed in a population.

adaptive evolution

Evolution by natural selection.

allele

An alternate form of a gene that has slight differences in the exact arrangement and type of nucleic acids compared to other versions.

allele frequency

The number of occurrences of an allele that one would expect to find in a population of a given size.

allopatric speciation

Speciation between two or more spatially disjunct (i.e., not in the same place) populations. The spatial separation disrupts gene flow and makes it easier for a reproductive isolating mechanism to evolve.

biological species concept

The definition of a species as consisting of all individuals that can actually or potentially interbreed and produce viable, fertile offspring.

chromosome

A tight coil of DNA, which is a double-stranded molecule of bonded nucleic acids.

directional selection

A shift in the trait frequency distribution of an organism whereby the mean trait value tends to shift through time toward one or the other end of the original distribution; a form of natural selection.

disruptive selection

A shift in a trait frequency distribution whereby the extremes of the frequency distribution become more common over time; a form of natural selection.

ecotype

A population of a species with locally adapted traits.

evolution

A change in gene frequency in a population over time. The four mechanisms of evolution are mutation, gene flow, genetic drift, and natural selection.

fitness

The genetic contribution that an individual makes to future generations. Traits that increase survival and reproduction increase an organism’s fitness, so long as the organism’s offspring also survive to reproduce.

gene

A sequence of deoxyribonucleic acid (DNA) that contains the code for a biological molecule with a particular physiological or behavioral function.

gene flow

The movement of alleles from one population to another via the movement of organisms or their gametes across space; one of the four mechanisms of evolution (mutation, gene flow, genetic drift, and natural selection).

genetic drift

The removal of genes from a population over time through random mating between individuals or by the random death of individuals; one of the four mechanisms of evolution (mutation, gene flow, genetic drift, and natural selection).

genetic mutation

Errors in the replication of DNA within a cell that create slight differences in nucleotide sequences, leading to novel alleles; one of the four mechanisms of evolution (mutation, gene flow, genetic drift, and natural selection).

genotype

A specific combination of alleles in an individual at a particular genetic locus. A genotype interacts with the environment to create a specific phenotype.

genus

A level in the taxonomic hierarchy; the first part of the Latin binomial (scientific name) that identifies a species.

geographic isolating mechanism

A physical barrier that prevents organism dispersal and limits gene flow.

heritable

Of a characteristic (phenotype): transmissible from parent to offspring via the genetic inheritance of alleles.

heterozygous

Having two different alleles for a particular gene.

homozygous

Having two copies of the same allele for a particular gene.

morphology

An organism’s appearance (from morpho, which means “shape”).

natural selection

The differential survival and reproduction of individuals in a population in response to biotic and abiotic factors in their environment acting on heritable variation in traits of individuals; one of the four mechanisms that produces evolutionary change (mutation, gene flow, genetic drift, and natural selection).

non-native species

A population founded by individuals transported by humans and released well outside their native range.

phenology

The cyclic and seasonal events in the life of a plant or animal; also the study of cyclic and seasonal biological phenomena in relation to climate.

phenotype

The specific observable physical, developmental, or behavioral trait of an organism; determined by the organism’s genotype.

population

(1) In the context of sampling and statistics, the largest group of things under study. (2) In the context of evolution, a group of individuals of the same species that can mate together. (3) In the context of ecology, a group of individuals of the same species that is spatially distinct from other groups of individuals of the same species.

recessive (allele)

An allele that codes for its trait only if there are two copies of the allele at a genetic locus.

relative fitness

An individual’s contribution to the gene pool of future generations relative to the contribution from other individuals in the same population.

reproductive isolating mechanism

A mechanism that separates two evolutionary lineages, making it so they can no longer interbreed; all speciation requires a reproductive isolating mechanism.

scientific name

The genus and specific epithet that provide a name for a species.

sexual selection

Evolutionary selection for traits that increase mating success rather than survival; a form of natural selection.

speciation

The process by which two species arise from one common ancestral species.

stabilizing selection

A change in a trait frequency distribution whereby the mean trait value does not change through time, but the variation away from that mean decreases over time; a form of natural selection.

sympatric speciation

Speciation that occurs when two (or more) population lineages occupy the same physical location but experience no gene flow between them.

taxon

The singular form of a general term (plural, taxa) referring to biological groups at a variety of different evolutionary organizational levels from subspecies up to orders.

dominant (allele)

An allele that codes for its trait even if there is only one copy of the allele at a genetic locus.

behavior

The way in which individuals of a species physically interact with each other, with individuals of other species, and with their environment.

biomass

Living tissue or growth, as well as storage of energy as fat, carbohydrates, or proteins.