Term | Definition |
abiotic factors | The non-living (physical or climatic) aspects of an environment. |
abscissic acid | A plant hormone with a range of effects e.g. promotes leaf and fruit abscission in some species. |
abscission | Leaf or fruit fall. |
actogram | An activity / time graph for an organism. |
adaptation | A feature of an organism which helps it to live successfully in its environment. |
adaptive advantage | The way in which the response helps to ensure the survival of the individual and therefore the population or species as a whole. |
aggression | Attempts by an animal to harm or kill another animal of the same species with which it is competing (not predation). |
agonistic behaviour | Ritualised behaviour between two members of the same species which are in conflict. Includes threat displays and submissive/dominance behaviours. Reduces actual physical fighting. |
allelopathy | An interspecific relationship in which a plant species produces a chemical which is toxic to other species. |
altruism | Behaviour in which an individual puts itself at risk for the benefit of the group e.g. warning of predators. |
amensalism | An interspecific relationship in which one species is harmed and the other species is unaffected (or benefits) e.g. antibiosis and allelopathy. |
antibiosis | An interspecific relationship in which one species releases a substance which inhibits the growth or kills another species (e.g. some fungi inhibit the growth of bacteria). |
apical dominance | Growth pattern where there is one main trunk/stem and much smaller side branches, due to suppression of lateral (side) buds by a high concentration of auxin near the top of the plant. |
auxin | A plant hormone. Involved in tropic responses because it affects cell elongation, also has various other roles and effects in plants. |
Batesian mimicry | When a palatable animal mimics (looks like) an unpalatable one, providing protection from predators. |
behaviour | The response of an organism to a stimulus. Can be innate or learned. |
biological clock | An internal timing system in organisms. |
biotic factors | Environmental factors which are the result of living things. |
camouflage | Concealment method in which an animal is coloured to match its environment. |
chemo- | Prefix for chemicals. |
chemotaxis | The movement of an animal towards or away from a chemical stimulus. |
chemotropims | Plant growth response towards or away from a chemical stimulus. |
circa- | Means ‘about / approximately’. ONLY used to describe rhythms occurring in constant environmental (free-running) conditions. |
circaannual | A rhythm of about one year occurring in constant environmental (free-running) conditions. |
circadian | A rhythm of about 24 hours occurring in constant environmental (free-running) conditions. |
circalunar | A rhythm of about one month occurring in constant environmental (free-running) conditions. |
circatidal | A rhythm of about 12.5 hours occurring in constant environmental (free-running) conditions. |
co-evolution | When two species with a strong ecological relationship influence each other’s evolution (the relationship acts as a strong selection pressure). |
commensalism | An interspecific relationship where one organism benefits, but the other is unaffected. |
competition | Occurs when organisms living in the same location require the same resource, for which demand exceeds supply. Can be interspecific or intraspecific. |
cooperative breeding | Cooperation between individuals for successful reproduction, which may include courtship, mating and parental care of offspring. |
cooperative interactions | When members of a species co-ordinate activities (e.g. food gathering, surveillance of predators) for their mutual benefit. |
courtship | A series of signals exchanged between male and female and ending in mating. |
crepuscular | Most active at dawn and dusk. |
critical day length | The photoperiod above which long-day plants flower, and below which short day plants will flower. NB: remember: later research discovered it’s actually the length of DARKNESS which is critical to the plant. |
cytokinin | A plant hormone. Various effects, including promoting cell division (and therefore growth). |
daily rhythm | Activity occurring every 24 hours (NB: zeitgeber(s) present!). |
day-neutral plant | A plant that flowers independently of the day length. |
diapause | A period of arrested development (especially in insects in cold climates). |
diurnal | Most active during the day. |
dormancy | A state of temporarily reduced metabolism. |
ectoparasite | A parasite which lives or feeds on the outside of its host. |
ecological niche | The role of the organism in its ecosystem. Includes its feeding role, activity pattern, habitat and adaptations. Each species has a unique niche. |
effector | Part of an organism where the response to the stimulus is carried out. |
endogenous rhythm | Controlled by an internal timing mechanism (biological clock). It continues in the absence of environmental cues. |
endoparasite | A parasite which lives on the inside of its host. |
entrainment | Process by which the internal clock is reset so that it is synchronised with an environmental rhythm. |
ethene / ethylene gas | A plant hormone which is produced and accumulates in aging fruit, promoting their ripening. |
exogenous rhythm | Controlled by an external cue or stimulus. |
exploitation | Interspecific relationship in which one species benefits while the other is harmed. Includes parasitism, herbivory and predation. |
fitness | This means evolutionary fitness and is a measure of an organism’s reproductive success. ‘Fitter’ organisms are more likely to survive, reproduce and pass on their favourable alleles. |
free running period | The length of an organism's activity period in the absence of external cues (zeitgebers). |
free-running | Occurring in the absence of environmental cues. |
Gause’s competitive exclusion principle | If two species have the same niche they cannot remain for long in the same habitat. One will be out-competed and eliminated (or at least reduced to a very small population.) |
germination | The process by which a plant grows from a seed. |
gibberellin | A plant hormone which promotes elongation of shoots. |
gravi- (or geo-) | Prefix for gravity. |
gravitropism | A plant growth response towards or away from the stimulus of gravity. |
habitat | The specific environment in which an organism lives. |
herbivory | A type of exploitation in which an animal eats plants (or their parts), benefiting the herbivore and (potentially) harming the plant. |
hibernation | A period of suspended activity / very low metabolic activity during winter, generally to survive a lack of food. |
hierarchy | When animals have a specific rank in the group. A linear hierarchy (or pecking order) has individuals ranked from highest (alpha individual) to lowest (omega individual). |
homing | The ability of an animal to return to its home site over unfamiliar territory. It occurs on a regular (e.g. daily) basis. |
hormone | Chemical messengers which control development and growth. Produced in one part of an organism and transported to another part where it takes effect. |
hydro- | Prefix for water. |
hydrotropism | A plant growth response towards or away from the stimulus of water. |
innate behaviour | A fixed response to a stimulus, controlled by genes. |
interspecific | Between two different species. |
intraspecific | Within one species. |
jet-lag | Condition caused when the endogenous circadian rhythm does not match external cues. Usually caused by travelling across time zones. |
kin selection | When an individual puts them self at risk to assist the survival of another individual to which they are related. This helps to ensure their alleles are passed on. |
kinesis | Non-directional movement response in animals in which the rate of activity is determined by the intensity of the stimulus. |
klinokinesis | Non-directional movement response in animals in which the rate of turning is determined by the intensity of the stimulus... faster in unfavourable conditions and slower in favourable conditions. |
learned behaviour | Behaviour which is modified by experience. |
limiting factor | Any variable factor of the environment that limits the activity of an organism or population. |
long-day plant | A plant that flowers when the day length exceeds the critical day length (i.e. requires a short night). |
magnetic compass | Ability of animals to use Earth’s magnetic field lines for orientation and navigation. |
meristem | Area at tips of shoots and roots where cells are dividing rapidly. |
migration | The mass movement, typically annually, of animals over a long distance between two habitats. One habitat is normally a breeding or feeding area. |
mimicry | The similarity in appearance of one species of animal to another unrelated species that provides a benefit (e.g. protection from predators). |
monogamy | Each male mates with only one female (and vice versa). |
mortality | The number or proportion of deaths in a population over time. |
Mullerian mimicry | Where several unpalatable (inedible) species resemble each other, providing protection from predators. |
mutualism | An interspecific relationship where both species benefit. |
navigation | Determining the position relative to other locations. |
nastic responses | A plant turgor response that is independent of the direction of the stimulus. Not a growth response. Rapid and reversible e.g. sensitive plant (Mimosa). |
niche differentiation | The process by which differences evolve in the niches of competing species, e.g.in resource use in time, space. This specialisation reduces interspecific competition. |
nocturnal | Most active at night. |
orientation | The ability of organisms to determine their location in relation to environmental stimuli. |
orthokinesis | Non-directional movement response in animals in which the speed of movement is determined by the intensity of the stimulus... faster in unfavourable conditions and slower in favourable conditions. |
pair bond | A long-lasting relationship between a particular male and female. |
parasitism | A form of exploitation in which one species (the parasite) feeds off another living species (the host). |
parasitoid | An organism which is parasitic at only one stage of its life cycle. |
parental care | Investment of resources by parents in the survival of offspring. |
period | The length of the activity cycle (how long it takes to repeat) of an organism. |
personal distance | The close-up distance around an animal that is never invaded except for mating or fighting. |
phase shift | A change in the starting time of a rhythm (but not its period). |
pheromone | Chemical used as a signal to other members of the same species. |
photo- | Prefix for light. |
photoperiod | The day length; this is the most reliable indicator of time of the year. |
photoperiodism | The control of seasonal activity by day length. |
phototaxis | Movement of an organisms towards or away from a light stimulus. |
phototropism | Plant growth response toward or away from a light stimulus. |
phytochrome | A plant pigment that controls the photoperiodic response (measures the length of darkness / light). |
plumule | The first shoot of a young plant. |
polygamy | A social system in which individuals mate with more than one member of the opposite sex during a breeding season. |
predation | A form of exploitation in which one species (the predator) kills and eats another species (the prey). |
r/K strategies | r-strategist: large number of offspring but little parental care; K-strategist: small number of offspring, but large investment in parental care of each. |
receptors | Part of an organism which is able to detect a change in the environment (stimulus). |
short-day plant | A plant that flowers when the day length is less than the critical day length (i.e. requires a long night). |
solar navigation | Using the position of the sun to navigate. NB: requires an internal clock to compensate for changing position of sun in sky. |
star compass | Ability of an animal to orientate and navigate using the pattern of stars. |
stellar navigation | Using the stars to navigate. |
stimulus | A change in the environment which causes a response in an organism. |
stratification | Two different biological meanings: where seeds are treated to simulate winter conditions so that germination may occur, OR a vertical pattern in the distribution of species - e.g. the layers of plants in a forest. |
submissive behaviour | When an individual indicates, by an act or posture, that it will not challenge a dominant individual in a social group. This behaviour is important in maintaining a dominance hierarchy. |
subordinate | Lower in rank e.g. in a linear hierarchy |
succession | A pattern in the distribution of species over time (e.g. in plants from bare rock to forest). |
sun compass | Ability of an animal to orientate and navigate using the sun’s position. NB: requires an internal clock to compensate for changing position of sun in sky. |
taxis | The movement of an organism towards or away from a directional stimulus. |
territoriality | When individuals or groups of a species have territories which they defend. |
territory | An area used by an animal for feeding or breeding, that the animal will defend against individuals of its own species. Territories do not overlap. |
thigmo- | Prefix for touch (physical contact). |
thigmonasty | A plant turgor response to the stimulus of touch (e.g. leaves close). |
thigmotropism | A plant growth response towards or away from the stimulus of touch (contact). |
tropism | A plant growth response to towards or away from a directional stimulus. |
vernalisation | Promotion of flowering by chilling (e.g. some bulbs such as tulips require this). |
zeitgeber | The external environmental cue used to ‘set’ the biological clock. In most species, this is the change from light to dark (or dark to light). |
zonation | A horizontal pattern in the distribution of species e.g. zones of plants of different types up a mountain or bands of particular species on the rocky shore. |
suprachiasmatic nuclei (SCN) | A tiny region within the hypothalamus of the brain, connected by nerves to the eyes. Responsible for controlling the circadian rhythm in animals. |