Animal and Plant responses to the Abiotic and Biotic Environment

Actogram

Graphical representation of an organism’s activity over 24 hour cycles

Auxin

Plant growth hormone which is important to plant growth and development. May promote or inhibit cell elongation.

Biological clock

Cells or groups of cells that are able to measure time. Partially driven by internal factors, including genes and the proteins they produce. Also, affected by signals from the environment

Where are humans biological clock

SCN in hypothalamus

Chemotaxis

The directional movement of an animal in response to chemicals in the environment

Circa

Rythym of about . . .

Circadian rythym

Behaviour in an organism which is approximately 24 hours - a solar day

Circalunar rhythm

Behaviour in an organism which is about 29 ½ days - approx the cycle of a lunar month

Circannual

Behaviour in an organism which is about 365 ¼ days, approx the length of a year

Circatidal rhythm

Behaviour in an organism which is about 12 ½ hours, appox the the tidal cycle

Community

All plants and animals living in a defined area

Competition

The interaction between two or more organisms, populations, or species that share some environmental resource when this is in short supply.

Adaptive advantage of having activity controlled by environmental cues which entrain an internal clock

• Allows organisms to predict or anticipate the onset of favourable environmental conditions

• Allows animals to prepare for activities that allow an organism to avoid unfavourable conditions and take maximum advantage of favourable conditions

Crepuscular animals

Animals that are most active at dawn and dusk

Day neutral plants

A plant in which flowering can occur irrespective of the day length

Dominance

Behaviour shown by an individual that is higher in hierarchy than the individual it is relating with

Endogenous

Rhythm controlled by an internal biological clock due to their DNA

Entrainment

The resetting of the biological clock on a regular basis, forcing it to take up the period of the environmental cycle

Environmental cues

A change in the external environment that triggers a change in behaviour or physiology

Exploitation

An interaction between species in which one benefits by using the other as a source of food or shelter

Free running period

The period of a biological rhythm in the absence of external environmental cues

Geotaxis

The directional movement of an animal in response to gravity

Geotropism

The directional growth of plant organs in response to gravity

Herbivorism

Form of exploitation where one animal eats a plant

Home range

A wide area of occupation that is not defended, but is used as a food source or to find a mate. Larger than the territory

Homing

The ability of an organism to find its way back to a specific area

Indoleacetic acid

A naturally occurring auxin, synthesised in the shoot tips and responsible for plant elongation in the plant stem

Innate behaviour

Behaviour which is controlled by our biological clock/DNA

Interspecific relationships

Interactions between different species

Intraspecific relationships

Interactions between members of the same species

Kinesis

The non-directional movement of an organism in response to a stimulus in which rate of movement depends on the intensity of the stimulus

k-strategy

A reproductive strategy where the parents produce a few young and give them lots of parental care. Most young survive

Learned behaviour

Behaviour not controlled by our biological clock/DNA

Long day plants

A plant in which flowering can be induced or enhanced by long days )short nights), usually with more than 12 hours of daylight

Migration

The seasonal mass movement of organisms from one area to another, often involving a return trip.

Mutualism

A relationship where two species benefit from the relationship

Nastic movements

Non-directional movements of plant in response to external stimuli

Navigation

Methods organisms use to find their way

• Solar

• Stellar

• Magnetic

• Landmarks, smells and sounds

Negative tropism

A plant growth response away from a stimulus

Nocturnal animal

Animals that are active at night

Parasitism

A form of exploitation where one species lives on another to obtain food

Period of activity

Time from the start of activity until start of activity again

Phase shift

When light/ dark is altered, the phase shift is the amount by which the period alters

Photoperiodism

biological response to a change in the proportions of light and dark in the 24 hour cycle

Phytochrome

A pigment which exists in two forms - Pr and Pfr
During the day Pr turns to Pfr and at night Pfr turns to Pr

Pineal Gland

Gland in the brain which acts as our timekeeper

Predation

A form of exploitation where one animal (predator) hunts another animal (prey) for food.

r-strategy

A reproductive strategy where parents use their energu to produce lots of offspring but give no parental care to the young.

SCN

Suprachiasmatic Nucleus: cells in the brain which keep track of day and night length

Short day plants

A plant in which flowering can be induced or enhanced by short days/long nights

Taxes

Directional movements of animals towards or away in response to an external stimulus

Territory

An area that an animal defends against others of the same species which contains their resources

Thigmotropism

The growth of a plant in response to physical contact

Tropsims

Directional plant growth towards or away from an external stimulus

Zeitgeber

The environment agent that resets the biological clock

External cues

• Shortening day length and drop in temperature

• Increase or decreased rain/precipitation

• Lack of food/water

Internal Cues

• Maturing of sex organs and a genetic drive/circadian clock

• Fat reserves

Solar navigation

As sun moves across the sky, animals use its position to navigate.
Over long journeys, animals must compensate for the movement of the Sun by using a biological clock or other navigation mechanism

Stellar navigation

Animals travelling at night may orientate to a particular constellation or to a celestial pole
Constellations move across the sky with time so animals require an internal clock
Celestial poles do not move so no clock is required

Earth’s magnetic field

• The angle of Earth’s magnetic field varies with latitude, so some animals may use this for navigation

• Strength of the field and local anomalies may help animals build a mental map of their territory

Landmarks smells and sounds

• Animals may finetune their location using landmarks smells and sounds when close to home

• Some animals leave pheromone trails to follow when they return

• Some animals may use echo-location (based on sounds)

Pheromone

Chemical produced by an animal and released into the external environment where it has an effect on the physiology or behaviour of members of the same species.

Orthokinesis

Speed of movement is related to the intensity of the stimuli

Klinokinesis

The amount of random turning/changing of direction is related to the intensity of the stimuli

Agonistic Behaviour

• Confrontation takes the form of a ritualised display which is recognisable to both parties. It signifies strength, pwoer, ability to win the fight. This lessens the need for an actual fight as one animal (weaker of the two) will usually submit)

lek

where males (usually) come together and perform mating displays, often

competitively, to attract female mates for the purpose of breeding

Gauses Law

Two species with the exact same ecological niche will not co-

exist indefinitely