Conditions and Resources: Major Determinants of Ecology

ESC 556 week 3

Definition: An abiotic environmental variable, which fluctuates in space and time, and to which organisms vary in their response

Temperature, moisture, pH, salinity Not the source of competition Niche concept (Hutchinson 1957)

Multidimensional (conditions and resources) space that can support a viable population

Spatial, functional, behavioural An organism’s adaptations, resources,

lifestyle Examples

Primary production Bioturbation

Fundamental vs. realized niches Overlap of niches

Temperature Moisture pH Salinity Soil structure Pollutants

Variation Latitudinal Seasonal Altitudinal

Continentality Microclimatic variation Depth variation

Terrestrial organisms Sea - Land Movement problem Relative humidity Temperature Plants

Roots Condition + resource

Adaptations Either live in humid environments

Soil and water 3 – 9 Indirect effects

Nutrient availability Toxin concentrations

Aquatic animals Osmoregulation Toxic ion concentration Food resources

Isotonic Hypotonic

Pumps Halophytes

Tolarate high salinity Vacuoles

Euryhalines Tolorate salinity fluctuations Osmoconformers Osmoregulators

Stenohaline Not tolerant of fluctuations

Volcanic activity Industrial activity OH + SO2 + O2 H2SO4 OH + NO2 + O2 HNO3 pH = 3 In many freshwater systems pH = 6 – 8

Direct mortality Reproduction Leaching – 1200 lakes in Canada devoid of life

Trees Canopy damage & Forest decline

Air Ventilation of an organism Aeration of a microhabitat Desiccating agent

Water Not desiccating Wave action Currents Movement of materials

Physical and chemical nature Rocky vs. particulate substrate Attachment strategies

Particulate – Anoxic Terrestrial soil

Affect plants + affected by plants

Strong attachment Holdfasts, byssus threads (mussels),

suction cups (limpets, chitons, fish) Physically resistant body structure Behavioral adaptations

Cracks + gregariousness

Lotic environments Micro-organisms

Wet rocks & epilithic film Flattened body profile Behavioural

Rheotactic Phototactic

Contaminants vs. Pollutants Pollution ecology Essential vs. Non-essential substances

Materials Space Competition Solar radiation Nutrients Organisms as food Essential vs. Substitutable Complementary vs. Antagonistic

The total yield or biomass of any organism will be determined by the nutrient present in the lowest (minimum) concentration in relation to the requirements of that organism

If not used, lost Change w/ latitude Resource continuum – different

wavelengths 400-700 nm - PAR

Euphotic zone

Seasonal vs. random variations Sun species vs. shade species Water

Restrict photosynthesis vs. suffer desiccation

C3 – phosphoglycerate – 3 carbon molecule

C4 – 4 carbon molecule CAM – crassulacean acid metabolism) –

4 C

Photosynthesis Water CO2

O2

Consumed Metabolism Plants – root systems Animals – drink

Kangaroo rats – metabolic water Influence distribution and abundance

Animals & Plants Limiting factor in aquatic systems Solubility

Terrestrial organisms

Vital for photosynthesis 0.033 % of air Terrestrial autotrophs & Aquatic

photsynthetic organisms Not a limiting factor

Animals – food Plants – soil/water

Lack of water lack of minerals Macronutrients

N, P, S (primary nutrients) K, Ca, Mg, Fe (secondary nutrients)

Trace elements Specialists

All heterotrophs Decomposers Parasites Predators

Grazers Generalists vs. specialists Seasonal Digestibility

Gizzard Ruminant mammals

Bird beaks Finches & European Shore birds

Physical defenses Chemical defense

Cyanides, acids, toxic substances Morphological defenses

Crypsis Aposematism Batesian mimicry

Behavioural defenses Nocturnality Living in holes or burrows Distraction Threatening methods

Plants Animals – territories Other resources Physical packing Breeding / hibernation Nesting