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The Environment

The Environment. Abiotic factors – the physical factors in the environment that can act as the stimuli for the organisms’ responses. Prefixes: Light (photo-) - intensity, colour, direction, duration Gravity (geo- , gravi- in some texts) - up, down, orientation in space. The Environment.

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The Environment

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  1. The Environment • Abiotic factors – the physical factors in the environment that can act as the stimuli for the organisms’ responses. • Prefixes: • Light (photo-) - intensity, colour, direction, duration • Gravity (geo-, gravi- in some texts) - up, down, orientation in space

  2. The Environment • Temperature (thermo-) - average and range • Water (hydro-) - humidity, salinity, depth, average rainfall, turbidity, speed of current • Current (rheo-) - align with current

  3. Chemical (chemo-) - CO2, O2, salinity, pH, pheromones, toxins, inorganic nutrients, Macro/micronutrients • Touch (thigmo-) - response to solid objects • Sound – pitch, loudness, range • Pressure – ocean depths, atmosphere, weather pattern formation

  4. Wind – velocity, gustiness, direction • Substrate – composition • Fire - recycling nutrients, seed germination

  5. Adaptations • Adaptations are features that help an organism to make the most of the opportunities provided by the environment. • Organisms with adaptations more suited to the environment are more likely, through the process of natural selection, to pass on their genes to the next generation.

  6. -Structural – morphological, e.g. colour, appendages -Physiological – biochemical/metabolic e.g. hormones -Behavioural – responses to the environment e.g. diurnal, aggression, courtship -Life History – reproductive strategies for survival

  7. Tolerance • Narrow range of physical factors that makes up the optimal range of tolerance for most organisms. If a factor is to extreme in either direction the organism suffers from physiological stress. • If a factor becomes too extreme (too high/too low) the environmental condition leads to death.

  8. Many animal and plant behaviours are to ensure the organism maintains an optimal condition for survival and ultimately reproduction • Animals must detect and be able to respond to key physical factor changes in their environment

  9. Biotic Factors – all relationships between members of the same species (intraspecific) and with members of other species (interspecific) Intraspecific relationships: Competition – for same resources; food, space, light, water, nesting sites, territory, nutrients etc

  10. Reproduction – availability of mates, competition between males, courtship, pair-bond formation, parental care Aggressive interactions - territories, hierarchies Co-operative interactions – group formation for defence (prevent predation/grazing), aid survival (hunt in packs)

  11. Biotic Factors – • Interspecific relationships: • Competition – for same resources; food, space, light, water, nesting sites, territory, nutrients etc • Predator / prey relationships • Plant / Animal – grazers, browsers • Succession – replacement of one species by another over time, each species modifying the environment to allow the new species to be established

  12. Stratification – vertical relationships in space with other organisms • Zonation – bands of organisms that form in relation to a gradient in a major environmental factor • Animal / Animal • Plant / Plant

  13. Symbiosis – variety of interactions involving close species contact. • Involves a host and a symbiot. • Mutualism (cooperation) - both species benefit • Commensalism - one species benefits, the other is unaffected

  14. Parasitism (exploitation) - one species benefits, the other is harmed • Competition - neither species benefits • Neutralism - both species are unaffected • Note: endoparasites – live in the host • ectoparasites – live on the host

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