E2 Flashcards
What do we need to know in order to understand the distribution and abundance of a species?
History, environmental conditions, resources required, life histories and population dynamics, interactions with their own and other species.
What is the definition of conditions and what are some examples?
Abiotic environmental factors, influence the functioning of an organism, e.g. temp, pH, salinity, humidity. May be modified by a presence of another organism. Not consumed or used up.
What are optimum conditions? How are they measured?
Those under which most offspring are produced. Measure effect on key properties e.g. enzyme activity, respiration rate, growth / reproductive rate. Organisms can survive over a range of conditions. Any condition that exceeds the limit of tolerance is a limiting factor, when a species is limited in distribution it is said to be restricted according to environmental tolerances.
What are the three types of response curves?
A) extremes are lethal, only optimal conditions allow reproduction
B) conditions only lethal at high intensities
C) condition required as a resource at low concentrations
What are temperature extremes?
Midday sun in desert, cold Antarctic winter
What factors can temperature effect?
Metabolism, growth, development, size.
Why is temperature important?
To understand the role of temperature in seasonal, annual and geographical variations in productivity in ecosystems. Appreciate the knock on consequences e.g. what is this effect of changing organismal size on their role within ecological communities due to temperature.
What are endotherms?
Regulate temp by production of heat within their own bodies?
What are ectotherms?
Rely on external heat sources
What is life like at low temps?
70% of plant is ocean, 10% of planet is polar ice caps. Two types of injury in cold. Chilling - >0 damages membranes permeability, freezing - <0 affects osmoregulation. Freeze-avoidance and freeze-tolerance. Acclimitisation is natural adaptation to temperature changes.
What is life like at high temps?
High air temp, fire - lightning strikes. Thermal vents - hot fluids rich in minerals expelled from sea bed. Hot springs - geothermally heated ground water
How does temp act as a stimulus?
Temp and arctic alpine plants - period of freezing stimulates germination. Interacts with photoperiod and therefore onset of growth. Egg laying stimulated by temperature and day length. Temperature stimulates breeding in many animal species.
What does temp correlate with?
Plant and animal distribution.
What are temperature interactions?
Humidity which has important consequences for evaporation, humidity can reach 100% under dense leaf canopies. Disease can be caused.
What impact does pH of soil and water have?
pH can exert a powerful influence on abundance and distribution of organisms. Roots damaged by toxic conc of H+ pH < 3 or OH- pH < 9. Indirect effects occur, soil pH influences nutrient availability and toxin conc. acidic soil high Al3+, Mn2+, Fe3+. Alkaline soil - PO43-, Mn2+, Fe3+.
How does soil pH influence plant species?
Chalk/limestone grassland have a higher diversity of flora than acid grassland. Similar for plants and animals inhabiting ponds, streams and lakes.
What pH conditions do prokaryotes tolerate?
Extremes of both, they live in geothermal springs, volcanic lakes. Sulphur oxidising bacteria. Optimum pH of 2-4. Soda lakes, Cyanobacteria. Optimal pH 9-11.
What effect does salinity have?
Salt conc in soils offers osmotic resistance to water uptake by plants. Halophytes are adapted to saline conditions (maintain osmolytes in vacuoles). In marine habitats organism are usually isotonic. Osmoregulation - maintenance of homeostasis, an energetic process.
What conditions are physical forces?
Wind and water. Streams and rivers - water shallow and turbulent upstream, fast-flowing downstream. Sea - currents and waves. Organisms have physical adaptations to cope.
What impact does climate change have?
CO2, most important greenhouse gas, has risen <300 to >400 ppm since the Industrial Revolution. Driving planetary warming rates >100% faster than natural post glacial warming. Many species cannot respond. Distribution shifts and widespread extinctions of flora and fauna are predicted. Fragmented and developed landscapes are barriers to range shifts.
What are resources?
All things consumed by an organism, consumed does not necessarily mean eaten. Resources are entities required by an organism that may be reduced by the activity of other organisms.
What are photosynthetic autotrophs and chemosynthetic autotrophs?
PA - Green plants and algae
CA - bacteria and archaea.
All other organisms use the bodies of other organisms as food sources
In each case the consumed resource is no longer available to another consumer.
The consequence is competition.
How are resources other dimensions of the ecological niche?
Green plants assemble inorganic resources into organic compounds - photosynthesis. CO2, H20, sunlight, and mineral nutrients converted into biomass. Consumers reassemble these packages at each successive stage in a web of consumer-resource interactions.
What is solar energy as a resource?
Must penetrate the atmosphere, absorption, reflection and scattering by water vapour, water surfaces, clouds, atmospheric particles. Varies with circumstance (latitude, season, time of day).
What is solar radiation as a resource?
Only source of energy green plants and algae use. A resource continuum of different wavelengths. PAR 400-700. Radiation intensity and quality varies continuously. Shade effects decreases resource. Woodland canopy, light attenuation by phytoplankton.
What is CO2 as a resource?
Used in photosynthesis obtained from the atmosphere. Availability to plants and algae varies according to position in habitat. C3, C4, CAM photosynthetic pathways.
What is water as a resource?
Critical resource, hydration is necessary for metabolic needs, must be replenished, plants and the transpiration stream. Terrestrial animals drink water or generate it from metabolism of food and body materials.
What is mineral nutrients as a resource?
Macronutrients - N, P, S, K, Ca, Mg, Fe
Trace elements - Mn, Zn, Cu, B, Mo
Plants obtain nutrients in inorganic forms from soil or water
Some groups have special requirements ; diatoms
Animals obtain nutrients as organic forms in their food
What is oxygen as a resource?
Diffusion and solubility of O2 is low in water
Limiting in aquatic and waterlogged environments.
Aquatic plants modify their roots and shoots
Aquatic animals either - maintain a constant flow over respiratory surfaces, have LSA:V ratio, specialised respiratory surfaces, low respiration rate
What are organisms as a resource - autotrophs?
Autotrophs - assimilate inorganic resources into organic packages consumed by heterotrophs
What are generalists and specialists?
Generalists are polyphagous - they take a wide variety of prey species. Specialists are monophagous or polyphagous - specialising on certain parts of prey. Resource use patterns reflect consumer lifespan. Must match food demands to prey timetable. Evolution of specialised structures.
What organisms as a resource - plants and animals?
Provide different nutritional contents, consequence on consumer, plant cells rich in cellulose, lignin. C:N plants 40:1. Animals and fungi 10:1. Diff parts have differing compositions - a variety of resources.
What organisms as a resource - defences to predators?
Physical and chemical defences. Behavioural and morphological defences. Animals have more options than plants.
What is the ecological niche?
Framework within each condition should be understood. A niche is not a place it is an idea. A summary of an organism tolerances and requirements. Niche describes how, rather than just where an organism lives.
What did Hutchinson say an ecological niche was?
A multi-dimensional hypervolume of resource axes. Temp is one dimension, relative humidity, pH, wind speed, flow rate, salinity. In 2 dimension of food size and behaviour, 3 dimensions of food size, temperature and humidity. In reality many more factors define an organisms niche. We call this the n dimensional hypervolume.
What is the fundamental niche?
Where an organism could live in abscence of competitors and predators.
What is the ecological niche?
Where an organism actually lives, when competitors reduce resources available
What are the dimensions of the niche?
Includes both conditions and resources, conditions considered as continuous variables. Some resource dimension can be plotted like condition dimensions : upper and lower limits. Predators can only handle a certain prey size. But many resources are discrete entities not continuous variables. Certain species can only use limited resources. Therefore have to consider as a discrete factor.
