Ugrás a tartalomhoz Lépj a menübe
 


02 A populációk és az életközösségek

2014.09.19

 

Ecology
 
Ecology: study of the relation of living organisms to each other and their surroundings
Population: all the organisms that both belong to the same species and live in the same geographical area
Features of a population:
          Distribution: in space, in time Mp 42/1, Mp 43/1
Population dynamics: studies short- and long-term changes in the size and age composition of populations
Features of population dynamics:
Reproductivity
Age
Fertility
Migration
Mortality
Population growth
          Exponential growth
          Carrying capacity: stops growing
Reproductive strategies
R-strategy: quick reproduction, short living period, fast population growing (e. g. vole)
K-strategy: low reproduction, long living period, constant population (e. g. eagle)
 
ENVIRONMENTAL FACTORS
Environment: all factors affecting an organism
          Abiotic factors: light, temperature, air, water, soil
          Biotic factors: other livings affecting an organism
Tolerance
Representation in a graph: normal distribution (minimum, optimum, maximum)
          Generalist species: is able to thrive in a wide variety of environmental conditions (whale, mouse)
          Specialist species: can only thrive in a narrow range of environmental conditions (coral, lichen)
Abiotic environmental factors
Light
          Can be direct, indirect
          Wave length is important (visibility, colours)
          Angle of incidence affects the temperature (tropical, arctic places)
          Intensity
          Mp: 48.1, 48.2
Temperature
          It depends on sunlight, earth surface, features of atmosphere
          Green house effect: Light is transformed to infrared radiation on the ground – greenhouse gases (CO2, methane, water vapour) trap the infrared rays – temperature of the atmosphere increases. Human effects: industry, traffic, livestock-breeding increase the green house gas concentration
          Tolerance: wide (lichens, whales), tight (corals, penguins)
          Adapdation: fox ears are larger in hot climate, penguin body height is larger in cold conditions
Air
          78% N2, 21% O2, 0,9% Ar, 0,03% CO2
          CO2: photosynthesis, greenhouse effect
          SO2: acid rain (indicators: lichens)
          Wind: evaporation, pollination, tree deformation, flying
Water
          Necessary: life processes, moving
          Changing water content: lichens, algae, mosses
          Stable water content: ferns, Gymnospermae, Angiospermae
Water loss dangerous:
          Vertebrates can lose 15-20%
          Invertebrates can lose  60%
Soil
          The upper fertile layer of the Earth
          Formation: physical, chemical and biological processes
          Structure: soil colloid grains – large surface – adsorption of water, ions
          Chemical properties: pH, content of alimentary substances
          Physical properties: structure – grain size – temperature – air and water content
Biotic factors
Interactions between individuals:
          Sleeping
          Protecting
          Migration
          Reproduction
          Territorial interactions
Interaction between populations (different species)
Can be advantageous (+), neutral (0), disadvantageous (-)
++
          mutualism (ants – aphids)
          synbiosis (feeding situation) (lichen = alga + fungi)
          mikorrhiza = tree + mushroom on the root
+-
          predator-prey relationship: kills and eats
        herbivores, omnivores, carnivores (predators, insectivores) (lion – gazelle, cow - grass)
           parasitism: does not kill the host (tick – deer)
+0
          Commensalism: lichen on the tree trunk
--
          Competition: trees in a forest
0-
          Amensalism
          Antibiosis: mould – bacteria (Flemming)
 00
          Neutralism
 
ASSOCIATIONS = communities
Association (biocoenosis, társulás): populations of different species at the same habitat (biotope)
Features:
          List of species (fajösszetétel)
          Biodiversity: „biológiai sokféleség”
GAIA theory (Lovelock- Margulis): Earth is a self-regulating system
ENERGY TRANSFER, MINERAL CYCLING
Trophic levels:
Producers: autotrophs
Consumers: heterotrophs
          Primary consumers: herbivores
          Secondary consumers: eat primary consumers
Decomposers: bacteria, fungi
Food chain, food web
Food chain: feeding hierarchy (linear)
          Rose – aphids – ladybird larvae – blue tit – hawk
          Types: herbivoric, parasitic, saprotrophic (65/2)
Food web: web of food-chains in an ecosystem (p. 65/1)
One-way energy transfer
Pyramid of numbers
Usually size increases, number decreases on the next trophic level
Mineral nutrient cycling
Nutrients are recycled
„During the course of our lives, each of us breathes out six carbon atoms that were once part of Napoleon Bonaparte”
          Carbon cycle
          Water cycle
          Nitrogen cycle
          Phosphor cycle
Dangers
          Bio-amplification (e. g. DDT)
          Eutrophication: nitrate and phosphate level increases – phytoplancton proliferates – water is not transparent, light is not enough in the deep – no photosynthesis, no oxygen - organisms die
Features of the communities
Zoocoenosis (animals) – phytocoenosis (plants)
Structure
Pattern: horizontal arrangement
Levels: vertical arrangement
          Canopy, understory, undergrowth, forest floor („grass” level, „moss” level)
Development of communities
Within a year: aspect (spring, summer, autumn,winter)
Within a long term (more years): succession
          Pioneer community: starts the succession
          Climax community: finishes the succession, stable (e.g. forests)
          Community: self-regulating system
          Predator-prey relationship: they control each other (74.1)
          Outer effects – answers against these effects
          Changing of biodiversity: harmful effects (pollution, invasion): biodiversity decreases – community is more endangered – WHIRLPOOL!
Types of communities
Natural communities
          Self-regulation
          High biodiversity
          No human effect
          Reserve of the genes
          Rare
          E. g. tropical rain forests, sea communities
Semi-natural communities
          Self-regulation is not perfect, but has priority
          Biodiversity is lower
          Human effects: have not priority
          To survive human intervention is needed
          E. g. grasslands, forests, marshlands
Artificial communities
          Is created by human
          No self-regulation
          Can not exist without human intervention
          E. g. agricultural areas
 
BIOMES
Biomes: units of communities located by climatic zones
Tropical zone
          Tropical rain forest
          Savannah
          Tropical desert
Temperate climate zone
          Temperate deciduous forests
          Temperate grasslands
          Coniferous forests (taiga)
Arctic zone
          Tundra
          Ice areas
Biomes not fixed in zones:
          Mountains
          Sea