Populations Flashcards
Habitat vs. Niche
Habitat - an area where an organism lives
Niche - exact role an organism plays in its habitat, including all the abiotic and biotic conditions required for the organism to survive and reproduce
Fundamental niche
- aka -> potential niche
- where it is possible for an organism to survive
- determined by abiotic factors
Realised niche
- aka -> actual niche
- where an organism actually survives
- reduces volume than the fundamental niche due to competition
- determined by abiotic and biotic factors
Competitive exclusion principle
- no two organism of different species can occupy the same niche indefinitely
- complété competitors cannot exist
- results in niche separation, to avoid competitive advantages
MRR
- allocate an area with a defined boundary
- capture a group of individuals and tag with a non-invasive, non-toxic market that would not result in any disadvantage to the organism
- reintroduce into population and allow enough time for even distribution
- capture another sample and count the number of tagged organisms
- déterminé population using Lincoln-Peterson Index
Lincoln-Peterson index
- multiply samples 1 and 2
- divide by the number of tagged individuals recaptured
- population estimate
Abiotic limiting factors on population
- temperature
- pH
- light
- humidity
- wind speed
- tidal range
- wave/water speed
- viral infection
Biotic limiting factors on population
- intraspecific competition
- interspecific competition
- predation
- bacterial disease
Sampling
- representation (proved accurate by statistical testing)
* affected by change (REPEAT) and bias (RANDOM)
Use systematic sampling for
Gradual change in conditions
Picking a quadrat
- species size
- evenness of distribution
- rarity of species
How does temperature affect carrying capacity?
- optimum for enzymes
- réduction in plant metabolic rate
- dénaturation
- higher homeostatic energy expenses; less energy for growth, maturation and reproduction
How does light affect carrying capacity?
- ultimate energy source for most ecosystems; basic necessity of life
- rate of photosynthesis increases with light intensity
- rate of growth and spore production increases with rate of photosynthesis
- increases plant and plant-eating carrying capacities
How does pH affect carrying capacity?
• any deviation from optimum means carrying capacity is tiny
How does water affect carrying capacity?
- lack of aquatic creatures
* only organisms adapted to dry conditions can survive
How does humidity affect carrying capacity?
• transpiration and evaporation affected
When abiotic conditions shift from optimum
Population sizes decrease- species without suitable adaptations become extinct (barring evolution through advantageous alleles)
Human population
• affected by natality, mortality, immigration and emigration
Population pyramids
- a series of stacked bars representing percentages of males and female in each age group
- useful because population growth depends on females of child-bearing age
- product future trends for populations
- show demographic transitions
Increasing populations
- base of population pyramid is higher than the apex
* typical of less economically developed countries
Competition
Arises from insufficient resources to fully satisfy the requirements of two individuals sharing
Availability of resources
Determines population size
Predation
- interspecific relationship
* consumption of one consumer with another
Predator
- a consumer that feeds on another (prey)
* evolved speed and camouflage
Prey
- a consumer consumed by another
* evolves canouflage, protective features and concealment behaviour
Predators and prey….
Evolve alongside each other, otherwise extinction would occur, which is rare
Prey escape due to
- greater area for travel
- potential refugee
- not being the only predated species
Describe the predator-prey graph
- predators consume prey, reducing their population
- greater intraspecitic competition between predators
- predators population decreases due to inability to survive and reproduce
- there are cyclic fluctuations in populations
- periodic population crashes influence evolution by creating selective pressures
Succession
Changes experiences by dynamic ecosystems due to population fluctuations
Succession stages
- colonisation of différent species, changing the abiotic conditions
- results in out-competition due to adaptations
- forms new community, altering biodiversity
Pioneer species
- colonise an inhospitable environment
- forma pioneer community
- use photosynthesis
- have wind-dispersed seeds or spores that undergo rapid germination without dormancy
- fix nitrogen
- xérophytic
Climax community
- many species flourish - relatively high biodiversity
* stable over long periods
Ramifications of stages of succession
- decrease is hostility of abiotic conditions
- proliferation of habitat and niche number
- increases biodiversity (decreases slightly with climax community with out competition of pioneer species)
- more complex food we’ve
- higher biomass
Secondary succession
- disruption of climax community by abiotic factors
- succession stages begin again
- faster due to established hospitality
