Cette leçon contient 11 diapositives, avec quiz interactifs et diapositives de texte.
La durée de la leçon est: 30 min
Éléments de cette leçon
Populations
Slide 1 - Diapositive
What is a population?
Slide 2 - Question ouverte
With reference to the following statements about a woodland ecosystem. Which statement describes a population?
A
All the oak trees
B
All the plants
C
All the plants and animals
Slide 3 - Quiz
Population size
immigration
emigration
death
birth
Slide 4 - Question de remorquage
Population growth
Involves:
Biotic potential: max reproduction rate given all the resources the population needs
Environmental resistance: all factors that may limit growth. (scarcity of resources, predation, climate conditions etc)
Carrying capacity: max population size that can be supported by a particular environment
Slide 5 - Diapositive
Population curves
J-curve: often seen in fast reproducing organisms that colonise a new environment. Exponential growth followed by hitting a limiting factor and often the population crashes
S-curve: Exponential growth until population hits environmental resistance and stabilises around the carrying capacity
Slide 6 - Diapositive
Carrying capacity
Environmental resistance
Few reproducing individuals
Exponential growth
Slide 7 - Question de remorquage
What is population density?
Slide 8 - Question ouverte
Environmental resistance
Can be:
Density indepent: these factors influence all organism in a population irrespective of population density. Can be biotic of abiotic
Density dependent: the influence of these factors on population size depend on the density of the population. Usually the higher the density the bigger the impact of these factors. Always biotic