B19. Population in Ecosystems (A2) Flashcards
What are species?
Group of organisms that share the same genes and are capable of breeding to produce fertile offspring
What is a community?
Multiple populations of different species living and interacting in the same area
What is an ecosystem?
Interaction between a community, biotic and abiotic parts of the environment
What is a niche?
Traits that allow an organism to fit into an environment
What is a habitat?
Place where a species lives
What are the main process of an ecosystem?
Flow of energy through the system; Cycling of elements within a system
What are the types of adaptations?
Anatomical, structural features; Behavioural, defensive; Physiological, Processes in the body eg digesting cellulose.
What is the carrying capacity?
Maximum population size of a species that an ecosystem can support
What are some exmaples abiotic factors affecting population size?
Light availability; Water supply; Temperature; Amount of space available; Soil pH
What are some examples of abiotic factors affecting population size?
Light availability; Water supply; Temperature; Amount of space available; Soil pH
What is a biotic factor and what are the subcategories?
Interactions between organisms, living factors of an ecosystem; Interspecific competition; Intraspecific competition; Predation
Describe interspecific competitions.
Competition for same resources between individuals from different species;
Describe interspecific competitions and it’s effects.
Competition for same resources between individuals from different species; Limiting population or decrease in one, increase (outcompeting) in another species
Describe intraspecific competition and its effect.
Competition for the same resources between individuals from the same species; Resources become limiting and population cannot grow
Describe the process of predation.
Producers eaten by primary consumer, in turn eaten by secondary consumers in turn eaten by tertiary consumers;
What is a predator?
Consumers that kill and eat other animals
What is a prey?
Animals that are eaten by predators
How does predation affect an ecosystem?
Limits both population sizes of predators and prey; Predator increases as more prey; Prey decreases as more predators so predators decrease; Prey increases as fewer predators
What is sampling and what are the types?
Method of investigating the abundance and distribution of species and populations; Random and Systematic
Describe random sampling.
Positions of sampling points are completely random or due to chance; No bias; When area is uniform , no clear pattern
Describe systematic sampling.
Position of sampling points are chosen; Bias possibility;
What are the three main sampling methods for population sizes?
Quadrats, slow moving species; Transects, slow moving species; Mark-release-recapture, motile species
How do you use quadrats?
Square frames laid randomly in area to avoid sampling bias
How do you avoid sampling bias?
Convert the sampling area into grid format, labelling each square with a number; Random number generator to pick sample points
What is species frequency?
Probability species will be found within any quadrat sample area; No. of quadrats species found in / Total quadrats
When should you use belt transects?
Area where there are changes in physical conditions eg. abiotic factors, altitude, soil pH, light intensity
How do you use belt transects?
Place quadrats at regular intervals along tape and record abundance of each species within quadrat; produces quantitative data
How do you use quadrats?
Square frames used to mark areas being sampled; Can be different sized squares; Layed out randomly
How do you use Mark-release-capture?
Large sample taken; Individuals are counted and marked; Marked individuals are returned to their habitat; When sufficient time has passed another large sample is capture; Number of marked and unmarked individuals within sampled are counted
What is Mark-release-capture used to calculate and what is the forumla?
Estimate of population size; N = (n1 x n2) / m2
Population estimate = (No. of marked released x No. in second sample) / Number of marked in second sample
What are the assumptions made with the mark-release-capture sample?
Individuals are given sufficient time to disperse and mix back full with main population; Marking doesn’t affect survival rates; Marking remains visible throughout sampling and doesn’t rub off; Population stays same size during study
Describe succession of an ecosystem.
Change of an ecosystem from very simple to very complex; Biotic and abiotic conditions change over time; Ecosystems are dynamic
Describe primary succession.
Newly formed/exposed land w/ no species is gradually colonised by an increasing number of species
Detail the stages of primary succession.
Colonisation by pioneer species; Change in environment, caused by organism; Enables others species to colonise; Change in biodiversity; Stability increases, hostility decreases; Climax community formed
Define humus.
Dead organic matter
Define pioneer species.
First species to colonise an ecosystem
Define climax community.
Stable, final community that exists in a balanced equilibrium and that makes up the final stages of succession
Define conservation.
Protection and management of an ecosystem
Why is preventing an area from reaching climax community a good thing sometimes?
Ecosystems at intermediate stage of succession hold distinct diversity of plant species
What are the methods of preventing succession?
Grazing animals introduced temporarily, eat shrub, growing shoots, trees; Managed burning, controlled fires burn away shrubs and trees
Explain what limits population size in a climax community.
Nutrient availability; No. of producers providing energy; Light intensity for photosynthesis; Pathogens and disease; Niches; Competition for resources; Intraspecific and interspecific competition; Predation