6.3.2- Populations and Sustainability Flashcards
what is the expected population size at the end of the century?
11.2 billion
what is carrying capacity?
the maximum population size that can be maintained over a period of time in a habitat
what is a limiting factor?
the factor that limits the rate of population growth because it is the factor that is in the shortest supply
what are the two limiting factors and give examples of them?
-abiotic factors= temp, light, pH, water/oxygen availability, humidity
-biotic factors= competition, predators, disease
what does the lag phase of the typical population growth curve show?
-slow growth
-individuals acclimatising to their habitat
-low reproductive rate
what does the log/expodential phase of the typical population growth curve show?
-rapid growth
-plenty of resources and good conditions
-fast reproductive rate
-low mortality rate
what does the stationary phase of the typical population growth curve show?
-zero population growth, stable state
-population size levels out at the carrying capacity
-further growth prevented by limiting factor
-reproductive rate=mortality rate
what other 3 factors effect the population size and what do these mean?
-immigration= movement of individuals into a particular organism
-emigration= movement of individual organisms away from a particular area
-density independent factors= factors that have an effect on the whole population size regardless of its size (eg- volcano eruptions, earthquakes)
what is the equation for population growth?
pop change during period/pop at start of period x 100
what are the two types of competition and what do these mean?
-interspecific= between individuals of different species
-intraspecific= between individuals of the same species
what is a niche?
the role of a species within it’s habitat, consisting of both it’s biotic interactions
what is an example of interspecific competition in the UK and why did this occur?
red vs grey squirrel
-grey squirrel introduced in UK
-can eat a more variety of food and so can store more fat
-increases survival and its ability to reproduce
is the relationship between predator and prey interlinked?
yes
what does the graph that shows predator-prey relationships look like?
peaks and troughs of the prey population are mirrored by peaks and trough of the predator population, after a time delay.
how many stages of the predator-prey relationship are there?
4
what happens in stage one of the predator-prey relationship graph?
increase in prey population provides more prey for predators, allowing more to survive and reproduce, and so predator population increases
what happens in stage two of the predator-prey relationship graph?
the increased predator population eats more prey organisms, causing a decline in the prey population, and so the predator population increases
what happens in stage three of the predator-prey relationship graph?
the reduced prey population can no longer support the large predator population, and so intraspecific competition for food increases, resulting in a decrease in the size of the predator population
what happens in stage four of the predator-prey relationship graph?
reduced predator numbers results in less of the prey population being killed, so more prey organisms survive and reproduce, increasing the prey population
what is conservation?
the maintenance of biodiversity through human action or management.
what is sustainable development?
the management of ecosystems so that the natural resources within them can be used without running out
what is reclamation?
the process of restoring ecosystems that have been damaged or destroyed
what is preservation?
the protection of an area by restricting or banning human interference, so that the ecosystem is left in its original state
what are the three important reasons for conservation?
-economic reasons
-social reasons
-ethical reasons
