Chapter 24 : Populations & sustainability Flashcards
What is carrying capacity ?
Maximum population size of a species that can be sustained by an ecosystem
What determines the carrying capacity of an ecosystem
limiting factors which can be grouped into
abiotic: light, temperature, ph, availability of water and oxygen
biotic: predators, disease and competition
What does the population growth curve look like ?
phase 1: small numbers of organisms present and reproduce
birth rate > death rate increasing total population
phase 2 : rapid growth occurs population multiplies exponentially before resources are exhausted
phase 3: further growth is prevented by external constraints birth rate = death rate leading to fluctuations in population
What do predator- prey relationships look like ?
stage 1 : an increase in the prey population provides more food for the predators allowing more to survive leading to an increase in predator population
stage 2: the increased predator population eats more prey leading to a decline in the prey population. in the prey population death rate > birth rate
stage 3: reduced prey population can no longer support large predator population, intraspecific competition for food increases ,decrease in size of predator population
stage 4 : reduced predator numbers lead to less prey population being killed, more prey organisms survive and reproduce increasing prey population. cycle begins again.
why do some predator prey relationships not lead to either species becoming extinct
due to adaptations undergone by either species e.g. physical adaptations in order to evade capture in prey
what is the difference between interspecific competition and intraspecific competition ?
interspecific competition is competition for the same resource that arises between two species
intraspecific competition is competition for the same resource that arises amongst a species
what does intraspecific competition look like ?
Stage 1: when the resource is plentiful in a habitat e.g. food and space all organisms have enough of the resource + can reproduce and survive = increase in population
Stage 2 : due to increased population more individuals share the food? space available, resources are now limited, not enough for all organisms to survive and population decreases
Stage 3 : less competition exists for same resources due to smaller population and smaller population means more organisms will survive and reproduce resulting in population growth
What does interspecific competition look like ?
different species are competing for the same resource leading to its reduction for both species
although if one species is better adapted than the other species this will lead to the other species being outcompeted eventually leading to the decline of one of the species
an example of this is the red squirrel and grey squirrels (red squirrels are outcompeted due to adaptability & ability to eat wider range of foods)
What is the difference between conservation and preservation ?
Conservation is the maintenance of biodiversity through human action and management. (humans play a large role here)
Whereas preservation is the protection of an area by restricting human interference
What are the main aims of preservation ?
To protect environmentally sensitive ecosystems (places that can be easily damaged or destroyed by disturbances) e.g. the Galapagos or Antarctica
What are the main aims of conservation ?
Sustainable development
- having enough resources for future generations, especially regarding future generations
maintaining biodiversity : (species, genetic and habitat biodiversity)
what are the reasons for conservation of biological resources linking back to sustainable development ?
economic: provides resources which can be harvested for money e.g. clothes food medication and can act as a source of income
social : providing enjoyment/ relaxation
ethical: all organisms have the right to exist and humans have the responsibility to enforce this
