Chapter 24- Populations and Sustainibility Flashcards
What is a limiting factor in terms of populations?
An environmental resource or constraint limiting population growth
What happens during Phase 1&2 of the population growth curve?
1- population gradually increases as existing population reproduce. Birth rate is higher than death rate, increasing total population
2- a period of rapid growth as amount of breeding pairs increase, so population multiplies exponentially. No limiting factors
What happens during Phase 3 of the population growth curve?
Stable state- External constraints restrict further growth of the population. Birth and death rates are approximately equal. Any fluctuations reflect fluctuations in external factors (eg predator size)
How can we divide up limiting factors in terms of population?
Abiotic
Biotic
Give an example of an abiotic limiting factor in terms of population size
Availability of oxygen, temperature, pH ect
Give an example of a biotic limiting factor in terms of population size
Predator populations, food availability, disease and competition
How does migration affect population size in two different ways?
Immigration- Movement of individuals into a particular area increases population size
Émigration- Movement of individual away from a particular areas decreases population
What is a density independent factor in terms of population?
Factors that have an effect on the whole population regardless of size (eg natural disasters)
What caused the explosion in human population?
The development of human society, eg the industrial revolution, medicine, agriculture creates imbalance between the birth and death rates.
What is the formula for population growth (%)?
Population change during the period/population at the start of period X100
Which unnatural factors also affect birth rate?
Culture, economic conditions, social pressures all can either limit or encourage the birth rate
What are the two different types of competition?
Intraspecific- Between individuals of the same species
Interspecific- Between different species
How does interspecific competition have an effect on populations?
Two or more different species compete for the same resource (normally food) resulting in the reduction of the resource for both populations. This means that each population has less energy for reproduction, resulting in smaller populations of both species.
How can interspecific competition be affected if one species is better adapted than the other, and what do we call this principle?
The better suited species is more likely to outcompete its competitors, resulting in a decline in the secondary species, until it can no longer coexist with the original species. This is called the competitive exclusion principle (eg red and grey squirrels)
How does intraspecific competition have an effect on population sizes?
This occurs when members of the same species compete for the same resource. Availability of the resource determines population size.
How can we graphically represent the effects of intraspecific competition in terms of population?
Stage 1- resource is plentiful, all organisms can survive and reproduce, leading to population growth
Stage 2- Increased population reduces availability of the resource for the whole population, causing a decrease
Stage 3- Less competition exists, more organisms survive and reproduce, population grows
What is predation?
A major biotic factor when an organism kills and eats another (a type of interspecific competition)
How are predator and prey populations interlinked?
As the population of one population increases, it has a direct impact on the size of the other population.
What is the general pattern of a graph depicting predator prey relationships?
Peaks and trophs in a time delay between species
Describe Stage 1&2 of a graph depicting a prey-predator relationship
Stage 1- Increase in prey population provides more food for predators, increasing their population size
Stage 2- decrease in prey population means less food available for the predator species, decreasing their population size
Describe Stage 3&4 of a graph depicting a prey-predator relationship
3- Decrease in predator populations allows the prey to survive and reproduce, increasing prey populations
4- Cycle begins again
Give an example of predator prey interdependence
Canadian lynx and the snowshoe hare
Describe the difference between conversation and preservation
Conservation- maintenance of biodiversity through human activity
Preservation- Protection of an area by restricting or banning human activity.
