Population dynamics Flashcards
what is the equation for population growth?
-(birth-deaths) + (immigration-emigration)
what are the 2 factors that lead to population growth of migratory bird species?
-high birth rates
-immigration
what is the seasonal effect on population growth? (4 things)
-breeding seasons
-food availability
-survival rates
-migration patterns
what are the reasons why population size can change from year to year?
-predator- prey cycle
-changes in food supply
-abiotic factors e.g. colder winter
what are the two ways species can be grouped?
-r or k selected species
what are the characteristics of r related species? what is the term to describe how they grow? what are examples of this species?
-tend to be opportunistic
-grow very quickly and decline very rapidly
-boom and bust
-bacteria, protoctistans, weeds
what are the characteristics of k related species? what is the term to describe how they grow? what are examples of this species?
-more stable population
-remains close to the carrying capacity
-survival and dominance
-large mammals and trees
what are 6 differences between r and k selected species?
-r are short lived and have a small body
-r reproduce rapidly
-population size of r varies
-inhabit unstable habitats so move frequently
-not specialised so can adapt to any environment
-very little parental care required
what are the 3 types of positive/ negative interactions?
-predator- prey interactions
-cows grazing on grass
-parasitism
what is the definition of a parasite?
-organism that lives in or on another organism benefiting from it and causing it harm over a period of time
what are the 4 ways parasites differ from predators?
-parasite lives in the host
-parasite causes harm to the host over a long period of time
-parasite smaller than the host
-the parasite kills the host over a long period of time
what is an example of a negative/ negative interaction? how is this shown?
-competition
-when two species which are grown together and neither grows as well as they would if they were separated
what is an example of a positive/ positive interaction?
what is an example of an organism which uses this technique?
-mutualism where both species gain
-lichens which provide a mutual relationship between fungi and green algae
what is the name of the bacteria which is used in mutualism?
-nitrogen fixing bacteria
what is the definition of a pest?
-a species that damages a valuable crop species causing economic damage
what does the term biological control mean? what are 3 examples of biological control?
-deliberately introducing an organism that will target the pest
-predator
-parasite
-pathogen
how does a biological control bene fit the environment? why are broad pesticides harmful?
-it reduces the need for chemical pesticides
-these pesticides can kill many beneficial organisms
look at the pest resurgence graph page 97
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why if a broad spectrum pesticide is sprayed does the number of pests increase?
-pest resurgence occurs due to the number of predators decreasing as consequence of the pesticide
what are the 5 advantages of introducing a natural biological control?
-no chemical damage
-targets only the pest species
-resistance is unlikely
-pest resurgence is unlikely
-requires little additional action so saves money
what are 3 limitations to biological control?
pest is unlikely to be totally eliminated
-it will only work if the introduced predator species will thrive in the pests environment
-it is important that the introduced species does not outcompete native species in the environment
