Year 11 Population Dynamics Flashcards
(32 cards)
Populations
group of individuals of the same species that occupy a specific area over a certain period of time.
population dynamics
populations of a species change in size and structure over time.
carrying capacity
maximum population size in the species that the environment can sustain with available resources.
Important factors in population dynamics
reproduction rates
deaths
migration
food sources
water sources
competition
Features of K selected species
longer life cycle
reproduce slowly
few young and provides parental care
Example sod K selected species
elephants
kangaroos
whales
K selected species characteristic in an ecosystem
predictable ecosystems
steady pop growth pattern
mortality density dependant
Features of R selected species
short life cycles
small
reproduce quickly
lack of parental care, lots of young
examples r selected species
frogs, rats, weeds, bacteria, insects
R selected species characteristics in ecosystem
unpredictable changes in ecosystems
mortality is density independent
Population abundance
total number of organisms of species in population
population density
no of individuals of same species living in the same habitat at a particular time
population distribution
the places in ecosystem where species is found (usually unevenly spread)
Population composition
mesurable characterics (sex ratios, ages structure, fertility rate)
Clumped distribution features
sociality leads to clumps
a number individuals are grouped together and the groups make up the population.
occurs around food, shelter.
clumped distribution examples
flocks of birds identify trees with plenty of fruit.
schools of fish trick predators with constant light reflections.
Uniform distribution features
organisms of same species are evenly spaced
often due to infraspecific competition : territorial, root and crown space
uniform distribution examples
penguin colony are evenly spaced so their nests don’t touch.
Random Distribution features
organisms are spaced irregularly
animals don’t maintain random due to mating seasons.
mostly plants, resources aren’t scarce enough to separate
Random distribution examples
clams, spiders, trees.
What organisms are measured using quadrants and transects?
Plants or sessile species
quadrant assumptions
- getting an accurate, representative sample (large trees)
- allocated to avoid bias.
- only suitable for sessile species or slowing moving organisms
- accurate for uniform distribution
When do you use transect surveys?
when an area of study is too large to be able to count enough populations using quadrants
what to transect surveys show?
changes in community, composition and population abundance along environmental gradients.
