10C. Interactions between species Flashcards
Population size
total number of members in any given population
Carrying capacity
maximum population size that an environment can sustain
Things that affect population size
Immigration (arriving), Emigration (leaving), births and deaths
Population growth formula:
Future population = initial population + births – immigration + deaths – emigration
Greater disease prevalence within a population may lead to
an increase in deaths
Less resources available may cause
Emigration
Distribution of population can change due to
environmental factors like, temperature, rainfall, invasive species, and habitat loss
Population density
number of individuals in a population per unit area.
Density-independent
environmental factors that aren’t affected by population density. E.g. climate, natural disasters
Density-dependent
environmental factors that get stronger as population density increases. E.g. disease, predation, competition
Symbiosis
an interaction between two organisms of different species living in close proximity to each other.
Mutualism
(+/+)
BOTH species experience some overall benefit
Commensalism
(+/0)
One organism gains benefit while the other, neither benefit nor harmed
Predation
(+/-)
One organism hunts and kills another organism for food. Predator benefits from obtaining food. Prey is harmed as it’s food for the predator.
Parasitism
(+/-)
One organism obtains nutrients at the expense of a host organism
Amensalism
(0/-)
One organism experiences some negative effect, the other experiences neither a benefit nor negative effect
Competition
(-/-)
2+ organisms competing for the same resources with no winners.
Keystone species
species whose effects on an ecosystem are greater than expected relative to its population size
Keystone species play a much larger role in maintaining
ecosystem structure and composition
Apex predators
Control numbers of the prey and number of other organisms in an ecosystem
Ecosystem engineers
Interact and significantly change the physical environment of their ecosystem
Mutualism example
Algae living inside coral tissue. Algae provide glucose and oxygen for the coral and the coral gives the algae a safe place to live
Commensalism example
A bird nesting in a tree, as the bird is benefiting for shelter while the tree is not affected.
Predation example
Predator = lion; prey = zebra.
Parasitism example
Ticks living in a host like possums.
Amensalism example
Cows walking on grass, grass is affected
Competition example
Weeds growing in a vegetable garden
