Environmental Science Chapter 8 Review
Populations
-same species, same place/time, interbreed
-density = # of individuals per unit area
-dispersion – even, clumped, or random
-described by size, density, and dispersion
Reproductive potential
-bacteria have high reproductive potential
- elephants low at 21 months
- breeding season – give birth during specific time
of year when food is available.
Environmental Science Chapter 8 Review
Reproducing earlier in life has the greatest
effect on reproductive potential.
The maximum number of offspring each
individual can produce will limit a population’s
biotic potential.
Generation time – the average age at which
members of a species reproduce.
Environmental Science Chapter 8 Review
Exponential growth
- Occurs in nature only with plenty of food/space
- Logarithmic growth, or #s increase rapidly
Carrying Capacity
-Maximum population that ecosystem can support
indefinitely.
-determined by the supply of the most limited
resources.
Environmental Science Chapter 8 Review
Population’s growth rate is its birth rate minus its
death rate.
Competition – members of a population use the
same resources in the same ways, so eventually
compete with each other.
Population regulation
-density dependent-predation, diseases, resources
-density independent-severe weather, nat.disasters
Environmental Science Chapter 8 Review
Niche – includes species home, environmental
factors for survival, and interactions with other
organisms.
Competition
-different individuals using the same limited
resource.
-cannot occur between animals from two different
ecosystems.
-a type of interaction in which both are harmed
since each has less access to the resource.
-niche’s overlap
Environmental Science Chapter 8 Review
Predation - predator = lynx, prey = hare
- predator usually kills and eats its prey
Parasitism – lives in or on another organism
- intestinal worms, ticks, mistletoe on a tree
Mutualism – benefit to each for survival
- bacteria in cows stomachs
- bats and flowers
- termites and protozoa
Environmental Science Chapter 8 Review
Commensalism – neither harmed, one may benefit
- orchids in trees
Symbiosis – two organisms live in close association
such as mutualism and commensalism.
Coevolution – over long time, two species develop
adaptations that benefit both of them.
Environmental Science Chapter 8 Review
Populations change – grow, shrink, remain the
same.
An organism’s habitat is a location.
If 2 species use the same food source, or
territory at different times, they are indirect
competitors.
Environmental Science Chapter 8 Review
Short answers
Predict what might happen to the population of
rabbits and coyote if the rabbits exceed the
carrying capacity of the environment.
Explain how two species can compete for the
same resource even if they never come into
contact with each other.
Environmental Science Chapter 8 Review
Essays
Zebra mussels were accidentally imported to
the Great Lakes from Europe and have no
natural enemies in the US. They have
multiplied rapidly clogging water intake pipes,
marine engines, etc. How could zebra mussels
be eliminated from the Great Lakes?
Environmental Science Chapter 8 Review
Essays
Viruses are the cause of many infectious diseases,
such as common colds and flu. Under what
conditions do you think viral diseases will spread
most rapidly between humans? What can be done
to slow the spread of these viruses?