2.1 Flashcards
ecosystem definition:
an ecological unit comprising biotic and abiotic factors that interact,
and is self-regulating.
ecology definition:
the study of organisms and their interactions in the environment.
species definition:
a group of organisms that share common characteristics that interbreed and produce fertile offspring
population definition:
a group of organisms of the same species living in the same area at the
same time which are capable of interbreeding and producing fertile offspring.
what are abiotic factors?
the non-living, physical factors that influence organisms and the
ecosystem.
these include temperature, pH, salinity, sunlight, etc.
what are biotic factors?
the living components of an ecosystem – organisms, their
interactions and their waste – that directly or indirectly affect other organisms.
habitat definition:
the environment in which a species normally lives
niche definition:
describes the particular set of abiotic and biotic conditions and resources to
which a particular population responds.
two species cannot inhabit the same ecological niche in the same place at the same time. If many species live together, they must have slightly different needs, so are not in the same niche.
fundamental niche:
describes the full range of conditions and resources in
which a species can survive and reproduce
realised niche:
describes the actual conditions and resources in which a species
exists due to biotic interactions
competition definition:
the demand by two or more organisms for the same resources
which are in short supply
intra-specific competition:
the competition between members of the same species.
harsher type of competition because all individuals are from the
same niche. as population grows, so does competition for the resources
– stronger individuals outcompete weaker ones for the resources.
inter-specific competition:
the competition between members of
different species.
it may result in a balance, in which both species share the resource. it
may also result in competitive exclusion, where one species out
competes the other
predation definition:
when one animal, the predator, kills and eats another animal, the
prey
herbivory definition:
defined as an animal (a herbivore) eating a green plant
parasitism definition:
a relationship between two species in which one species (the parasite) lives in or on another (the host), gaining food and shelter from it.
parasites usually do not kill the host, but simply affect it negatively
symbiosis definition:
a relationship between two organisms (known as symbionts) that
live together to benefit from one another
mutualism definition:
a relationship between two or more organisms in which all benefit
and none suffer. however, they do not have to live together to benefit
commensalism definition:
a relationship between two organisms wherein one is benefitted and the other is not affected
carrying capacity definition:
the maximum number of species, or ‘load’, that can be sustainably supported by a given area
limiting factors definition:
factors which slow down the growth of a population as it reaches
its carrying capacity. (e.g. limited supply of phosphates in aquatic systems, low
temperatures in tundra freeze soil and limit water availability for plants)
- for animals – food, water, space, mates, shelter, temperature
- for plants – water, nutrients, sunlight, carbon dioxide, space, natural calamities, temperature
s curve:
start with exponential population growth. no limiting factors affect growth at first.
however, above a certain population size (close to carrying capacity), growth
gradually slows down resulting in a constant population size.
j curve:
o boom and bust pattern
o grows exponentially at first and then collapses. collapses are called diebacks.
o population can exceed carrying capacity in a long-term basis before the collapse occurs. It can also happen on a short-term basis, known as overshooting.
