DAT Ecology Flashcards
Abiotic factors
nonliving factors (temperature, climate, light,
water availability, and topology.0
Photic zone
zone in water
where light penetrates.
Aphotic zone
zone in water has
almost no light penetration.
Biotic
all living things that directly or
indirectly influence the life of the organism.
Population
a group of individuals of the same
species living in the same area.
Community
a group of populations living in
the same area.
Ecosystem
describes interrelationships
between organisms in a community and their
physical environment.
Biosphere
combination of all the ecosystems
of the earth. The biosphere includes the
atmosphere, hydrosphere, lithosphere, and
geosphere as well.
Habitat
type of place where an organism
usually lives. The habitat includes all the other
organisms present as well as the physical and
chemical environment.
Niche
this describes all the biotic and abiotic
resources in the environment used by an
organism.
Dispersion
- describes how individuals
in a population are distributed. The
dispersion may be clumped, uniform, or
random
Survivorship curves
how mortality of
individuals in a species varies during
their lifetimes.
Type I SURVIVAL curve
most individuals survive to
middle age but mortality increases
quickly in old age. Humans have a
type I survivorship curve
type ii survival curve
the probability of survival is
generally constant and independent
of age. Hydras have a type II
survivorship curve
Type III survivorship curve
most individuals die young,
with few surviving to reproductive
age and beyond.
Biotic potential
the maximum
growth rate of a population under
ideal conditions (unlimited resources
and no restrictions).
Carrying capacity (K)
the
maximum number of individuals of a
population that can be sustained by
a habitat
Limiting factors
elements that
prevent a population from reaching
its full biotic potential.
density dependent limiting factors
- the
limiting effect becomes more
intense as the population density
increases.
Density-independent limiting factos
limiting
effect’s intensity occurs
independently of the density of the
population.
Intrinsic rate
when the reproductive
rate (r) is at its maximum (biotic
potential)
Exponential growth
occurs whenever
the reproductive rate (r) is greater than
zero. This creates a J-shaped curve.
viii.Logistic growth
occurs when limiting
factors restrict the size of the population
to the carrying capacity of the habitat.
viii.Population cycle
population size
fluctuates in response to varying effects
of limiting factors. When the population
grows over carrying capacity, the
population may then be limited to a size
lower than the initial K due to the
damage caused to the habitat.
K-selected population
members have low
reproductive rates with longer
maturation times, and their size is
roughly constant at K (e.g., human
population).
R-selected population
- these species
have rapid exponential population
growth. They have numerous offspring
that are small and have fast maturation,
so little parental care is needed (e.g.,
bacteria).
lag phase,
when
bacteria are adapting to growth conditions.
log phase
` is the exponential growth
of the population as it doubles with every time
period (using log # produces a straight line
here).
stationary phase,
the growth rate equals the death rate
due to growth-limiting factors.
Ecological footprint
- the aggregate land and
water area necessary to produce all the
resources to sustain an individual/group of
people and absorb all their wastes.
Shannon diversity index
species diversity is
measured by the Shannon diversity index. The
higher the value, the more diverse the community
Competitive exclusion principle (Gause’s
principle)
when two species compete for
exactly the same resources (or occupy the same
niche), one is likely to be more successful.
Resource partitioning
when two species
occupy the same niche but pursue slightly
different resources, individuals can minimize
competition and maximize success through
resource partitioning.
Character displacement (niche shift)
certain traits
allow for more success in obtaining resources in
their partitions. This reduces competition and
increases the divergence of features. Thus,
character displacement occurs where unique
differences among species diverge even more
when they coexist near each other.
Realized and fundamental niches
fundamental niche is the area
that a species could potentially survive in. The
realized niche is the area that the species
actually lives in due to factors such as
competitors.
Parasitoid
this is an insect that lays its
eggs on a host (insect or spider).
Symbiosis
an intimate, often permanent
association between two organisms.
