Module 1: Ecology: The Study of Our World (VOCAB) Flashcards
ecology
Study of how populations interact with one another and with their nonliving environment.
interdependence
The survival of species is dependent on other living organisms and nonliving components.
ecological model
Model that represents or describes components of an ecological system.
biotic
LIVING components of a system.
abiotic
NONLIVING components of a system (i.e., temperature, water, inorganic nutrients, and organic compounds found in the soil).
niche
The role, or way of life of a species within its environment.
generalist
A species that is able to thrive in a wide variety of environmental conditions and can make use of a variety of different resources (i.e., a heterotroph with a varied diet).
specialist
A species that can thrive only in a narrow range of environmental conditions or has a limited diet (i.e., the koala, which subsists almost entirely on eucalyptus leaves).
biosphere
The layer around the Earth within which all living organisms live.
lithosphere
The rock layer around the surface of the Earth.
autotroph
These are organisms that acquire their food from an abiotic source. Most autotrophs are photosynthetic organisms although there are a few that use inorganic compounds as a source of energy.
heterotroph
These are organisms that acquire their food (energy) from an organic source. Organisms that feed from living organisms are often referred to as consumers, while organisms that feed from dead organic matter are often referred to as decomposers or reducers.
population ecology
The science that studies the processes occurring within populations.
population
Group of organisms of the same species that live in the same area and interbreed.
demographics
Statistics that describe a population’s traits.
population size
Total number of individuals in a population.
plot sampling
Method of estimating population size of organisms that do not move much by making counts in small plots and extrapolating from this to the number in the larger area.
mark-recapture sampling
Method of estimating population size of mobile animals by marking individuals, releasing them, then checking the proportion of marks among individuals later recaptured.
population density
Number of individuals per unit area or volume.
population distribution
Describes whether individuals are clumped, uniformly dispersed, or randomly dispersed in an area.
clumped distribution
Members of a population are closer to one another than would be predicted by chance alone. Most populations have a clumped distribution. (i.e., A patchy distribution of resources encourages clumping, as when hippopotamuses gather in muddy river shallows.)
near-uniform distribution
Competition for limited resources can produce a near-uniform distribution, with individuals more evenly spaced than would be expected by chance. (i.e., Creosote bushes in deserts of the American Southwest grow in this pattern. Competition for water among the root systems keeps the plants from growing in close proximity.)
random distribution
Members of a population are distributed randomly when resources are uniformly available, and proximity to others neither benefits nor harms individuals. (i.e., When wind-dispersed dandelion seeds land on the uniform environment of a suburban lawn, dandelion plants grow in a random pattern.)
age structure
Of a population, the number of individuals in each of several age categories (pre-reproductive, reproductive, or post-reproductive).
reproductive base
Of a population, all individuals who are of pre-reproductive or reproductive ages.
immigration
Movement of individuals INTO a population.
emigration
Movement of individuals OUT of a population.
zero population growth
Interval in which the number of births = the number of deaths.
per capita growth rate
For some interval, the added number of individuals divided by the initial population size.
∙ [b − d = r]
∙ b = per capita birth rate
∙ d = per capita death rate
∙ r = per capita growth rate
exponential growth model
Model of unlimited population growth. The population grows by a fixed percentage in each successive time interval; the size of each increase is determined by the current population size.
** population growth plots out as a J-shaped curve **
∙ [N × r = G]
∙ N = number of individuals
∙ r = per capita growth rate
∙ G = population growth per unit time
biotic potential
Maximum possible population growth rate under optimal conditions.
density-dependent limiting factor
Factor that increasingly limits population growth as population density increases. Density-dependent limiting factors include competition, predation, parasitism, and disease.
intraspecific competition
Competition among members of the same species.
logistic growth
Density-dependent limiting factors cause population growth to slow as population size increases.
** population growth plots out as a S-shaped curve **
∙ [G = (r)max × N × (K − N) / K]
∙ G = population growth per unit time
∙ (r)max = maximum per capita population growth rate
∙ N = number of individuals
∙ K = carrying capacity
∙ (K − N) / K = proportion of resources not yet used
carrying capacity (K)
Maximum number of individuals of a species that an environment can sustain.
density-independent limiting factor
Factor that limits population growth to the same degree regardless of population density. Natural disasters, weather-related events, or human-caused events can decrease population size (these events are density-independent because crowding does not influence the likelihood of their occurrence or the magnitude of their effect).
life history
Schedule of how resources are allocated to growth, survival, and reproduction over a lifetime.
cohort
Group of individuals born during the same time interval.
survivorship curve
Graph showing the decline in numbers of a cohort over time. Ecologists have described three generalized types of curves: type I, type II, and type III.
type I curve
A type I curve is CONVEX, indicating survivorship is high until late in life. Humans and other large mammals that produce one or two young and care for them show this pattern.
type II curve
A DIAGONAL type II curve indicates that the death rate of the population does not vary much with age. In lizards, small mammals, and large birds, old individuals are about as likely to die of disease or predation as young ones.
type III curve
A type III curve is CONCAVE, indicating that the death rate for a population peaks early in life. Marine animals that release eggs into water have this type of curve, as do plants that release enormous numbers of tiny seeds.
r-selection
Selection that favors traits that allow their bearers to produce the most offspring the most quickly (short generation time and small body size).
** maximize QUANTITY **
K-selection
Selection favoring traits that provide a competitive advantage when population size is near carrying capacity (long generation time and large body size).
** maximize QUALITY **
total fertility rate
Average number of children the women of a population bear over the course of a lifetime.
replacement fertility rate
Fertility rate at which each woman has, on average, one daughter who survives to reproductive age.
demographic transition model
Model describing changes in birth and death rates that occur as a region becomes industrialized.
ecological footprint
Area of Earth’s surface required to sustainably support a particular level of development and consumption. It includes the amount of area required to grow crops, graze animals, produce forest products, catch fish, hold buildings, and take up any carbon emitted by burning fossil fuels.
habitat
Type of environment in which a species typically lives.
species richness
Of a community, the number of species.
