-Favorable conditions that occur from time to time (weather, climate, good habitat)
-Normal cycle, stable, but can increase suddenly
Cyclic (periodic/less stable)
NO wildlife pop is constant in numbers
Why a pop fluctuates through time…
-gains from birth
-losses from death
Steady state (input = output)
Relatively constant in number from period to similar period.
-Minor ups and downs from births and deaths (CC)
-Biomes with constant temp. and rainfall
Less stable, fluctuate at regular intervals.
–Short (3-4, 2-5 years) and 10-year
-Biomes with low temp. and rainfall (arctic, temperate)
-Less complex communities
-Buffer species live longer, less importance (hare)
3-4, 2-5 years
-Lemmings, mice overrun natural habitat
-Tied to cycles of naturalpredators (fox, owl)
-Time lag effect
Time lag effect
Predator/prey relationship is offset. One controls the other.
-American game birds
-Not well studied, but well known
–Affect great # of species at same time
Growth Curves (Animals)
Way a pop responds to new environment through time, or the carrying capacity of the environment.
-basic GC express the slope of a pop’s growth when organisms introduced to new environment.
-Biotic potential (push up) and environmental resistance (push down)
An interval of time during which a sequence of recurring succession of events is completed.
Biotic Potential (GC)
Flies and DDT
-Good light, temp, chem. environment
-High repro rate
-Good food supply, habitat
-Can compete, defend themselves
Environmental Resistance (GC)
-Bad light, temp, chem. enviro.
-Low repro. rate
-Bad food supply, habitat
-Too many competitors, can’t defend
Biotic Potential – define
Max. sustained rate of natality and min. rate of mortality.
-Rate of increase limited by physiological limitation of species, not environment
Environmental Resistance – define
Sum total of all decimating (Limiting) factors, operate to cause mortality.
-Prevents Biotic Potential from being realized.
Nr = dN/dt (# offspring/period of time)
–Exponential, uncontrolled growth
S = Nr [(K-N)/K]
-When a species becomes established in new habitat with good CC
The two Growth Curves
-show type of pop growth exhibited in situations where
-CC of habitat is constant
-BP of species modified by density dependent factors.
Density Dependent factors
-Increase in intensity as pop numbers approach CC of the environment.
–Mortality increases as pop increases.
population size at a point in time
ois point of starting
Maximum rate of increase
-# of organisms that will breed (females)
Number of individuals added for a time period
a specific time period (change in time)
growth rate for time period
S-Shaped curve graph
P.F. Verhulst (1838)
-Developed original model for population growth.
L.J. Reed (1920)
-Wrote paper that plotted US growth, fit the curve of Verhulst
-Broad terminology and classification system
-Dynamics of energy flow and nutrient cycles at the community and ecosystem level
-Man’s role as a principle factor of change in the resources of natural systems
-Historical perspective which includes important people and dates
Students articulate/list environmental conditions and ecological principles that influence, control, and determine, the ecological factors that affect an organism’s presence in selected areas.
-A fundamental truth that explains the relationship b/w 2 or more variables.
-It is descriptive and predictive, NOT prescriptive.
-Was synthesized from observation
-Can’t be disproved, but can be modified through time.
-Describes how nature behaves, what should happen under certain conditions
-describes what may happen given a certain set of circumstances.
Resource Management Functions
planning, organizing, and implementing
-A building block of a theory, the mental image formed by the generalization of ideas.
-Describes some regularity, relationship w/in a group of facts
-an element of memory
-vehicle of thought
-entity by means of which thinking is carried on
-is not the meaning in the sense of things signified
-an explanation of a potential law of nature
-a belief or procedure proposed or followed as the basis of action.
-a plausible general concept or body of principles offered to explain phenomena
a tentative assumption made in order to draw out and test its logical or empirical consequences.
-Proposition thought to be true because its consequences are true.
-Has NOT been tested
Law of Minimum (who)
Justus Von Liebig
Law of Tolerance (who)
Combined concept of Limiting Factors
presence and success of an organism, etc. depends on a complex set of conditions (Law of Min, Law of Tolerance)
Abiotic environmental conditions, such as precipitation, soil type, temp., and sunlight.
Its composed of biotic and abiotic elements that interact and interrelate.
-The separation of organic matter into similar compounds.
Living systems consume and produce energy.
-Energy in plants = Primary Production
The maintenance of constancy w/in a biological system. In terms of interaction b/w organisms in a community or internal environment of an individual.
-All living systems are in equilibrium with the environment
-The amount of living tissue produced per unit time by the population is a function of availableresources and the environment.
Food chains/food web
-Number of organisms forming a series through which energy is passed.
1. First trophic level: green plant (autotroph), traps energy, makes food for consumer levels.
-Energy passes through a system, it passes through trophic levels. In steady-state conditions, rate of energy production by one level MUST EXCEED the rate of energy utilization by succeeding level.
Metabolism/size of indivduals
All chemical reactions, which take place in a living organism.
Trophic structure/ecological pyramids
Pyramid shaped diagram representing a series of organisms, allocated to certain trophic levels. For complete ecosystems isolated from other systems: little material is gained or lost b/w them
Cycle involving movement of more earth bound elements:
Elements that pass back n forth b/w organisms and environment, many involved in sedimentary cycle.
–No known value to organism, but concentrated in tissues, similarity to vital elements.
-Atomic bombs = radioactive isotopes of these elements and get into environment and food chains.
Amino acids, carbohydrates, proteins, other carbon-containing substances produced by plants or animals, required by some organisms.
Cycling of chemicals like carbon, oxygen, phosphorus, nitrogen and water w/in (intrasystem) or b/w (intersystem) ecosystems.
-Assimilated and broken down over n over again by organisms
Pathways of Cycles
Directions taken by a set of operations that are repeated as unit.
within or among a community
A collection is said to have high degree of diversity if it contains many species of fairly equal abundance. Diversity is low when species are few or uneven abundance.
similar environments support similar or equivalent communities or organisms even though the species and locations may be different.
Area where two different communities (physical areas) come together, a favorable margin b/w two plant communities. The narrow part adjacent to boarder.
It has characteristics above that of the individual, like age structure, sex ratios, etc.
-Generally function of food, water, shelter.
A rough estimate of population density of a given species.
(Number of individuals in period of time/total species in community) = percentage
Rates of Increase
Increase of a population over time, function of age composition, sex composition, specific growth rates due to reproductive potential of components of age groups.
Natality, Mortality, Age distribution
Differences in which mortality, natality, fecundity, age composition, and manner in which variability relates to the environment and permits survival.
Growth Forms, Cycles
Characterize community structure by the fact that certain growth forms are dominant, or conspicuous in the community. Classification according to size, morphology, and length of vegetative body.
the maximum population that a habitat will support indefinitely. Function of food, water, shelter.
adjustments that a population makes to remain w/in carrying capacity of its environment.
role of biotic factors in the determination of population density
Density Independent (regulation)
-Population species is not regulated by its size or factors that are not influenced by population size (weather extremes)
Factors increase intensely as population numbers approach the carrying capacity of the environment.
branch of biology dealing with energy transformations in living organisms.
Population structure – lateral patterns
Lateral patterns expressed by communities are a function of elevation, soils, exposure, etc. Each species has its own pattern of population distribution related to the environment. No two are exactly the same.
Individuals or pairs defend an area against intruders of the same or different species.
Occurrence of organisms in isolation from others of their species
Struggle b/w organisms of the same or different species striving for a limited resource in the same area in a similar time frame.
competition among same species
competition b/w different species that use the same resource
Living together, various lasting close associations b/w organisms of different species.
killing and eating of an individual of one species by an individual of another species
the organism is dependent on its host for essential nutrient factors. Doesn’t usually destroy the host.
specific part of a habitat occupied by an organism. No two species occupy the same niche.
Different species that have similar roles (niches) in similar ecosystems located in different parts of the biosphere
-anteaters in South America, aardvarks in Africa
Different species or subspecies whose areas of distribution do not overlap
Different species or subspecies whose areas of distribution overlap or coincide.
Like responses in which organisms respond to stimuli, including the accommodation of a population. Individual interactions w/in a pop, reproductive behavior.
any behavior on the part of an organism stimulated by, or acting upon, another member of the same species.
process of change ecosystems go through to the biotic components that is capable of modifying and controlling the physical environment to varying degrees. High production-biomass ratio.
a community is in equilibrium with existing environmental conditions, and forms the final stage of natural succession.
the study of interactions b/w and among organisms and the environmental factors which determines organism’s distributions, abundance, rates of productivity, and evolution.