Ecology Flashcards
Source-Sink-Meta populations
the populations in the better areas continually send out dispersers that bolder the populations in the poorer habitats
metapopulations
existing as a network of distinct populations that interact with one another by exchanging individuals
demography
quantitative study of populations
generation time
average interval between the birth of an individual and the birth of its offspring
fecundity
number of offspring produced in a standard time
mortality
number of individuals that die in a standard time
age structure
the relative number of individuals in each cohort
life table
tabulates the fate of a cohort from birth until death, showing the number of offspring produced and the number of individuals that die each year
mortality rate
the proportion of individuals that started that interval alive but died by the end of it
survivorship
the percentage of an original population that survives to a given age
cost of reproduction
the reduction in future reproductive potential resulting from current reproductive efforts
biotic potential
the rate at which a population of a given species increases when no limits are placed on its rate of growth
semelparity
focus all their reproductive resources on a single large event and then die
itereoparity
produce offspring several times over many seasons
carrying capacity
the maximum number of individuals that the environment can support
sigmoidal growth curve
as the size of a population stabilizes at the carrying capacity, its rate of growth slows
density-dependent effects
as population size increases, either reproductive rates decline or mortality increases or both
Allee effect
growth rates increase with population size
density-independent effects
the rate of growth of a population at any instant is limited by something unrelated to the size of the population
k-selected
adapted to thrive when the population is near carrying capacity
r-selected
selection tat favors individuals with highest reproductive rates
what impact does the growth of human populations have?
more control over food supply
superior weapons
cures for many diseases
improvement in shelter
population pyramid
a bar graph displaying the number of people in each age category
community
species that occur at any particular locality
species richness
number of species present
primary productivity
amount of energy produced
assemblage
species included are only a portion of those present within the entire community
individualistic concept
a community is an aggregation of species that happen to occur together at one place
holistic concept
views communities as an integrated unit
ecotones
places where the environment change apruptly
niche
the total of all the ways it uses the resources of its environment
interspecific competition
occurs when two species attempt to use the same resource and there is not enough of the resource to satisfy both
interference competition
physical interactions over access to resources
exploitative competiton
consuming the same resources
fundamental niche
the entire niche that a species is capable of using, based on its physiological tolerance limits and resource needs
realized niche
the actual set of environmental conditions in which the species can establish a stable population
competitive exclusion
no two species with the same niche can coexist when resources are limiting
resource partitioning
niche subdivision to avoid direct competition
character displacement
the differences evident between sympathetic species are thought to have been favored by natural selection as a means of partitioning resources and reducing competition
coevolution
the simultaneous development of adaptations in two or more populations, species, or other categories that interact so closely that each is a strong selective force on the other
mullerian mimicry
several unrelated but protected animal species come to resemble one another
batesian mimicry
this type of mimicry is used so that the mimics would be avoided by predators, who would be fooled by the disguise into thinking the mimic was the distasteful species
commensalism
one species benefits and the other neither benefits nor is harmed
mutualism
both species benefit
parasitism
one species benefits but the other is harmed
ectoparasites
parasites that feed on the exterior surface of an organism
endoparasites
parasites that live within the body of their hosts
keystone species
species whose effects on the composition of communities are greater than one might expect based on their abundance
succession
the tendency for communities to change from simple to complex
secondary succession
a succession that occurs in areas where an existing community has been disturbed but organisms still remain
primary succession
occurs on bare, lifeless substrate, where organisms gradually move into an area and change its nature
aquifers
permeable, underground layers of rock, sand, and gravel that are often saturated with water
nitrogen fixation
the synthesis of nitrogen-containing compounds from N2
nitrification
after NH3 has been synthesized other prokaryotic microbes oxidize part of it to form NO3-
denitrifcation
the conversion from NO3- into N2
autotrophs
synthesize the organic compounds of their bodies from inorganic precursors
photo autotrophs
use light as their source of energy
chemoautotrophs
obtain energy by means of inorganic oxidation reactions
What is the order of the trophic levels?
primary producers herbivores primary carnivores secondary carnviores detritivores
decomposers
mostly microbes and other minute organisms that live on and break up dead organic matter
productivity
the rate at which the organisms in the trophic level collectively synthesize new organic matter
respiration
the rate at which they break down organic compounds
Gross Primary Productivity (GPP)
the raw rate at which the primary producers synthesize new organic matter
Net Primary Productivity (NPP)
GPP minus the respiration of the primary producers. represents the organic matter available for herbivores to use as food
secondary productivity
the productivity of a heterotroph trophic level
tropical rainforest
South America, 140-450 cm annual precipitation, terrestrial plants, 1200 species of butterflies
savannas
tropical or subtropical grasslands, 50-125 cm rain, spaced trees and shrubs, herds of grazing animals
desert
dry places where rain is both sparse and unpredictable (25-40 cm) vegetation is sparse
temperate grasslands
halfway between the equator and the poles (praries)
deciduous forest
eastern United States, eastern canada, and eurasia. plentiful rains, deciduous trees that drop their leaves in the winter, deer, bears, beavers and raccoons
Tiaga
northern forest, coniferous trees
tundra
far north, little precipitation, small trees
What are the three characteristics of population Ecology?
- population range, the area throughout which a population occurs
- the pattern of spacing of individuals within that range
- how the population changes in size though time
Biogeochemical cycles
a cyclic path involving both biological and chemical processes
Water Cycle
Water serves as a source of hydrogen (H) ions whose movements drive the production of ATP (energy) in organisms
Land- 90% of the water that goes into the atmosphere comes from plants via transpiration
Water Table
upper, confined portions of groundwater that flows into streams and is partially accessible to plants
Carbon Cycle
Is based on CO2- makes up .03% of atmosphere
Photosynthesis plants, bacteria, protists “fix” Co2 in atmosphere each year
All heterotrophic organisms must get their carbon indirectly from others that fix it
Most organic compounds formed as a result of carbon fixation are broke down and returned to the atmosphere or water
Nitrogen Cycle
Nitrogen gas makes up 78% of the atmosphere
Few organisms can convert (fix) nitrogen into forms they can use
Most of the bacteria that can fix nitrogen are free-living but some live in symbiotic relations with the roots of plants called Legumes (The pea family)
Plants that live with symbiotic bacteria can live in nitrogen-poor soils because bacteria can fix it for them
Ammonification
when Bacteria break down nitrogen-containing compounds, use them to make their own proteins and release excess ammonium ions (NH4+)
Phosphorous Cycle
main component is a mineral
phosphorous is the only one whose absence could limit plant growth
phosphates exist as phosphorous anions in soils, are relatively insoluble and exist only in certain types of rocks
Biomass
net weight of all organisms in the environment
Pyramid of Biomass
weight of everyone
Pyramid of Numbers
how many individuals
Pyramid of Energy
amount of production
Bottom up effects
when the productivity of an ecosystem is low, the herbivore population will be too small to support any predators
