Unit 8: Ecology Flashcards
Biotic
= living (organisms – behaviors & interactions between organisms)
Abiotic
nonliving (temp, water, salinity, sunlight, soil)
Climate
long-term prevailing weather conditions in a particular area, (temperature + precipitation + sunlight + wind)
Macroclimate
work at seasonal, regional or local level
Microclimate
small-scale environmental variation (eg. under
a log)
Climate change effect on species
some species may not survive
shifting ranges
Biomes
major types of ecosystems that occupy very broad geographic regions
What abiotic factors determine biomes?
climate, temperature, salinity, soil type, amount of sunlight, and amount of water that is available
Role of Abiotic factors in the formation of biomes
The create suitable or ill suitable conditions for various life forms to live in
- climate influences the distribution of plants - temperature & perception help to determine what type of biome it is
- pH & composition of rocks limits the distribution, helping certain dominate plants to thrive
How do biotic factors help biomes?
The primary producers and autotrophs (biotic factors) support the rest of the biome.
Population:
group of individuals of same species living in a particular geographic area
Community
group of populations of diff species in an area
Ecosystem
community of organisms + physical factors
Landscape
mosaic of connected ecosystems
biosphere
global ecosystem
Global climate patterns
Sunlight intensity, Air Circulation & Precipitation Patterns, Ocean Currents, Mountains affect rainfall
Climograph
plot of annual mean temperature & precipitation in a particular region
Tropical Rain Forest
A terrestrial biome characterized by relatively high precipitation & temperatures year-round.
Desert
A terrestrial biome characterized by very low precipitation
Savana
A tropical grassland biome w/ scattered individual trees, large herbivores & maintained by occasional fires/drought
Chaparral
Biome characterized by mild, rainy winters & long, hot, dry summers; dominated by dense, spiny evergreen shrubs
Temperate Grassland
A terrestrial biome that exists at midlatitude regions & is dominated by grasses & forbs.
Northern Coniferous Forest
A terrestrial biome characterized by long, cold winters and dominated by cone-bearing trees.
Temperate Broadleaf Forest
A biome located throughout midlatitude regions where there is sufficient moisture to support the growth of large, broadleaf deciduous trees
Tundra
A terrestrial biome at the extreme limits of plant growth. At the northernmost limits, it is called arctic tundra, and at high altitudes, where plant forms are limited to low shrubby or matlike vegetation, it is called alpine tundra.
- long, cold winters w/ high winds & cold temperatures, less precipitation, low biotic diversity
Lakes
bigger & deeper than ponds. Some of the water in lakes is in the aphotic zone, where there is too little sunlight for photosynthesis. Plankton and plants = producers
Wetlands
saturated soil, very little water present at some times, but deeper amounts of water at other times. They are also home to specialized plants called hydrophytes, which are able to grow in super wet areas.
Streams & RIvers
continuously moving bodies of water that carry large amounts of water from the source, or headwater, to a lake or ocean.
Estuaries
brackish water, a mix of freshwater & salt water. Estuaries are unique ecosystems, providing animals w/ food, shelter, and a place for breeding and nesting, as well as a place for resting during migrations.
Intertidal zones
submerged w/ water during high tide & exposed to the air during low tide. The zone can take many forms, from sandy beaches to rocky cliffs.
Oceanic Pelagic Zone (Open Water)
organisms inhabiting the zone do not come in contact w/ the bottom or the shore throughout their lives. The pelagic zone is nutrient-poor. The large fish find their food by swimming long distances or drifting w/ currents and feeding on nutrient-deficient organisms.
Coral Reefs
structures that provide habitat for the fish and invertebrate species that make up the ecosystem. Hard corals create the reef itself. They typically consist of a layer of colonial polyps that live on the surface of a calcium carbonate skeleton that is secreted by the coral polyps
Marine Benthic Zone
begins at the shore and extends to the bottom of a waterbody. It is found all over the world. Only a small amount of sunlight reaches this zone. characterized by low temperature & high pressure.
Biogeography
geographic distribution of
species
Biogeography Factors
Dispersal, Behavior, Biotic & Abiotic
Dispersal that affect biogeography
movement away from area of origin
Behavior that affect biogeography
Habitat Selection
Biotic factors that affect biogeography
other species, food resources,
competition, pollinators, predators
Abiotic Factors that affect biogeography
temp, water, oxygen, salinity,
sunlight, rocks & soil
Density
individuals / area
Dispersion
pattern of spacing between
individuals
Determining population size and density
Count every individual, Random sampling, Mark-recapture method
Patterns of Dispersal
Clumped, Uniform, Random
Clumped Dispersal
most common; near required resource
Uniform Dispersal
usually antagonistic interactions
Random Dispersal
unpredictable spacing, not common in nature
Demography count
Additions: birth & immigration,
& subtractions: death &
emigration
Survivorship Curve
represent # individuals alive at
each age
Type I
low death rate early in life (humans)
Type II
constant death rate over lifespan (squirrels)
Type III
high death rate early in life (oysters)
Change in Pop Size calculation
birth-death
Zero Pop Growth
Birth = Death
Exponential population growth
ideal conditions,
population grows rapidly (just goes up in like u-shape)
Exponential Growth Equation
dN/dt = change in population = r*N
r = growth rate of pop.
N = population size
Logistic Model & Carrying capacity
Unlimited resources are rare! incorporates carrying capacity (K) K = maximum stable population which can be
sustained by environment
(looks like s)
Logistic Growth Equation
dN/dt = change in population
= rN (K-N/K)
r = growth rate of pop.
N = population size
K = carrying capacity
Life History
traits that affect an organism’s
schedule of reproduction & survival
3 Variables of Life History
offspring produced per reproductive episode
Age of sexual maturation
How often organism reproduces
# offspring produced per reproductive episode
Semelparity
Big-bang reproduction
Many offspring produced at once
Individual often dies afterwards
Less stable environments
Iteroparity
Repeated reproduction, Few, but large offspring, More stable environments
Critical factors:
survival rate of offspring and repeated reproduction when resources are limited
K-selection
pop closed to carrying capacity, Live around K, High prenatal care, Low birth numbers, Good survival of young, Density-dependent, humans
r-selection
maximize reproductive success, Exponential growth, Little or no care, High birth numbers, Poor survival of young, Density independent, ex: cockroaches
Factors that limit population growth
Density Dependent & Density Independent
Density-Dependent factors:
population matters
i.e. Predation, disease, competition, territoriality,
toxic wastes, physiological factors
Density-Independent factors
population not a factor
i.e. Natural disasters: fire, flood, weather
If there is a drought and plants wither -> certain animals cant eat and that affects everyone else
Interspecific competition
Can be positive (+), negative (-) or neutral (0)
resources are in short supply
Species interaction is -/-
Competitive exclusion principle
2 species cannot coexist in a community if their niches are
identical
The one w/ the slight reproductive advantage will eliminate the other
Resource partitioning
differences in niches that
enable similar species to coexist
Ecological niche
the sum total of an organism’s use of abiotic/biotic resources in the environment
Fundamental niche
niche potentially
occupied by the species (entire set of conditions to reproduce/survive)
Realized niche
portion of fundamental niche the species actually occupies after interactions with other species (predation and especially competition) have been taken into account.
competitive exclusion in interspecific competition.
2 species can’t coexist if they occupy exactly the same niche (competing for identical resources). Two species whose niches overlap may evolve by natural selection to have more distinct niches, resulting in resource partitioning.
Interspecific interactions
Competition (-/-), Predation (+/-), Herbivory (+/-), Symbiosis – parasitism, mutualism, commensalism
Facilitation (+/+ or 0/+)
Cryptic coloration
camouflaged by coloring
Aposematic or warning coloration
bright color of poisonous
animals
Batesian mimicry
harmless species mimic color of harmful species
Mullerian mimicry
2 bad-tasting species resemble each other; both to be avoided
Herbivory
plants avoid this by chemical toxins, spines, & thorns
Symbiosis:
2+ species live in direct contact with one
another: Parasitism (+/-), mutualism (+/+), commensalism (+/0)
Species diversity
= species richness (# of
different species) + relative abundance of each
species.
Simpson Diversity Index:
Calculate diversity
based on species richness & relative abundance
Highly diverse communities more resistant to invasive species
Simpson’s Diversity Index EQ
1- Sum of (n/N)^2 n=total # organisms in a species, N=total organisms in all species
High D(close to 1) = high biodiversity, Low D(close to 1)=less biodiversity
Invasive species
Organisms that become established outside
native range
Characteristics of Invasive species
Tolerates a wide range of conditions, long growing season, short generation
time. few natural controls such as predators, disease, or insects, Disperses itself with ease, Produces lots of seeds or eggs, New location has climate and environmental
conditions similar to native habitat
Trophic Structures
determined by the feeding relationships between
organisms.
Trophic levels = links in the trophic structure
food chain.
The transfer of food energy from plants -> herbivores -> carnivores -> decomposers
What limits the length of a
food chain?
Inefficiency of energy transfer along chain, Long food chains less stable than short chains
food webs.
Two or more food chains
linked together
Dominant species:
has the highest biomass or is the most abundant in the community
Keystone species:
exert control on community structure by their important ecological niches
Ecological succession:
transitions in species
composition in a certain area over ecological time (comes in after something dies)
Disturbance
changes a community by
removing organisms or changing resource availability (fire, drought, flood, storm, human activity)
Primary Succession
Plants & animals invade where soil has not yet formed
Ex. colonization of volcanic island orglacier (plants growing on volcano)
Secondary Succession
Occurs when existing community is cleared by a
disturbance that leaves soil intact Ex. abandoned farm, forest fire
Biogeographic Factors
Latitude: species more diverse in tropics than poles
Area: larger areas more diverse
Biogeographic Islands
Influenced by size & distance
Larger islands: greater immigration, lower extinction
Far from mainland: immigration falls, extinction rates increase
Ecosystem
*** IMPORTANT: sum of all populations living in a specific area (biotic community) + abiotic
factors with which they interact
Where is energy supplied from?
the sun
can energy be recycled?
no
autotrophs
(“self feeders”) = primary producers, & are usually photosynthetic (plants
or algae).
use light energy to synthesize sugars & other organic compounds.
Heterotrophs
(“other feeders”) – can’t make own
food
primary consumers
Herbivores that eat primary producers
secondary consumers
Carnivores that eat herbivores are called
tertiary consumers
Carnivores that eat secondary consumers
detritivores/decomposers
group of heterotrophs, get energy from detritus, nonliving organic material, & play an important role in material cycling
Primary production
amount of light energy -> converted to chemical energy
Gross primary production (GPP)
total primary production in an ecosystem
Net primary production (NPP)
gross primary production minus the energy used by the primary producers for respiration (R): storage of chemical energy available to consumers in an ecosystem
NPP = GPP – R
Energy Transfer between Trophic Levels
Only 10% efficient
Biogeochemical cycles
cycles: nutrient cycles that contain both biotic & abiotic components
organic -> inorganic parts of an ecosystem
Carbon Cycle
CO2 removed by photosynthesis,
added by burning fossil fuels
Nitrogen Cycle
Nitrogen fixation: N2 -> plants by bacteria
Nitrification: ammonium -> nitrite -> nitrate, Absorbed by plants Denitrification: Release N to atmosphere
Why is biodiversity important?
1) More diverse ecosystems = more stable & able to resist threats
2) Many drugs have been derived from plant, fungi & bacterial species.
3) More likely for species to escape extinction if new pathogen emerges
Habitat loss
Human alteration of habitat is the single greatest threat to biodiversity
4 major loss of biodiversity
Habitat loss, introduced species, global change, overharvesting
Introduced species
invasive/nonnative/exotic
species
Overharvesting
harvest wild plants & animals
Global change
alter climate, atmosphere, &
ecological systems -> reduce Earth’s capacity to sustain life
Bioremediation
use of organisms (prokaryotes,
fungi, plants) to detoxify polluted ecosystems
Bioaugmentation
introduce desirable species
(eg. nitrogen-fixers) to add essential nutrients
Human activities changing the earth
overpopulation, pollution, burning fossil fuels (CO2 increase), & deforestation, depleting atmospheric ozone
Biological Magnification
Toxins become more concentrated in
successive trophic levels of a food web
Toxins can’t be broken down & magnify inconcentration up the food chain
