Ecology key terms
Ecology Key Terms
• ECOLOGY
• HABITAT
• COMMUNITY
• ECOSYSTEM
• ABIOTIC FACTOR
• BIOTIC FACTOR
• BIODIVERSITY
• PIONEER SPECIES
Ecology Key Terms
• FOOD CHAIN
• FOOD WEB
• AUTOTROPH
• HETEROTROPH
• HERBIVORE
• CARNIVORE
• OMNIVORE
• DETRITIVORE
• PREDATION
• SYMBIOSIS
• MUTUALISM
• COMMENSALISM
• PARASITISM
• NICHE
Biomes
• A biome is a large geographical area of distinctive plant
and animal groups, which are adapted to that particular
environment. The climate and geography of a region
determines what type of biome can exist in that region
• Try to remember the climate or plants & animals
• Can be terrestrial, freshwater, or marine
Estuary
Biomes
• Tropical Rainforest - Wet, humid, warm
year-round, tall trees w/ undergrowth, comp.
for sunlight, high biodiversity - provides
effective response to change, occurs
through speciation
• Desert - low precipitation, may be very hot
or very cold, low pop. density, succulents
and deep rooted shrubs - plants and animals
adapted for water conservation
Biomes
• Savanna - seasonal rainfall, long dry
season, some trees adapted to long dry
season, grasses and forbs, large grazing
animals, watering holes
• Chaparral - Coastal, rainy winters and
long, hot, dry summers. CALI!, fire
common, drought common, good plant
diversity, browsers and small mammals
Biomes
• Grassland - the great plains, semi-arid,
perennials, large grazing animals, ideal
for agriculture
• Deciduous/Temperate Forest - eastern
US, cold winters w/ snow, warm
summers, broadleaf plants which drop
their leaves, hibernation and migratory
birds
Biomes
• Taiga/ Coniferous forest - long, cold
winters and short cool summers, conebearing trees, large mammals (moose,
bears), few reptiles
• Tundra - long, cold winters, very short
growing seasons, lichens, mosses,
permafrost, large, grazing mammals.
Limiting Factors
• Aspects of the environment which will restrict
population growth
• 2 types of limiting factor:
• Density-dependent - greater impact as
population increases
• Density-independent - same impact
regardless of population size/density
• Determine carrying capacity ( K )
Hardy Weinberg Law
• If certain criteria are met, then allelic and genotypic frequencies will remain
stable over time.
• Criteria: large pop., random mating, no migration (gene flow), no mutations,
no selection or genetic drift
• p+q=1
p2 + 2pq + q2 = 1
• p - allelic freq. - dom. allele
• q - allelic freq. - rec. allele
• p2 - genotypic freq. - hom. dom.
• q2 - genotypic freq. - hom. rec.
• 2pq - genotypic freq. - heterozygous
Ecosystems
• A biological community and it’s abiotic factors
• Includes all of the interactions within the system - interdependence
• biotic - biotic
• biotic-abiotic
• Energy travels through an ecosystem - in and out
Trophic Levels
• Autotrophs - self + food,
producers, most energy, biomass,
largest pop.
Apex Predators
• Heterotrophs - other + food,
consumers, progressively less
available energy, biomass, and
numbers as you move up through
trophic levels
• Types of eaters: herbivores,
carnivores, omnivores, detritivores
- a.k.a. decomposers - return
essential minerals to the soil
Food Chains + Food Webs
• Display the transfer of energy in a
system
• Food chain - one pathway
• Food web - all pathways, alternative
pathways
• Arrows indicate feeding
relationships
• Only arrows leaving an item =
producer
Biogeochemical cycles
• Continual, cyclical transfer of essential substances
• Part of transfer is through living things because these substances are essential
for life
• Carbon, Nitrogen, Phosphorus
• Carbon - carbon-based life, photosynthesis, cellular resp., fossil fuels,
dissolved CO2 in oceans, detritivores
• Nitrogen - req. for amino acids and nucleic acids, atmospheric N, nitrogenfixing soil bacteria, legumes and root nodules, ammonification --> ammonia,
nitrification --> nitrites --> nitrates - all used by plants, denitrification -->
releases N back into air
• Phosphorus - ATP, NADP, Ca:P balance, released from rocks, dissolved in
H2O, incorporated into plants and travels through food chain
Hydrologic Cycle
• Another essential cycle that supports
life.
• Evaporation, Condensation,
Precipitation, Surface Runoff,
Infiltration/Percolation, Groundwater,
Aquifers, Recharge, Plant Uptake,
Transpiration
• Also involved in the cycling of other
minerals
• Plant matter increases percolation
and prevents surface runoff
Niche and Symbiosis
• Species fill a niche within their ecosystem - a special role which incorporates
their requirements and the survival strategies, feeding relationships and
symbiotic relationships they engage in
• Symbiosis - close, permanent, different species
• Mutualism - 2 benefit
• Commensalism - 1 benefits,1 unaffected
Ex. Epiphytes
• Niche includes habitat - the physical place an organism lives in and shares
with other organisms
Habitat, Niche, and Competition
• Species in the same habitat with overlapping niches will compete with one
another for resources
• Outcomes:
• limited overlap: both may survive
• great overlap: competitive exclusion - one survives, the other does not
• Don’t forget that individuals within a population compete as well!
• Outcome:
• Fittest survive, but we will save evolution for another time...
Invasive Species
• Newcomers to a habitat may disrupt the interactions between predators and
prey and create imbalance within a system.
• Typically, these new, exotic species lack a predator, experience a
population explosion, and outcompete native species for resources
• Leading cause of extinctions.
• As native populations become smaller, there is reduced genetic variability
(greater chance of inbreeding + genetic drift) and are subject to rapid
change due to chance
Invasive Species and Population Growth
• Invasive species that are r-strategist will be particularly successful.
• r- strategists: mature early, reproduce quickly, have many offspring and limited
parental care, and experience boom and bust periods
• Boom periods demonstrate exponential growth - J-shaped curve.
• Requires resources!
Logistic Growth
• When population size is restricted by density dependent limiting factors we
would see a sigmoid (s-shaped) curve.
• The plateau created represent carrying capacity (K) - the maximum number of
organisms the environment can support.
• K-strategists - mature later, few offspring, extensive parental care, growth rate
slows as environmental resistance increases.
Size, Density, Dispersion
• Population size (N) - how many?
• Population Density - how many per unit of space?
• Population dispersion - how is the population arranged in that space?
• clumped, even, random