Ecology Flashcards
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~Ecology
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● Study of the interactions of organisms with their physical environemtn and wth each other
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~Population
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● Group of individuals of one species living in one area who have the ability of interbreeding and interacting with each other
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~Community
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● Consists of all the organisms living in one area
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~Ecosystem
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● Includes all the organisms in a given area as well as the abiotic (nonliving) factors with which they interact
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~Abiotic factors
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● Nonliving and include temperature, water, sunlight, wind, rocks, and soil
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~Biosphere
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● Global ecosystem
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~Size
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● The toal number of individuals in a population and is represented by N
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~Density
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● Number of individuals per unit area or volume
● Scientists use sampling techniques to estimate the number of organisms living in one area
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~Mark and recapture
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● One sampling technique
● Organisms are captured, tagged, and then released
● The same process is repeated and the a formula is used for hte collected data
● N = (number marked in first catch) x (total number in second catch) / (number of recaptures in second catch)
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~Dispersion
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● The pattern of spacing of individuals within the area the population inhabits
● The most common pattern of dispersion is clumped (fish)
● Some spread in a uniform pattern (platns may secrete toxins that keep away other plants that would compete for limited resources)
● Random spacing occurs in the absence of any special attractions or repulsions (forest)
11
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~Survivorship/mortality curves
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● Show the size and composisiton of a population
● Three tyeps
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~Type I survivorship curve
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● Show organisms with low death rates in young and middle age and high mortality in old age
● There is a great deal of parenting, which accounts for the high survival rates of the young
● This is characteristic of humans
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~Type 2 survivorship curve
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● Describe a species with a death rate that is constant over the life span
● Describes the hydra, reptiles, and rodents
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~Type 3 survivorship curve
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● Show a very high death rate among the young but then shows that death rates decline for those few individuals that have survived to a certain age
● Characteristic of fish and invertebrates that release thousands of eggs, have external fertilization, and have no parenting
15
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~Age structure diagram
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● Shows the relative numbers of individuals at each age
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~Zero population growth
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● The number of people at each age group is about hte same and the birth rates and the death rates are about equal
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~Biotic potential
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● Maximum rate at which a population could increase under ideal conditions
● Different populations have different biotic potentials, which are influenced by several factors
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~Exponential growth
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● The population has no predatin, parasitism, or competition
● No immigration or emigration and is in an environment with unlimited resources
● Characteristic of a population that has been recently introduced into an area
19
Q
~Carrying capacity (K)
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● Limit to the number of individuals that can occupy one area at a particular time
● Each particular environemnt has its own carrying capacity around which the population size oscillates
● Changes as the environemntal conditions change
20
Q
~Limiting factors
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● Factors that limit population growth
● Density-dependnet and density-independent
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~Density-dependent factors
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● Those factors that increase directly as the population dnsity increases
● Include competition for food, the buildup of wastes, predation and disease
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~Density-independent factors
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● Those factors whose occurrence is unrelated to the population dnsity
● include earthquakes, storms, and naturally occurring fires and floods
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~R-strategists
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● Opportunistic ● Reproduce rapidly when the environemnt is uncrowded and resources are vast ● Many young population ● Little or no parenting ● Rapid maturation ● Reproduce once ● Ex) insect
24
Q
~K-stategists
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● Live at a density near the carrying capacity (K) ● Few young ● Intensive parenting ● Slow maturation ● Reproduce many times ● Ex) mammals
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~Species richness
● The number of different species in the community
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~Relative abundance
● The proportion of different species within a community
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~Diverse communities
● More productive because they are more stable and survive for longer periods of time
● Better able to withstand adn recover from environemntal stresses such as drought or an incursion by invasive species
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~G.F. Gause
● Developed the competitie exclusion principle after studying the effects of interspecific competition in a laboratory setting
● When he cultured two species separately, each population grew rapidly and then leveled off at the carrying capacity
● When he put the two cultures together, one species had the advantage and dorve hte other species to extinction
● He stated that two species cannot coexist in a community if they share a niche (use the same resources)
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~Resource partitioning
● If two species inhabit the same niche and therefore compete for resources, one of the species will evolve through natural selection to exploit different resources
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~Character displacement
● Occured on the Galapagos Islands
● Finches evolved different beak sizes through natural selection and were able to eat different kinds of seeds and avoid competition
● Divergence in body structure
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~Predation
● One animal eating another animal or animals eating plants
| ● For their protection, animals and plants have evolved defenses against predation
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~Active defenses
● Animals have evolved active defenses such as hiding fleeing or defending themselves
● Very costly in terms of energy
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~Passive defenses
● Animals have also evolved passive defenses such as cryptic coloration or camouflage that make the prey difficult to spot
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~Aposematic coloration
● Very bright, often red or orange, coloration of poisonous animals as a warning that possible predators should avoid them
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~Bastesian mimicry
● Copycat coloration where one harmless animal mimics the coloration of one that is poisonous
● One example is the viceroy btterfly which is harmless but looks very similar tot he monarch butterfly, which stores poisons in its body from the milkweed plant
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~Mullerian mimicry
● Two or more poisonous species, such as the cuckoo bee and hte yellow jacket, resemble each other and gain an advantage from their combined numbers
● Predators learn more quickly to avoid any prey with that appearance
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~Herbivory
● Interaction in which an organism eats part/s of a plant or alga
● They have special adaptations for gazing the right plant body or flower, such as specialized teeth or a modified digestive system
● Platns have evolved spines and thorns and chemical poisons such as strychnine, mescaline, morphine and nicotine to fend off attack by animals
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~Symbiosis
● When two ro more species live in direct and intimate contact with each other
● Can be helpful, harmful or neutral
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~Mutualism
● Symbiotic relationship where both organisms benefit
| ● An example is the bacteria that live in the human intestine and produce vitamins
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~Commensalism
● Symbiotic relationship where one organism benefits and one is unaware of the other organism
● Barnacles that attach themselves to the underside of a whale benefit by gaining access ot a variety of food osurces as the whale swims into different areas
- In addition, the whale is unaware of hte barnacles
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~Parasitism
● Symbiotic relationship where one organism, the parasite, benefits while the host is harmed
● A tapeworm in the human intestine is an example
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~Facilitation
● Organisms can have positive effects on the survival and reproduction of toher species without livign in direct and intimate contact with them
● Ex) Black rush Juncus gerardi, which makes the soil more hospitable for other species in New England slat marshes
- it helps prevent salt buildup int he soil by shading the soil surface and reducing evaporation
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~Gross primary productivity (GPP)
● Amount of light energy that is converted to chemical energy by photosynthesis per unti time
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~Net primary productivity (NPP)
● Equal to the GPP minues the energy used by producers for their own cellular respiration
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~Food chain
● Pathway along which food is transferred from one trophic or feeding level to another
● Energy, in the form of food, moves from the producers to the herbivores to the carnivores
● Only about 10% of the energy stored in any trophic level is converted to organic matter at the next trophic level
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~Food pyramid
● A good model to demonstrate the interaction of roganisms in the food chain and hte loss of energy is the food pyramid
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~Food web
● Food chains are interwoven with other food chains into a food web
● An animal can occupy one trophic level in one food chain and a different trophic level in another food chain
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~Producers
● Autotrophs
● Green platns
● Convert light energy to chemical bond energy
● Have the greatest biomass of any trophic level
● Ex) diatoms and phytoplankton
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~Primary consumers
● Heterotrophs
● Herbvores
● Eat the producers
● Ex) grasshoppers, zooplankton
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~Secondary consumers
● Heterotrophs
● Carnivores
● Eat the primary consumers
● Ex) Frogs, small fish
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~Tertiary consumers
● Heterotrophs
● Carnivores
●Eat the secondary consumers
● Top of the food chain
● Havee the leat biomass of any other trophic level in the food chain
● Least stable trophic level level and most sensitive to fluctuations in populations of the other trophic levels
● Ex) hawk
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~Species diversity
● The variety of kinds of organisms that make up a community
● Has two components: species richness and relative abuncance
● Communities with greater diveristy are generally better able to withstand invasive species
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~Invasive species
● Organisms that become established outside their native range
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~Dominant species
● Species that are the most abundant or that collectively have the highest biomass in a community
● They exert control over the abundance and distribution of other species
● Ex) Sugar maples in North Ameircan forests
- They affect the biotics factors, such as shade and soil nutrients (from rotting leaves) which in turn provide special habitats for many other species
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~Keystone species
● Not abundant in community
● They exert major control over other species in the community
● Ex) Sea otters in North Pacific
- They are high in the food chain and feed on sea urchins, which feed mainly on kelp
- Where the sea otters are abundant, there are few sea urchins and kelp forests are abundant
- In contrast, where orcas feed on sea otters, sea urchins are abundant and kelp is rare
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~Bottom-up model
● Focuses on influence from lower to higher trophic levels
● Ex) An increase of minerals available in the environment will increase the biomass of the producers, and will increase the biomas up to and including the highest trohic level
- If you add or remove predators to the bottom-up community, the effect will not extend down tot he bottom levels
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~Top-dwon model/Trophic cascade model
● Removing the top carnivores from a community increases the abundance of lower primmary carnivores, which decreases the number of herbivores, resulting in an increase in the mass of producers
● Ex) Worlves in Yellowstone Park
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~Biological magnification
● Organisms at higher trophic levels have greater concentrations of accumulated toxins stored in their bodies than those at lower trophic levels
● The bald eagle almost became extinct because Americans sprayed heavily with the pesticide DDT in the 1950s, which entered the food chain and accumulated int he bald eagle
- It interferes with the deposition of calcium in eggshells, the thin-shelled eggs were broken easily and few eaglets hatched
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~Decomposers
● Bacteria and fungi
● Usually not depicted in any diagram of a food chain
● Without decomposers to recycle nutrients back to the soil to nourish plants, there would be no food chain and no life
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~Ecological successtion
● Process that follows the destruction
| ● Primary and secondary
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~Primary ecological succession
● If the rebuilding begins in a lifeless area where even soil has been remove
● Essential and dominant characteristic of primary succession is soil building
● The pioneer organisms are lichens and mosses
● Soil develops gradually as rocks weather and organic matter accumulates from the decomposed remains of the pioneer organisms
● Once soils is presnet, pioneer organisms are overrun by other large organisms: grasses, bushes, and then trees
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~Lichen
● A symbiont consisting of algae and fungi
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~Mosses
● Introduced to the area of succession as spores by wind
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~Pioneer species
● The first organisms to inhabit an area
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~Climax community
● THe final stable community that remains in an area after succession
● Remains until dstroyed by a blowout
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~Blowout
● A disaster that destroys the ecosystem once again
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~Secondary succession
● When an existing community has been cleared by some disturbance that leaves the soil intact
● Happed in 1988 in Yellowstone National Park when fires destroyed all the old growth that was dominated by lodgepole pine but left the soil intact
● Wihin one year, the burned areas in Yellowstone were covered with new vegetation
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~Biomes
● Large regions of the earth whose distribution dependso n the amount of precipitation and temperature in an area
● Each biome is characterized by dominant vegetation and animal life
● From the equator to the most northerly climes, there is a trned in terrestrial biomes: tropical rain forest, desert, grasslands, temperate deciduous forest, taiga and tundra
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~Tropical rain forest
● Found near the equator with abundant rain fall, stable temperatures, and high humidity
● Most diversity of species (trees and animals)
● Dominant trees are very tall
● Many trees are covered with epiphytes
● Some are bdiversity hotspots, meaning that many species are endangered
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~Epiphytes
● Photosynthetic plants htat grow on other trees rather than supporting themselves
● THey are not parasites but may kill the tress inadvertently by blocking the light
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~Desert
● Less than 10 in (25 cm) of rainfall per year; not even grasses can survive
● Experiences the most extreme temperature fuctuations of any biome
● Characteristic plants are the drought-resistant cactus with shallow roots to capture as much rain as possible during hard and hsort rains, which are characteristic of the desert
● Other plants include sagebrush, creosote bush and mesquite
● Most animals are active at night
● Ex) Sahara Desert
● Animals are rodents, kangaroo rats, snakes, lizards, arachnids, insects, and a few birds
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~Temperate deciduous forest
● Found in the northeast of North America, south of hte taiga and characteriazed by trees that drop their leaves in winter
● Includes many more plant species than does the taiga
● Shows vertical stratification of plants and animals
● Soil is rich due to decomposition of leaf litter
● Principal mammals include squirrels, deer, foxes, and bears--dormant or hibernate through the cold winter
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~Vertical stratification
● Species that live on the group, the low branches, and the treetops
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~Conifer forest--taiga
● Located in northern Canada and much of the world's northern regions
● Dominated by conifer (evergreen) forests, like spruce and fir
● Landscape is dotted with alkes, ponds, and bogs
● Very cold winters
● Largest terrestrial bmoe
● Characterized by heavy snowfall
● Mammals include moose, black bear, lynx, elk, wolverines, martens, and porcupines
● Flying insects and birds are prevalent in summer
● Has greater variety in species of animals than does the tundra
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~Tundra
● Located int he far northern parts of North America, Europe, and Asia
● Characterized by permafrost
● Commonly referred to as the frozen desert--very little rainfall
● Gently rolling plains with many lakes, ponds, and bogs in depressions
● Insects particualrly flies are abundant
● Mammals include reindeers, caribou, arctic wolves, arctic foxes, arctic hares, lemmings, and polar bears
● Number of individual organisms is large, the number of species is small
● Strong carbon sink
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~Permafrost
● Permanently frozen subsoil found in the farthest point north including Alaska
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~Aquatic biomes
● Cover about 75% of Earth
| ● Primary distinction is salinity
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~Freshwater biomes
● Salinity of less than 0.1% and include rivers, streams, ponds, and wetlands
● Stored in groundwater
● makes up less than 4% of aquatic biomes
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~Estuaries
● Located at the mouths of rivers where saltwater and freshwater mix
● Salt marshes and mangrove forests are estuaries atht support enormous populations of animal life
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~Marine biome
● Salinity of 3% on average
● Large biome
● Most stable biome with temperature that vary little
●Provides most of the earth's food and oxygen
● Divides into different regions classified by amount of sunlight, desiance from the shore, open water/ocean bottom and water depth
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~Water cycle
● Water evaporates from the earth, forms clouds, and rains over the oceans and land
● Some rain percolates through the soil and makes its way back to the seas
● Some evaporates directly from the lands, but most evaporates from plants by transpiration
● The ocean contain 97% fo the water, about 2% in glaciers and 1% in lakes, rivers, and ground water
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~Carbon cycle
● Basis are photosynthesis and respiration
● Cell respiration by animals and bacterial decomposers add CO2 to the air and removes O2
● Burning of fossil fuesl adds CO2 to the air
● Photosynthesis removes CO2 from the air and adds O2
● Major reservoir of carbon is fossil fuels, plant and animal biomass
● Also found in soil, oceans, sediments in aquatic ecosystem and atmosphere
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~Nitrogen cycle
● Very little nitrogen enters ecosystem directly from the air
● Most of it enters ecosystems by way of bacterial processes
- Nitrogen fixing bacteria
- Nitrifying bacteria
- Denitrifying bacteria
- Bacterial of decay
● The main reservoir of nitrgoen is the atmosphere
● Also found bound in the soil, lake, river nad ocean sediments or fixed into animal and plant biomass
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~Nitrogen-fixing bacteria
● Live in the nodules in the roots of legumes
| ● Convert free nitrogen intot he ammonium ion (NH4+)
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~Nitrifying bacteria
● Convert the ammonium ion into nitrites and then into nitrates
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~Denitrifying bacteria
● Convert nitrades into free atmospheric nitrogen
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~Bacteria of decay
● Decompose organic matter into ammonia
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~Eutrophication
● Humans disrupt freshwater ecosystem
● Runoff from sewage and manure from pastures increase nutrients in lakes and cause excessive growth of algae and other plants
● Shallow areas become choked with weeds, and swimming abd boating become impossible
● Ultimately, the lake disapears
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~Acid rain
● Caused by pollutants in the air from combustion of fossil fuels
● Nitrogen and sulfur pollutants int he air turn into nitric, nitrous, sulfurous, and sulfuric acids, which cause hte pH of the rain to be less than 5.6
● This kills the organisms in lakes and damages ancient sone architecture
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~Toxins
● From industry have gotten into the food chain
● most cattle and chicken feed contain antibiotic snad hormones to accelerate animal growth but may heave serious ill afects on humans who eat them
● Any carcinogens/teratogens that get into the food chain accumualte and remain in the human body's fatty tissues because we occupy the top of the food chain
- Biological magnification
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~Carcinogens/teratogens
● Causing birth defects
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~Greenhouse effect
● CO2 and water vapor int he atmosphere abosrb and retain much of hte light and heat that comes to Earth from the sun
● Increased by more than 40% during the last 150 years due to burning of fossil fuels and deforestation
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~Global warming
● Increase in temperature around the world
● Snow and ice melt, uncovering darker and more absorbent surfaces in the north
● More radiation is absorbed nad Earth is wamred even more
● Greenhouse effects
● Increase likelihood of fires
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~Acidification of the oceans
● CO2 from the atmosphere normally dissolves in the oceans by combining with H2O to form carbonic acid
● With increased atmospheric CO2, the ocean becomes more acidic
● Results in a decrease in [Carbonate ions] that is reuired by many organisms
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~Depleting the ozone layer
● The accumulations in the air of chlorofluorocarbons have caused the formation of a hole in the protective ozone layer
● This allows more ultraviolet (UV) light to reach the earth, which is responsible for an icnrease in the incidence of skin cancer (melanoma) worldwide
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~Introducing new species
● Humans have moved species from one area to another with serious consequences
● Ex) killer honeybees and azebra mussel
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~Pesticides
● Chemicals that kill organisms that we consider to be undesirable
●Include insecticides, herbicides, fungicides, and mice and rat killers
● Save lives by increasing food production and by killing animals that carry and cause diseases like bubonic plague and malaria
● Exposure to pesticides can cause cancer in humans
● Ensures the development of resistant strains of pests
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~What are the five properties of populations?
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● Size
● Density
● Dispersion
● Survivorship curves
● Age structure diagrams
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~What are the factors that influence biotic potentials?
● Age at which reproduction begins
● Life span during which the organisms are capable of reproducing
● number of reproductive periods in the lifetime
● Number of offspring the organism is capable of reproducing
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~What are communities characterized by?
● How diverse and dense they are
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~What are the two components of species diversity?
● Species richness
| ● Relative abundance
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~What can interactions within a community be divided into?
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● Competition
● Predation
● Herbivory
● Symbiosis
● Facilitation
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~What are the two related outcomes of competition, besides extinction?
● Resource partitioning
| ● Character displacement -- Galapagos Islands
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~What are examples of herbivores?
● Cattle graze on grass
● Invertebrates like beetles and grasshoppers also eat vegetation
● In the ocenas, herbivores include snails, sea urchins, and manatees
105
~How do differnet ecosystems vary in their NPP and contibution to the global NPP?
● Tropical rain forests are among the most productive terrestrial ecosystems and contribute a large portion of Earth's overall net proimary production
● Coral reefs have a very high NPP but contribute relatively little to the global NPP because they occupy such a tiny part of the planet
● Open oceans have low NPP per unit area but their global NPP is higher than any other biome becuase they occupy 3/4 of the globe
106
~How long are food chains and why?
● They are rather short because of the loss of energy from one trophic level to the next
● They never have more than four or five trophic levels
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~Why are long food chains less stable than short ones?
● Population fluctuations at lower trophic levels are magnified at higher levels, causing local extinction of top predators
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~What are the two modles for the structure of a community based on direction of influene?
● Bottom-up model
| ● Top-down model
109
~What factors can alter the community?
● Migration of a new species into a habitat can alter the netire food chain
● Major disturbances, whether natural or human-made, like volcanic eruptions, stirring minig, clear-cutting a forest, and forest fires, can suddenly and drastically destroy a community or an entire ecosystem
110
~What is an example of primary succession?
● As lakeshore gradually receded northward after the last ice age at the osuthern edge of Lake Michigan, it left a series of new beaches and sand dunes exposed
● The communities represent the various stages beignning with bare, sandy beach and ending with a climax community of old, well-established forests
- In some cases, the climax community is a beech-sugar maple forest, in other areas the forest is a mix of hickory and oak
111
~What happens when large populations of photosynthetic organisms die during eutrophication?
● Organic material accumaltes on the lake bottom and reduces the depth fo the lake
● Detrivores use up oxygen as they decompose the dead organic matter
- Lower oxygen levels make it impossible for some fish to live
- As fish die, decomposers expand their activity and oxygen levels continue to decrease
● ultimately, the lake disappears
112
~What are the solutios to global warming?
● Reduce CO2 emissions by industrialized nations
● Reduce deforestation
- FOrests abosrb CO2 form the atmosphere and store carbon in their wood, leaves, and soil
113
~What disastrous effects would global warming have on the population?
● Polar ice caps to melt, raising the level oft he seas
● Coral reefs are under increased physiological stress
● Oysters and sea urchins are also suffering becuase of increased acidificaiton of hte oceans due to an increase in CO2 dissovled in the ocaen
114
~How did killer honeybee impact the ecosystem?
● The African honeybee is a very aggressive subspecies of honeybee that was brought to Brzail in 1956 to breed a variety of bee that would produce more honey in the tropics than the Itlalian honeybee
● The African honeybees escaped by accident and have been spreading throughout the Americas
● Ten people were killed by these bees in the US by the year 2000
115
~How did the zebra mussel impact the ecosystem?
● In 1988, the zebra mussel, a fingernail-sized mollusk native to Asia, was discovered in a lake near Detroit
● WIthout any local natural predator to limit its growth, the mussel population exploded
● They were first discovered when they were found to have clogged the water intake pipes of those cities whose water is supplied by Lake Erie
● The influx of the zebra mussel threatens several native species with extinction by outcompeting indigdnou species
116
~What are some biolgocia control instead of pesticides?
● Use crop rotation--change the crop planted in a field
● Introduce natural enemies of the pests--don't disrupt an ecologicla balance
● Use natural plant toxins instead of synthetic ones
● USe insect birth control--expose them to radiation
