2What is Ecology?* Ecology is the study of interactions among organisms and between organisms and their environment.
3Levels of Organization Biosphere – contains the combined portions of the planet in which all of life exists, including land, water, and air/atmosphere. It is our planet as a whole and where ecology takes place.Biome – a group of ecosystems that have the same climate and similar dominant communities.Ecosystem – a collection of organisms that live in a particular place along with their non-living, or abiotic, environment.Communities – assemblages of different populations living together in a defined area.Populations – groups of individuals that belong to the same species and live in the same area.Organism – an individual living thing.Example:Whole Planet↓Temperate ForestPond, plants, animals, water, O2, rocksPond, frogs, fish, plants, algaeAll bullfrogs in pondBullfrogBiotic Factor = living organisms influencing the environmentAbiotic Factor = non-living influences on environment
5A Hierarchy of Interactions Ecology can be divided into four increasingly comprehensive levels:organismal ecology,population ecology,community ecology, andecosystem ecology.
6(a) Organismal ecology (b) Population ecology(c) Community ecology(d) Ecosystem ecology
7A Hierarchy of Interactions Organismal ecology is concerned with evolutionary adaptations that enable individual organisms to meet the challenges posed by their abiotic environments.
8A Hierarchy of Interactions Population ecologyaddresses populations, groups of individuals of the same species living in a particular geographic area andconcentrates mainly on factors that affectpopulation density andgrowth.
9A Hierarchy of Interactions Community ecologyis concerned with communities, all the organisms that inhabit a particular area andfocuses on how interactions between species affect a community’sstructure andorganization.
10A Hierarchy of Interactions Ecosystem ecologyis concerned with ecosystems, all the abiotic factors in addition to the community of species in a certain area andfocuses on energy flow and the cycling of chemicals among the various abiotic and biotic factors.
11Feeding Relationships Trophic structure is the feeding relationships among the various species in a community.A community’s trophic structure determines the passage of energy and nutrients from plants and other photosynthetic organismsto herbivoresand then to predators.
12Feeding Relationships Autotrophs – Producers – produce their own food using sun or chemicalsPlants and algae - by photosynthesis (sun’s energy)Some bacteria – by chemosynthesis (chemical energy)Heterotrophs – Consumers – rely on autotrophs for foodHerbivore – eat autotrophs directly (primary consumers)Secondary consumers and up:Carnivore – eat herbivoresOmnivore – eat both autotrophs and heterotrophsScavengers – feed on carcassesDetritivores – eat decaying plant and animal materialDecomposers – break down organic material and release nutrients
14Food ChainsFood Chains – show the sequence of food transfer between trophic levelsalgae → zooplankton → small fish → squid → shark(notice direction of the arrowheads!!!)This food chain idea works for simple food chains but....
15Food Webs…Food webs are able to show the complexity of more complicated ecosystemsFood webs link all food chains in a community together
18Biological Magnification Organisms can’t metabolize many of the toxins produced by industrial wastes or pesticidesToxins become concentrated as they pass through a food chain in a process called biological magnification.
20Energy Flow**** Sunlight is the main energy source for life on Earth.*****Energy flows through an ecosystem in one direction, from the sun or inorganic compounds to autotrophs (producers) and then to various heterotrophs (consumers). Energy is NOT reused.Chemical cycling is the use and reuse of chemical elements such as carbon and nitrogen within the ecosystem.
22Primary Production and the Energy Budgets of Ecosystems The amount, or mass, of living organic material in an ecosystem is the biomass.The rate at which an ecosystem’s producers convert solar energy to the chemical energy stored in biomassis primary production andyields about 165 billion tons of biomass per year.Different ecosystems vary considerably in their primary production.
23Average primary production (g/m2/yr) Open oceanEstuaryAlgal beds and coral reefsDesert and semidesert scrubTundraTemperate grasslandCultivated landNorthern coniferous forest (taiga)SavannaTemperate broadleaf forestTropical rain forest5001,0001,5002,0002,500Average primary production (g/m2/yr)
24Ecological Pyramids****Pyramid of production (aka energy pyramid) – only roughly 10% of energy can be transferred to next trophic level because organisms use energy for respiration (breathing), movement, and reproducing. More levels between a producer and a top-level consumer means less energy remains from original amount = limited food chain length supported and more room needed for top level consumers****
25Tertiaryconsumers10 kcalSecondaryconsumers100 kcalPrimaryconsumers1,000 kcalProducers10,000 kcal1,000,000 kcal of sunlight
26Ecological PyramidsBiomass Pyramid – shows amount of potential food for each trophic level (grams per unit area)Pyramid of Numbers – shows number of individuals at each trophic level.
27Ecological Pyramids Energy Pyramid Shows the relative amount of energy available at each trophiclevel. Organisms use about 10percent of thisenergy forlife processes.The rest is lostas heat.Pyramid of NumbersShows the relativenumber of individualorganisms at eachtrophic level.Biomass PyramidRepresents the amount ofliving organic matter at eachtrophic level. Typically, thegreatest biomass is at thebase of the pyramid.