Ecology O2 Nutrients CO2 Ecology is the study of therelationships betweenorganisms and their physicaland biotic environment: Relationships involveinteractions with the physicalworld as well asinterrelationships with otherspecies and individuals of thesame species. Biological Complexity
Living organisms can bestudied at different levels ofcomplexity. From least to mostcomplex, these levels are(in an ecological context): Individual Population Community Ecosystem Biome Biosphere Biosphere Biome Ecosystem Community Population Individual The Biosphere The biosphere isthe region within which all living things are found on Earth. It is the narrow belt around the Earth extending fromthe bottom of the oceans to the upper atmosphere. Image: NASA Exploring the Biosphere
Life exists in all places, from blind white crabs in lightless environments... Our knowledge of what constitutesthe biosphere continues todevelop as scientists continuetheir exploration of the Earth. The biosphere extends into theEarths crust, below the oceansand deep into rock fissures; itextends well into the Earths upper atmosphere. to tube worms in the crushing ocean depths. Lichens are found on rocks, trees, and bare ground.
Habitat An organisms habitat is the physical place or environment inwhich it lives. Organisms show a preference for a particular habitat type, butsome are more specific in their requirements than others. Most frogs, like this leopard frog, live in or near fresh water, but a few can survive in arid habitats. Lichens are found on rocks, trees, and bare ground. Habitat Range An organisms habitat is not always of a single type. Some organismsoccupy a range of habitats. There are various reasons why: Highly adaptable in habitat requirements. Different, but equivalent, resources available in different habitats. Reduced competition for resources in sub-optimal habitats. Habitat extremes may influence growth form, especially in plants. Habitat Preference Organisms may select particularareas within their general habitat,even in apparently homogeneousenvironments, such as water.This is termed habitat preference. Example: Aquatic organisms mayshow a preference for a particularsubstrate type, water depth orvelocity, water clarity, or degree ofvegetation cover or habitatdisturbance. Knowledge of habitat preferencecan be used to protect species intheir environment. Damselfly nymph Rainbow trout Resources in a Habitat The habitat provides organismswith the following resources: Food and water sources Mating sites Nesting sites Predator avoidance Shelter from climatic extremes However, the organism may ormay not have the adaptationsto exploit all the availableresources fully. Adaptations An adaptation (or adaptivefeature) is an inheritedfeature of an organism thatenables it to survive andreproduce in its habitat. Adaptations are the endresult of the evolutionarychanges that a species hasgone through over time. Adaptations may be: behavioral physiological structural (morphological) Osprey: a diurnal bird of prey Spotted owl: a nocturnal bird of prey Exploiting a Habitat Organisms have adaptations toexploit, to varying extents, theresources in their habitat. Where resource competition isintense, adaptations enableeffective niche specializationand partitioning of resources. In the African savanna, grazingand browsing animals exploitdifferent food resources withinthe same area or even withinthe same type of vegetation.