An Introduction to Ecology

Objective

What are the abiotic and biotic components of ecosystems and how do they affect living organisms?

What is ecology?

The study of the interactions between organisms and the environmentEcology and evolution are very closely related topics

What is ecology?The environment an organism inhabits includes all the abiotic components – water, soil, sunlight, temperature, etc. AND all the biotic components – other organisms that must compete, defend, prey upon, etc.When studying ecology and organisms, we often want to know what effect a particular component has on a population

What factors affect the kangaroo distribution?Temperature?Water?Predators?Competition?

The hierarchy of ecology

OrganismPopulationCommunityEcosystemBiosphere

Ecology is complex!It is difficult to know all the connections between organisms and their environmentBut decisions must be made…The precautionary principal is usually followed – cautions us to consider carefully the consequences of our actions and work to prevent problems rather than try to fix them after the fact

When a course of action might have a potentially serious impact, one approach is to adopt the precautionary principle. Rather than assuming something is safe until proven otherwise, the precautionary principle argues the opposite: that something should be considered potentially harmful unless shown to be safe.While the precautionary principle aims to protect us against possible dangers, an excessively 'safety-first' approach may have its own drawbacks. For example, we may lose the benefits that a new technology might provide.With Tibbs the cat, doubts about the safety of FelineFine may persuade us to stop using it. That may stop Tibbs being poisoned, but it might harm her in other ways.

The environment limits the distribution of species

– or – not everyone can live everywhereDispersal – movement out of a high density area

Natural range expansions Species transplants – intentional or accidental introduction of a species to a new area

Actual range vs. potential range

Climate Major components:

TemperatureWaterSunlightWind

Macroclimate – global/regionalMicroclimate – very small

(like under a fallen log)

MacroclimateAffected by

WaterLarge bodies of water have a moderating effectCurrents carry warm or cold air

Climate

Affected by Mountains

Windward vs. leeward sides

ClimateAffected by

Seasonality

BiomesA biome is an ecosystem type, classified by dominant vegetation and organism adaptations

Aquatic BiomesLakesCoral ReefsRiversOpen OceanEstuariesIntertidal ZonesAbyssal Zones

Aquatic BiomesMany are physically and chemically stratifiedPhotic zone - where light is absorbedAphotic zone - little to no light penetratesBenthic zone - the bottom

Organisms that live here called benthic or benthos

They eat detritus

Terrestrial BiomesTropical forestSavannaDesertChaparralTemperate grassland

Temperate broadleaf forest Coniferous forestTundraHigh mountainsPolar ice

Terrestrial BiomesInfluenced mostly by climateSince climate varies by latitude, we see latitudinal patterns of distribution in biomes

Terrestrial BiomesVertical stratification importantPlants provide the stratification

CanopyLow treesShrubsLitter layer (forest floor)

Many organisms adapted to a particular layer

Terrestrial BiomesDon’t have clear, defined boundariesEcotone - area where one biome grades into another

Find different organisms here

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