Introduction to EcologyIntroduction to EcologyChapter 50Chapter 50

What is ecology?

• Ecology is the study of how organisms interact with their environment;

• “Eco” from “Oiko” = “home”

• What factors control the distribution and abundance of organisms?

1. Types of Ecology1. Types of Ecology•Organismal (physiological and behavioral)Organismal (physiological and behavioral)•PopulationPopulation•CommunityCommunity•EcosystemEcosystem•GlobalGlobal

Organismal ecologyOrganismal ecology

• Questions center on how organisms respond Questions center on how organisms respond to biotic and abiotic factors in their to biotic and abiotic factors in their environmentenvironment

• Physiology, morphology, and behaviorPhysiology, morphology, and behavior

Population ecologyPopulation ecology• A population is a group of organisms of the same species A population is a group of organisms of the same species

living in the same place at the same time.living in the same place at the same time.• Questions are related to factors that affect the number of Questions are related to factors that affect the number of

individuals living in a habitat individuals living in a habitat

– – size, distribution of population?size, distribution of population?

- birth and death rates?- birth and death rates?

- population growth rate?- population growth rate?

Community ecologyCommunity ecology

• A community consists of the organisms that A community consists of the organisms that live in an area and interactlive in an area and interact

• Questions focus on Questions focus on – the interactions between organisms (who eats the interactions between organisms (who eats

who, who helps who)who, who helps who)– how those interactions affect community how those interactions affect community

structurestructure

Mutualism

Predators and parasites

Competition

Species Interactions

Ecosystem ecologyEcosystem ecology

• An ecosystem consists of the biotic (living) An ecosystem consists of the biotic (living) community and the abiotic (nonliving) community and the abiotic (nonliving) factors that affect it.factors that affect it.

• Abiotic factors are things such as soil, Abiotic factors are things such as soil, atmosphere, water, nutrients, energy, atmosphere, water, nutrients, energy, temperaturetemperature

• Questions emphasize energy flow and Questions emphasize energy flow and cycling of nutrientscycling of nutrients

Global ecologyGlobal ecology

• Controls and patterns of worldwide Controls and patterns of worldwide circulation of energy and nutrientscirculation of energy and nutrients

• Factors that affect climateFactors that affect climate

Atmospheric CO2 and Temp.

2. What factors affect the 2. What factors affect the distribution of organisms?distribution of organisms?

• Species dispersalSpecies dispersal

• Behavior and habitat selectionBehavior and habitat selection

• Biotic factors-Other organisms such as Biotic factors-Other organisms such as predators, competitors, or facilitatorspredators, competitors, or facilitators

• Abiotic factors such as nutrient availability, Abiotic factors such as nutrient availability, water, temperaturewater, temperature

What affects the distribution of What affects the distribution of organisms?organisms?

Fig. 50.6 Flowchart of factors limiting geographic distribution. As ecologists study the factors limiting a species’ distribution, they often consider a series of questions like these.

Species dispersalSpecies may not inhabit Species may not inhabit an area because of an area because of biogeographical biogeographical boundaries.boundaries.

Transplantation Transplantation studies can give us studies can give us information about information about potential ranges.potential ranges.

Fig. 50.6

- Breakdown in dispersal barriers- Breakdown in dispersal barriers- Most do not cause problems- Most do not cause problems- Some do- Some do- Problems can be large, - Problems can be large, expensive, and difficult or expensive, and difficult or impossible to reverseimpossible to reverse

Fig. 50.8 – Zebra mussel

Application: Introduced speciesApplication: Introduced species

Behavior and habitat selectionBehavior and habitat selection

• Organisms do not always occupy all Organisms do not always occupy all available, suitable habitatavailable, suitable habitat

• May be specific in reproduction needsMay be specific in reproduction needs

• In insects- larval needs may be different In insects- larval needs may be different from adult needsfrom adult needs

Biotic factorsBiotic factors

• Interactions with Interactions with other organismsother organisms– Negative: Negative:

predation or predation or competitioncompetition

– Positive: Positive: facilitation (e.g., facilitation (e.g., pollinatorspollinators

urchin vs. limpets Fig. 50.9

Abiotic factorsAbiotic factors• TemperatureTemperature

– high temperature cause cell high temperature cause cell membranes to leak and membranes to leak and enzymes to stop workingenzymes to stop working

– low temperature causes low temperature causes freezingfreezing

- some animals have some animals have antifreezes that allow antifreezes that allow them to survive below them to survive below freezing temperatures.freezing temperatures.

Antarctic notothenioids

Fig. 27.1 – thermophilic bacteria, Nevada

Abiotic factorsAbiotic factors• Water availabilityWater availability

- too little water (desiccation)too little water (desiccation)- Deserts, saltwaterDeserts, saltwater

- too much water (anaerobic)too much water (anaerobic)

Organ pipe cacti, desert shrubs

Mangroves

Abiotic factors – Water availabilityAbiotic factors – Water availabilityAllAll terrestrial organisms terrestrial organisms

Leaves, stomata Insects – tolerate, cuticle

Abiotic factorsAbiotic factors• SunlightSunlight

- Competition, shade tolerance for Competition, shade tolerance for plantsplants

- Photic zone, different wavelengths Photic zone, different wavelengths for aquatic organismsfor aquatic organisms

Abiotic factorsAbiotic factors• WindWind

– exacerbates the effects exacerbates the effects of temperature and of temperature and water losswater loss

– also exerts forces on also exerts forces on organisms (waves act organisms (waves act in the same manner)in the same manner)

Flagging of tree limbs due to wind

TemperatureTemperature

• Temperature is Temperature is partly determined partly determined by the amount of by the amount of solar radiation solar radiation hitting an areahitting an area

• Depends on Depends on latitude, angle of latitude, angle of incidenceincidence

Fig. 50.11

What causes the seasons?What causes the seasons?We know:- Earth has elliptical orbit- Earth is tilted on axis (23.5o)-Seasons are opposite in northern and southern latitudes

-It can NOT be the distance of the earth from the sun since the seasons are opposite in the northern and southern hemispheres.

TemperatureTemperature• Seasons are caused by the tilt of the earth as Seasons are caused by the tilt of the earth as

it revolves about the sunit revolves about the sun

Fig. 50.12

WaterWater• Warming air absorbs water and cooling Warming air absorbs water and cooling

releases water, causing more rain at some releases water, causing more rain at some latitudeslatitudes

Fig. 50.13

WaterWater• Wind patterns interact with mountains to cause Wind patterns interact with mountains to cause

increased rain on windward sides, rain shadows increased rain on windward sides, rain shadows on lee sides.on lee sides.

Fig. 50.14 How mountains affect rainfall.

MicroclimatesMicroclimates• Within a biome, region or habitat, temp., water, Within a biome, region or habitat, temp., water,

sunlight and other factors can vary dramaticallysunlight and other factors can vary dramatically• These form small areas with microclimates or These form small areas with microclimates or

microhabitatsmicrohabitats• Can have strong effects on species rangesCan have strong effects on species ranges

Fig. 50.26

Aquatic biomes cover about 75% of the earth’s surface

• Wetlands

• Oceanic pelagic

• Lakes

• Rivers, streams

• Intertidal zones

• Coral reefs

• Benthos

Oligotrophic Lake: Nutrient poor, water is clear, oxygen rich; little productivity by algae, relatively deep with little surface area.

1. Lakes

• Eutrophic lake: nutrient rich, lots of algal productivity so it’s oxygen poor at times, water is murkier often a result of input of agricultural fertilizers

1. Lakes

Rivers and Streams: Organisms need adaptations so that they are not swept away by moving water; heavily affected by man changing the course of flow (E.g. dams and channel-straightening) and by using rivers to dispose of waste.

Wetlands: includes marshes, bogs, swamps, seasonal ponds.

Among richest biomes with respect to biodiversity and productivity. Very few now exist as they are thought of often as wastelands.

Estuary: Place where freshwater stream or river merges with the ocean. Highly productive biome; important for fisheries and feeding places for water fowl. Often heavily polluted from river input so many fisheries are now lost.

Intertidal Zone: Alternately submerged and exposed by daily cycle of tides. Often polluted by oil that decreases biodiversity.

Coral Reefs: occur in neritic zones of warm, tropical water, dominated by cnidarians (corals); very productive, protect land from storms; most are now dying from rise in global temperatures

Deep-sea vent: Occurs in benthic zone; diverse, unusual organisms; energy comes not from light but from chemicals released from the magma.

BiomesBiomes• Regions of the earth Regions of the earth

that are similar in that are similar in organism type organism type although the although the particular species particular species differdiffer

• Driven largely by Driven largely by climate – temp., climate – temp., water, seasonalitywater, seasonality

• Other factors – soil, Other factors – soil, topography topography

Fig. 50.10 – Biomes of North America

BIOMES

Any Questions??