Ecologyand the

Biosphere

Chapter 50

Ecology is the scientific

study of the interactions between

organisms and their environment

Emphasis

scientific study

interactions

environment

Environmental Components

Abiotic Components(non-living chemical and physical factors)

Temperature Light Water Nutrients

Biotic Components(other organisms)

Predators and their PreyPathogens and their Hosts

Competitors …same species or other Organisms that modify the environment

Broad Range of Research

Adaptatons of Organisms

Ecosystem Dynamics

Four Major Sub disciplines

Organismal Ecology

Population Ecology

Community Ecology

Ecosystem Ecology

Increasing

complexity

adaptations of individuals to

their environment

all of the individuals of a species in a site

all of the populations in a site

all of the biotic (community) and

abiotic factors in a site

Ecology

Biomes of the Biosphere

Abiotic factors of Biosphere

Temperature

Water

Sunlight

Wind

Substrate: Rocks and soil

Disturbances

Temperature

• Temperature influences biological processes …chemistry and physiology

a) freezing can rupture cellsb) high temperatures denature proteins & NAs

• Organisms can only regulate body temperatures within narrow ranges of temperature

a) metabolism slows down at low and high temperaturesb) endotherms and extreme specialists are exceptions, but

still operate within ranges of acceptable temperatures

Water

• Aquatic and marine organisms face challenges of maintaining osmotic balance

• Terrestrial organisms confront the problem of dessication, which has been an vital factor in the evolution of many lineages

Sunlight

• Virtually all ecosystems rely on sunlight for energy

• But sunlight is not the prime determinent of plant distribution

• Light can be limiting under canopies and in aquatic environments …both are shade conditions

• Sunlight heats the earth uneavenly, resulting in climate variation

Wind

• Wind chill exacerbates cold temperatures

• Wind can exacerbate water loss by increasing evaporation

• Wind moves air masses and moisture, influencing the distribution of temperature and moisture variation

Rocks and Soil

• physical structure, pH, nutrient content

• limits the distribution of plants and the animals that feed on them …resulting in patchiness of biotic communities

Disturbance

• Fires, extreme stroms, volcanic eruptions

• Disturbance can devastate biota

• Resets community, resulting in succession

• Succession of biota, emphasizing disperal early, then competitive ability later …major trade-off

Climate

Sunlight

Temperature

Water

Wind

Climograph of Biomes (major ecosystems)

overlap indicates that other factors are involved too

Climograph of Biomes (major ecosystems)

identify at least three patterns in this climograph

Biomes of the Biosphere

Causes of Global Climate Patterns

Causes of Global Climate Patterns

Causes of Global Climate Patterns

Solar energy incident to planet's surface

Movement of planet through space

Solar Energy

• Half of the solar radiation is aborbed in the atmosphere, especially high energy wave lengths (e.g., UV radiation absrobed by ozone)

• Solar radiation heats the planet's surface unevenly

• Which creates patterns of atmospheric activity

• Which influences where moisture is captured or deposited

Why does the falling air at 30° move to the west if it moves toward the equator,

and to the east if it moves to the poles?

30°

60°

90°

0°

30°

60°90°

BiomeDistributions

Effects of Mountains

• Rain shadows

• Slopes facing the equator are warmer

• Increases in altitude mimic increases in latitude:

6° C per 1000m altitude

or 880 km latitude

Aquatic Biomes

Turnover mixes stratified lakes and ponds,moving oxygen down and nutrients up

Biotic Zonation in Lakes and Ponds

Nutrient Conditions

• Deep lakes are often nutrient poor

oligotrophic

• Lakes in between are

mesotrophic

• Shallow lakes are often nutrient rich

eutrophic

Zonation in Marine Communities

Organismal Ecology Concepts

Regulators & Conformers

• Regulators: use physiological & behavioral mechanisms to achieve homeostasis in variable environments

e.g., Salmon: marine/aquatic conditions, osmoregulation

• Conformers: allow body conditions to vary with those of external environment, usually in stable environments

e.g., spider crabs (Libinia): doesn't osmoregulate

Tradeoffs

• Energy is the limiting currency

• Competing functions

Regulators and Conformers

Regulatorsand

Conformers

Principle of Allocation

• Organisms have limited energy to invest in competing needs◊ growth, survival & reproduction (maintenance)◊ homeostasis

• Homeostasis is costly◊ grasshoppers (moderately active ectotherms): 70/30◊ weasel (active endotherms): 97.5 versus 2.5 %◊ wren (very active endotherms): 99.5 versus 0.5 %

• Results in Tradeoffs◊ Regulators:

Generalists with broad distributions over variable conditions

◊ Conformers:Specialists with narrow distributions under stable conditions

Responses to Environmental Change

Physiological

Morphological

Behavioral

Physiological Responses: Tolerance and Acclimation

Morphological Responses

sometimes reversible

occurs over developmental time

Behavioral Responses

• Can be almost instantaneous, often reversible

• Examples:

◊ desert animals that burrow in the day to escape heat

◊ seasonal migration

◊ hibernation

◊ honey bees cool their hives by fanning their wings or heat them up by through their activity