Ecology

The study of organisms and their

interaction with the environment

Ecology Biosphere– broadest,

most inclusive level of

organization

- deepest part of the

ocean to 6 miles

above the earth

- all organisms are

found within the

biosphere

The biosphere is

divided into biomes.

The biosphere is a thin layer at

Earth’s surface that extends

from about 9km above the

Earth’s surface down to the

bottom of the ocean. Observe a visual model of Earth's spheres.

The Biosphere- includes all

life forms of all sizes in all

habitats.

Ecosystems • found within the biosphere

• all organisms and non-living

environment

- biotic factors – living components

of the environment

- abiotic factors – physical and

chemical characteristics of the

environment

• interdependence/interconnectedness –

disturbance affects all organisms

• organisms alter their environment and

are influenced by the environment

Ecosystems

Food webs • Predator – an

organism that

captures and

consumes another

organism (plants too

– poison spines)

• Prey – an organism

that is caught and

devoured

• Natural Selection

favors adaptations

that improve

predation and

improve avoidance

for prey

Food Web Relationships

• Producers – autotrophs; base of any

food chain

• Gross primary productivity – rate at

which producers capture energy

• Producers add biomass by making

more organic material

• The rate at which biomass

accumulates is the net primary

productivity.

– Only energy stored as biomass is

available to other organisms

Food Webs & Chains • Food chain – a single pathway of

feeding relationships among

organisms in an ecosystem that

results in energy transfer

• Food web – interrelated food

chains in an ecosystem showing

all the feeding relationships

among the organisms

Food Chains

Food Webs

Trophic Diagrams A trophic level indicates the organisms

position in the sequence of energy transfers

• Producers are the first trophic level in an

ecosystem

• Consumers – heterotrophs

– Herbivores – eat producers (plants) – second

trophic level

– Carnivores – eat other consumers

– Omnivores – eat both producers and consumers

– Detritivores – feed on dead organisms, leaves,

wastes

– Decomposers – decay dead organisms

Trophic Diagrams

Energy Transfer in Food Webs

• The energy transfer between

trophic levels can vary from 1% to

20 %. This means the top trophic

level will always be smaller than

the one below it.

Water Cycle

Nitrogen Cycle

Carbon Cycle

Niches Niche – a species way of life or the role it plays in its

environment; a range of conditions a species can tolerate;

interactions with its environment

– Fundamental Niche – the range of conditions that a

species can potentially tolerate and the range of resources

it can potentially use.

– Realized Niche –of a species is the range of

resources a species actually uses.

– Generalists – can live just about

anywhere Ex: cockroach or opposum –feeds

on almost anything

• Specialists – only live in a small range of niches Ex:

koala of Australia feeds only on leaves from the Eucalyptus tree

Niches

A niche is different than a habitat. A habitat is an

area where an organism lives while a niche is its

role or position in a habitat.

Ecology • Tolerance Curve – the range of conditions in which an

organism can survive

• Acclimation – the process of adjusting an organisms tolerance

• Conformers – change as their external conditions change; ectotherms (Can NOT regulate its internal environment The body temperature is regulated by the environment.)

• Regulators – use energy to control their internal conditions; endotherms -generates their own body heat.

• Dormancy – a state of reduced activity during periods of unfavorable environmental conditions

• Resources – the energy and materials a species needs to survive

Competition • Competition: the use of the same limited

resources by 2 or more species occurs

when fundamental niches overlap

• Competitive exclusion occurs when 1

species is eliminated from a community

because of competition for resources

– One species uses the resources more efficiently

and has an advantage that eliminates the other

species

• Resource partitioning – each species only

use part of the available resources

Resource Partitioning

Five species of warblers live in

spruce and fir trees and feed on

insects.

Each individual species forage

for insects only in a particular

section of the tree.

Results- Competition among the

species is reduced.

an adaptation that enables species to use different resources when they coexist in an area. Ex: Darwin's finches. (beaks) reduces competition.

Organism Relationships

Parasitism – a relationship where one

organism lives in/on/off another

causing the host organism harm

• Ectoparasites – external parasites

• Endoparasites – internal parasites

Ectoparasite Endoparasite

Organism Relationships • Mutualism – a

relationship between

two organisms where

both organisms will

benefit

Example: pollinators

and plants

• Commensalism – a

relationship between

two organisms where

one benefits and the

other is not affected

Succession

• Succession – the gradual, sequential

re-growth of species in an area

– Primary – development of a community in

an area that has not supported life –

pioneer species

Slow…lack of minerals for growth

– Secondary – sequential replacement of

species that follows disruption of an

existing community

• Soil is left intact, easier regrowth

Succession

Biomes

• Tropical Rain Forest

• Tropical Dry Forest

• Tropical

Grassland/Savanna/Shrubland

• Desert

• Temperate Grassland

• Temperate Woodland &

Shrubland

• Temperate Forest

• Northwestern Coniferous

Forest

• Boreal Forest

• Tundra

Aquatic Ecosystems

Aquatic Ecosystems

Populations in an Ecosystem Community (Biological Community)

• all interacting organisms living in an area

Population

• all the members of a species that live in one

place at one time

• Population size – number of individuals

(usually estimated)

• Population density – number of organisms per

area

• Dispersion – spatial distribution of the

organisms

– 3 patterns of dispersion: clumped/even/random (can

depend upon scale at which they are looked at)

Population Dispersion Patterns

Changes in Populations All populations change over time

• birth rate – number of births in a given period of time

• mortality/death rate number of deaths in a given period of

time

• life expectancy – how long an animal lives

• Age structure – distribution of individuals among different

ages in a population

• Growth rate – the amount a populations size changes in a

given time

4 processes contribute to growth rate

1. Immigration – movement of individuals into a population

2. Emmigration - movement of individuals out of a population

3. Birth

4. Death

Growth Rate = Birth Rate – Death Rate

• Carrying capacity – the number of individuals the

environment can support over a long period of time

Changes in Populations

• Limiting Factors – restrains the growth of a

population

Limiting factors that control population size:

1. Density independent factors – natural

disasters, weather reduce the size of the

population by the same proportion

2. Density dependent factors – resources;

triggered by increasing population density

Ecosystem Diversity • The number of species an

ecosystem contains is known as

the species richness (simple

count)

• Species diversity – number of

species in a community compared

to the abundance of each species

(number of each)

Ecosystem Diversity

• Closer to the equator the greater

the species richness.

• Larger area = more species =

more habitats

• Stability – community’s resistance

to change

function of species richness