Ecology

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Ecology is The study of the distribution and
abundance of organisms, AND the flows of energy
and materials between abiotic and biotic
components of ecosystems.
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Ecology is an integrative/ interdisciplinary
science -Understanding of the biological
(biotic) and physical (abiotic)
sciences -Provides a context for the reductionist
sciences in biology -Closely tied to genetics and
evolution -Ecology can be studied at different
spatial and temporal scales -Includes the role of
humans in their environment ( global change)
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Factors to consider

• Non living (abiotic) factors such as light,
  temperature, salinity, water, oxygen.
• Living factors (biotic) such as competition,
  predation, symbiosis, disease, mating, camouflage

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Abiotic Factors

• Light necessary for photosynthesis, affects
  distribution and growth of plant and animals.
  Adapt to low levels of light.
• Temperature affect metabolic rate, most organisms
  cannot adapt to extreme temperatures and seasonal
  changes (eg. Plant wilt, animals hibernate)
• Water necessary for life (metabolism), adquate
  supply necessary. Xerophytes (plants) and desert
  animals have adaptations to low levels of water.
  Hydrophytes are adapted to high water conditions
• Oxygen necessary for metabolism, adaptations to
  receive oxygen (Pneumatophores in magrove) fishes
  have gills and come to the surface.

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Salinity important for water organisms (high
salt, low salt). Microbes have contractile
vacuole to pump out excess water. Fishes have
adaptations to extreme salinity. pH value is
important, for ponds and streams, the pH value
can change whether plants absorb CO2 or give off
CO2. (more acidic)
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1. Camouflage

• Cryptic coloration
• a. Hides from predators.
• b. Example English Peppered Moth

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2. Aposematic

• Bright colors
• a. Advertises noxious trait
• b. Example Monarch Butterfly

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3. Mimicry

• Two examples
• 1. Mullerian Mimicry when two unpalatable
  species mimic each other in the same habitat.
• 2. Batesian Mimicry palatable species mimic
  unpalatable species.

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Symbiotic Relationships

• Help structure communities.
• Three examples
• 1. Parasitism
• 2. Commensalism
• 3. Mutualism

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1. Parasitism

• Symbiotic relationship which benefits one
  organism and harms the other.
• Example
• 1. Tick on a coyote
• 2. Tapeworm in a dog
• 3. Flea on a cat

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2. Commensalism

• Symbiotic relationship which benefits one
  organism while the other is unaffected.
• Example
• 1. Cattle egrets and cattle in field

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3. Mutualism

• Symbiotic relationship which benefits both
  organisms.
• Examples
• 1. Acacia ants and acacia tree
• 2. Termites and gut protozoa
• 3. Legumes and nitrogen-fixing bacteria

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Scales of Ecological Organization
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Scales of Ecological Organization
Organism Survival and reproduction unit of
natural selection
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Individuals

• Important to ecologists who study
• Behavioral ecology
• Feeding patterns of predators feeding optimally
• Symbioses
• Lichens are partnerships between an alga and a
  fungus

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Scales of Ecological Organization
Population Population dynamics unit of
evolution demography sex ratios
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Population

• A group of individuals, all belonging to just one
  species
• A community may have several populations

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Scales of Ecological Organization
Community Interactions among populations specie
s diversity, trophic dynamics competition,
succession
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Community

• All of the living species in an area
• These species may interact
• DOES NOT include abiotic factors

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Scales of Ecological Organization
Ecosystem Energy flux and nutrient cycling,
primary productivity material fluxes
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Ecosystem

• The largest unit of biological organization
• Includes both the biotic (living) and the abiotic
  (non-living) factors in an area
• Biotic all the plants, animals, bacteria, fungi,
  molds
• Abiotic temperature, wind, soil nutrients, fire,
  flood, rain

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Scales of Ecological Organization
Biosphere Global processes includes biotic and
physical systems oceans, atmosphere, geology
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Biosphere

• Includes all of Earths resources and life forms
• A large variety of habitats
• Important to ecologists who study distribution of
  organisms (biogeographers)

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Ecosystem Services
the processes and conditions provided by
ecosystems that are beneficial to humans and
other organisms
the processes and conditions provided by
ecosystems that are beneficial to humans and
other organisms
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Ecosystem
-- a community of animals and plants interacting
with one another and their physical environment
-- includes physical and chemical components such
as soils, water, nutrients that support the
organisms that live within them, ranging from
bacteria to rainforest trees to elephants and
humans too
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Food Chains and Food Webs
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Food Webs
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Global Cycles
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Ecosystem Ecology

• Definition All the organisms living in a
  community AND the abiotic factors with which they
  interact
• Scale depends on questions asked
• One, small habitat, up to
• The biosphere
• Energy flow through trophic levels
• Biogeochemical cycling
• Carbon (climate change)
• Inorganic nutrients (eutrophication)

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Ecosystem Dynamics
54.1

• Energy flows through ecosystems
• ultimately lost as heat
• Matter cycles around ecosystems
• Elements are not lost but cycle through pools

Heterotrphs
Fig. 54.1
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Energy Flow

• HEAT OUT

• 1st Law of Thermodynamics
• Energy is conserved
• Ecosystems
• energy in from outside sources
• passed from trophic level to trophic level
• 2nd Law of Thermodynamics
• Energy transformation is not 100 efficient
• Ultimately all lost as heat
• Trace energy flow
• Outside source to heat
• Compute energy budgets at each transfer

Fig. 54.1
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Trophic Structure

• The different feeding relationships that
  determine the route of energy flow and the
  pattern of chemical cycling.
• According to the rules of ten, approximately
  10 of the potential energy stored in the bonds
  of organic molecules at one trophic level fuels
  the growth and development of organisms at the
  next trophic level.

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Trophic Structure

• Five examples
• 1. Primary Producers
• 2. Primary Consumers
• 3. Secondary Consumers
• 4. Tertiary Consumers
• 5. Decomposers and Detrivores

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NICHE
In ecology, a niche is a term describing the
relational position of a species or population in
an ecosystem. All living things have their
niches. A niche is the role and position of a
species in nature. Another way of looking at it
is that a niche is basically an organism's "job"
in nature. Two different populations can not
occupy the same niche at the same time, however.
The description of a niche may include
descriptions of the organism's life history,
habitat, and place in the food chain. The full
range of environmental conditions (biological and
physical) under which an organism can exist
describes its fundamental niche. As a result of
pressure from, and interactions with, other
organisms (e.g. superior competitors) species are
usually forced to occupy a niche that is narrower
than this and to which they are mostly highly
adapted. This is termed the realized niche.
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Ecological Adaptations

•     1.   Camouflage (Cryptic)       2.
    Disruptive Markings           3.   Warning
  Coloration           3.   Mating
  Coloration           5.   Batesian
  Mimicry           6.   Automimicry       

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Camouflage Cryptic Concealing form and
coloration which enables a species to avoid its
natural predators by camouflage. Good examples of
this adaptation are the katydid, walking stick
and tomato hornworm. The spittlebug secretes a
foamy mass to conceal itself on a branchlet. An
interesting resident bird of the alpine tundra is
remarkably camouflaged by seasonal coloration.
During the summer months the plumage is a mottled
brownish color. During winter, when the ground is
covered with snow, the plumage is snow white.
Two examples of camouflage in San Diego County A
canyon tree frog (Hyla arenicolor) on
granodiorite canyan wall (left) and a desert
horned lizard (Phrynosoma platyrhinos) on a sandy
riverbed.
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Disruptive Markings

• Disruptive Markings The markings on some
  insects, reptiles and mammals make it difficult
  to distinguish them from shadows and branches or
  from other members clustered together. The
  stripes on a zebra may appear quite distinctive,
  but to a colorblind lioness it is difficult to
  single out an individual zebra among a dense
  population in the African grasslands.

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Warning Colouration

• Insects with an obnoxious quality (at least to
  would-be predators), such as bad taste, bad smell
  or powerful sting, often exhibit bright colors to
  warn of their presence. Warning coloration is
  well developed in the insect order Hymenoptera,
  including bees and wasps. Small poison dart frogs
  of the tropical rain forest also exhibit warning
  coloration. These frogs contain very toxic
  neurotoxic alkaloids in their skin. Their
  coloration (called aposematic coloration) is an
  adaptation for diurnal foraging in which
  predators can easily recognize and avoid these
  posonous amphibians.

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Mating Colouration
Bright colorations among the males of some
animals (particularly the plumage of birds) gives
the male a definite advantage in sexual selection
and mate attraction. Mating coloration and
behavior of the most "fit" and aggressive males
serves to stabilize the population density
because only the most sexually select males are
able to mate with females of the species.
Left A male frigatebird (Fregata magnificens)
photographed on North Semour Island in the
Galapagos Archipelago. The male uses his bright
red, inflated throat pouch (gular sac) to attract
a female. The male sits in the branches of a tree
or shrub and waits for a female to fly over. On
sighting a female he turns his head up to expose
his red pouch, shakes his wing vigorously and
makes a loud, resonating courtship call. If the
female is impressed she will land next to him.
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Batesian Mimicry

• Mimicry One insect (called a mimic) that is
  perfectly palatable to its predator resembles
  another insect (called the model) that is quite
  disagreeable to the same predator. There are
  actually two types of mimicry Batesian and
  Mullerian. Mimicry in which the mimic is
  essentially defenseless is called Batesian
  Mimicry. A harmless moth (Aegeria) is a Batesian
  mimic because it is incapable of stinging another
  animal, but yet it resembles the yellow jacket
  wasp (Vespula). Mimicry in which the mimic shares
  the same defensive mechanism as the model is
  called Mullerian mimicry. The yellow jacket wasp
  and bumblebee (Bombus) are Mullerian mimics
  because they both have bright yellow and black
  colors and use powerful stings as a defensive
  mechanism.

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Automimicry

• In automimicry, an animal mimics parts of its own
  body. For example, some snakes have a tail that
  resembles their head and a head that resemble
  their tail. A predatory bird swooping down on its
  prey might miss its capture when the prey
  suddenly moves in an unexpected (backwards)
  direction. Automimicry is well developed in
  Malaysian lanternflies of the large insect order
  Homoptera. Since they are not true flies of the
  order Diptera, the word fly is not written as a
  separate word. If they were true flies, their
  common name would be written as lantern fly.
  Some of these remarkable insects have tails with
  false eyes and antennae, and heads with false
  tails. The false tail is actually a long
  extension of the head between the eyes. What
  appears to be the front is really the rear end
  and vice versa. When the insect moves it appears
  to jump backwards.

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POPULATION DYNAMICS

• Introduction to population dynamics
• Intraspecific competition
• Interspecific competition
• Predator Prey Dynamics

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Introduction to Population Dynamics

• Our working definition for a population is a
  group of individuals of the same species that are
  capable of interacting with each other in a
  localised area. Four fundamental processes
  determine the change in population size (births,
  deaths, immigrations and emigrations). Knowing
  this, we can write the fundamental equation of
  population change as
• Nt1Nt births - deaths immigration -
  emigration.
• This equation reads as the numbers at time t1
  (Nt1)are determined by the numbers at time t
  (Nt) plus births and immigrants - deaths and
  emigrants. This equation always predicts the
  population change from one time step to the next.
  Five concepts are at the centre of population
  ecology. These are 1) population growth, 2)
  population equilibrium, 3) limitation, 4)
  regulation and 5) persistence. Population growth
  is defined as the change in population size from
  one generation to the next. A population is at
  equilibrium if it does not change in size through
  time. Limitation is the processes that set the
  equilibrium and regulation is the process by
  which a population returns to its equilibrium.
  The regulatory processes act in a density
  dependent manner. That is deaths increase and/or
  births decrease with increasing density.
  Population persistence requires that density
  dependent processes operate.

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Intraspecific Competition

• Intraspecific competition occurs when two or more
  individuals of the same species strive for the
  same resource. Intraspecific competition can be
  of scramble (resources divided equally) or
  contest (resources divided unequally). Under
  scramble competition, all individuals suffer
  equally as resources become depleted. Under
  contest competition, there are winners and
  losers. Intraspecific competition has effects on
  individuals that cascade up to the population
  level. At the individual level, competition for
  resources can affect development, fertility and
  survival. At the population level, intraspecific
  competition for resources can give rise to
  "logistic" population growth. However, this
  density dependence is only a necessary condition
  for population stability. It is not sufficient to
  always lead to stable population dynamics.
  Changes in the strength and/or type of the
  intraspecific competitive process can lead to a
  range of population dynamics from stable
  equilibrium to stable limit cycles and chaos. The
  effects of intraspecific competition can be
  observed in many populations. For example, in the
  winter annual Vulpia fasciculatus increases in
  density lead to a reduction in seed production.
  The effect of density dependent regulation leads
  to a predicted population of about 3,500 plants.
  Under low seed survival (a density-independent
  process) the equilibirum population size can be
  reduced to about 100 plants. This highlights the
  role that density-dependent and
  density-independent process have on limiting
  (setting) the equilibrium of a population.

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Interspecific Competition

• Interspecific competition when individuals from
  different species compete for a single resource.
  Under interspecifc competition both species may
  suffer reductions in growth rate or only one
  species may be affected (amensalism). Extensions
  of the logistic population growth model show that
  the effects of interspecific competition can be
  described by competition coefficients. This is
  the ratio of the decrease in growth (of species
  1) due to species 2decrease in growth (of
  species 1) due to species 1. If the ratio is less
  than one then a species inhibits its population
  growth more than the population growth of its
  competitors. Under this condition coexistence is
  possible. Zero-isoclines and phase-plane analysis
  can be used to determine the outcome of
  interspecific competition.
• There are four possibilities 1) species 1
  outcompetes species 2, 2) species 2 outcompetes
  species 1, 3) the outcome depends on initial
  abundances of species 1 and 2 and 4) the outcome
  is coexistence. One prediction is that species
  that share the same ecological niche can coexist
  unless the intraspecific competitive effects
  outweigh the interspecific effects. Additional
  ecological factors such as the presence of
  natural enemies (e.g. predators, parasites) or
  the availability of refuges can mitigate the
  outcome of interspecific competition. Mechanistic
  models of interspecific competition predict that
  the best competitor is the one that is most
  efficient at harvesting the limiting resource.

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Predator Prey Interactions

• The key questions in predator-prey interactions
  are firstly whether predators limit prey
  populations and secondly whether predators
  regulate prey populations. Two theoretical
  frameworks have been developed to explore
  predator-prey interactions. The discrete-time
  Nicholson-Bailey model was formulated
  specifically to examine the interaction between
  insect hosts and their specific natural enemies,
  parasitic wasps. This model predicts diverging
  oscillations in the dynamics of host and wasp
  populations. These oscillations are the result of
  the lag in the response of the wasp population to
  changes in the host population (the numerical
  response). Lotka and Volterra independently
  formulated a more general continuous-time
  predator-prey model. This model predicts neutral
  cycles in which the predator population lags the
  prey population by 1/4 of a cycle. Again, the
  oscillatory dynamics arise due to the numerical
  response of the predator to prey. Although
  predators limit prey populations, they do not
  regulate prey to a stable point. Additional
  ecological processes such as prey intraspecific
  competition, complex functional responses or prey
  refuges are necessary for stable predator-prey
  interactions. More complex predator-prey
  interactions such as apparent competition,
  intraguild predation and trophic cascades require
  an understanding of the processes and mechanisms
  of predation and interspecific competition.

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Population Growth

• All populations undergo three distinct phases of
  their life cycle
• growth
• stability
• decline
• Population growth occurs when available resources
  exceed the number of individuals able to exploit
  them. Reproduction is rapid, and death rates are
  low, producing a net increase in the population
  size.
• Population stability is often proceeded by a
  "crash" since the growing population eventually
  outstrips its available resources. Stability is
  usually the longest phase of a population's life
  cycle.
• Decline is the decrease in the number of
  individuals in a population, and eventually leads
  to population extinction.

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Factors influencing population growth

• Nearly all populations will tend to grow
  exponentially as long as there are resources
  available. Most populations have the potential to
  expand at an exponential rate, since reproduction
  is generally a multiplicative process. Two of the
  most basic factors that affect the rate of
  population growth are the birth rate, and the
  death rate. The intrinsic rate of increase is the
  birth rate minus the death rate.

Two modes of population growth. The Exponential
curve (also known as a J-curve) occurs when there
is no limit to population size. The Logistic
curve (also known as an S-curve) shows the effect
of a limiting factor (in this case the carrying
capacity of the environment).
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Energy flow Primary production
54.2

• Primary Production
• Nonorganic source energy converted to organic
  chemical energy by autotrophs
• Measurement (per unit area per unit time)
• Energy (Joules / m2 / yr)
• Biomass - organic molecule dry weight (g Carbon /
  m2 / yr)
• Primary production sets the spending limit for
  the ecosystems energy budget
• 1 of the available visible light energy is
  converted to chemical energy by photosynthetic
  organisms!
• A few systems depend entirely on chemosynthetic
  primary production

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II. Energy and the ecosystem

• Primary production capture of light energy and
  its conversion into energy of chemical bonds in
  carbohydrates by plants, algae, and some bacteria
• Primary productivity rate at which primary
  production occurs
• Gross primary productivity (GPP) the total
  energy assimilated by plants through
  photosynthesis
• Net primary productivity (NPP) the total energy
  assimilated by plants through photosynthesis
  minus energy used in respiration
• ? NPP represents energy in an ecosystem
  available to consumers
• ? NPP usually expressed in g/m2/year
• incorporation of any material into the
  tissues, cells and fluids of an organism

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Trophic Levels - Definitions
1 Primary producer Autotrophs that support all
other trophic levels by synthesizing sugars and
other organic molecules using light energy.
2. Primary consumers Herbivores that consume
primary producers.
3. Secondary consumers Carnivores that eat
herbivores.
4. Tertiary consumers Carnivores that eat other
carnivores.
5. Detritivores Consumers that derive energy
from organic wastes and dead organisms.
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II. Energy and the ecosystem

• Ecological pyramid of energy
• ? width of each bar represents the net production
  of each trophic level
• ? ecological efficiency of energy transferred
  across trophic levels
• ? efficiencies are 20, 15 and 10 between
  trophic levels

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Biomass Pyramid
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Trophic pyramids

• Trophic efficiency (TE) of production
  transferred from one trophic level to the next
• TE less than PE because 2 losses arent included
  for PE
• energy produced by the next lower level but not
  actually consumed
• unassimilated food at the present level (lost in
  urine, feces)
• 80-95 of energy is lost between each level not
  consumed, not digested, respired
• Compounding of loss throughtrophic pyramid
  explains why food webs usually have only four or
  five trophic levels

Fig. 54.11
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Number pyramids

• Predators are usually larger than the prey they
  eat
• Limited biomass at the top of an ecological
  pyramid is concentrated in a relatively small
  number of large individuals
• Top predators are particularly vulnerable to
  extinction

Fig. 54.13
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Energy Flow in Ecosystems
Ecological efficiency Ratio of net
productivity at one trophic level compared to net
productivity at the level below. Ecological
efficiencies are 5-20
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Energy flow through trophic levels
54.3

• Secondary production
• Chemical energy in consumers food converted to
  new chemical energy (growth of new consumer
  biomass)
• Amount ultimately determined by
• NPP
• Efficiency of energy transfer between trophic
  levels, usually 5-20

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Secondary Production

• Production efficiency
• of a consumers assimilated food that goes into
  growth
• Range 1 to 40
• Ex PE 33/10033
• Unassimilated food doesnt count in calculation
  because it is available to other consumers

Heat
eaten by caterpillar
Detritivores
Fig. 54.10
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II. Energy and the ecosystem

• Only 5 to 20 of energy passes between trophic
  levels
• ? net production of one trophic level becomes
  the ingested energy of the next higher level
• ? amount of energy reaching each trophic level
  depends on
• NPP at the base of the food chain
• efficiencies of energy transfer at each
  trophic level

Ricklefs Fig. 6.2
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Production efficiencies
PE 1-3
PE 10
PE 40
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Energy Budget
primary producers 15-70 of assimilated energy
used for maintenance
herbivores and carnivores 80-95 of
assimilated energy used for maintenance
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Energy Budget
Net production efficiency () growthenergy
in offspring assimilated energy
birds lt 1 small mammals up to 6 cold blooded
animals 75
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General Rules for Energy Flow through Ecosystems
1) Assimilation efficiency increases at higher
trophic levels
2) Net and gross production efficiencies decrease
at higher trophic levels
3) Ecological efficiencies average about 10
Thus, only about 1 of NPP ends up as production
in the third trophic level
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WATER CYCLE
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• The Water Cycle (also known as the hydrologic
  cycle) is the journey water takes as it
  circulates from the land to the sky and back
  again. The Sun's heat provides energy to
  evaporate water from the Earth's surface (oceans,
  lakes, etc.). Plants also lose water to the air
  (this is called transpiration). The water vapor
  eventually condenses, forming tiny droplets in
  clouds. When the clouds meet cool air over land,
  precipitation (rain, sleet, or snow) is
  triggered, and water returns to the land (or
  sea). Some of the precipitation soaks into the
  ground. Some of the underground water is trapped
  between rock or clay layers this is called
  groundwater. But most of the water flows downhill
  as runoff (above ground or underground),
  eventually returning to the seas as slightly
  salty water.

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CARBON CYCLE
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• Carbon exists in the nonliving environment as
• carbon dioxide (CO2) in the atmosphere and
  dissolved in water (forming HCO3-)
• carbonate rocks (limestone and coral CaCO3)
• deposits of coal, petroleum, and natural gas
  derived from once-living things
• dead organic matter, e.g., humus in the soil

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• Carbon CycleThe movement of carbon, in its many
  forms, between the biosphere, atmosphere, oceans,
  and geosphere is described by the carbon cycle,
  illustrated in the adjacent diagram. In the cycle
  there are various sinks, or stores, of carbon
  (represented by the boxes) and processes by which
  the various sinks exchange carbon (the arrows).
• We are all familiar with how the atmosphere and
  vegetation exchange carbon. Plants absorb CO2
  from the atmosphere during photosynthesis, also
  called primary production, and release CO2 back
  in to the atmosphere during respiration. Another
  major exchange of CO2 occurs between the oceans
  and the atmosphere. The dissolved CO2 in the
  oceans is used by marine biota in photosynthesis.

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• Two other important processes are fossil fuel
  burning and changing land use. In fossil fuel
  burning, coal, oil, natural gas, and gasoline are
  consumed by industry, power plants, and
  automobiles. Notice that the arrow goes only one
  way from industry to the atmosphere. Changing
  land use is a broad term which encompasses a host
  of essentially human activities. They include
  agriculture, deforestation, and reforestation.

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• Before the Industrial Revolution the release of
  carbon from fossil fuels was very low.
• Now deforestation and burning of fossil fuels.
  Has upset the carbon Cycle and caused a sudden
  increase in atmospheric CO2.

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NITROGEN CYCLE
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• Nitrogen is essential to all living systems,
  which makes the nitrogen cycle one of Earth's
  most important nutrient cycles.
• Eighty percent of Earth's atmosphere is made up
  of nitrogen in its gas phase.
• Atmospheric nitrogen becomes part of living
  organisms in two ways. The first is through
  bacteria in the soil that form nitrates out of
  nitrogen in the air. The second is through
  lightning. During electrical storms, large
  amounts of nitrogen are oxidized and united with
  water to produce an acid that falls to Earth in
  rainfall and deposits nitrates in the soil.

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• Plants take up the nitrates and convert them to
  proteins that then travel up the food chain
  through herbivores and carnivores. When organisms
  excrete waste, the nitrogen is released back into
  the environment. When they die and decompose, the
  nitrogen is broken down and converted to ammonia.
  Plants absorb some of this ammonia the remainder
  stays in the soil, where bacteria convert it back
  to nitrates. The nitrates may be stored in humus
  or leached from the soil and carried into lakes
  and streams. Nitrates may also be converted to
  gaseous nitrogen through a process called
  denitrification and returned to the atmosphere,
  continuing the cycle

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• Both atmospheric and soil phases.
• Plants cant use Nitrogen out of the air. It must
  be in mineral form.
• Ammonium ions (NH4-)
• Nitrate ions (NO3-)
• Many bacteria and cyanobacteria convert N2 to
  ammonia (NH3). This process is called Nitrogen
  Fixation.
• Rhizobium bacteria lives in the root nodules of
  legumes (peas, beans) and fixes N2 (symbiosis).
• Some nitrogen is also fixed by lightning.
• Other bacteria reconverts nitrogen compounds back
  to N2 gas.

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• Nitrification
• By aerobic bacteria
• NH3 ? NO2- (ammonia ? nitrite (toxic)
• NO2- ?NO3- (nitrate ? nitrate (plant nutrient))
• Nitrogen compounds ? usable organic molecules
  ?eaten
• Ammonification
• Decomposers convert complex compounds to ammonia
  and ammonium ions.
• Denitrification
• Anaerobic bacteria convert N2 compounds to N2
  gas and nitrous oxide (N2O) ? atmosphere

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Human Effect on the Nitrogen cycle.

• Nitric acid (HNO3) from acid rain.
• Nitrous Oxide from manure and inorganic
  fertilizers.
• Nitrous Oxide is a greenhouse gas and depletes
  the ozone layer.
• Mining
• Nitrogen runoff into water can trigger algal
  blooms.
• Eutrophication.

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Deforestation

• Deforestation is the permanent destruction of
  indigenous forests and woodlands. The term does
  not include the removal of industrial forests
  such as plantations of gums or pines.
  Deforestation has resulted in the reduction of
  indigenous forests to four-fifths of their
  pre-agricultural area. Indigenous forests now
  cover 21 of the earth's land surface.

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• Deforestation is brought about by the following
• conversion of forests and woodlands to
  agricultural land to feed growing numbers of
  people
• development of cash crops and cattle ranching,
  both of which earn money for tropical countries
• commercial logging (which supplies the world
  market with woods such as meranti, teak, mahogany
  and ebony) destroys trees as well as opening up
  forests for agriculture
• felling of trees for firewood and building
  material the heavy lopping of foliage for
  fodder and heavy browsing of saplings by
  domestic animals like goats.
• To compound the problem, the poor soils of the
  humid tropics do not support agriculture for
  long. Thus people are often forced to move on and
  clear more forests in order to maintain
  production.

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• CONSEQUENCES OF DEFORESTATION Alteration of
  local and global climates through disruption of
• a) The carbon cycle. Forests act as a major
  carbon store because carbon dioxide (CO2) is
  taken up from the atmosphere and used to produce
  the carbohydrates, fats, and proteins that make
  up the tree. When forests are cleared, and the
  trees are either burnt or rot, this carbon is
  released as CO2. This leads to an increase in the
  atmospheric CO2 concentration. CO2 is the major
  contributor to the greenhouse effect. It is
  estimated that deforestation contributes
  one-third of all CO2 releases caused by people.
• b) The water cycle. Trees draw ground water up
  through their roots and release it into the
  atmosphere (transpiration). In Amazonia over half
  of all the water circulating through the region's
  ecosystem remains within the plants. With removal
  of part of the forest, the region cannot hold as
  much water. The effect of this could be a drier
  climate.

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• Soil erosion With the loss of a protective
  cover of vegetation more soil is lost.
• Silting of water courses, lakes and dams This
  occurs as a result of soil erosion.
• Extinction of species which depend on the
  forest for survival. Forests contain more than
  half of all species on our planet - as the
  habitat of these species is destroyed, so the
  number of species declines (see Enviro Facts
  "Biodiversity").

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Water pollution is a large set of adverse effects
upon water bodies (lakes, rivers, oceans,
groundwater) caused by human activities. Although
natural phenomena such as volcanoes, storms,
earthquakes etc. also cause major changes in
water quality and the ecological status of water,
these are not deemed to be pollution. Water
pollution has many causes and characteristics.
Increases in nutrient loading may lead to
eutrophication. Organic wastes such as sewage and
farm waste impose high oxygen demands on the
receiving water leading to oxygen depletion with
potentially severe impacts on the whole
eco-system. Industries discharge a variety of
pollutants in their wastewater including heavy
metals, organic toxins, oils, nutrients, and
solids. Discharges can also have thermal effects,
especially those from power stations, and these
too reduce the available oxygen. Silt-bearing
runoff from many activities including
construction sites, forestry and farms can
inhibit the penetration of sunlight through the
water column restricting photosynthesis and
causing blanketing of the lake or river bed which
in turns damages the ecology.
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•    Principal sources of water pollution are
• Litter in the Water in the U.K.
• industrial discharge of chemical wastes and
  byproducts
• discharge of poorly-treated or untreated sewage
• surface runoff containing pesticides
• slash and burn farming practice, which is often
  an element within shifting cultivation
  agricultural systems
• surface runoff containing spilled petroleum
  products
• surface runoff from construction sites, farms, or
  paved and other impervious surfaces e.g. silt
• discharge of contaminated and/or heated water
  used for industrial processes
• acid rain caused by industrial discharge of
  sulfur dioxide (by burning high-sulfur fossil
  fuels)
• excess nutrients added by runoff containing
  detergents or fertilizers
• underground storage tank leakage, leading to soil
  contamination, thence aquifer contamination.

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• Many causes of pollution including sewage and
  fertilizers contain nutrients such as nitrates
  and phosphates.  In excess levels, nutrients over
  stimulate the growth of aquatic plants and
  algae.  Excessive growth of these types of
  organisms consequently clogs our waterways, use
  up dissolved oxygen as they decompose, and block
  light to deeper waters. This, in turn, proves
  very harmful to aquatic organisms as it affects
  the respiration ability or fish and other
  invertebrates that reside in water.
• When natural bacteria and protozoan in the water
  break down organic material that is run off into
  streams, lakes and rivers, they begin to use up
  the oxygen dissolved in the water.  Many types of
  fish and bottom-dwelling animals cannot survive
  when levels of dissolved oxygen drop below two to
  five parts per million.  When this occurs, it
  kills aquatic organisms in large numbers which
  leads to disruptions in the food chain

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Contaminants Contaminants may include organic and
inorganic substances. Some organic water
pollutants are insecticides and herbicides, a
huge range of organohalide and other chemicals
bacteria, often is from sewage or livestock
operations food processing waste, including
pathogens tree and brush debris from logging
operations VOCs (Volatile Organic Compounds,
industrial solvents) from improper storage Some
inorganic water pollutants include heavy metals
including acid mine drainage acidity caused by
industrial discharges (especially sulfur dioxide
from power plants) chemical waste as industrial
by products fertilizers, in runoff from
agriculture including nitrates and phosphates
silt in surface runoff from construction sites,
logging, slash and burn practices or land
clearing sites
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• Oil pollution is a growing problem, particularly
  devestating to coastal wildlife.  Small
  quantities of oil spread rapidly across long
  distances to form deadly oil slicks. In this
  picture, demonstrators with "oil-covered" plastic
  animals protest a potential drilling project in
  Key Largo, Florida. Whether or not accidental
  spills occur during the project, its impact on
  the delicate marine ecosystem of the coral reefs
  could be devastating.

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Air Pollution
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• What is air pollution?
• There are several main types of pollution and
  well-known effects of pollution which are
  commonly discussed. These include smog, acid
  rain, the greenhouse effect, and "holes" in the
  ozone layer. Each of these problems has serious
  implications for our health and well-being as
  well as for the whole environment .

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One type of air pollution is the release of
particles into the air from burning fuel for
energy. Diesel smoke is a good example of this
particulate matter . This type of pollution is
sometimes referred to as "black carbon"
pollution. The exhaust from burning fuels in
automobiles, homes, and industries is a major
source of pollution in the air. Another type of
pollution is the release of noxious gases, such
as sulfur dioxide, carbon monoxide, nitrogen
oxides, and chemical vapors. These can take part
in further chemical reactions once they are in
the atmosphere, forming smog and acid rain.
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• Smog is a type of large-scale outdoor pollution.
  It is caused by chemical reactions between
  pollutants derived from different sources,
  primarily automobile exhaust and industrial
  emissions. Cities are often centers of these
  types of activities, and many suffer from the
  effects of smog, especially during the warm
  months of the year.

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• Another consequence of outdoor air pollution is
  acid rain. When a pollutant, such as sulfuric
  acid combines with droplets of water in the air,
  the water (or snow) can become acidified . The
  effects of acid rain on the environment can be
  very serious. It damages plants by destroying
  their leaves, it poisons the soil, and it changes
  the chemistry of lakes and streams. Damage due to
  acid rain kills trees and harms animals, fish,
  and other wildlife.

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• The Greenhouse Effect, also referred to as global
  warming, is generally believed to come from the
  build up of carbon dioxide gas in the atmosphere.
  Carbon dioxide is produced when fuels are burned.
  Plants convert carbon dioxide back to oxygen, but
  the release of carbon dioxide from human
  activities is higher than the world's plants can
  process. The situation is made worse since many
  of the earth's forests are being removed, and
  plant life is being damaged by acid rain. Thus,
  the amount of carbon dioxide in the air is
  continuing to increase. This buildup acts like a
  blanket and traps heat close to the surface of
  our earth. Changes of even a few degrees will
  affect us all through changes in the climate and
  even the possibility that the polar ice caps may
  melt.

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• Ozone depletion is another result of pollution.
  Chemicals released by our activities affect the
  stratosphere , one of the atmospheric layers
  surrounding earth. The ozone layer in the
  stratosphere protects the earth from harmful
  ultraviolet radiation from the sun. Release of
  chlorofluorocarbons (CFC's) from aerosol cans,
  cooling systems and refrigerator equipment
  removes some of the ozone, causing "holes" to
  open up in this layer and allowing the radiation
  to reach the earth. Ultraviolet radiation is
  known to cause skin cancer and has damaging
  effects on plants and wildlife

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Conservation
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• Conservation biology is the protection and
  management of biodiversity that uses principles
  and experiences from the biological sciences,
  from natural resource management, and from the
  social sciences, including economics. The
  conservation movement seeks to protect plant and
  animal species as well as the habitats they live
  in from harmful human influences . The term
  "conservation biology" refers to the science and
  sometimes is used to encompass also the
  application of this science. The concern of this
  branch of biology is to help save the diversity
  of life on Earth through applied conservation
  research. In the realm of research, biologists
  seek creative and effective ways to address a
  wide diversity of ecological problems, ranging
  from endangered species to regional conservation
  planning. This translates to developing better
  conservation tools, analyses, and techniques.

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Good conservation policy

• Protection laws for sustainable areas to support
  viable populations.
• Limit use of areas for particular
  industrial/resource use
• Prohibit importing of foreign plants/animals,
  control measures
• Pest education about dumping of household garden
  refuse.
• Captive breeding programs
• Feral pests/disease controls
• Reduction of introduced species, removal of these
  animals from areas
• Sufficient water levels/waterways for natural
  fish movement.
• Rehabilitation of degraded area
• Limit human use and impact on these areas
• Ongoing research on factors affecting these areas
• Animal/plant control, firefighting, education and
  sufficient funds for these activities
• National parks, nature reserves
• Culling programs
• Decrease and control pollution/dumping into
  natural waterways
• Control gas emissions and burning
• Control use of chemical affecting the
  environment, increase awareness

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Land clearing
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Ecological impact of clearing land

• Breaks landscape into isolated areas that are not
  sustainable
• Affects water movement increase run off from
  surface and waterways
• Increase erosion by wind and water
• Affects water table increasing soil salinity and
  waterlogging
• Breakdown of soil structure and nutrient
  depletion
• Desertification and local climate change
• Decreased bio-diversity and increase danger of
  extinction

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Reafforestation
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Reafforestation reasons
Reduce soil salinity, water tables Prevent
erosion, nutrient leeching Conserve endangered
species, biodiversity Aesthetics (picnic areas,
natural beauty) Improve water quality
(reservoir) Reestablish area after logging,
mining Cultural heritage issues Ethics rights
to destroy other species? Ecosystem stability
food web, nutrient
cycles, mutalism, clean air Source of
medicines or industrial raw materials
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Reafforestation program features
Survival of species adapted to that area Species
with high rate of survival Local species to
support local animal populations Disease
resistant strains Variety of species that
naturally grow together.