Transcript LECTURE 13: POPULATION ECOLOGY & ECOSYSTEM

POPULATION ECOLOGY & ECOSYSTEM
Food out
Oxygen out
1. Carbon dioxide in
2. Light in
3. Water in
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Population Ecology
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Ecology is the study of
interactions among organisms
and their environment
• Not concerned with individuals
• Populations - same area, same time
• Population ecology - looks at the
dynamics of populations that are similar
between species
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• Population density - number of individuals of a
given species in a specific area at a given time
• Range - geographic area or limit of a population
• Dispersion - frequency or patterns of individuals
within a range:
• uniform
• random
• clumped
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Population change
• Growth rate = births - deaths
+immigration - emigration
• Doubling rate (time it takes for a
population to double) = 0.7/growth rate
(see page 911)
• Biotic potential = maximum rate of
population growth given ideal
circumstances
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Limits on growth
• Environmental resistance - combination
of the limiting factors and effects
• Limiting Factors - any resource or
requirement that acts to limit population
when in short supply
• Carrying capacity (K) - the greatest
population that can be maintained
indefinitely by a given system or place
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Density dependent factors
• As population increases the rate of
growth is slowed by density
dependent factors either by
increasing the death rate or
decreasing the birth rate
• predation, disease, intraspecifc
(within a species) competition and
interspecific competition
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Density independent factors
• Weather events
• Natural disasters (=bencana alam)
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Survival tactics - reproduction
• r strategies - (r = growth rate) - small
body size, large brood, short life
span, may be opportunistic and
found in disturbed or variable
environments
• K strategies - (K=carrying capacity) large body small brood, long life, care
for young, constant or stable
environments
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Human population growth
• 1800 human population reaches 1
billion
• 1930 - in 130 years 2 billion
• 1960 - in 30 years 3 billion
• 1975 - in 15 years 4 billion
• 1987 - in 12 years 5 billion
• 1999 - in 12 years 6 billion
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What are the density
dependent limits to growth
acting on human population?
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Demographic transition
• Preindustrial stage - high birth and
death rates - slow population growth
• transitional stage - lower death rate
but birth rate remains high - rapid
population growth
• industrial stage - birth rate declines rate of growth slows
• post industrial stage - low birth and
death rates
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Communities of organisms
• Producers - autotrophs
• Consumers - heterotrophs
• primary and secondary
• Decomposers - heterotrophs
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Producers in an Ecosystem
Categories of Organism in an ecosystem
• Autotrophs – self-nourished species (e.g.
plants)
• Heterotrophs – other-nourished species
(humans and animals)
1. Producers: Green Plants responsible for
photosynthesis and the release of energy into
an ecosystem.
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Consumers and Decomposers
2. Consumers
a) Primary Consumers - Herbivores
b) Secondary Consumers – Carnivores
c) Tertiary Consumers - Carnivores
d) Multiple-level Consumers - Omnivores
3. a) Detritivores –e.g. crab (kepiting), vulture
(burung hering), termites (rayap)
b) Decomposers – e.g. fungi and bacteria
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No organism lives in
isolation. Every living thing is
part of a community.
• Predation – pursuit (=mengejar) and
ambush (menyerang)
• Defenses (=bertahan) – camouflage
(=menyamar), chemical defense,
mimicry - (batesian mimicry or mullerian
mimicry)
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Interactions among species in an
Ecosystem
Plants compete amongst themselves for:
1. water, 2. nutrients 3. sunlight and 4. space
Animals compete over
1. food, 2. water, 3. mating and 4. territory
2 main types of relationships
– Predation – one species (the predator) feeds on
the other (prey) e.g. cat and mouse
– Symbiosis – species live in an intimate
association with each other
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Types of symbiotic relations
• Parasitism - one species feeds on another
(the host) and may kill it.
• Mutualism – both parties benefit equally
from the relationship (flowers and butterflies)
• Commensalism – the relationship benefits
one species but neither helps nor harms the
other
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Mutualism
• A symbiotic relationship
• both partners benefit
– rhizobium bacteria and plants
– pilot fish and sharks (=ikan hiu)?
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Commensalism
• One benefits , the other is neither harmed
(=dirugikan) nor helped
– epiphytes
– sea ducks and sting rays (=ikan pari)
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Parasitism
• Parasite and host
• pathogen - parasite that causes disease
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Niche
• The ecological role of an organism is its
niche
• fundamental niche - potential niche
• realized niche - actual
• interspecific competition leads to
competitive exclusion - absolute
overlap cannot exist in nature
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Diversity in communities
• Isolated or places with harsh
(=keras/kasar) environments have less
diversity
• edge effect - diversity is usually
greatest at the margins
• old communities (tropical rainforests)
tend to be more diverse than new
communities (Canadian shield, artic)
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Succession
• Primary succession - change in species
composition over time in a habitat not
previously inhabited by organisms
• Pioneer community - first community to
appear
• Secondary succession - change in species
composition over time in a habitat already
modified by previous organisms
• Climax community 24
Ecosystems and
Environment
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Biogeochemical cycles
• All materials flow through the environment over
time - materials cycle through the environment
• Comprise processes through which elements
that sustain life (water, carbon, phosphorus and
nitrogen) are continuously made available to
living organisms.
• Nitrogen cycle
• Hydrological cycle
• Carbon cycle
• Phosphorus cycle
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Most plants depend on bacteria to
supply nitrogen
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The Hydrological Cycle
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The Carbon Cycle
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Phosphorus Cycle
• Phosphorus is the key to energy in living
organisms, for it is phosphorus that moves
energy from ATP to another molecule,
driving an enzymatic reaction, or cellular
transport. Phosphorus is also the glue that
holds DNA together, binding deoxyribose
sugars together, forming the backbone of
the DNA molecule. Phosphorus does the
same job in RNA.
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Rocks
In some cases,
phosphorous will travel
to a lake, and settle on
the bottom. There, it may
turn into sedimentary
rocks, limestone, to be
released millions of
years later. So
sedimentary rocks acts
like a back, conserving
much of the phosphorus
for future eons.
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Interruptions in an Ecosystem
Causes:
a) Natural causes – volcanic eruptions
b) Human causes – e.g. construction,
agriculture, mining, etc.
List some of the consequences that can
result from an abrupt interruption in the
smooth functioning of an ecosystem?
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What lessons can we learn from the
way a natural ecosystem operates?
• Natural ecosystems gain resources, use it and
dispose of wastes through recycling.
• Ecosystems sustain themselves by running on Solar
Energy which is exceedingly abundant, nonpolluting,
constant and long lasting.
• Far less of Carnivores can be supported by each
ecosystem. Many would soon face extinction
(=kepunahan)
• Every species in a community play an important role in
the sustenance (=makanan) of the ecosystem
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Energy
• Energy flows through the environment
• Sunlight to chlorophyll to photosynthesis
to sugars to plant biomass to….
• Food chains - energy passes from one
organism to another - it is a one way tripenergy passed through the environment
in a linear fashion- unlike materials
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Food chains
• Trophic levels
• Available energy and biomass
decrease at each trophic level
• Gross primary productivity - rate at
which energy is captured and stored in
plant tissues
• Net primary productivity - energy after
plant’s requirements
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The Food Chain
• A food chain or food web is represented by a
sequence of organisms through which energy and
nutrients flow from one organism to another.
• A major step in the transfer of energy through the
food chain is termed as a Trophic level
– Primary consumers
– First trophic level
– Secondary consumers - Second trophic level
– Tertiary Consumers
- Third trophic level
• The amount of usable energy in the food chain
decreases as we move down the trophic level
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An example of a marine food chain
Phytoplankton is the first
level of marine food chain
Zooplanktons are eaten by
krill and other Small fish
which are all eaten in turn
by Big fish, including
penguins, seals and
whales. The marine food
chain continues when these
big fishes are eaten by
Mammals like polar bears
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A marine food chain
A marine food
chain
•
•
•
•
•
Polar bear - 5
Seal (anjing laut) - 4
Cod - 3
Krill - 2
Algae - 1
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A terrestrial-based food chain
A Terrestrial food
chain
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•
•
•
Hawk …
Snake eaten by hawk
Frog eaten by snake
Grasshopper eaten by
frog
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• The path of
energy from one
feeding level to
another.
(chain reaction)
• Which direction
is the energy
flow?
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What is missing from the food web?
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Tertiary Consumer
Secondary
Consumer
Primary Consumer
Decomposer
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Food Pyramid
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Energy Flow
• Photosynthesis explains
how energy from the sun is
captured by green plants
and used to make food.
• Most of this energy is used
to carry on the plant's life
activities.
• The rest of the energy is
passed on as food to the
next level of the food chain.
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Impact of pesticides (i.e., DDT) on the
species of an ecosystem
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Major ecosystems
• Biomes - large distinct ecosystem
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–
–
–
–
–
Tundra (=padang lumut)
boreal forest (=hutan cemara)
temperate rainforest
temperate deciduous forest
temperate grasslands
Chaparral (=vegetasi xerophyta /tanaman tahan
kering)
– Deserts (=daerah dengan curah hujan kurang)
– Savanna (=padang rumput dengan pohon yang
bertebaran)
– tropical rainforests
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Factors Affecting Ecosystems
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•
•
•
•
Soil
Available Water
Temperature
Sunlight
Abiotic factors will determine biotic factors
– Climates (sunlight, temperature and rainfall)
will determine which types of vegetation can
exist which will determine what type of
animals can exist.
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Soil
• pH of soil determines which
plants grow best.
• Soil Layers
– Litter - the upper layer of soil,
composed mainly of partially
decomposed leaves or grasses
– Topsoil - the soil layer beneath
the litter, composed of small
particles of rock mixed with
humus
– Humus - decaying plant and
animal matter
– Subsoil - the soil layer beneath
the topsoil, usually containing
more rock particles and less
organic matter than the topsoil
– Bedrock - the layer beneath the
soil, composed of rock
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Available Water
• The amount of available water is
determined by the amount and type of
precipitation.
• Amounts of rainfall determined by distance
form equator, mountains ranges ocean
and wind currents.
• The amount of available water will
determine the type of vegetation that can
exist
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Temperature
• Plants and animals must be well adapted to the
temperatures that exist within their ecosystems.
– Chinophobes – snow haters (ex. Geese)
– Chinoeuphores – snow adaptors (ex. Snowshoe hare)
– Chinophiles – snow lovers (ex. Polar bears)
• Temperature also influences rates of
evaporation which can influence the amount of
available water.
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Plant Adapted for Specific Habitats
• Xerophytes – plants that live in the
desert biome
• Epiphytes – plants that are not rooted
in soil but grow directly on other plants
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Aquatic ecosystems
•
Lakes and ponds (=danau dan kolam)
– littoral zones - nearest to shore (=tepi)
– limnetic zones - open water
– profundal zone (=tempat yang paling dalam) - no
light
• Marine (=laut)
– Intertidal (= bagian pantai yang terkena pasang
surut) - very productive
– pelagic - open ocean
– euphotic - light is present (100 m)
– neritic - 100 m to 200 m
– oceanic - no light
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Stratification in water
• In summer warm layers on top, colder
at the bottom, separated by thermocline
• in fall, water turns over and some
mixing between layers occurs
• in winter cold at top, warmer at bottom
• in spring another turnover!
• Spring turnover stimulates algae
growth...
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Environmental effects
• living factors in the environment
affect the species that are present
like temperature, amount of
rainfall, predation, availability of
food, and population size. As a
result, organisms may evolve.
Group Discussion: Discuss each
environmental effect and possible outcomes
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How do organisms evolve?
• by adapting to their environments,
two or more organisms evolve
together.
• To "make the best of" where they
live, organisms make use of other
organisms by eating them, living on
or in them, and/or building a
"partnership" with them.
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Predation
• describes an interaction where a
predator organism feeds on
another living organism or
organisms known as prey
(=mangsa).
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Habitats
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• A habitat is the place where living
things live.
• It is more than just a home it includes
the whole surrounding area.
• The habitat provides the animal or plant
with food or shelter.
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People and their habitats
People can live all over the
world.
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We can do this
because we are
able to build homes
for different
conditions.
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Also we can change our clothes
to best suit the temperature
around us.
Animal skin and fur
act as insulators and
keep heat in.
White clothes
reflect the heat
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Animals and plants
• Most plants and animals are specially
adapted to survive in a particular
habitat.
• They have developed special features
to suit the demands of their
environment.
• This is called adaption.
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Some examples of
adaption
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All birds have similar
characteristics.
But many water birds
have features that are
different from those
birds live on land.
Webbed
feet for
swimming
Long legs are good for wading
These wings act as flippers
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Some animals are
camouflaged to blend in
with their surroundings.
This lion blends in well
with the grassy
background.
This keeps them safe as it is
more difficult for other
animals to see them or
catch them for food.
These zebra could
easily be mistaken
for bushes from
a distance.
This lizards skin is so
similar to the rock
colour.
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Aquatic animals
have streamlined
bodies to move
more easliy in the
water.
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Camels store water in their
humps.
Snakes glide across the hot
sands and can shed their skin
These animals have
adapted to live in
the hot climate of
the desert.
Ostriches have
long eyelashes to
keep out the sand.
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These animals have
adapted to be more
suited to cold
temperatures.
Layers of fat keep the
seals body warm, and small
ears stop heat loss.
Polar bears are kept warm by
their body fat.
Deer have a
warm layer
of fur.
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Even plants have
adapted to their
habitats.
The cactus has fleshy stems
that store water.
Dandelions seeds are
easily dispersed.
The water provides support for this lily
as it has less developed roots to hold it
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in place.
Animals and plants help each other
Plants and animals depend on each
other for a wide variety of things.
Protection
Nests to reproduce
Food
Shelter
Gas exchange70
The Earth has many different
environments, varying in temperature,
moisture, light, and many other factors.
Each of these habitats has distinct life
forms living in it, forming complex
communities of interdependent
organisms. A complex community of
plants and animals in a region and a
climate is called a biome.
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Some of the biomes on Earth include:
•Desert - very dry, either hot or cold
•Tundra - cool, treeless, and dry
•Chaparral or scrub - coastal area with hot, dry summers and mild, cool, rainy winters
•Taiga or Coniferous Forest - cool and dry, with coniferous trees
•Temperate Deciduous Forest - cool and rainy, with deciduous trees
•Grassland - Windy, partly dry sea of grass with few trees, including tropical savanna,
prairie, steppe, pampas, etc.
•Mountina biomes: there are a lot of different biomes that exist on a mountains, from
grasslands at low altitudes, taiga (coniferous forests) below the treeline, and alpine (the same
as tundra)
•Temperate Rain Forest - cool and wet
•Tropical Rain Forest - warm and very wet
•Land Caves - cool and dark
•Wetlands - there are many types of wetlands, including swamps, marshes, moors, bogs,
fens, sloughs, etc.
•Freshwater Marsh - a wetland located near creeks, streams, rivers and lakes
•Temperate ponds
•Marine (ocean or sea) - including benthic biomes (bottom), coral reef (warm shallow saltwater environments based on coral formation), pelagic biomes (open seas near the surface),
littoral or intertidal zones, estuarine biomes (where rivers meet oceans), etc.
•Sea Caves.
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Deserts
• Little rainfall
• High evaporation
• Low humidity
• Biodiverse
• Arid or semiarid
• Desertification
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Dry Shrublands, Woodlands,
and Grasslands
• Drought and fires
• More rain than
deserts
• Drought-tolerant
plants
• Hot summers, cold
winters
• Chaparral
• Savannas
– Grazing animals
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Tropical Rain Forests and
Broadleaf Forests
• Canopy Trees
• Evergreen Broadleafs
– Tropical rain forests
– Rapid decomposition and mineral cycling
– Humus poor
• Deciduous Broadleafs
– Leaves drop
– Tropical and Temperate Forests
– Decomposition not as rapid
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Tropical Rain Forests and
Broadleaf Forests
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Coniferous Forests
• Canopy Trees
– Coniferous
– Boreal
– Southern pine
– Evergreen
Conifers
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Tundra
• Treeless plain between polar ice cap and
boreal forests
• Cool short summers
• Below freezing winters
• Sunlight nearly continuous in summers
• Permafrost
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Lake Ecosystems
Standing freshwater
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Seasonal Changes in Lakes
• Changes in
density and
temperature
• Spring
overturn
• Fall overturn
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Seasonal Variation in Primary
Production in Oceans
Phytoplankton blooms
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Upwelling Along Coasts in the
Northern Hemisphere
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Environmental Issues
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•
•
•
•
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Habitat destruction
pollution
foreign or exotic species
deforestation
global warming
ozone depletion
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