21-3 Ecology of Fungi
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21-3 Ecology of Fungi
21-3 Ecology of Fungi
The oldest known fungi fossils are about 460 million
years old.
Fungi may have helped early plants obtain nutrients
and may have been essential to plants’ colonization
of the land.
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21-3 Ecology of Fungi
All Fungi Are Heterotrophs
All Fungi Are Heterotrophs
Fungi rely on other organisms for energy.
Their mycelia can grow very rapidly into the tissues
and cells of other organisms.
Many fungi are saprobes, which are organisms that
obtain food from decaying organic matter.
Other fungi are parasites, which harm other
organisms while living directly on or within them.
Other fungi are symbionts that live in close and
mutually beneficial association with other species.
A few feed by capturing live animals.
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21-3 Ecology of Fungi
Fungi as Decomposers
Fungi as Decomposers
Fungi maintain equilibrium in nearly every
ecosystem, where they recycle nutrients by breaking
down the bodies and wastes of other organisms.
Without decay, the energy-rich compounds that
organisms accumulate during their lifetimes would be
lost forever.
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21-3 Ecology of Fungi
Fungi as Parasites
Fungi as Parasites
Parasitic fungi cause serious plant and animal
diseases.
A few fungi cause diseases in humans.
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21-3 Ecology of Fungi
Fungi as Parasites
Plant Diseases
Fungal diseases are responsible for the
loss of approximately 15% of the crops
grown in temperate regions of the
world.
Ex: corn smut, mildews, wheat rust
In tropical areas, where high humidity
favors fungal growth, the loss of crops
is sometimes as high as 50%.
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21-3 Ecology of Fungi
Fungi as Parasites
Human Diseases
Examples of fungus-caused disorders include:
• Athlete’s foot
• Ringworm
• Thrush
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21-3 Ecology of Fungi
Symbiotic Relationships
Symbiotic Relationships
Some fungi form symbiotic relationships in which
both partners benefit.
Two such mutualistic associations, lichens and
mycorrhizae, are essential to many ecosystems.
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21-3 Ecology of Fungi
Symbiotic Relationships
Lichens
Lichens are symbiotic associations between a
fungus and a photosynthetic organism.
The fungus is usually a ascomycete or sometimes
a basidiomycete.
The photosynthetic organism is either a green
alga or a cyanobacterium, or both.
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21-3 Ecology of Fungi
Symbiotic Relationships
Structure of a Lichen
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21-3 Ecology of Fungi
Symbiotic Relationships
Lichens are extremely resistant to drought and cold.
The algae or cyanobacteria carry out photosynthesis,
providing the fungus with a source of energy.
The fungus provides the algae or bacteria with water
and minerals and protects the green cells from intense
sunlight.
Lichens are often the first organisms to enter barren
environments, breaking down rocks into soil.
They are remarkably sensitive to air pollution, and are
used as an air quality monitor.
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21-3 Ecology of Fungi
Symbiotic Relationships
Mycorrhizae
Fungi also form mutualistic relationships with plants.
The associations of plant roots and fungi are called
mycorrhizae.
Mycorrhizae is essential for the growth of many plants.
80% of all plant species form mycorrhizae with fungi.
The hyphae aid plants in absorbing water and
minerals. The plants provide the fungi with the
products of photosynthesis.
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