Section 16.4 Threats to Biodiversity
KEY CONCEPT
The impact of a growing human population threatens
biodiversity.
Preserving biodiversity is important to the future of the
biosphere.
• The loss of biodiversity has long-term effects.
– loss of medical and technological advances
– extinction of species
– loss of ecosystem stability
Loss of habitat eliminates species.
• Habitat fragmentation prevents an organism from
accessing its entire home range.
– occurs when a barrier forms within the habitat
– often caused by human development
• Habitat corridors are a solution to the problem.
– corridors can be road overpasses or underpasses
– allow species to move between different areas of
habitat
Loss of habitat eliminates species.
Introduced species can disrupt stable relationships in an
ecosystem.
• An introduced species is one that is brought to an
ecosystem by humans.
– accidental
– purposeful
• Invasive species
can have an
environmental
and economic
impact.
• Invasive species often push out native species.
– Burmese python (Florida Everglades)
Introduced species can disrupt stable relationships in an
ecosystem.
• Invasive species often push out native species.
– mice (Australia)
Introduced species can disrupt stable relationships in an
ecosystem.
• Invasive species often push out native species.
– kudzu (southeastern United States)
Introduced species can disrupt stable relationships in an
ecosystem.
Section 19.1 Diversity of Protists
KEY CONCEPT
Kingdom Protista is the most diverse of all the
kingdoms.
Protists can be animal-like, plantlike, or fungus-like.
• Protists are eukaryotes that are not animals, plants, or
fungi.
• Animal-like protists consume other organisms.
– heterotrophs
– single-celled
Protists can be animal-like, plantlike, or fungus-like.
• An amoeba is an animal-like protist that feeds by engulfing
food.
Protists can be animal-like, plantlike, or fungus-like.
• A paramecium is an animal-like protist that has no cell
wall.
Protists can be animal-like, plantlike, or fungus-like.
• Plant-like protists are photosynthetic.
– single-celled, colonial, or multicellular
– no roots, stems, or leaves
Protists can be animal-like, plantlike, or fungus-like.
• A euglena has both animal-like structures—such as an
eyespot, contractile vacuoles, and flagella—and plantlike
structures, such as chloroplasts.
Protists can be animal-like, plantlike, or fungus-like.
• Fungus-like protists decompose dead organisms.
– heterotrophs
– can move, whereas fungi cannot
Protists can be animal-like, plantlike, or fungus-like.
• A slime-mold is a fungus-like protist.
Protists can be animal-like, plantlike, or fungus-like.
Protists are difficult to classify.
• Protista is one kingdom in the domain Eukarya.
• Protist classification will likely change.
– Some protists are not closely related.
– Molecular evidence supports reclassification.
Protists are difficult to classify.
Section 19.6 Ecology of Fungi
KEY CONCEPT
Fungi recycle nutrients in the environment.
Fungi may be decomposers, pathogens, or mutualists.
• Fungi and bacteria are the main decomposers in any
ecosystem.
– decompose dead leaves, twigs, logs, and animals
– return nutrients to the soil
– can damage fruit trees and wooden structures
• Fungi can act as pathogens.
– human diseases include ringworm and athlete’s foot
– plant diseases include Dutch elm disease
Fungi may be decomposers, pathogens, or mutualists.
• Fungi can act as mutualists.
– lichens form between fungi and algae
– mycorrhizae form between fungi and plants
Fungi may be decomposers, pathogens, or mutualists.
– relationships form between fungi and some insects
• Fungi can act as mutualists.
Fungi may be decomposers, pathogens, or mutualists.
Fungi are studied for many purposes.
• Fungi are useful in several ways.
– as food
– as antibiotics
– as model systems for molecular biology