Section 16.4 Threats to Biodiversity KEY CONCEPT The impact of a

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
Loss of habitat eliminates species.
• Habitat corridors are a solution to the problem.
– corridors can be road overpasses or underpasses
– allow species to move between different areas of
habitat
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.
Introduced species can disrupt stable relationships in an
ecosystem.
• 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)
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.
Protists can be animal-like, plantlike, or fungus-like.
• 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 are difficult to classify.
• Protista is one kingdom in the domain Eukarya.
Protists are difficult to classify.
• Protist classification will likely change.
– Some protists are not closely related.
– Molecular evidence supports reclassification.
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 may be decomposers, pathogens, or mutualists.
• 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.
• Fungi can act as mutualists.
– relationships form between fungi and some insects
Fungi are studied for many purposes.
• Fungi are useful in several ways.
– as food
– as antibiotics
– as model systems for molecular biology