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