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Biodiversity

Conserving Biodiversity

5.1 Biodiversity

Main idea: Biodiversity maintains a healthy

biosphere and provides direct and indirect value

to humans.

Objectives:

 Describe three types of biodiversity.  Explain the importance of biodiversity.  Summarize the direct and indirect value of biodiversity.

Review Vocabulary:

 Gene: functional unit that controls the expression of inherited traits and is passed from generation to generation

Genetic Diversity

The variety of genes or inheritable

characteristics that are present in a

population comprises its genetic diversity.

Genetic diversity within an interbreeding

population increases the chances that

some species will survive during changing

environmental conditions or during the

outbreak of disease.

Species Diversity

The number of

different species

and the relative

abundance of each

species in a

biological

community is called

species diversity.

The Importance of Biodiversity

There are direct and indirect economic,

aesthetic, and scientific reasons for preserving

biodiversity.

Domestic corn plant Teosinte plant Madagascar periwinkle

Direct Economic Value

Humans depend on plants and animals to provide food, clothing, energy, medicine, and shelter. Genetic diversity in species that might be needed in the future is important because…  (^) Most of the world’s food crops come from just a few species.  (^) Wild species serve as reservoirs of desirable genetic traits that might be needed to improve domestic crop species (disease- and insect-resistance).  Many of the medicines that are used today are derived from plants or other organisms.  (^) Scientists continue to find new extracts from plants and other organisms that help in the treatment of human diseases.  (^) However, many species of organisms are yet to be identified, especially in remote regions of Earth, so their usefulness in providing extracts or useful genes is unknown.

Indirect Economic Value

It is difficult to attach an economic value to the services that a healthy biosphere provides humans. An economic study determined that restoring the biodiversity in the ecosystem (1.5 billion) that filtered the water supply for New York City was less expensive than building a new water filtration system (6 billion).

Aesthetic and Scientific Value

It is difficult to attach a value to something

that is beautiful or something that is

interesting to study.

Perhaps it is best to consider how life

would be if all that was present on Earth

was a barren and desolate landscape.

The value of biodiversity and healthy

ecosystems would be more obvious to us

then.

Extinction Rates

The gradual process of species becoming extinct is known as background extinction. Mass extinction is an event in which a large percentage of all living species become extinct in a relatively short period of time. Five Most Recent Mass Extinctions

1. Cretaceous Period - about 65 million years ago – Ammonite
2. Triassic Period – about 200 million years ago – Cynognathus
3. Permain Period – about 251 million years ago – Trilobite
4. Devonian Period – about 360 million years ago – Dinichthys
5. Ordovician Period – about 444 million years ago – Graptolites

Extinction Rates

Factors that Threaten Biodiversity

The current high rate of extinction is due to the

activities of a single species— Homo sapiens.

Humans are changing conditions on Earth faster

than new traits can evolve to cope with the new

conditions.

Evolving species might not have the natural

resources they need.

Natural resources are all materials and

organisms found in the biosphere, including

minerals, fossil fuels, nuclear fuels, plants,

animals, soil, clean water, clean air, and solar

energy.

Overexploitation

Overexploitation, or excessive use, of species that have economic value is a factor increasing the current rate of extinction. Historically, overexploitation was the primary cause of species extinction.  Bison  Passenger Pigeons  Ocelot  Rhinoceros

Fragmentation of Habitat

The separation of an ecosystem into small

pieces of land is called habitat fragmentation.

 The smaller the parcel of land, the fewer species it can support.  Fragmentation reduces the opportunities for individuals in one area to reproduce with individuals from another area. (Genetic diversity decreases over time)  Carving the large ecosystem into small parcels increases the number of edges—creating edge effects.

Edge Effects

Edge effects are different environmental

conditions (abiotic factors) that occur

along the boundaries of an ecosystem.

Edge effects often make species more

vulnerable to predators and parasites.

Edge effects do not always create a

disadvantage for all species.

Some species find these conditions

favorable and they thrive.