Welcome to SCI 204, Environmental Science

Biodiversity (Continuation)

In this presentation we look at the dynamics of Biodiversity including

1. Natual Selection2. Biological Evolution3. Ecological Succession4. Natural History5. Geologic Time

How does nature sustain ecosystems?Nature sustains ecosystems by promoting amaximum of species variety (or biodiversity) acrosswith the system, including

1. Maximum population within a species within a habitat2. Maximum number of different species within a habitat

There are four processes which explain how biodiversity is accomplished

1. Natural selection2. Biological evolution3. Ecological succession4. Extinction

Anaticipated BlendOf Population

vs Wilderness

c 2050

What is Natural Selection?

Natural Selection is the process by which 1. Particularly favorable traits within a species of a particular

environment are promoted through the entire population2. Beneficial genes, within a population, are reproduced in

succeeding generations more than other others less beneficial genes

3. A population is made more adaptable to its environment than might otherwise be found

4. The variety of individuals within any single species can produce an entire new generation of the same species, with an equal or greater variety

It is the process which governs how biodiversity in one generationIs passed on to the next

The first scientific observations of Natural Selection became popular when Charles Darwin published his observations of various popuations within the species of the galapagos islands.

What is Biological Evolution?

Biological Evolution is a process by which

1. The change in genetic makeup within a population of species over successive generations

2. When change is great enough, the population can become an entirely new species

3. Evolution refers to the process whereby an entire population becomes differentiated from the existing or previous species

Evolution is about differentiation among different populations andhow these transform into new species.

How does Biological Evolution proceed?

Biological Evolution is generally the product ofgenetic mutation caused by

• Random events within the replication of genetic code• Chemicals or radiation which causes inheritable changes in the

DNA molecules resulting in variant genes and qualities within a population

• Geographic isolation, where a population is isolated from other populations of the same species

Evidence of Evolutionary changes are often often visible in fossil records buried in sedimentary rock formations.

What is Ecological Succession?

Ecological Succession is the process in which

1. Communities of species in a particular area become replaced over time by a series of different more complex species

2. The populations of plant and animal species change over time, usually to a greater more elaborate biodiversity

3. An area transforms from one ecological stage, with a partilcular diversity of species, to another

Succession occurs from the introduction of exotic species,and/or populations alien to the indiginous populations nativeto the area

Current Blend of Population

vs Wilderness

c 2000

Ecological Succession transforms an ecosystem such that

1. Some populations and species dieback, even to the point of extinction

2. Other populations and species multiply by filling new and existing ecological niches

3. Ecosystems, decimated by the extinction of some species, acquire new populations to replace them

It is often thought of in terms of a state of balance or equilibriumIn nature which, when upest or disrupted, finds a new state. Thecontinuous change of state makes the ecosystem dynamic.

How does Ecological Succession proceed?

Ecological Succession is often times explained in terms of progressive ecological stage going from pioneer or primary stage through secondary and tertiary stages, to mature or climax stage.

How do Environmentalists use natural selection, evolution and

ecological succession?

An understanding of the effort by nature to expandbiodiversity, and the processes for creatingbiodiversity helps wildlife managers

1. To recognize the health of an ecosystem2. To develop strategies for protecting ecosystems3. To design plans for expanding or creating ecosystems 4. To coordinate efforts to restore ecosystems which are under

stress

Knowledge of natural selection, biological evolution and ecologicalselection is at the heart of wildlife and land management

How are the Changes in the Biosphere Affected by Nature and/or Human Kind?

Changes occurring in the biosphere can begenerated from• Natural causes• Anthropogenic causes

Changes occuring in the biosphere • Do so over long periods of time• On a global scale they are recorded over geologic time• Are recorded as Natural History• Are integrally connected with the atmospheric, geologic,

and pedospheric changes which have occurred within an area

Natural changes may be caused by 1. Changes in climate ()2. Introduction of new species into an ecology ()3. Violent weather ()

Anthropogenic changes may include lawsand regulations imposed 1. To protect an endangered or threatened species2. To support soil conservation in the face of erosion or

degradation3. To promote organic farming and ranching practices as

opposed to ecological reconstruction to support mechanized agriculture

Example: How might a population of Pacific Coral be affected by natural changes?

Pacific coral reefs can be reduced by temperature changes or salinity in the ocean water due to El Nino, new prediators can migrate in and decimate a Pacific coral reef, heavy Pacific storms can dislodge sections of Pacific coral reefs setting them adrift.

Example: How might a population of Pacific Coral be affected by natural changes?

Pacific coral reefs can be reduced by temperature changes or salinity in the ocean water due to El Nino, new prediators can migrate in and decimate a Pacific coral reef, heavy Pacific storms can dislodge sections of Pacific coral reefs setting them adrift.

What Are the Consequences of the Biosphere’s Changes on Civilization?

Geologic time is recorded by Eons, Eras, and periods

There are four Eons (or Ages)1. Hadean 4500-3800 million ya2. Archean 3800-2500 million ya3. Proterozoic 2500-650 million ya4. Phanerozoic 650 million ya to the present

Within the Phanerozoic Eon there are Three Eras1. Paleozoic (old life) 650-250 million ya2. Mesozoix (middle life) 250-65 million ya3. Cenozoic (present life) 65 million ya to the present

Within the Cenozoic Era there are Two periods1. Paleogene (old period) 65-23 million ya2. Neogene (new period) 23-1.8 million ya3. Quaternary 1.8 million ya to present