California Science Content StandardsToday's lecture and activity will cover the

following content standards:

5d) Students know different kinds of organisms may play similar ecological roles in similar biomes. (Grade 6)

5e) Students know the number and types of organisms an ecosystem can support depends on the resources available and on abiotic factors, such as quantities of light and water, a range of temperatures, and soil composition (Grade 6)

7b) Select and use appropriate tools and technology (including calculators, computers, balances, spring scales, microscopes, and binoculars) to perform tests, collect data, and display data. (Grade 6)

California Science Content StandardsToday’s lecture and activity will cover the

following content standards:

7c) Construct appropriate graphs from data and develop qualitative statements about the relationships between variables. (Grade 6)

6a) Students know biodiversity is the sum total of different kinds of organisms and is affected by alterations of habitats. (Grades 9-12)

Communities, Ecosystems and Biomes

Community: all the populations in a specific area or region. Studies of communitiesinclude examining interactions between different species

Ecosystem: refers to the biological community and the associated abiotic environment.

Biomes Def: major regional complex of plant (and

animal) communities; largest scale community types

Are identified by climax vegetation, which is influenced by temperature and rainfall

Distribution of Biomes

Within communities, ecosystems and biomes,scientists are concerned with studying:

BIODIVERSITY

What is Biodiversity?

def: biodiversity = biological diversity = the variety of life and their habitats

There are three components:

GeneticDiversity

Habitat Diversity

Species Diversity

Past extinction rates = 2-25 spp./yr.

Losses in Biodiversity

Current extinction rates = up to 10,000+ spp./yr.

* past extinctions due to natural

phenomena

* present extinctions due to human-caused phenomena

Genetic Diversity

Def: amount of genetic variation present:

* within individuals* between individuals within a population* between populations

Habitat Diversity

Def: variety of ecosystems in an area

Includes:* communities * functional properties

*physical properties

Species Diversity

Def: the variety of species in an area

Two subcomponents: species richness species evenness

Species Richness vs. EvennessSpecies Richness: measurement of the

number of species in a given area

Species Evenness: measurement of how evenly distributed organisms are among species

Community A Community B

species 1 25 1species 2 0 1species 3 25 1species 4 25 1species 5 25 96

Determining Species Diversity

Scientists may want to:

* get an estimate of # of species in an area

* compare species diversity of two communities

To be accurate, need to:

* take both species evenness and species richness into account

Species Diversity Indices

Shannon-Weiner (Shannon-Weaver) Index

Diversity =

(p spp 1 - ln(p spp 1)) + (p spp 2 - ln(p spp. 2) + …

(p spp N - ln(p spp. N)

Simpson Index

Diversity = 1 (pspp1)2 + (pspp2)2 + … (psppN)2

Why should we care about measuring

biodiversity(species diversity)?

Biodiversity Factoids

~ 2,000,000 spp. have been described  ~ 10-30,000,000 species actually exist (est.)

~ 8,000,000 – 22,000,000 spp. unidentified

~ 40 – 60% of all spp. occur in two areas:

* tropical rainforests* coral reefs

Past extinction rates = 2-25 spp./yr.

Losses in Biodiversity

Current extinction rates = up to 10,000+ spp./yr.

* past extinctions due to natural

phenomena

* present extinctions due to human-caused phenomena

Loss of biodiversity caused by:

Introduction of Habitat Destruction Exotic Species

Human-Caused Factors of Biodiversity Loss

Biodiversity loss caused by:

Overharvesting/ Pollution Overhunting

Human-Caused Factors of Biodiversity Loss

There have been 5 mass extinction events

during the history of the earth 

Extinction

Are we on the verge of a 6th?