Post on 28-Dec-2015
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
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
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