systematic 4b

• Biodiversity is the heritage of million years of evolution
• Diversity is a basic property of life
• Biological diversity is the variety of different types of organisms present and interacting in an ecosystem
• A diversity index is a mathematical measure of species diversity in a community
• Diversity indices provide more information about community composition than simply species richness
• Alpha diversity:

  • Diversity within a particular sample
  • Refers to the average species diversity in a habitat or specific area
  • It is a local measure
• Beta Diversity:

  • Refers to the ratio between local or alpha diversity and regional diversity
  • This is the diversity between two habitats or regions
• Gamma Diversity:

  • It is the total diversity of a landscape
  • It is a combination of both alpha and beta diversity
  • Example: diversity of a forest landscape
• Types of biodiversity indices:

  1. Species richness

  2. Simpson's index

  3. Shannon-Wiener index

  4. Evenness
• Richness:

  • Total number of species found in an environment or sample
  • More species does not always equal more diversity
  • Richness tends to increase over area
• Simpson's Diversity Indices:

  • Measures the probability that two randomly selected individuals belong to two different species/categories
  • Simpson's Index of Diversity ranges between 0 and 1
  • The greater the value, the greater the sample diversity
• Shannon Index:

  • Another index commonly used to characterize species diversity in a community
  • Accounts for both abundance and evenness of the species present
  • Typical values range between 1.5 and 3.5 in most ecological studies
• Evenness:

  • A measure of how similar the abundance of different species/categories are in a community
  • Ranges from 0 to 1
  • As species richness and evenness increase, diversity increases
• Biodiversity indices uses:

  • A way of measuring biodiversity
  • To restore and maintain the chemical, physical & biological integrity of the ecosystem
  • Provide important information about rarity and commonness of species in a community