Lecture 11

• what are the two ways to measure diversity?

  species richness and evenness or both
• species richness -> total number of species found in an area
• Evenness -> relative representation of each species in an area
• assemblages don't always include everything
• within a habitat -> alpha diversity ->species richness for a single habitat
• Between habitats -> beta diversity -> species richness of whole region
• nestedness -> how similar the habitats are
• Evolution = ultimate source of biodiversity
• what are the two key factors of Evolution?

  1. Time
  2. reproductive isolation
• endemic species -> species with restricted distributed
• geologically ancient habitats have greatest diversity and a high degree off endemism
• Habitats serve as a template for evolution

  • organisms are specialized to a habitat
  • habitat interfaces tend to be species rich
• Dispersal determines the ability of a species to reach new habitats
• high dispersal abilities tend to lead to cosmopolitan distribution
• the amount of endemism is a function of time and isolation
• What are the short term factors that influence distribution?

  Habitat and dispersal ability
• diversity metrics are used to describe distribution of taxa for a given area