Getting the measure of biodiversity
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GETTING THE MEASURE OF BIODIVERSITY. How do we define ‘biodiversity’?. The sum of all biotic variation from the level of genes to ecosystems. The number, variety, and variability of living organisms in a quantified area. Methods to Measure Biodiversity. Species Richness Species Evenness

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Getting the measure of biodiversity


How do we define biodiversity

How do we define ‘biodiversity’?

  • The sum of all biotic variation from the level of genes to ecosystems.

  • The number, variety, and variability of living organisms in a quantified area.

Methods to measure biodiversity

Methods to Measure Biodiversity

  • Species Richness

  • Species Evenness

  • Disparity

  • Species Rarity

  • Genetic Variability.

Measuring biodiversity

Measuring Biodiversity…

  • Species Richness; the total number of given species in a quantified area.

  • Species Evenness; the degree to which the number of individual organisms are evenly divided between different species of the community.

Measuring biodiversity1

Measuring Biodiversity…

  • Disparity; measures the phenotypic differences among species resulting from the differences genes within a population.

  • Species Rarity; the rarity of individual organisms within a quantified area.

Biodiversity genetics

Biodiversity & Genetics

  • Genetic Variability:each population of a species contributes to additional biodiversity due to variations between genes.

Biodiversity and the relationship to ecosystem functions

Biodiversity and the Relationship to Ecosystem Functions

  • Diverse communities are typically more stable and function more efficiently.

  • Loss of a umbrella species leads to a unoccupied niche, in turn potentially affecting ecosystem processes.

  • Extinction events are commonly followed by high rates of diversification. Ex) Species turnover



  • Increase of productivity in an area corresponds with an increase in biodiversity.

  • Ex) tropical rain forest compared to semi-desert or tundra

Biodiversity exotic species

Biodiversity & Exotic Species;

  • Ecosystems with high measures of biodiversity are more resistant to invader species.

  • Ex) Cheatgrass & Tamarisk

Keystone umbrella species

Keystone & Umbrella Species

  • Species whose presence or resource requirements affect ecosystem functions.

  • Health of an umbrella species is a way to monitor the health of an ecosystem.

  • Ex) Northern Spotted Owl & Grizzly Bears



  • New Discoveries

  • Grouping together

  • Splitting apart

  • Phylogenies; showing past relationships between organisms using evolutionary lineages.

Increasing species worldwide

Increasing Species Worldwide

  • Phylogenic Species Concept

  • Computer databases

  • Increased human exploration

  • Technology; electron microscope and evidence using mDNA.

Species richness

Species Richness

Taxonomic methods used in relation to quantifying biodiversity

Taxonomic methods used in relation to quantifying biodiversity

  • Phylogenic Species Concept

  • Biological Species Concept

  • Evolutionary Species Concept

Phylogenic species concept

Phylogenic Species Concept

  • taxa are separate species if they can be diagnosed as distinct either by phenotypic or genotypic information.

  • Leads to an increase in the number of species.

  • Does not allow for natural variations within populations to be listed as separate species.

Biological species concept

Biological Species Concept

  • Groups of organisms that can interbreed freely under natural conditions.

  • Most commonly used of the three

Evolutionary species concept

Evolutionary Species Concept

  • Groups organisms together using an ancestral/descendant relationship that is traceable in the fossil record

  • Focuses on studying the morphological features of closely related organisms.

Problems in general

Problems in General

  • Measuring biodiversity is ultimately a complex process involving many facets.

  • Various applications of species concepts either divide and/or group organisms together.

  • Biodiversity can’t be reduced to a single number.

  • Studying biodiversity using all ecosystem processes at all scales.

  • In attempting to preserve biodiversity we often are ‘speciesists’ ;favoring the cute and popular species.



  • Generally, areas of higher productivity correlate with increases in biodiversity.

  • Biodiversity is also measured using the genetic variability of different populations of a single species.

  • Biodiversity can’t be reduced to a single number, thus creating complications when comparing biodiversity in different ecosystems.

  • The importance of biodiversity is accepted by some and disregarded by many others.



  • How do different taxonomic methods create potential problems in measuring biodiversity?

  • How do difficulties in measuring biodiversity create complications for policy makers and administrative regulations?

  • Can we study all processes at all scales?

    Why should anyone care about‘biodiversity’ ?



  • Purvis, Andy. Hector, Andy. May 2000. Getting the Measure of Biodiversity. Nature Magazine. Vol.405 pgs 212-219. Berkshire, United

  • Wildland Invasive Species Team. July 2002.Vernal, UT. Retrieved on 10-26-02

  • Macdonald, Glen. 2003. Biogeography; Introduction to Space, Time, and Life. New York. John Wiley & Sons Inc.

  • Sartore, Joel. 2002. National Geographic Society. Retreived

    10-20-02 wallpaper13.html

  • Dr. Robert Rothman: Darwin’s Finches. Retrieved on 10-18-02.

  • Paul Walker. Balam Na Project. Rainforest Preserve. 8-28-02

  • Paul Williams, 2002 ”Biodiversity: Measuring the variety of nature and selecting the priority areas for conservation.” London, 10/23/02,

  • Bryant, Peter J., 2001, “Biodiversity and Conservation: A Hypertext book”. Irvine, 10/23/02,

  • Dooley, Laura Lee S., 1982-2002, “Biodiversity and Protected Areas”, Washington D.C., 10/23/03,

Getting the measure of biodiversity

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