Introduction to Biodiversity

Biology/Env S 204Spring 2009

The variety of life

is biological diversity.

Use of the term “biological diversity”in its current sense beganin 1980.

Biodiversity = biological diversity

Coined in 1985 for a conference, the proceedings of which were published as the book “Biodiversity”edited by E. O. Wilson.

What does it mean?

The variability among living organisms from all sources including terrestrial and aquaticsystems and the ecological complexes of which they are a part; diversity withinspecies, among species, and of ecosystems;interactions at all levels among organisms.

From Frankel et al., 1995, The conservation of plant biodiversity.

Fundamental levels of organization

•Genetic

•Organismal

•Ecological

Ecological Diversity

• Communities of species, their interactions

• Communities + resources (energy, nutrients, etc.) = ecosystem

• Measured primarily in terms of vegetation but relative abundance of species also important

• No unique definition and classification at the global level

Organismal Diversity

• Individuals, species• Mostly measured by numbers of

species• Estimated 1.7 million species

described to date• Estimated total number ranges

from 2 to 50 million (up to 100 million) species

• Mostly microorganisms and insects

Genetic diversity

• Heritable variation within and between populations of organisms

• Encoded in the sequence of 4 base-pairs

that make up DNA• Arises by mutations in genes and chromosomes• Very small fraction of genetic diversity is outwardly expressed

Why care about what we can’t see?

• Genetic variation enables evolutionary

change and artificial selection• Estimated 109 different genes across the Earth’s biota• Represents a largely untapped

genetic library