Introduction to Biodiversity Biology/Env S 204 Spring 2009
The variety of life is biological diversity.
Use of the term “biological diversity” in its current sense began in 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 aquatic systems and the ecological complexes of which they are a part; diversity within species, 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