GEOB 102 Lecture Notes - Lecture 13: Species Evenness, Species Richness, Local Extinction
2 Nov 2016
School
Department
Course
Professor
Biodiversity
GEOB 102
October 31, 2016
Lecture:
- What is biodiversity?
- How do we measure it?
- Where does it come from? (Speciation)
- Where are we losing it? (Extinction)
1. Define: biodiversity, extinction, extirpation
2. Contrast species richness and species evenness
3. Measure richness and evenness
4. Describe 4 major threats to biodiversity
Biodiversity
- The variability among living organisms from all sources and the ecological complexes of
which they are a part
- This includes diversity within species, between species, within communities, ecosystems
and landscapes
- ~1.45 million species exist today, mostly insects
- ~15000 new species are named and described each year
- Most recent estimate: 8.7 million, but it’s tricky
- If we could count the number of microbial species, would there be 1 trillion species?
o More likely: several millions of species of microbes
Measuring Biodiversity
- Species composition: list of all species (usually in defined area)
- Species diversity: combination of species per unit area (count)
- Species evenness: distribution of individuals among species=relative abundance
- Richness: number of species per unit area
- Evenness: equitability or relative abundance of individuals
- Diversity Indices: combine richness and evenness
Extinction
- Global extinction: loss of all individuals of a given species, genus family or order over its
entire range
- Ultimately, the fate of all species
- Unique genome is lost forever
- Ancestor becomes extinct as a new species evolves
- Local extinction: extirpation: species is lost from one or more geographic areas but
persists else where
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GEOB 102 Full Course Notes
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Document Summary
Where are we losing it? (extinction: define: biodiversity, extinction, extirpation, contrast species richness and species evenness, measure richness and evenness, describe 4 major threats to biodiversity. The variability among living organisms from all sources and the ecological complexes of which they are a part. This includes diversity within species, between species, within communities, ecosystems and landscapes. ~1. 45 million species exist today, mostly insects. ~15000 new species are named and described each year. Most recent estimate: 8. 7 million, but it"s tricky. If we could count the number of microbial species, would there be 1 trillion species: more likely: several millions of species of microbes. Species composition: list of all species (usually in defined area) Species diversity: combination of species per unit area (count) Species evenness: distribution of individuals among species=relative abundance. Richness: number of species per unit area. Evenness: equitability or relative abundance of individuals.
