1. Biodiversity
1.1. Formal Definition:the variability among living organisms from all sources including ... terrestrial, marine, and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species, and of ecosystems
1.2. Types of Biodiversity
1.2.1. Species Diversity
1.2.1.1. 1.2-1.5 million species described
1.2.1.2. lots of undescribed species - mostly invertebrates - just haven't been discovered, not "new" species
1.2.1.3. turnover/eveness = variation of species distribution in space
1.2.2. Genetic Diversity
1.2.3. Population Structure
1.2.4. Communities
1.2.5. Functional Diversity
1.2.6. Biological Phenomena
1.3. Factors that affect biodiversity
1.3.1. Abiotic Factors
1.3.1.1. Features and Processes: water/ nutrient availability
1.3.1.2. Affect ecosystem function, species distribution & amount of diversity
1.4. Diversity Patterns
1.4.1. Hard to predict because of unknown species
1.4.2. species richness varies
1.4.2.1. Habitat diversity
1.4.2.2. Habitat size - "area-sensitivity"
1.4.2.3. Elevation and depth (in water)
1.4.2.4. Latitude - peaks at equator - decreases with increasing latitude
1.4.2.5. It has predictable patterns
1.4.2.6. Exceptions = southern US trees, less parasitic insects in tropics, salt marshes
1.4.3. Hotspots
1.4.3.1. Areas of high species richness
1.4.3.2. used to maintain species richness
1.4.3.3. Both terrestrial and marine
1.4.3.4. zones of endemism = large # of species found nowhere else
1.4.3.5. rarity hotspots
2. Extinction
2.1. Natural process that happens all the time but current rates are much higher than during all of history
2.1.1. Hard to predict
2.1.1.1. passenger pigeon
2.2. Terminology
2.2.1. Extinction = no members of a species remain alive
2.2.2. local extinction = gone from a particular area
2.2.3. extirpation = local extinction
2.2.4. extinct in the wild = extinct in the wild but only in captivity/ under cultivation
2.2.5. ecologically extinct = still persist, but is so rare that its ecological role is negligible
2.2.6. extant = not extinct
2.2.7. endemic = only found in one (small) area
2.3. Mass extinctions
2.3.1. Large extinctions in the past - >50% of all species and >30% of animal families
2.3.1.1. ordovician
2.3.1.2. devonian
2.3.1.3. permian
2.3.1.4. triassic
2.3.1.5. cretaceous
2.3.2. Current mass extinction rates are high like past mass extinctions - most are human caused
2.4. Extinction rates
2.4.1. The “background” rate is the typical rate that is thought to have occurred during most of the Earth’s history.
2.4.2. 1 in every million to 10 million species
2.4.3. current rate: ~1 in 10,000 species extinct each year but there's a lot of variation in the estimates
2.4.4. S = cAz
2.4.5. the extinction is likely to keep increasing instead of decreasing
2.4.6. we are not experiencing a mass extinction yet because the rates are not high enough yet
2.4.7. extinction debt = species expected to go extinct but that have not yet gone extinct
2.5. Extinction patterns
2.5.1. we can't verify that a species is extinct
2.5.2. time-based criteria
2.5.3. search-based criteria
2.5.4. statistical criteria
2.5.5. extinction rates vary because of extinction debt and due to developed adaptations from many species
2.6. Vulnerability to extinct causes
2.6.1. Small populations
2.6.2. Small geographic range
2.6.3. Population size fluctuations
2.6.4. Habitat specialists
2.6.5. Species in symbiotic relationships
2.6.6. Large species (mainly animals) that require lots of space
2.6.7. Low reproductive rates
2.6.7.1. species with low dispersal rates
2.6.8. complex life-histories
2.6.9. Island species
2.7. Population decline causes
2.7.1. isolates catastrophic events
2.7.2. long-term ecological change
2.7.3. loss of species integrity
2.7.4. habitat destruction
2.7.4.1. habitat fragmentation
2.7.5. Usage by humans
2.7.5.1. food
2.7.5.2. pet-trade
2.7.5.3. trophy-hunting
2.7.5.4. medicine
2.7.6. disruption of behavior
2.7.7. increased homozygosity
2.7.8. pollution
2.7.9. The causes are usually compounded on each other and are not mutually exclusive
2.7.9.1. habitat loss is the most important cause of extinction