7a. Biodiversity and Conservation

Biodiversity

Variability of organisms from all sources; typically measured in species, but can be measured ecologically, genetically, organismal, and chemical (definition we use changes diversity)

Adaptive Radiation

Rapid branching of a clade into many closely related species through speciation

Factors that Dictate Biodiversity

1) Space/area 2) Energy

Space/Area

More space = more diverse (BUT it plateaus at a certain point); more space=more habitats and more places to colonize (allows development of niche) --> more speciation and smaller likelihood of extinction

Energy

More solar radiation=more energy=more species; more producers (need sunlight) --> more biodiversity; warmer = more liquid water

Why Biodiversity Increases at Equator

1) Age of tropical ecosystems 2) Increased energy from sun 3) Increased heterogeneity (# of ecological niches) 4) Increased stability

Biodiversity Hotspot

Area that contains a high number of ENDEMIC (unique to that area) species; 34 in the world that only cover 2.3% of the surface but have 42% of terrestrial vertebrate species and 50% of the world's plants endemic to them

Endemic Species

Species only found in one location

Measures of Biodiversity

1) Abundance (total # of organisms in an area) 2) Richness (total # of species in an area) 3) Evenness (how close in # diff species are in an area; ratio) 4) Diversity (relationship between # of species and their abundance)

Shannon Diversity Index (H)

Notes number of species in a habitat (richness) and their relative abundance (evenness); higher=more diverse

Simpson Index (DI)

Measures relative diversity (notes richness and evenness); DI is chance of selecting 2 organisms of the same species if you're randomly selecting from a population (higher DI=less diverse); 1/DI is reciprocal (higher=more diverse)

Problems with Indices

Shannon: information statistic index, assumes sample is accurate reflection of all species in an area; Simpson: dominance index, gives more weight to common/dominant species (rare species won't affect diversity)

Background Extinction Rate

One per million species per year; may underestimate because 1) many species weren't described until much later, so their loss would go unnoticed 2) number of recently extinct species is increasing because extinct species are being identified by skeletal remains 3) some species are probably already extinct even though they aren't named as such

Importance of Conservation

1) Direct Value (role of biological resources in consumption/production, e.g. food/medicine/etc.) 2) Indirect Value (functions that are indirectly useful b/c they are not directly traded, e.g. atmospheric + climatic regulation, photosynthesis) 3) Non-Use Value (option value for the future, bequest value for future generations, existence value for members of society, intrinsic value for moral obligation)

Species-Area Relationship

Rate at which new species are seen when the area surveyed is increased; ay overestimate

Threats to Biodiversity

1) Habitat loss 2) Overharvesting (e.g. overfishing) 3) Exotic/invasive species 4) Climate change

How to Preserve Biodiversity

1) Grab data (citizen science) 2) Change human behavior through laws (e.g. EPA) 3) Preserve pristine areas 4) Habitat restoration and genetic biodiversity preservation