The Biodiversity Crisis
o Extinction is a natural process, but current RATE is not
--- Rate expressed as the # or % of species expected to disappear within a given area in a unit of time
--- Know most about birds - use as indicator
--- With a 90% loss of habitat, 50% of species will become extinct
--- 11% of known bird species are endangred
--- 3% of plant species, 2% of fishes have become extinct
--- Habitat destruction
--- Over-exploitation
--- Competition by exotics
o Biodiversity is vital to human welfare
--- 25% of prescriptions contain plant substances
--- Loss of species, loss of genes
--- Ecosystem "services"
--- Preservation
--- Select areas set aside
o Resource conservation
--- Balancing multiple uses
o Evolutionary/ecological view
--- Result of evolution
o To preserve individuals, species, and ecosystems
--- Gradual variation in biodiversity correlates with geographical gradients
o Clines
--- Bird species increases from Arctic to tropics
--- Benthic species increase with depth
o Energy availability: solar radiation greatest in tropics, resource base greatest
o Habitat heterogeneity: tropical regions = more local disturbances = greater patchiness = greater diversity
o Niche Specialization:tropics allows more specialization (more resources)
o Population interactions: diversity is self-propagating because population interactions coevolve. Value of predator-prey, symbiotic interactions
--- Biodiversity Hot Spot = relatively sm. Area with exceptional concentration of species
--- Endemic = found no where else
--- 18 vascular plant hot spots
--- Island bird extinction hot spots
--- Complicated by life history
o Monarchs, songbirds, sea turtles, marine mammals
--- Requires international cooperation
--- Endangered
--- Threatened
--- Goal: sustain genetic diversity & areas for evolution
o Efforts often lag behind
o Crisis management
--- Caused by habitat degradation
--- Metapopulation+ subdivided population or network of subpopulations
o Separated into habitat patches
--- Dispersal critical
--- Where a population’s reproductive success exceeds mortality
--- To distinguish:
o Analysis of birth & death rates
o Identification of dispersal factors
o Identification of habitat factors
o Sink Habitat
--- Where population’s mortality exceeds reproductive success
o Method of predicting whether or not a particular given will persist in a specific environment
--- Computer simulation
--- Genetic variability & life history
--- Response to environmental factors
--- Response to human activities
o Predicts long-term viability
o Designed to predict a species’ minimum viable population size (MVP) & minimum dynamic area
o (Ne) - based on # of adults that successfully breed
o Ne= (4Nm x Nf), (Nm+Nf)
o Life history traits can effect
o Low (Ne) = many prone to inbreeding (not all: grizzly bear, cheetah)
o Conserving species involves weighing conflicting demands
--- Habitat use
o Which do we save?
o Why?
Conservation at the Community, Ecosystem, Landscape Level
o Landscape ecology - application of ecological principles to land use patterns
o Edges & corridors influence landscape diversity
o Nature reserves must be functional
--- Mining, oil spills
o Restoration ecology = to find ways to restore degraded ecosystems to near original state
--- Bioremediation
--- Augmenting ecosystem processes
o Global change
o Biological diversity
o Sustainihng natural productivity
Conservation Biology
o Major threats:
o Conservation Biology
o Geographic Diversity
Four hypothesis
o Hot Spots:
o Migratory Species
o Conservation at population & species level
o Subdivided populations:
o Source Habitat
Population viability analysis (PVA)
o MVP need effective population size (Ne)
o Analyzing selected species viability may help others
o Restoring degraded areas is an increasingly important conservation effort
The goal of sustainable biosphere initiative is to acquire the basic ecological information needed for intelligent development, management, and conservation of the Earth’s resources.
