Lecture 23: Biogeography and Conservation Ecology Flashcards
Island Biogeography Theory givens
Immigration of individuals form mainland are constantly occurring
Deaths of individuals on the island are constantly occurring, at times causing extinction
Theories of local species coexistence (how species pass biotic filter)
Niche differentiation
Janzen Connell
Neutral Theory
Island Biogeography Theory
Immigration is higher if islands are close to the mainland
Extinction is higher if islands are smaller and population sizes of each species are thus smaller
Niche differentiation
Lower overlap across species –> greater species richness
Lotka Volterra result: alpha, beta less than 1 helps with coexistence
Species with niche differences are more likely to coexist
Janzen Connell Theory
Natural enemies prevent recruitment of offspring near their parents, thus facilitating coexistence among species
Ex. Specialist herbivores present seedings die
Specialist herbivores absent seedlings live
Assumptions for Neutral Theory (hubbell)
Assume all species have equivalent vital rates (fecundity, survival)
Assume there is a constant number of individuals in the community
Once an individual dies, the open spot is filled at random by an existing individual
Neutral Theory
All species equal, abundance will drift until you have a single species
Mechanisms that slow this march to extinction should increase diversity
- Proximity to other communities
- Number of individuals
- Area of the local community
- Speciation rate
Criticisms of neutral Theory
Species are observably different
Distribution fitting is not great way to test mechanistic hypotheses
Stable coexistence
When relative abundances of species are perturbed, mechanisms
direct them back.
Species tend to recover from low density
Niche differentiation, Janzen-Connell
Unstable coexistence
When relative abundances of species are perturbed, nothing returns
them to the original state
Coexistence is maintained by immigration and speciation
neutral theory
biodiversity can provide
stability
Complementarity hypothesis
Redundancy hypothesis
Ecosystem functions
Plant productivity
Soil fertility
Water quality and availability
Atmospheric gas exchange
Resistance to disturbance
Ecosystem services
Food and fuel production
Water purification
O2 and CO2 exchange
Protection from catastrophic
events like floods, tsunamis
Richness is
species diversity
Phylogenetic diversity is
genetic diversity
Water availability is
Ecosystem diversity
Conservation biology
scientific study of the phenomena that affect the maintenance, loss, and restoration of biodiversity
Conservation
preservation and restoration of biodiversity
Biodiversity
of individual species in a community
genetic diversity of each species
of communities
of ecosystems
Rare species
low numbers
many ways to be rare
Endemic species
rare
species found only in a certain area
Threatened species
species at risk of becoming endangered in the near future
Endangered species
species in danger of extinction locally or globally (biological definition)
species legally protected by Endangered Species Act (legal definition)
Extinct species
locally or globally
no longer exist on Earth
Reasons for preserving biodiversity
indirect economic benefits (ecosystem services)
direct economic benefits
aesthetic and recreational reasons
Indirect economic benefits (ecosystem services) to why we should preserve biodiversity
carbon uptake and storage
erosion control nutrient uptake, which prevents downstream eutrophication
absorption of storm and hurricane energy
Direct economic benefits to why we should preserve biodiversity
recreation
Causes of loss of biodiversity
Land use change or habitat loss
Habitat degradation
Habitat fragmentation
Invasive species
Overexploitation
Conflicting human interests
Climate Change
Land use change or habitat loss
Conversion of habitat to another use
Habitat degradation
changes that reduce quality of habitat for many species
Habitat fragmentation
breaking up of once-continuous habitat into series of patches
Invasive species
species introduced
from outside their native range,
rapidly increasing in population size
Overexploitation
fishing or
otherwise getting food from a
natural system at an unsustainable
rate
Conflicting human interests
forest
management for deer or fowl versus
plant diversity, chickens versus
wolves.
Climate change
Rapidly changing
temperature, rainfall, CO2
concentration, sea level all influence
ecosystems
Think about problems to decrease biodiversity?
Biology is powerful (ability to adapt) and sensitive
