401 Midterm 2
Types of Overexploitation
subsistence
recreational
commercial
incidental
General Pattern of Commercialization of Renewable Natural Resources
resource identified, market develops
local population extracts and sells
if not sustainable, becomes rare or locally extinct
market substitution
Boom and Bust Cycle
Resource
Extraction
Sustainability (?)
Market Substitution
Commodity value
profits decrease as extraction becomes difficult
people unwilling to pay more
market substitution/supply switching
"commercial extirpation", recovery
Collector value
people still willing to pay more
greater price and profits
market incentive to harvest last units
extinction
Management of commercial exploitation
address local harvesting
supply chain and transportation
end user demand
Exotic species
A species living outside its native range.
Introduced species
An exotic species that has been released to the wild.
Established species
An introduced species that maintains its local populations. Self-perpetuating populations.
Invasive species
An established species with special ecological characteristics that permit it to expand its range into new areas
Rule of 10's
For every 100 species introduced, 10 will be established
for every 10 established, 1 will become invasive.
Introduction
by accident
intentional (4)
How do invasive exotic species affect native species? (3)
facilitate other non-native species
indirect
direct
Traits of a Successful Invader
weedy
large group
invade islands
why weedy species are successful invaders
r selected, high reproductive rate
often associated with humans
early successional
generalists
why species that come in large groups are successful invaders
more genetic diversity
less subject to stochastity
lag time (?)
why species that invade islands are more successful
island species are naive
don't have large predators
are endemic
few mammals (and few large ones)
Managing exotic species
Preventative (2)
Elimination/Restriction (2)
Exotic Diseases
Random (esp small populations)
Habitat destruction can make more susceptible (2)
Resistance
Demes have
carrying capacity
size
Probability of extinction
Four types of metapopulations
Classical (Levin's)
Patchy Population
Core-Satellite
Stepping Stone
Classical (Levin's) Metapopulation
identical patches
migration between all
some may be empty
n
E
M
Patchy Population-Cat tails
all different in size, population, shape
migration between all, high migration rate
quickly repopulated-rescue effect
Core-Satellite metapopulation
core has p(E)=O
satellites receive dispersers from core but no reverse migration
extirpation in satellites but not core
persistence of core population is what maintains entire network