3.14
Exotic, Invasive, and Nuisance Species
Non-native crops…
with non-native pollinators
Exotic?
Invasive?
Nuisance?
Native/indigenous species: presence in an area is the result only
of natural processes
Endemic species: native and unique to a location
Exotic/non-native: a species living outside its natural range
Naturalized species: an exotic reproducing without
human intervention
Invasive species: a species that spreads rapidly in time and space
Nuisance: adversely affects economy and or ecology, a pest
-not always exotic
A Hierarchy of Terms
Native/Indigenous
Endemic
Scimitar-horned Oryx?
Non-native/Exotic
Require human assistance
to reproduce
(Livestock, Crops, & Pets)
Noninvasive
Invasive
Nonnuisance
Reproduce without human
assistance
(Non-native/Exotic & Naturalized)
Noninvasive
Nuisance
Invasive
Nonnuisance
Nuisance
Most extinctions are due to multiple factors interacting
simultaneously
For example: causes of fish extinctions in N. America:
physical habitat alteration (73%)
introduced species (68%)
chemical pollution (38%)
hybridization (38%)
overharvest (15%)
Exotic species are a global issue
How they arrive
Strategies that help a species invade
-Are all invasives exotic?
-Why aren’t invasives everywhere?
Some systems are more vulnerable to invasion
Ecosystem effects
Intentional release-For harvest:
Crops &
Livestock
-Cultural reasons
-Biocontrol
Accidental release-International commerce
Hitchiking with ships, passengers, cargo
Hitchiking with deliberately introduced species
-Escapes from trade
-Habitat alteration facilitates spread
Zebra Mussel North American Expansion 1986-2010
2010
2009
2008
2007
2006
2005
2004
2003
2002
2001
2000
1999
1998
1997
1996
1995
1994
1993
1992
1991
1990
1989
1988
1987
1986
Accidental release-International commerce
Hitchiking with ships, passengers, cargo
Hitchiking with deliberately introduced species
-Escapes from trade
-Habitat alteration facilitates spread
When will you see your first Giant Gambian Pouched Rat?
1968
1886
1860-1869
1851-1860
House Sparrow range expansion
Traits that make a species a good invader
-Generalists- diet and habitat
-High fecundity
-Vegetative or clonal reproduction
-High dispersal rates
-Urban/suburban cavity nester
-Diverse diet includes seeds, food scraps
-1-4 broods per year, 1-8 eggs/brood
-Wings
Some invasives are native
-Invasion is the result of landscape scale habitat change
Male Birds in Michigan
700
600
500
400
300
200
100
Cowbird Trapping: 1972
ESA: 1973
Mack Fire
From Solomon, 1998
Why are species not evenly mixed the world over?
Most invasions fail – probably less than 10-40% succeed
“rule of tens” (Williamson and Fitter 1996)
Some systems are more vulnerable to invasion
-Low native species diversity
-Empty niches
-disturbance/primary succession
-Absence of predators, parasites, diseases
Ecosystem effects
-Predation on native species
-Competition with native species
-Habitat alteration
-Trophic alteration
-Hybridize with native species
-Secondary effects
-Ecosystem engineers
This South Florida Burmese Python had 59 eggs
PNAS February 14, 2012 vol. 109 no. 7 2418-2422
Ecosystem effects
-Predation on native species
-Competition with native species
-Habitat alteration
-Trophic alteration
-Hybridize with native species
-Secondary effects
-Ecosystem engineers
Islands are at higher risk of invasion and ecosystem damage
-High endemism coupled with limited migration
L.A.
Flora of SCI
Exotic
110
Endemic
47
Native
non-endemic
225
San Clemente
Island (SCI)
From Moody 2000
And many feral cats
Home to:
Nesting seabirds
San Clemente Island Fox (T)
San Clemente Sage Sparrow (E)
San Clemente Loggerhead Shrike (E)
(~14 birds in 1990)