Class Notes (1,100,000)
CA (620,000)
UTSG (50,000)
BIO (2,000)
BIO120H1 (1,000)
Lecture

Lecture 22 Notes


Department
Biology
Course Code
BIO120H1
Professor
Doug Thomson

Page:
of 3
BIO120 LECTURE 22
LECTURE 22: CONTEMPORARY EVOLUTION AND INVASIVE SPECIES
Biological Invasions
Invasive species underappreciated in terms of the economic losses they cause the US
Example: lantana camara
oTiger attacks have increased in India
oInvasive species lantana camara introduced to environment forces tiger out of its
environment
Example: Cane toad invasion
oControlled cane beetles
oIntroduced cane toad to Australian environment
oOne of major causes of loss of biodiversity
Example: the Nile perch
oPerch causes extinction of endemic cichlid fish species
Example: brown tree snake invasion on Guam
oStowaway on ship from south pacific
oCauses much human trauma, home invasions
Argentian ant can identify other ant biochemically and does not harm or bother
oHighly aggressive
oOutcompetes other native species
Guava is most invasive species in the Galapagos
No natural predators to keep population in check
What ecosystems are more vulnerable to invasion?
Undisturbed ecosystems are less susceptible to invasion
Disturbance is often caused by humans but there are also natural disturbances
Introduced species are very much adapted to disturbances
www.notesolution.com
Seeds need open disturbed areas for establishment
Phenotypic plasticity
The ability of an individual to alter its phenotype in response to changes in its environment
Invasive species attributes
Rapid development to reproduction
High reproductive output
Well-developed dispersal mechs
Broad ecological tolerance
High phenotypic plasticity
Invasion in the context of agriculture
MimicrY
oExamples: weeding
Pulling out weeds that look different from crops
Weeds develop resemblance by mimicking crop
Over time selection can alter phenotype
Weeds adapt to resemble rice
Invasive species in Ontario
Zebra mussels
oHigh fecundity
oAbundant
oExtensive damage to water intake pipes
Effects households, electrical utilities and sport fishing
oHigher costs than benefits
Benefit: filter feeder cleaner water
oLead to high avian mortality
www.notesolution.com
Purple Loosestrife
oIntroduced from Europe as an ornamental
oAquatic perennial
oHigh genetic variability
oOutbreeder
oChristopher Eckert, Rob Colautti, Jessica Montague
oWill degrade marshlands and make them unsuitable for hunting
oPOYPLOID POPULATIONS
oRob Colautti: COMMON GARDEN EXPERIMENT
Biological control
Introduces natural predators to control invasive speciesenemy release
When weed is controlled, the weed and enemy will go under and then control can be permanently
effective
What is the reproductive system of the invader?
Asexual species were much more likely to be controlled than sexual speciesthere is no genetic
diversity
Over time, resistance will evolve in sexual species
www.notesolution.com