1.C.3 Populations Evolve - EDHSGreenSea.Net
Transcript of 1.C.3 Populations Evolve - EDHSGreenSea.Net
1.C.3 Populations Evolve
Populations of organisms continue to evolve.
Scientific evidence supports the idea that evolution has occurred in all species.
Scientific evidence supports the idea that evolution continues to occur.
As predicted in Rachel Carson’s book Silent Spring, we now are
confronted with the unintentional artificial selection
of organisms resistant to pesticides. Chemical-tolerant
individuals are surviving to reproduce until resistant
individuals are beginning to outnumber the ones susceptible
to our methods of control.
Pesticide Resistance
Pesticide-Resistant Organisms:
• Super Rats that can consume up to five times the lethal amount of rat poison
• Head lice resistant to treatment • DDT no longer effective against disease
vectors such as mosquitoes • Fruit flies resistant to malathion • The Colorado potato beetle has evolved
resistance to 52 different compounds belonging to all major insecticide classes (multiple resistance)
Pesticide Resistance
http://www.pbs.org/wgbh/evolution/library/10/1/image_pop/l_101_02.html
Grants’ observations of
Darwin’s finches in the Galapagos
Peter and Rosemary Grant have been studying the beaks of Galapagos
finches since 1973.
drought
drought
Directional selection occurred after a drought in 1977.
The finch beaks became larger as they adapted to thickly-shelled nuts. Large beaks are
energetically expensive, though, and the allele frequencies soon began to reverse.
Evolution of limbs in
tetrapods
Some evidence that evolution continues to occur:
• Increase in antibiotic-resistant bacteria such as MRSA and Clostridium difficile
• Evolution of the SARS virus and other emergent diseases
• Lactose tolerance in Europeans
• Butterflies in the South Pacific have evolved resistance to a killer bacteria in a single year