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How effective is Natural Selection? Micro-evolution small evolutionary changes within species Macro-evolution large evolutionary changes that result in classification as a new species Agricultural Pests Alternating Crops Farmers alternate corn & soy; corn-borers have evolved to remain dormant one season….or more Agricultural Pests Winnowing & Sieving Weed seeds have evolved sizes & shapes of the predominant crop Weeding Weed leaf shape & color has evolved to match the crop where it grows Rice Vetch (weed) Lentil Barnyard Grass (weed) Agricultural Pests Pesticides Insects rapidly evolve tolerance, via many mechanisms….. 1960 - 100 species tolerant 1970 - 313 species tolerant 1980 - 829 species tolerant Tolerance to Heavy Metals Agrostis grass • Small strip mines abandoned for fifty years • Iron, copper, zinc, lead: greater than 2000 ppm – (normal is less than 10 ppm) • Each mine with its own mix of metals • Only 3 plants per 1000 could tolerate these conditions Tolerance to Heavy Metals Agrostis grass • Mine plants’ offspring tolerant of metals particularly those of the mine of origin • Mine plants also grow well in unpolluted soil • However, mine plants are displaced when competing against non-mine plants in unpolluted soil • Mine plants have evolved earlier flowering times - effectively avoid crossing with non-mine plants! Protective Coloration The Pepper moth • All populations originally whitish • In polluted areas, black moths increases from 1% to 95% in 50 years Protective Coloration The Pepper moth Kettlewell’s experiment • Release marked white and black moths • Capture moths after a period of time • Is the proportion of recaptures different between the two forms?
