You placed equal number of dark and light varieties of feeder crickets into a terrarium containing a species of lizards. After two days you notice that the dark variety of the crickets was less...

You placed equal number of dark and light varieties of feeder crickets into a terrarium containing a species of lizards. After two days you notice that the dark variety of the crickets was less common than the light variety. What process is taking place on a small scale within the terrarium? Design an experiment in which you would try to determine if color or taste is the primary factor responsible for the selective feeding of the lizards.

CONTROL GROUP IS NEEDED!

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tjbrewer | Elementary School Teacher | (Level 2) Associate Educator

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It appears that natural selection is going on.  For one reason or another, the lizards are eating the dark crickets more than the light crickets, thus the genetic tendency towards lighter colors is gaining dominance over darker colors. 

To test if this is a function of taste or camouflage, you need 4 terrariums.  Terrarium A is your control group: it contains no lizards, only crickets 50-50 light and dark so that you also account for the rates of reproduction, and natural death of the crickets.  Terrarium B has no hiding places, so the lizards can see both colors with equal ease. Terrarium C has habitat that provides better camouflage for lighter crickets.  Terrarium D has habitat that provides better camouflage for darker crickets. 

If Terrarium B exhibits a different ratio of light crickets to dark crickets than Terrarium A by the end of the expirement, then taste is a factor.  If there is no signifcant difference, then taste isn't a factor.  If Terrariums C&D show sigificant differences in the survival rates of the color pattern they favor, then color is a factor.  If they show no difference from each other, or match the patterns in A or B, then color is not a factor, but taste is.  If none of the patterns are conclusive, then it is likely that another factor is behind the natural selection in your terrarium. 

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