The Effect of Aposematic Coloration on the Food Preference of ...

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IntroductionI. Description <strong>of</strong> <strong>Aposematic</strong> <strong>Coloration</strong><strong>Aposematic</strong> coloration is an interesting phenomenon, characterized by the conspicuouscoloration <strong>of</strong> potentially harmful or noxious organisms.Also called warning coloration, thisunique patterning <strong>of</strong> external appearance serves to defend an organism through advertisement <strong>of</strong>its <strong>of</strong>fensive or hazardous traits (Speed 2000).Color as a defensive mechanism in nature isappealing to study because, though frequently observed, it is unusual in that it functions in avariety <strong>of</strong> seemingly opposing ways.For example, camouflage, or crypsis, <strong>of</strong> organismscommonly occurs as protection against predation by blending the potential prey against itsnatural background.Unlike crypsis, however, aposematic coloration and its generated protectionrely on the obvious appearance <strong>of</strong> an organism against its background.Why have some organisms evolved this higher visibility?<strong>The</strong> answer lies in the function<strong>of</strong> the long-term memory in predators (Speed 2000).When a predator comes in contact withunpalatable or harmful prey for the first time, it will likely have a nasty experience. To avoidrepetition <strong>of</strong> such incidents, it is helpful to the individual predator if it can remember somethingabout the prey to aid recognition in the future. Conversely, it is helpful to the survival <strong>of</strong> thewhole prey species if the predator avoids future encounters; fewer prey will be removed from thegene pool.Conspicuous coloration <strong>of</strong> the prey reinforces this avoidance learning in predators byproviding a memorable signal to associate with the experience.Future sightings <strong>of</strong> prey bearingthe same, or even just similar, aposematic coloration then stimulate memory jogging in thepredator, causing it to remember the previous encounter and avoid the prey (Speed 2000).II.Evolution <strong>of</strong> <strong>Aposematic</strong> <strong>Coloration</strong><strong>The</strong> evolution <strong>of</strong> aposematic coloration and the interactions between predators and
aposematic prey are not clearly understood. However, according to Speed (2000), it is likelythat the learning abilities and memory <strong>of</strong> predators may have contributed to the success andevolution <strong>of</strong> the bold appearance <strong>of</strong> noxious prey.Without the ability <strong>of</strong> predators to recallexperiences, warning coloration would serve no adaptive purpose because each encounter wouldtrigger an independent response - a response based on no previous knowledge.Another factorthat may have contributed to the adaptive value <strong>of</strong> aposematic coloration is the aggregation <strong>of</strong>aposematic prey. It is expected that a predator would have readily attacked a solitaryconspicuous individual due to its visibility (Alatalo and Mappes 1996).Distaste for the unusualindividual would not have contributed to avoidance learning because there were no otherexamples <strong>of</strong> the conspicuous prey to immediately avoid.This absence <strong>of</strong> repetitive encounterswould have mitigated the effects <strong>of</strong> avoidance learning, providing no evolutionary benefit to theprey species.Aggregation <strong>of</strong> aposematic prey, on the other hand, would have resulted inpredator attack on the prey, rejection based on the unpalatable nature <strong>of</strong> the prey, and association<strong>of</strong> that individual with the surrounding group.Thus, the result would have been abandonment <strong>of</strong>the group for different prey, leaving the brightly colored survivors to pass on their genes andincrease the frequency <strong>of</strong> warning coloration within their species (Alatalo and Mappes 1996).As emphasized by Shettleworth (2001) in a review <strong>of</strong> animal cognition and behavior, bothaggregation <strong>of</strong> aposematic prey and learning response <strong>of</strong> predators seem to have played relatedroles in the advancement <strong>of</strong> aposematic coloration.III.Examples <strong>of</strong> <strong>Aposematic</strong> <strong>Coloration</strong>Observations in nature have played a significant role in understanding and identifying theaposematic predator-prey interactions that exist.A specific example <strong>of</strong> functioning aposematiccoloration in nature is seen in the South American arrow-poison frog.This frog has a bright red
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The Effect of Aposematic Coloration on the Food Preference of ...

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