Evolution of Colors in Nudibranchs
by Dr. Terry Gosliner
Director of Research, California Academy of Sciences
Golden Gate Park, San Francisco, CA
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The Color characteristics of organisms serve various purposes and are the result of several different processes. Most of what we know about the adaptive significance of color is based on what we have learned from studying terrestrial organisms. As technology has increased our abilities to observe marine environments for more prolonged periods, we are learning that the same principles apply to marine organisms.
The example presented here is that of nudibranchs in which part of a color pattern is inherited from a common ancestor and part is due to convergent evolution which can result from Batesian or Mullerian mimicry. A series of experiments observed fish and their reactions to different organisms and various color patterns. The experiments demonstrated that one of the things that mimicry of either kind requires is that the potential predator must experience a negative reaction to eating prey with a particular color pattern for mimicry to be
Modern systematic techniques, having a hypothesis of phylogeny, can inform our understanding of how different color patterns have evolved. A phylogenetic hypothesis allows us to look at the direction of evolutionary change that takes place within a lineage. By having a phylogeny, one can make predictions and test map those various color characters onto a phylogenetic tree to see how many times those characters have evolved. This allows us to determine the direction of evolutionary change of a particular organism. A tremendous amount of information can be assembled about the biology of living organisms once
there is a hypothesis of phylogeny that is testable and modifiable.
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