A Red-Shifted Beetle

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Science  09 Jan 2004:
Vol. 303, Issue 5655, pp. 146
DOI: 10.1126/science.303.5655.146a

Evolution is a process that manifests itself at every level of biological organization, from molecule to population. However, it is rare that it can be observed and measured at all these levels simultaneously to provide an unbroken chain of cause and effect. Stolz et al. have made such a connection of natural selection for bioluminescence in the Jamaican click beetle, Pyrophorus plagiophthalamus, which is unique among light-producing organisms in having a color polymorphism: yellow-green to orange in the ventral light organs, and green to yellow-green in the dorsal organs. The variation results from individual amino acid substitutions in luciferase, the enzyme involved in the light-generating reaction, which in turn can be traced to individual nucleotide substitutions in luciferase genes. A phylogenetic analysis shows that there has been a series of such substitutions, producing an adaptive trend toward orange ventral organs in P. plagiophthalamus in Jamaica. The final step to complete this picture will be to identify the selective agent; likely candidates are sexual selection or preferential predation on beetles with yellow ventral organs. — AMS

Proc. Natl. Acad. Sci. U.S.A. 100, 14955 (2003).

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