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Fig. 1 | Evolution: Education and Outreach

Fig. 1

From: Opening the “Black Box”: The Genetic and Biochemical Basis of Eye Evolution

Fig. 1

Morphological series of eyes. a Salvini-Plawen and Mayr (1977) illustrated six eyes of varying complexity, from different living species of gastropods. They made the implicit assumption that the eyes of living species approximate the ancestral states of a pectinate (i.e., comb-like, where one descendent of each node does not branch any more) tree. This is illustrated by placing dashed lines leading to living species. b An actual estimate of gastropod phylogeny (based on molecular data and analyses of Ponder and Lindberg (1997) indicates that the tree is not pectinate. Therefore, the actual history of gastropod eyes is more complicated than a direct march from simple to complex. c Two cephalopod eyes (asterisks) were added to the gastropod eyes by Strickberger (1990). d An estimate of mollusk phylogeny again shows how the actual history is more complicated than a direction march to the complex eye. One interpretation is that the lens of the eyes originated separately in gastropods and cephalopods

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