From the simple burrowing, equivalve ancestor, the various bivalve groups have repeatedly evolved an elongated, triangular or circular shell; thus, similar body adaptations have been responses to similar modes of life.
Superposition eyes have repeatedly evolved in both insects and in crustaceans and are thus taxonomically widespread (Land and Nilsson 2002, Nilsson 1989; see Fig. 1).
More complex image-forming eyes may have repeatedly evolved from such phototactic eyes.
We observed two modes of MS genesis in two regions of tRNA SINEs in which MSs have repeatedly evolved.
For example, they have repeatedly evolved changes in body shape, skeletal armor, trophic apparati, pigmentation, osmoregulatory functions, life history, and behavior [ 5].
Dioecy or separate sexes are rare among flowering plants but have repeatedly evolved from hermaphroditic ancestors possibly involving male or female sterility mutations.
Our data suggest that body shape changes have repeatedly evolved into a more limnetic-like form in several of these natural replicates.
The 2 phenotypes of heat-tolerance and mammal pathogenicity appear to have repeatedly evolved in the genus Lagenidium, and several recent studies have shown that members of Oomycota can acquire pathogenicity genes by horizontal gene transfer (21 – 21 ).
