Horizontal Genetic Transfer

Abstract

The preceding chapters of this book have been largely filled with examples of larvae that seem out of place in the life histories of the species or groups in which they occur, but in most cases the incongruous larva resembles the larva of some distantly related group. I contend that these similar larvae in distantly related groups are not the result of chance, convergent evolution, or inheritance from a remote common ancestor. I believe they have resulted from transfers of genetic material between species on different branches of the phylogenetic tree, and in the present chapter I wish to discuss four questions relating to these transfers.

Distinction between larvae evolved within group and larvae acquired from another—Phases in development which can be transferred between groups—Transfers between individuals more likely than mass transfers—Hybridization, usually between forms with external fertilization, most likely method of transfer—Expected effects of crossing one species with larva and one without—Expected effects of crossing two species with larvae