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EARLY EVOLUTION OF THE GENETIC BASIS FOR SOMA IN THE VOLVOCACEAE
Author(s) -
Hanschen Erik R.,
Ferris Patrick J.,
Michod Richard E.
Publication year - 2014
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/evo.12416
Subject(s) - biology , soma , evolutionary biology , basis (linear algebra) , neuroscience , mathematics , geometry
To understand the hierarchy of life in evolutionary terms, we must explain why groups of one kind of individual, say cells, evolve into a new higher level individual, a multicellular organism. A fundamental step in this process is the division of labor into nonreproductive altruistic soma. The regA gene is critical for somatic differentiation in Volvox carteri , a multicellular species of volvocine algae. We report the sequence of regA‐ like genes and several syntenic markers from divergent species of Volvox . We show that regA evolved early in the volvocines and predict that lineages with and without soma descended from a regA ‐containing ancestor. We hypothesize an alternate evolutionary history of regA than the prevailing “proto‐ regA ” hypothesis. The variation in presence of soma may be explained by multiple lineages independently evolving soma utilizing regA or alternate genetic pathways. Our prediction that the genetic basis for soma exists in species without somatic cells raises a number of questions, most fundamentally, under what conditions would species with the genetic potential for soma, and hence greater individuality, not evolve these traits. We conclude that the evolution of individuality in the volvocine algae is more complicated and labile than previously appreciated on theoretical grounds.