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The social evolution of somatic fusion
Author(s) -
Aanen Duur K.,
Debets Alfons J.M.,
de Visser J. Arjan G.M.,
Hoekstra Rolf F.
Publication year - 2008
Publication title -
bioessays
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.175
H-Index - 184
eISSN - 1521-1878
pISSN - 0265-9247
DOI - 10.1002/bies.20840
Subject(s) - allorecognition , biology , kin selection , evolutionary biology , multicellular organism , somatic cell , selection (genetic algorithm) , clonal selection , negative selection , genetics , major histocompatibility complex , gene , artificial intelligence , computer science , genome , immunology
The widespread potential for somatic fusion among different conspecific multicellular individuals suggests that such fusion is adaptive. However, because recognition of non‐kin (allorecognition) usually leads to a rejection response, successful somatic fusion is limited to close kin. This is consistent with kin‐selection theory, which predicts that the potential cost of fusion and the potential for somatic parasitism decrease with increasing relatedness. Paradoxically, however, Crozier1 found that, in the short term, positive‐frequency‐dependent selection eliminates the required genetic polymorphism at allorecognition loci. The ‘Crozier paradox’ may be solved if allorecognition is based on extrinsically balanced polymorphisms, for example at immune loci. Alternatively, the assumption of most models that self fusion is mutually beneficial is wrong. If fusion is on average harmful, selection will promote unconditional rejection. However, we propose that fusion within individuals is beneficial, selecting for the ability to fuse, but fusion between individuals on average costly, selecting for non‐self recognition (rather than non‐kin recognition). We discuss experimental data on fungi that are consistent with this hypothesis. BioEssays 30:1193–1203, 2008. © 2008 Wiley Periodicals, Inc.