Why Cyanobacteria Produce Toxins? Evolutionary Game Theory Suggests the Key

Beatriz Baselga-Cervera, Camino García Balboa, Eduardo Costas, victoria Lopez-Rodas

Abstract


Cyanobacteria are a source of potent toxins among which the microcystin (a hepatotoxic peptide encoded by the mcy gene cluster of Microcystis spp.) is a frequent cause of poisoning in inland waters worldwide. Although the molecular basis of microcystin production is known, its role is still unknown. It was suggested that microcystin production have a metabolic cost that could be offset by some benefit (e.g. protection from grazing). We check that: i) microcystin-producing and non-producing strains occurs simultaneously in the Microcystis spp. blooms, ii) evolutionary forces (mutation, genetic drift) control frequencies of microcystin production and non-production strains, and iii) microcystin producing strains have diminished fitness compared with non-producing strains. We employ evolutionary game theory to explain the maintaining of microcystin-producing genotypes in natural populations of Microcystis spp. A two-strategy (to produce or not microcystin), two-players game of cooperators (microcystin-producing genotypes) and cheaters (non-producing genotypes) explains the coexistence of both genotypes in the same bloom. A bloom composed mostly by the microcystin-producing “cooperators” genotype, the “temptation of defection” (increase of non-producing genotypes) is counteracted by kin selection, which enable that natural selection can favour the cooperators. The closest related individuals occur within cyanobacteria blooms, cyanobacteria reproduces asexually providing sets of clones.


Full Text:

PDF


DOI: http://dx.doi.org/10.5539/ijb.v7n1p64

International Journal of Biology   ISSN 1916-9671(Print)   ISSN 1916-968X  (Online)

Copyright © Canadian Center of Science and Education

To make sure that you can receive messages from us, please add the 'ccsenet.org' domain to your e-mail 'safe list'. If you do not receive e-mail in your 'inbox', check your 'bulk mail' or 'junk mail' folders.

------------------------------------------------------------------------------------------------------------------------------

scholar_logo_lg_2011_120 proquest_logo_120 lockss_logo_2_120