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Open Access Research article

The role of deleterious mutations in the stability of hybridogenetic water frog complexes

Pasquale Bove1, Paolo Milazzo1 and Roberto Barbuti12*

Author Affiliations

1 Dipartimento di Informatica, Università di Pisa, Largo B. Pontecorvo, 3, 56127 Pisa, Italy

2 Museo di Storia Naturale, Università di Pisa, Via Roma, 79, 56011 Calci (Pisa), Italy

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BMC Evolutionary Biology 2014, 14:107  doi:10.1186/1471-2148-14-107

Published: 16 May 2014



Some species of water frogs originated from hybridization between different species. Such hybrid populations have a particular reproduction system called hybridogenesis. In this paper we consider the two species Pelophylax ridibundus and Pelophylax lessonae, and their hybrids Pelophylax esculentus. P. lessonae and P. esculentus form stable complexes (L-E complexes) in which P. esculentus are hemiclonal. In L-E complexes all the transmitted genomes by P. esculentus carry deleterious mutations which are lethal in homozygosity.


We analyze, by means of an individual based computational model, L-E complexes. The results of simulations based on the model show that, by eliminating deleterious mutations, L-E complexes collapse. In addition, simulations show that particular female preferences can contribute to the diffusion of deleterious mutations among all P. esculentus frogs. Finally, simulations show how L-E complexes react to the introduction of translocated P. ridibundus.


The conclusions are the following: (i) deleterious mutations (combined with sexual preferences) strongly contribute to the stability of L-E complexes; (ii) female sexual choice can contribute to the diffusion of deleterious mutations; and (iii) the introduction of P. ridibundus can destabilize L-E complexes.

Hybridogenesis; Water frogs; Sexual selection; Computational models; Simulations