A theoretical muddle of the conditional strategy: a comment on Neff and Svensson.

Neff & Svensson [1] recently reviewed the literature relating to the theoretical modelling of alternative mating tactics. Their review presents insightful future perspectives on how genomics could unveil the molecular genetics and proximate mechanisms of tactic expression, and we fully agree with their statements that a better understanding of the field can be achieved through the integration between quantitative and molecular genetics. However, we feel that it is important to draw attention to two significant oversights: their review (i) neglects previous studies that provided theoretical and empirical contributions to the understanding of the genetics underlying the conditional expression of alternative mating tactics (i.e. conditional strategies) and (ii) presents ideas that have been previously published (by other authors) as a new 'unified theory for the evolution and phenotypic expression of alternative mating tactics'. Below we elaborate why we believe that Neff and Svensson's verbal model ('the conditional alternative strategy') is not a new model, but is instead based on a misinformed view that current models do not account for genetic variation underlying conditional strategies. As a result, Neff and Svensson's 'conditional alternative strategy' unnecessarily muddles our understanding of conditional strategies. Phenotypic plasticity is a ubiquitous evolutionary phenomenon [2] and nowhere perhaps, is plasticity more apparent than when single genotypes can produce different alternative phenotypes depending upon environmental conditions [3]. Such polyphenisms are synonymous with conditional strategies and have been described in a wide range of traits, including the presence, shape and colour of morphological traits, alternative mating tactics, diet, sex and caste determination, as well as paedogenesis and diapause [4]. Understanding their genetic architecture and evolution is therefore vital for our understanding of these important adaptations. Dawkins' conditional evolutionary stable strategy model [5] provided an important theoretical framework for understanding polyphenisms, but also conveyed the message that genetic polymorphism is not necessary for a conditional strategy to be evolutionary stable. This message was an attempt to distinguish conditional strategies from 'alternative strategies', which represent a genetic polymorphism with Mendelian inheritance. However , it also led numerous authors to erroneously associate conditional strategies with complete genetic monomorphism [1,6,7]. It is well established, however, that underlying genetic variation is prevalent in plastic traits [8,9], and its role in polyphenisms has been modelled [10,11] and supported empirically numerous times [12 –15]. The conditional strategy was recently criticized based on this false assumption of genetic monomorphism [7]—a misconception that was subsequently laid to rest [16]. …