Genes neutral to selection, but carrying the potential of altering animal behavior would be good candidates for initiating speciation.
Hybridization may occasionally result in the extinction of a population [1], [4], may trigger the evolution of plant invasiveness [5], or initiate speciation [6], [7].
Specifically, our data point to an essential role for divergent selection in initiating speciation, and we also see signs consistent with genome hitchhiking later in the process.
A potentially generative role for frog calls in morphological evolution is reflective of generally increased research interest in the role of the MRS in initiating speciation, especially with respect to sexual selection [ 9, 11, 27].
To conclude, CMS would not permanently prevent gene flow in case of secondary contact of the two A. lyrata populations studied, and we hypothesize that dynamics of CMS may be limited in initiating speciation of allopatric outcrossing populations.
This process can facilitate species coexistence, enhance phenotypic differences between sympatric species and promote or even initiate speciation and adaptive radiation (Rice and Pfennig 2010; Martin and Pfennig 2011).
These hypotheses share the prediction that MRS evolution may precede the evolution of other hallmarks or correlates of species status (including morphological distinctiveness) and may even initiate speciation [ 11].
Disruptive selection has long been viewed as important in maintaining and increasing variation within natural populations [ 1- 3]; favoring the evolution of alternative phenotypes [ 4, 5] and sexual dimorphism [ 6- 8]; and even initiating speciation [ 6, 8- 12].
The reason is that the conditions for female preference branching are mutually exclusive with the conditions for male ornament branching in standard models of sexual selection (Van Doorn et al. 2004), such that an additional, independent source of disruptive selection on the mating traits is necessary to initiate speciation.
This result is consistent with the hypothesis that a migration of Castor from Eurasia to North America as early as 7.5 mya could have initiated their speciation.
