19 - Epigenetics of Sympatric Speciation—Speciation as a Mechanism of Evolution

Abstract

This chapter deals with the epigenesis of sympatric speciation. Sympatric speciation is the process through which new species evolve from a single ancestral species while inhabiting the same geographic region. Recently, models are presented of sympatric speciation without disruptive selection, in the absence of physical barriers or predators. Most importantly, empirical evidence is accumulating, indicating that sympatric speciation occurred and is still occurring in nature. The bone of contention on sympatric speciation is the issue of reproductive isolation, which from the neo-Darwinian view cannot arise between two sympatric populations, i.e., in the absence of spatial separation and the resulting prevention of gene flow between them. In general, there is no reliable evidence on the existence of a relationship between the degree of morphological and physiological changes and speciation. This study elucidates the relationship between natural selection and sexual selection in sympatric speciation. Following this, it presents a neurocognitive populational breakup and describes reproductive isolation via mate choice. The evolution of mating processes is described by Fisher’s runaway hypothesis, the “good gene” hypothesis, and the sensory exploitation hypothesis. Furthermore, the study deals with neurocognitive and visual cognitive mechanisms of reproductive isolation, also discussing auditory-cognitive reproductive isolation, acoustically determined reproductive isolation in sympatry, and the electrocognitive mechanism of reproductive isolation. Finally, it illustrates neurocognitive sympatric speciation in nature through various examples.