Diet alters species recognition (as it always does)
October 2, 2013 | James Kohl
Karin S. Pfennig, Verónica G. Rodriguez Moncalvo, and Sabrina S. Burmeister
Biol. Lett. October 23, 2013 9 20130599; doi:10.1098/rsbl.2013.0599
Abstract: Whether environmental effects during juvenile development can alter the ontogeny of adult mating behaviour remains largely unexplored. We evaluated the effect of diet on the early expression of conspecific recognition in spadefoot toads, Spea bombifrons. We found that juvenile toads display phonotaxis behaviour six weeks post-metamorphosis. However, preference for conspecifics versus heterospecifics emerged later and was diet dependent. Thus, the environment can affect the early development of species recognition in a way that might alter adult behaviour. Evaluating such effects is important for understanding variation in hybridization between species and the nature of species boundaries.
My comment: Diet-dependent preferences manifested in adult mating behavior are clearly nutrient-dependent and pheromone-controlled. That fact has been fully explored and detailed. The fact that diet-dependent conspecific recognition in these toads develops into a preference for conspecifics versus heterospecifics is another example of nutrient-dependent pheromone-controlled adaptive evolution via conserved molecular mechanisms in species from microbes to man. No data from any experiment suggests that adaptive evolution occurs in any organism via any other means.
Instead, LeVay notes: My “… model is attractive in that it solves the “binding problem” of sexual attraction. By that I mean the problem of why all the different features of men or women (visual appearance and feel of face, body, and genitals; voice quality, smell; personality and behavior, etc.) attract people as a more or less coherent package representing one sex, rather than as an arbitrary collage of male and female characteristics. If all these characteristics come to be attractive because they were experienced in association with a male- or female-specific pheromone, then they will naturally go together even in the absence of complex genetically coded instructions.” (p. 210)
See also: Sexually dimorphic androgen and estrogen receptor mRNA expression in the brain of túngara frogs. “Our results suggest that sex steroid hormones have sexually dimorphic effects on auditory processing, sexual motivation, and possibly memory and, therefore, have important implications for sexual communication in this system.”
My comment: The regulation of sex steroid hormones is nutrient-dependent and pheromone-controlled via the epigenetic effects of olfactory/pheromonal input on vertebrate gonadotropin releasing hormone (GnRH) in all vertebrates. The sensory environment modulates receptor-mediated mRNA expression in the brains of vertebrates and invertebrates via effects on hormones that affect behavior (sans mutations).