Creation of different species without physical barriers (Part Two)

By: James V. Kohl | Published on: March 5, 2012

From Genes, Brain and Behavior
DNA methylation changes elicited by social stimuli in the brains of worker honey bees (pages 235–242) G. A. Lockett, R. Kucharski and R. Maleszka
Social environments are notoriously multifactorial, yet studies in rodents have suggested that single variables such as maternal care can in fact be disentangled and correlated with specific DNA methylation changes. This study assesses whether non-detrimental social environmental variation in a highly plastic social insect is correlated with epigenomic modifications at the DNA methylation level. Honey bee workers perform tasks such as nursing and foraging in response to the social environment in the hive, in an age-linked but not age-dependent manner. In this study, the methylation levels of 83 cytosine–phosphate–guanosine dinucleotides over eight genomic regions were compared between the brains of age-matched bees performing nursing or foraging tasks. The results reveal more changes correlated with task than with chronological age, and also hive-associated methylation at some sites. One methylation site from a gene encoding Protein Kinase C binding protein 1 was consistently more methylated in foragers than nurses, which is suggested to lead to production of task-specific protein isoforms via alternative splicing. This study illustrates the ability of the neural epigenome to dynamically respond to complex social stimuli.
Does anyone know how else to link the social environment directly to brain changes and behavior in invertebrates or vertebrates? In the honeybee and in rodents it appears that olfactory/pheromonal stimuli provide this direct link.  The proposal that visual input is responsible for changes in hormones and dominance or for sex changes in fish or in the behavior of other vertebrates does not seem to come with any evidence for the required evolved neurophysiological mechanism(s).
I attempted to discuss the biological fact that the study of asexual selection in microbes and sexual selection mechanisms in vertebrates must be approached from the same perspective, which does not allow for asexual selection, sexual selection, or the Creation of new species of cichlid fish to be based on spectral input and/or visual perception. My claim that there is no model for the influence of visual input was met with the comment that “you will need to drop your model to understand the biology of behavior.” This comment came from an expert on the behavior of fish who refuses further comment about whatever mechanisms might be involved in fish that change sex from female to male when no male is present.

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