“Social” Chromosome Discovered By Sabrina Richards | January 16, 2013
“Researchers identify a chromosome in ants that influences colony social structure and, much like the mammalian Y sex chromosome, doesn’t recombine.”
Excerpt: The results help us “understand behavioral plasticity and alternative behavioral forms in as broad a genomic context as possible.” — Gene Robinson
My comment: Dr. Robinson helped detail nutrient-dependent pheromone-controlled social behavior in the broadest genomic context possible, which is now detailed even further in this report on the “social” chromosome. For example, Elekonich and Robinson (2000) added invertebrates to our model of genetically predisposed hormone-organized and hormone-activated vertebrate social and sexual behavior. Their “from egg to adult” approach played nicely off our approach in From fertilization to adult sexual behavior.
In our review we did not limit ourselves to the molecular biology of invertebrates or vertebrates. We included what was known about the molecular epigenetics of social behavior and sexual behavior in species from microbes to man. “Parenthetically it is interesting to note even the yeast Saccharomyces cerevisiae has a gene-based equivalent of sexual orientation (i.e., a-factor and alpha-factor physiologies). These differences arise from different epigenetic modifications of an otherwise identical MAT locus (Runge and Zakian, 1996; Wu and Haber, 1995).”
Nutrient chemical uptake is clearly responsible for these epigenetic modifications of the MAT locus and also responsible for pheromone-controlled reproduction. What we now see is that nutrient-dependent pheromone-controlled reproduction and species divergence is the broadest genomic concept possible.
Wang et al (2013) make it clearer that epigenetic modifications of genes found in social chromosomes entered the continuum of adaptive evolution before the sex chromosomes. They also make it clearer that chemical ecology is the driving force of adaptive evolution. We now have the ecological niche construction of “fat” queens for comparison to that of multiple queens with downstream differences in nutrient-dependent pheromone-controlled social niche construction, which determines differences in behaviors of individuals and differences in the behaviors of entire colonies. These epigenetic effects of nutrient-dependent pheromone-controlled genetically predisposed plasticity have also been detailed in the honeybee model organism.
That’s why I was able to use the honeybee to clarify the roles of ecological, social, neurogenic, and socio-cognitive niche construction in the context of nutrient-dependent pheromone-controlled behavior in species from microbes to man. “The concept that is extended is the epigenetic tweaking of immense gene networks in ‘superorganisms’ (Lockett, Kucharski, & Maleszka, 2012) that ‘solve problems through the exchange and the selective cancellation and modification of signals (Bear, 2004, p. 330)’. It is now clearer how an environmental drive probably evolved from that of food ingestion in unicellular organisms to that of socialization in insects.“
Now that genes on chromosomes in cells have been epigenetically linked to behavioral plasticity, to alternative behavioral forms, and to socialization in ants, models of molecular epigenetics that extend across all species may become better accepted. For example, “It is also clear that, in mammals, food odors and pheromones cause changes in hormones such as LH, which has developmental affects on sexual behavior in nutrient-dependent, reproductively fit individuals across species of vertebrates.”
The “bottom line” of molecular biology has not changed in more than 3 billion years of adaptive evolution. “Olfaction and odor receptors provide a clear evolutionary trail that can be followed from unicellular organisms to insects to humans.”
Kohl, J.V. (2012) Human pheromones and food odors: epigenetic influences on the socioaffective nature of evolved behaviors. Socioaffective Neuroscience & Psychology, 2: 17338. DOI: 10.3402/snp.v2i0.17338.
