Increased chemosensory ability and eye regression: a "Just-So" fish story

Evolution of an adaptive behavior and its sensory receptors promotes eye regression in blind cavefish  Yoshizawa M, Yamamoto Y, O’Quin KE, Jeffery WR  BMC Biology 2012, 10:108 (27 December 2012) [Provisional PDF]

Excerpt: “…loss of eyes as a result of selection for increased tactile sensitivity is an attractive general hypothesis for the convergent evolution of eye regression in cave fauna.”

My comment: The authors start with eye regression and increased chemosensory abilities required for foraging in the dark / nutrient poor environment of the cave fish. They later suggest that the same quantitative trait loci (QTL) clusters, which are involved in eye regression and increased chemosensory abilities are the clusters that control groups of potentially advantageous traits during the rapid evolution and species diversification of African cichlids (with eyes) and three-spined sticklebacks (with eyes). In the species with eyes, the QTL clusters somehow came to be involved in  sex determination, body color, and body shape. But in the species with eyes that regressed increased tactile sensitivity evolves for nutrient chemical acquisition and mate choice.

Does that make sense? Loss of eyes associated with increased chemosensory abilities leads to a hypothesis  of increased tactile sensitivity for food choice and mate choice.  However, RNA-mediated adaptive evolution of eyes that enable sexual reproduction associated with visual input has nothing to do with either tactile or chemosensory ability.

Here’s the problem I have with their hypothesis. The blind Astyanax cave fish and the sighted Astyanax surface fish produce viable offspring because they are the same species. In my model, species-specific pheromones control nutrient chemical-dependent reproduction. Visual, auditory, and tactile stimuli do not control nutrient chemical-dependent reproduction in any species.

Moving across an evolutionary continuum of eye development and/or regression while explaining that eye regression in cave fish is due to increased tactile sensitivity but normal eye development in other fish is required for visual perceived physical features important to sexual reproduction is confusing. It is also amazing because there is no mention of the role of olfaction or pheromones that enable the response to food and potential mates in every other species on the planet, whether or not the species has eyes that evolved, or first evolved and then regressed.


About James V. Kohl 1308 Articles
James Vaughn Kohl was the first to accurately conceptualize human pheromones, and began presenting his findings to the scientific community in 1992. He continues to present to, and publish for, diverse scientific and lay audiences, while constantly monitoring the scientific presses for new information that is relevant to the development of his initial and ongoing conceptualization of human pheromones. Recently, Kohl integrated scientific evidence that pinpoints the evolved neurophysiological mechanism that links olfactory/pheromonal input to genes in hormone-secreting cells of tissue in a specific area of the brain that is primarily involved in the sensory integration of olfactory and visual input, and in the development of human sexual preferences. His award-winning 2007 article/book chapter on multisensory integration: The Mind’s Eyes: Human pheromones, neuroscience, and male sexual preferences followed an award winning 2001 publication: Human pheromones: integrating neuroendocrinology and ethology, which was coauthored by disinguished researchers from Vienna. Rarely do researchers win awards in multiple disciplines, but Kohl’s 2001 award was for neuroscience, and his 2007 “Reiss Theory” award was for social science. Kohl has worked as a medical laboratory scientist since 1974, and he has devoted more than twenty-five years to researching the relationship between the sense of smell and the development of human sexual preferences. Unlike many researchers who work with non-human subjects, medical laboratory scientists use the latest technology from many scientific disciplines to perform a variety of specialized diagnostic medical testing on people. James V. Kohl is certified with: * American Society for Clinical Pathology * American Medical Technologists James V. Kohl is a member of: * Society for Neuroscience * Society for Behavioral Neuroendocrinology * Association for Chemoreception Sciences * Society for the Scientific Study of Sexuality * International Society for Human Ethology * American Society for Clinical Laboratory Science * Mensa, the international high IQ society