Re: CONTRARY EVIDENCE (WASRe: Evide)nce!

On 16/03/2024 22:37, Ron Dean wrote:

Explain how if eyes evolved independently about 40 times, how is it that the same master control gene exist in fruit flies, mice and humans. The eye gene (Pax6 gene) was taken from a mouse and placed into a fruit fly embryo and the mouse gene produced eyes in the fruit fly, but not mouse eyes, but fruit fly eyes. . Furthermore, some of the first complex organisms ie certain species of trilobites had highly complex functioning eyes. Is there reason to think the same Pax6 gene was not involved in the eyes of trilobites with vision?

One of the functions of DNA binding regulatory proteins is to "specify" parts of the body. For example the Hox proteins divide the bilaterian body into regions along the anterior/posterior axis. Some MADS box genes in plants divide the developing flower along the proximal/distal access into the floral whorls of calyx, corolla, androecium and gynoecium.
There is an obvious hypothesis for the role of Pax6 genes in independently evolved eye development - that Pax6, among it's other roles, specifies a forward facing region of the head, which is where eyes usually developed, and has been pressed into service as a switch in the early stages of eye development. One possible test for this hypothesis is look at the control of eye development in organisms with non-cephalic eyes - is the claim that Pax6 is a "master control gene" for eye development across all Bilateria an overly hasty generalisation?
Having conceived of this issue, I identified a group of organisms with non-cephalic eyes, i.e. Pectinidae (scallop), and asked a question of the web. The reply was Wang et al, Scallop genome provides insights into evolution of bilaterian karyotype and development, Nature Ecology and Evolution 1: 0120 (2017), which reports that eye development in Patinopecten yessoensis does not utilise Pax6, nor several other genes involved in eye development in Homo.
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alias Ernest Major