- Author: Kathy Keatley Garvey
Professor and ophthalmologist Ivan Schwab, UC Davis Health System, will explore that topic when he discusses “Vision from Trilobites to Trichogammatids: How the Arthropods See” at the UC Davis Department of Entomology and Nematology seminar on Wednesday, Oct. 23 in 122 Briggs Hall, UC Davis campus.
Lynn Kimsey, director of the Bohart Museum of Entomology and professor of entomology, will be the host.
“The first eye is known from a trilobite of approximately 540 million years ago at the beginning of the Cambrian explosion,” Schwab said. “Trilobites are long extinct arthropods but the phylum Arthropoda includes four other branches that are alive and well. All branches have at least some animals with eyes, and these eyes are sensory masterpieces for their respective niche requirements. From the trilobites to the fairy wasps, we can tell the story of how fantastic evolutionary development has forged the sensory visual elements necessary for survival.”
Schwab directs the Cornea and External Disease Service and serves as the medical advisor of the eye bank, as well as professor of ophthalmology in the Department of Ophthalmology and Vision Science.
A former director on the American Board of Ophthalmology, he now serves on several editorial boards for ophthalmology journals, Cornea (associate editor), Ophthalmology, British Journal of Ophthalmology, and the PanAmerican Journal of Ophthalmology.
Schwab is active in the American Academy of Ophthalmology, chairing committees on education and alternative medications. His publications of more than 240 peer-reviewed papers, 35 chapters, many white papers, and abstracts include work on bioengineered tissues and ocular surface rehabilitation as well as infectious ocular diseases.
The UC Davis ophalmologist writes a blog, Evolution’s Eyewitness. “Life first emerged approximately 3.75 billion years ago from the swirling broth of the prebiotic soup,” he wrote, in prefacing and explaining his blog. “The process leading to its appearance is only partially understood, but has several possibilities. The harsh conditions on earth at the time would have permitted only an organism capable of withstanding such bleak surroundings. It would have been very different from any alive today. Survival of any life form in that environment would have required analysis and interaction with its birthplace habitat, skills that would require sensory abilities. Such sensory understanding would have been essential for, and crucial to, life’s evolution.”
“Sight is but one member of a family of sensory abilities, yet for most creatures it is a dominant and pivotal one,” Schwab wrote on his blog. “But sight is probably not the first sense acquired by those early cells, nor were the necessary components of vision secured for the purpose of sight. As often occurs, evolution co-opted various molecules that were assembled for other purposes. These changes and biochemical redirection leave traces suggesting the path of early photoreception."
Schwab, in his blog about jumping spiders and their "magnificent eyes," described them as "positively charming creatures, and you will know that to be true if you have ever watched one closely. These are common spiders and range from approximately 3 to 17 mm in length and will watch you closely as you approach them. They have four pairs of eyes, with the large anterior median (AM) set the most obvious/ These circular eyes provide an ‘attentive child’ appearance because they are fixed and are relatively large based on body size, but are tiny on an absolute scale. These placid eyes belie the organized complexity and evolutionary genius that lies beneath the carapace.”
Schwab received his medical degree from West Virginia University School of Medicine, Morgantown, in 1973. He completed his internship at Santa Clara Valley Medical Center, San Jose, in 1974 and his residency at the California Pacific Medical Center, San Francisco, in 1980.
(Editor's Note; See list of upcoming seminars hosted by the UC Davis Department of Entomology and Nematology. All are held Wednesday noon in 122 Briggs Hall.)
