Please join the Great Lakes Center for a seminar presented by Dr. Katharina Dittmar de la Cruz, associate professor of biology at the University at Buffalo. The seminar will be held on Thursday, February 19th from 12:15 to 1:30 p.m. in Classroom Building B118.
One of the most consistent morphological features of parasitic arthropods (ectoparasites) is the rudimentary manifestation of their visual systems. This is apparent in such distantly related clades as fleas (Siphonaptera), mites (Acari), scale insects (Sternorrhyncha), ked flies (Hippoboscoidea), or lice (Pthiraptera), to name a few. Dr. Dittmar will present data on the trajectory of visual evolution in parasites, using an organismal system with diverse morphologies of eye reduction that shows species specific variation in light environments, and in host recognition needs. The study organisms are bat flies, which are obligate, blood-feeding, viviparous parasites of bats (Diptera, Hippoboscoidea, Streblidae and Nycteribiidae).
Preliminary data show that despite stark anatomical reductions (e.g. number of ommatidia) and nocturnal or crepuscular life styles, some species have functional eyes, as evidenced by behavioral responses, such as startle reflexes, and negative phototaxis. Furthermore, photoreceptor spectral absorbance studies show peak absorbance for 2 species in the blue spectrum range. Micromorphological studies suggest modifications of optics, and cell arrangements resembling known adaptations to low light levels, thus directly challenging the broad stroke idea that parasitism leads to non-functional eye reduction. Results will be discussed in the context of bat fly evolution, and the presumed influences of photic environment, and relaxed constraints for visual host recognition on eye reduction and loss in parasites.
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