Paloma Gonzalez Bellido
“For many problems there is an animal on which it can be most conveniently studied” A. Krogh 1929.
My research applies this famous principle to gain further knowledge about the evolution of visual systems. Sensory systems have evolved to provide each species with information relevant to their ecology in a timely and efficient manner. Thus, by carrying out comparative studies, my research elucidates how the structure and function of visual systems is selected to perform optimally when faced with niche-specific challenges.
Current research: “Neural circuitry of the visually guided predatory behaviour of the percher dragonfly L. lydia”
In dragonflies, Target Sensitive Descending Neurons are thought to steer the flight during prey‑predator interactions. This is because TSDNs respond exclusively to a small object moving in a particular direction. In addition, TSDNs relay visual information from the brain to the thoracic ganglia and stimulating them electrically changes the pitch of the wings. However, such work was carried out exclusively in “flier” dragonfly species. “Fliers” detect, catch and consume their prey in mid-flight. In contrast, a different group of dragonflies, called “perchers”, show a sit-and-wait strategy, taking-off only after detecting a flying prey. Such behavioural difference is reflected in the specializations of their dorsal eye area, the element used for prey recognition.
Are the properties of the TSDNs, and thus the motor outputs which drive the predatory behaviour, also adapted to and reflective of the “flier” vs. “percher” behaviour? To answer this question I am describing through in vivo electrophysiology the visual receptive fields of the TSDNs in the percher dragonfly Libellula lydia. In parallel, I am creating a 3D reconstruction atlas of the TSDNs morphology. This atlas will serve to compare the changes of neural circuitry in dragonfly species which exhibit different predatory flight trajectories.
For my graduate project, I chose to test the widespread notion that size constraints in miniature dipterans becomes the leading selection force for eye design, independent of the specific behavioral task. I studied the cornea design and the photoreceptor performance in the diurnal predatory killer fly (Coenosia attenuata, picture 1) and the crepuscular prey species D. melanogaster. I found that the killer fly eye doubles the resolution of the fruit fly retina simply by decreasing the width of their light sensors. My results further emphasize that the bad resolution of the fruit fly eye is not a direct limitation of a small body size, but an adaptation for a crepuscular lifestyle. (Gonzalez‑Bellido et al. PNAS In press. 2011). For this work I was awarded the 1st prize of the Young Scientist Competition, organized by the Society of Experimental Biology (Glasgow 2009).
During my PhD work I also developed transgenic animals to investigate the following sensory biology question: Can crepuscular species sum the input from many photoreceptors to increase sensitivity at the expense of resolution? However, what I found is that the most widely used genetic tool for disrupting synaptic circuits (shibire) caused major toxic effects when expressed in the fly retina (Gonzalez-Bellido et al. 2009 J Neurosci.).