Faculty & Staff Directory
Department of Biology
University of South Carolina
|Office:||CLS 606||Phone Number:||803-777-6597||Email:||firstname.lastname@example.org|
Organisms often answer similar questions of function by evolving structures that differ in morphology, physiology, and molecular composition. For certain functional problems, why do we tend to see certain solutions more often than others? What may we learn from rare or unique solutions? What are the evolutionary and ecological consequences of different solutions? To answer these questions and others, the Speiser Lab uses an integrative approach to study relationships between structure and function in an evolutionary context. In particular, we study the structure, function, and evolution of visual systems. Eyes are a fascinating and pragmatic topic of research because we can use the morphology and physiology of an eye to estimate how it may perform under different conditions. We can then test predictions of visual function (e.g. acuity or sensitivity) through behavioral experiments. Further, many of the molecular components of eyes (e.g. opsins) are well-characterized, which allows us to predict how changes in genotype may influence changes in phenotype. Finally, eyes evolve in a step-wise manner and certain lineages of animals contain taxa that display eyes at separate stages of evolution; thus, by generating a robust phylogenetic context and applying comparative methods, we can use the natural variation present in these lineages to understand how and why eyes evolve.
The Speiser Lab works with invertebrate animals because of their diverse phenotypes and because it allows us to target taxa specifically well-suited for particular questions. For example, we study the function and evolution of the eyes of scallops, a family of swimming bivalves. The eyes of scallops are single-chambered like the camera eyes of vertebrates and cephalopods, but use a mirror for image-formation instead of a lens. We also study certain chitons (Mollusca: Polyplacophora) that have hundreds of eyes embedded in their dorsal shell plates. These unique shell-eyes are the only eyes known to form images using lenses made of solid aragonite and they may be the most recently evolved eyes of any animal. Finally, we are using the separate instances of eye evolution in mollusks to learn about the co-evolution of spatial vision and complex brains. Despite a current focus on the visual systems of mollusks, the Speiser Lab welcomes proposals for any new projects or collaborations centered on the evolutionary physiology or visual ecology of invertebrates.
Li, L, M.J. Connors, M. Kolle, G.T. England, D.I. Speiser, X. Xiao, J. Aizenberg, and C. Ortiz (2015). Multifunctionality of chiton biomineralized armor with an integrated visual system. Science 350(6263):952-956. DOI: 10.1126/science.aad1246
Stahl, B.A, J.B. Gross, D.I. Speiser, T.H. Oakley, N.H. Patel, D.B. Gould, and M.E. Protas (2015). A Transcriptomic Analysis of Cave, Surface, and Hybrid Isopod Crustaceans of the Species Asellus aquaticus. PLoS ONE 10(10):e0140484. DOI: 10.1371/journal.pone.0140484
Oakley, T.H. and D.I. Speiser (2015). How Complexity Originates: The Evolution of Animal Eyes. Annual Review of Ecology, Evolution, and Systematics, 46: 237-260. DOI: 10.1146/annurev-ecolsys-110512-135907
Battelle, B.A., K.E. Kempler, S.R. Saraf, C.E. Marten, D.R. Dugger, D.I. Speiser, and T.H. Oakley (2015). Opsins in Limulus eyes: characterization of three visible light-sensitive opsins unique to and co-expressed in median eye photoreceptors and a peropsin/RGR that is expressed in all eyes. Journal of Experimental Biology 218:466-479. .
Speiser, D.I, M.S. Pankey, A.K. Zaharoff, B.A Battelle, H.D. Bracken-Grissom, J.W. Breinholt, S.M. Bybee, T.W. Cronin, A. Garm, A.R. Lindgren, N.H. Patel, M.L. Porter, M.E. Protas, A.S. Rivera, J.M. Serb, K.S. Zigler, K.A. Crandall, and T.H.Oakley (2014). Using phylogenetically-informed annotation (PIA) to search for light-interacting genes in transcriptomes from non-model organisms. BMC Bioinformatics 15:350. DOI:10.1186/s12859-014-0350-x.
Speiser, D.I, D.G. DeMartini, and T.H. Oakley (2014). The shell-eyes of the chiton Acanthopleura granulata (Mollusca, Polyplacophora) use pheomelanin as a screening pigment. Journal of Natural History 48: 2899-2911. DOI: 10.1080/00222933.2014.959572.
Gagnon, Y.L, D.I. Speiser, and S. Johnsen (2014). Simplifying numerical ray-tracing for characterisation of optical systems. Applied Optics 53: 4784-4790. DOI:10.1364/AO.53.004784.
Porter, M.L, D.I. Speiser, A.K. Zaharoff, R.L. Caldwell, T.W. Cronin and T.H. Oakley (2013). The evolution of complexity in the visual systems of stomatopods: Insights from transcriptomics. Integrative and Comparative Biology 53: 39-49. DOI:10.1093/icb/ict060.
Speiser, D.I, R.I. Lampe, V.R. Lovdahl, B. Carrillo-Zazueta, A.S. Rivera and T.H. Oakley (2013). Evasion of predators contributes to the maintenance of male eyes in dimorphic Euphilomedes ostracods (Crustacea). Integrative and Comparative Biology 53: 78-88. DOI: 10.1093/icb/ict025.
Ramirez, M.D, D.I. Speiser, M.S. Pankey, and T.H. Oakley (2011). Understanding the dermal light sense in the context of integrative photoreceptor cell biology. Visual Neuroscience 28: 265-279. DOI:10.1017/S0952523811000150.
Speiser, D.I, D. Eernisse, and S. Johnsen (2011). A chiton uses aragonite lenses to form images. Current Biology 21: 665-670. DOI:10.1016/j.cub.2011.03.033.
Speiser, D.I, E.R. Loew, and S. Johnsen (2011). Spectral sensitivity of the concave mirror eyes of scallops: Potential influences of habitat, self-screening and longitudinal chromatic aberration. Journal of Experimental Biology 214: 422-431. DOI:10.1242/jeb.048108.
Speiser, D.I, and S. Johnsen (2008). Comparative morphology of the concave mirror eyes of scallops (Pectinoidea). American Malacological Bulletin 26: 27-34. DOI:10.4003/006.026.0204.
Speiser, D.I, and S. Johnsen (2008). Scallops visually respond to the presence and speed of virtual particles. Journal of Experimental Biology 211: 2066-2070. DOI:10.1242/jeb.017038.