Gibb Lab: Research Questions and Projects

I am broadly interested in environmental and evolutionary functional morphology and physiology and research conducted in the Gibb lab is framed by three interrelated questions within these disciplines.

How does the same morphological structure function effectively across disparate environments?

In collaboration with graduate students and collaborators at other institutions, we have examined terrestrial locomotion in amphibious and non-amphibious teleosts. Amphibious species, like the mudskipper, voluntarily spend extended periods on land. As a consequence of the different physical demands of the two environments (high-viscosity/low-gravity vs. high-gravity/low-viscosity), amphibious species often have morphological modifications of the fins or vertebral column to facilitate terrestrial locomotion. Our work on amphibious fish species has been disseminated in several papers, including a recent paper on mudskipper pectoral fin locomotion on land (Pace & Gibb, 2009). Recently, we have documented a surprising behavior in non-amphibious fishes: many non-amphibious species (e.g. mosquitofish, Gambusia affinis) can produce a coordinated and effective terrestrial “jump” in response to stranding. A non-amphibious fish may find itself stranded on land as a result of leaping out of the water to escape a predator; once stranded, it must quickly return to the water or die from asphyxiation or desiccation. Interestingly, this critically important behavior requires no obvious morphological or physiological adaptations—species that produce this behavior possess a “typical” aquatic morphology. Our preliminary work on this topic has recently been submitted to a major journal and is currently in the review process.

How do musculoskeletal systems develop, and what are the performance consequences?

In derived bony fishes (teleosts), young individuals interact with the environment with a larval (non-adult) phenotype. During the transformation from larva to adult, teleosts develop new morphological structures (morphogenesis) in the axial skeleton, fins and jaws. Because these structures are used to obtain food and escape from predators, changes in morphology have ramifications for behaviors critical for survival, and thus, for individual fitness. The primary model system we have used to examine the association between morphogenesis and performance is the development of the aquatic escape behavior, or C-start. We have examined fish from a variety of teleost orders that represent different developmental “strategies” to test hypotheses about the association between performance and acquisition of key anatomical structures. My students and I have performed a series of experiments relating to these questions, and results have been disseminated in peer-reviewed publications (for example, Gibb et al., 2006). Ongoing research in my laboratory examines the ramifications of morphogenesis on feeding performance, thus expanding our work to encompass the trophic (feeding) ecology of young fishes.

What are the ecological ramifications of variation in morphology and behavior?

With the assistance of students and collaborator, I have used a species-rich group of freshwater fishes (the killifish, Cyprinodontiformes; Teleostei) to examine the evolution of feeding behavior and underlying neuromuscular elements. In these projects, we have described previously unrecognized modifications of the feeding apparatus that facilitate trophic diversity. One family within the order contains carnivores, piscivores (fish-eaters), omnivores and grazing herbivores; we have documented key morphological modifications of the musculoskeletal system of the jaw that enable the group to demonstrate such high trophic diversity. For example, in herbivorous species, the lower jaw contains a second joint that facilitates the production of a 180° gape—which allows maximum contact between the teeth and substrate during the removal of plant material (see Gibb et al., 2008).

An Environmentally Relevant Model System: The Native Fishes of Arizona

chub


Roundtail chub

A related objective of my laboratory has been to employ the tools of comparative physiology and functional morphology to evaluate swimming and feeding performance of native species of the Southwestern U.S., relative to introduced, non-native competitors. For these projects, we collaborate with local management officials (especially David Ward, Arizona Game and Fish, Bubbling Ponds Native Fish Hatchery). In these studies, we use native fish to test fundamental questions (as above) about the relationship between morphology and performance—but with the additional objective of describing life history characteristics of the imperiled fishes of the American Southwest. To date, six graduate students have conducted research on native fish (four completed M.S. thesis projects) and this work has been supported by two state-funded, environmentally-oriented grants.

Research methods

We use some innovative technologies and methods in the lab that help us investigate some of these research questions. We use a very high speed video system from Vision Research, which allows us to slow motion down and see things the human eye could miss. With this system, we can capture up to 1000 frames per second in high resolution color. We assign marker points on the animal's body and track their movement in space from frame to frame using specially developed software such as Didge and ImageJ, which allow us to precisely measure tiny changes in distance. We have used underwater digital video cameras to record feeding behavior under natural conditions. We use electromyography (EMG) techniques to determine which muscles are firing, and in what sequence, during the production of these feeding and escape response behaviors. We have pioneered the use of Botulinum toxin, commonly know as "botox," as a method for temporarily blocking the activity of specific muscles to non-destructively test their functions. Our interest in larval fish has led us to design filming chambers that contain only milliliters of water but maintain the subjects in healthy condition during recording.

Dr. Alice Gibb

alice.gibb@nau.edu

Office: Peterson 313
Office Phone: (928) 523-1524
Lab: Wettaw 204
Lab Phone: (928) 523-2831


Postdoc: CSU Fullerton '97-'99
PhD: UC Irvine '97
BA: Mount Holyoke '89
Northern Arizona University, Biology Department, P.O. Box 5640, Flagstaff, AZ 86011