Jeffrey Levinton's Lab

Research Interests and Recent Publications

 

Overview: I am a marine ecologist with broad interests in trophic ecology, functional morphology, soft-bottom benthic ecology, and some evolutionary aspects of marine ecological processes. I also work in the field of macroevolution, with the most recent work being engaged in timing the radiation of the animal phyla by means of molecular divergence estimates. My students have worked a wide range of marine biological problems.

Current and Recent Research:

Current Research

Behavior, biomechanics, evolution of fiddler crabs. The overall objective of this study is to link the origin of an evolutionary innovation, namely the giant major claw of fiddler crabs, to reproductive function, behavioral evolution and biogeography of a widespread group. The fiddlers are pantropical and the major claw is nearly half the weight of the animal. It is used by males in threat display and combat. We are investigating the following questions: (1) Does the claw function as mainly display, or does its biomechanical features reflect a fully functioning closing structure? (2) Is sexual selection a cause of variability in this structure, much as the process works to increase variability of other structures and colors controlled by sexual selection? (3) Did behavioral complexity increase in this group, or did other factors allow the evolution of complex reproductive behavior? (3) Did this group arise in the IndoPacific as previously believed? Our work combines field studies of behavior, morphometrics, molecular phylogenetic tools, and biomechanics to answer these questions.

Recent research has focused on the functional morphology of the sexually selected major claw, which is nearly half the mass of a male fiddler crab. The claw is used in display and combat. Our previous work demonstrated that the major claw is fully functional and that variation of closing force with body size can be predicted successfully from simple measurements of claw dimensions, related to a simple lever system. However, there is a paradoxical result: As body size increases the closing force of the smaller feeding claw increases with the square of any linear measurement, as expected from a proportional increase to muscle cross-sectional area. But the closing force of the major claw proportionally decreases with increasing body size, mainly because the mechanical advantage decreases. Thus a fighting male is weaker than it would otherwise be if it maintained the same claw mechanical proportions of smaller crabs. I have been working on explaining this paradox - why be weaker than you were going to be? Is the claw used more for display? Is some other function being served? Thus far, we have concluded that there is a tradeoff between strength and closing speed and have tested this successfully. Thus larger crabs may require speed of clasping more than strength. This fits in with observations of combat and the usual lack of severe damage that one male might inflict upon another. I believe that this general result applies to many beetles bearing pincers as well. The race is to the swift, not necessarily to the strong.

Measurement of Uca claw closing speed, using high-speed video

 

We are also working on measuring the costs encumbered by having such a large structure as the major claw. In males of Uca pugilator and other species, this size is so large that the walking limbs beneath the cheliped are more robust than the legs beneath the much smaller feeding claw. Do males pay a price by carrying this large structure? Do they escape more poorly from predators? Do they have high metabolic loads, since this claw as a high proportion of the total striated muscle of the whole crab? We have been investigating the cost by measurements of metabolic rate, subjecting crabs to stress on a treadmill, and measuring running speeds of males in the field, as compared with males not bearing the large major claw.

A final emphasis is on the thermal component of fiddler crab performance. Fiddler crabs are an excellent model for the study of thermal stress on a mobile species in the intertidal zone and climate change may have strong impacts on behavior, mating strategies and survival. We have found that male size is related to vulnerability to thermal stress and this may contribute to larger-male mating success. We are investigating tradeoffs between sexual display and physiological stress.

Levinton, J., Lord, S., Higeshide. 2015. Are crabs stressed for water on a hot sand flat? Water loss and field water state of two species of intertidal fiddler crabs. J. Exp. Mar. Biol. Ecol. 469: 57-62.

Allen, B.J., and J.S. Levinton. 2014. Sexual selection and the physiological consequences of habitat choice by a fiddler crab. Oecologia 176:25-34. DOI 10.1007/s00442-014-3002-y

Levinton, J.S., Mackie. 2013. Latitudinal diversity relationships of fiddler crabs: biogeographic differences united by temperature. Global Ecology and Biogeography.DOI: 10.1111/geb.12064

Munguia, P., Levinton, J.S., Silbiger, N.J. 2013. Latitudinal differences in thermoregulatory color change in Uca pugilator. Journal of Experimental Marine Biology and Ecology 440: 8-14.

Allen, B.J., Rodgers, B., Y. Tuan, Levinton, J. 2012. Size-dependent temperature and desiccation constraints on performance capacity: implications for sexual selection in a fiddler crab. Journal of Experimental Marine Biology and Ecology 438:93-99.

Allen, B., Levinton, J.S. 2007. Costs of bearing an ornamental weapon in a fiddler crab. Functional Ecology 21:154-161.

Levinton, J.S., B. Allen. 2005. The paradox of the weakening combatant. tradeoff between closing force and clasping speed in a sexually selected combat structure. Functional Ecology 19: 159-165

Allen, B., Levinton, J.S. in preparation. Three measures of cost of a sexually selected combat structure.

Levinton, J.S. in preparation. Positive correlations rather than a tradeoff between mass of a sexually selected structure and a developmentally related feeding structure. in preparation

Levinton, J.S., Sturmbauer, C., J. Christy. 1996. Molecular data and biogeography: resolution of the evolutionary history of a pantropical group of invertebrates. Journal of Experimental Marine Biology and Ecology, 203:117-131.

Sturmbauer, C., J. Christy, J. S. Levinton. 1996. Molecular phylogeny analysis of fiddler crabs: Test of the hypothesis of increasing behavioral complexity in evolution Proc. Nat. Acad. Sci. USA, 93:10855-10857.

Levinton, J.S., Judge, M., Kurdziel, J. 1995. Functional differences between the major and minor claws of fiddler crabs (Uca, family Ocypodidae, Order Decapoda, Subphylum Crustacea): A result of selection or developmental constraint. Journal of Experimental Marine Biology and Ecology 193: 147-160.

Levinton, J.S., and M. L. Judge. 1993. The relationship of closing force to body size for the major claw of Uca pugnax (Decapoda: Ocypodidae). Functional Ecology, 7: 339-345.

RECENT PAST RESEARCH PROJECTS

Physiological Performance, and Potential for Restoration of the eastern oyster, Crassostrea virginia. The overall objective of our work is to produce a physiological map of growth, survival, susceptibility to disease, and recruitment of oysters in the New York region. Oysters were once very abundant but are now rare, owing to overexploitation and pollution. We are focusing on areas thought to be useful for restoration to take advantage of the oysters useful ecosystem services, including enhancement of fish and invertebrate biodiversity and local reduction of phytoplankton density. We have chosen nine sites with strongly varying water quality, salinity to develop a map of performance. This will be combined with the development of a strategy for deploying artificial oyster reefs that produce a sustainable metapopulation of oysters in a restricted region, such as Jamaica Bay, New York and Haverstraw Bay, in the Lower Hudson estuary. This work is being done in collaboration with Michael Doall, Director, Functional Ecology Research and Teaching Laboratory, Stony Brook University.

Oyster bag, before placement in Wire Cage, Haverstraw Bay, Hudson River

Tappanzee Bridge, which crosses Haverstraw Bay

Publications and Reports

Sebastiano, D., Levinton, J., Doall, M., Kamath, S. 2015. Using a shellfish harvest strategy to extract high nitrogen inputs in coastal bays: Practical and economic implications. Journal of Shellfish Research, 34: 573-583.

Levinton, J., Doall, M., Allam, B. 2013. Growth and mortality patterns of the eastern oyster Crassostrea virginica in impacted waters in coastal waters in New York, USA. Journal of Shellfish Research. 32: 417-427.

Levinton J, Doall M, Ralston D, Starke A, Allam B, 2011 Climate Change, Precipitation and Impacts on an Estuarine Refuge from Disease. PLoS ONE 6(4): e18849. doi:10.1371/journal.pone.0018849

Starke, A., Levinton, J., Doall, M. 2011. Restoration potential of Crassostrea virginica to the Hudson River, USA: A Spatio-temporal modeling approach. J. Shellfish Res., 30(3):671-684.

Hear Jeff Levinton and Mark Kurlansky on the Brian Lehrer Show, WNYC

Hear Jeff Levinton and Ken Paynter on the Leonard Lopate Show, WNYC, March 25, 2010

 

Evolution of resistance to metals and restoration ecology. We have discovered rapid evolution of resistance to cadmium in an aquatic oligochaete and have shown that the trait is strongly heritable and probably controlled by one gene. The evolution of resistance in this system was under strong selection and likely occurred in less than five generations. In the lab we were able to accomplish 2/3 of the resistance observed in the field over three generations of selection. We are now attempting to understand the molecular basis of the resistance and also are studying the reversion of resistance as the cove is being cleaned up in a Superfund project. We are also actively investigating the impacts of a major Superfund cleanup that occurred at Foundry Cove, Hudson River, in 1994-1995. We observed a reversion of the resistance to background levels in onlhy nine years following the cleanup (Levinton et al. 2003). We also observed strong reorganization in the benthic community following the cleanup (Kelaher et al. 2003). We are now working further on the question of cost of evolution of the resistance trait. As a side project we analyzed mercury concentrations, using a large data base of fish analyses in the Hudson River USA. We found a 30 year decline in concentrations by a factor of 2-3, but a persistent increase of Hg concentrations toward the north. We speculated that the source might be the Adirondack watershed.

Sampling at Foundry Cove, Hudson River

 

Klerks, P., Xie, L., Levinton, J.S. 2011. Quantitative genetics approaches to study evolutionary processes in ecotoxicology; a perspective from research on the evolution of resistance. Ecotoxicology 20: 513-523.

Mackie, J., Levinton, J.S., Przselawski, R., DeLambert, D., Wallace, W. 2010. Loss of Evolutionary Resistance by the oligochaete Limnodrilus hoffmeisteri to a Toxic SubstanceŚCost or Gene Flow? Evolution, 64:152-165.

Levinton, J.S., S.T. Pochron. 2008. Temporal and geographic trends in mercury concentrations in muscle tissue in five species of Hudson River, USA, fish. Environmental Toxicology and Chemistry 27: 1691-1697.

Mackie, J., Natali, S., Levinton, J., Sanudo-Wilhelmy, S. 2007. Declining metal levels at Foundry Cove (Hudson, New York): response to localized dredging of contaminated sediments. Environmental Pollution, 149: 141-148.

Levinton, J.S., S.T. Pochron, M.W. Kane. 2006. Superfund dredging restoration results in widespread regional reduction of cadmium in blue crabs. Environmental Science & Technology 40: 7597-7601.

Levinton, J. S., Suatoni, L., Wallace, W. P., Junkins, R., Kelaher, B.P., Allen, B.J. 2003. Rapid Loss of genetically-based resistance to metals, following the cleanup of a Superfund site. PNAS 100: 9889-9891.

Note: Here is a corrected figure for this publication.

Press Release Pictures



Kelaher, B. P., Levinton, J. S., Oomen, J. Allen, B. J., Wong, W.H. 2003. Changes in benthic communities following the clean up of a severely metals polluted cove in the Hudson River Estuary: environmental restoration or ecological disturbance? Estuaries, 26: 1505-1516.

Levinton, J.S., P. Klerks, D.E. Martinez, C. Montero, C. Sturmbauer, L. Suatoni,W. Wallace. 1999. Running the Gauntlet: Pollution, Evolution and Reclamation of an Estuarine Bay and its Significance in Understanding the Population Biology of Toxicology and Food Web Transfer. IN M. Whitfield, ed., Aquatic Life Cycles Strategies. Plymouth U.K., The Marine Biological Association.

Wallace, W.G., Lopez, G.R., Levinton, J.S. 1998. Cadmium resistance in an oligochaete and its effect on cadmium trophic transfer to an ominvorous shrimp. Mar. Ecol. Prog. Ser. 172: 225-237.

Martinez, D.E., and J.S. Levinton 1996. Adaptation to cadmium in the aquatic oligochaete Limnodrilus hoffmeisteri: Evidence for control by one gene. Evolution, 50: 1339-1343.

Klerks, P., Levinton, J. 1992. Evolution of resistance and changes in community composition in metal-polluted environments: A case study on Foundry Cove.In Dallinger, R., Rainbow, P. (eds.), Ecotoxicology of Metals in Invertebrates. Lewis Publ., Chelsea, pp. 223-241.

Klerks, P.L., and J.S. Levinton. 1989. Rapid evolution of resistance to extreme metal pollution in a benthic oligochaete. Biol. Bull. 176:135-141.

  Biodynamics of Particle Selection by Suspension Feeders. With Evan Ward and Sandy Shumway, I am working on the mechanisms of bivalve feeding, using flow cytometry, surgical telescopes, and videotaping to study the ability of bivalves to sort particles and adjust feeding rates in response to variations in particle concentration and complex particle arrays. The questions involve whether given parts of the feeding apparatus comprise a rate-limiting step to feeding, and whether bivalves can use selectivity to sort among complex arrays of non-living and living particles in environments such as estuaries. We hope to do a comparative study among different bivalve groups but are concentrating on a few oyster, scallop, mussel, arcid spp. as well as Zebra mussels.

Recent results have combined video endoscopy with flow cytometry to sample in different parts of the pallial cavity. We have discovered extensive particle selectivity on the gills of oysters and zebra mussels. In oysters, rapid shunting allows particles of poor nutritive quality to be rejected and nutritious particles to be diverted towards the mouth. A video of these results can be found here. In the case of zebra mussels, the selectivity has been related to a change in phytoplankton species dominance, following the invasion by zebra mussels of the Hudson River. We have also recently shown that oysters and mussels can detect the presence of polyphenolics in kelp detrital particles. Evan Ward's summary of particle transport in the mussel Mytilus edulis can be found here.

Mytilus gill, ventral margin, photo by Evan Ward.

Our most recent work has focused on the possibility that bivalves may be able to capture and consume much larger and more active food particles than previously appreciated. A number of studies have suggested that bivalves can feed upon zooplankton particularly smaller forms such as ciliates. We have demonstrated that zebra mussels and two species of marine mussels can clear rotifers from the water column and can assimilate carbon at levels high enough to be meaningful to bivalve nutrition. We have suggested that there is a benthic-zooplankton loop that might strongly implicate dense populations of benthic suspension feeders in control of near shore water column communities. Instead of competing with zooplankton for microphytoplanktonic food, they may be top-down predators on the whole system.

The capture of zooplankton by bivalves has been demonstrated in a number of field studies, but the most intriguing evidence comes from invasions of the Asiatic clam and the Zebra mussel, both of which were followed in some water bodies by precipitous declines of micro and mesozooplankton. In the lab we demonstrated that zebra mussels can capture, ingest, and assimilate rotifers of lengths as large as ca. 300 micrometers. Using 14C labeled rotifers, we found high efficiencies (Wong et alo. 2003a, b). We also found a positive synergistic interaction resulting in high shell growth ot the mussel Mytilus edulis, when fed combined rotifers and phytoplankton, as opposed to either alone (Wong and Levinton 2004). Our most recent work in collaboration with Jeannette Yen, Brock Woodson and Marc Weissberg of Georgia Tech demonstrates very different capture success of copepods by mussels in still and moving water. These results will be presented at ASLO in 2005. Some preliminary movies and images can be viewed here.

 

Wong, W.H., 2006. The trophic linkage between zooplankton and benthic suspension feeders: Evidence from fecal pellets. Marine Biology 148: 799-805.

Wong, W. H., Levinton, J.S. 2005. Consumption rates of two rotifer species by zebra mussels Dreissena polymorpha. Marine and Freshwater Behaviour and Physiology. 38: 149-157.

Wong, W. H., Levinton, J. S. 2004. Culture of the blue mussel Mytilus edulis (Linnaeus, 1758) fed both phytoplankton and zooplankton: A microcosm experiment.Aquaculture Research, 35:965-969.

Wong, W.H., Levinton, J. S., Twining, B. S., Fisher, N. S. Kelaher, B. P., Alt, A. K. 2003. Assimilation of carbon from a rotifer by the mussels, Mytilus edulis and Perna viridis: A potential food web link between zooplankton and benthic suspension feeders. Mar. Ecol. Prog. Ser. 253: 175-182.

Wong, W.H., Levinton, Twining, B.S., Fisher, N.S. 2003.Assimilation of micro- and mesozooplankton by zebra mussels: a demonstration of the food web link between zooplankton and benthic suspension feeders. Limnol Oceanogr. 48: 308-312.

Baker, S. M., Levinton, J. S. 2003. Selective feeding by three native North American freshwater mussels implies food competition with zebra mussels. Hydrobiologia 505: 97-105.

Ward, J. E., J. S. Levinton, S. E. Shumway. 2003. Influence of diet on pre-ingestive particle processing in bivalves I: Transport velocities on the ctenidium. J. Exp. Mar. Biol. Ecol. 293: 129-149.

Levinton, J. S., J. E. Ward, S. E. Shumway. 2002. Feeding responses of the bivalves Crassostrea gigas and Mytilus trossulus to chemical compositon of fresh and aged kelp detritus. Mar. Biol. 141: 367-376.

Levinton, J.S., J.E. Ward, S.E. Shumway, S. M. Baker. 2001. Feeding Processes of Bivalves: Connecting the Gut to the Ecosystem. Pp. 385-400. In Organism-sediment Interactions, ed. J. Y. Aller, S. A. Woodin, R. Aller, Belle W. Baruch Library in Marine Science no. 21. University of South Carolina Press, Columbia, SC 29208

Baker, S., J.S. Levinton, J.E. Ward. 2000. Particle transport in the zebra mussel, Dreissena polymorpha (Pallas). Biol. Bull. 199:116-125.

Baker, S. M., J.S. Levinton, J. P. Kurdziel, S.E. Shumway. 1998. Selective feeding and biodeposition by zebra mussels and their relation to changes in phytoplankton composition and seston load. J. Shellf. Res. 17: 1207-1213.

Ward, J.E., J.S. Levinton, S.E. Shumway, T. Cucci. 1998. Particle sorting in bivalves" in vivo determination of the pallial organs of selection. Mar. Biol. 131: 283-292.

Ward, J.E., J.S. Levinton, S.E. Shumway, T. Cucci. 1997. Site of particle selection in a bivalve mollusc. Nature 390: 131-132.

Levinton, J.S., J. E. Ward, R. Thompson. 1996. Biodynamics of particle processing in bivalve molluscs: models, data, and future directions. Invertebrate Biology 115: 232-242.

Levinton, J.S. 1991. Variable feeding behavior in three species of Macoma (Bivalvia: Tellinacea) as a response to water flow and sediment transport. Marine Biology 110:375-383.

2. Testing the Cambrian Explosion Hypothesis. With Gregory Wray, and Leo Shapiro, I have used molecular distance - fossil divergence data to estimate the time of divergence of the animal phyla. Our results, based on analyses of large number of taxa for 7 genes, suggests that the animal phyla (protostome-deuterostome split) diverged far before the Cambrian. We are now using simulations to test whether one can recover a "tree of life" when divergences occur at varying times before the present and over different periods of time. Initial results suggest that the extreme version of the Early Cambrian explosion could never be detected. Our analyses of real molecular sequences, however, do allow us to define the order of appearance of major groups. This suggests that the radiation of animals took place over a more protracted period.

Levinton, J.S., 2008. The Cambrian explosion: How do we use the evidence? BioScience 58: 855-864.

Recent Interview about the Cambrian Explosion by AIBS

Levinton, J.S., L. Dubb, G. A. Wray. 2004. Simulations of evolutionary radiations and their application to understanding the probability of a Cambrian explosion. J. Paleontol. 78: 31-38.

Levinton, J. S. 2001. Genetics, Paleontology and Macroevolution. 2nd ed. New York, Cambridge Univ. Press.

Wray, G., J.S. Levinton, L. Shapiro. 1996. Molecular evidence for deep Precambrian divergences among metazoan phyla. Science 274: 568-573.

Levinton, J.S. 1992. The big bang of animal evolution. Scientific American, November issue, pp. 84-91.

 Trophic limitation and population dynamics of deposit feeding invertebrates. For many years I have been working on food limitation of deposit feeders. The overall objective is to study functional aspected of feeding and to connect these studies to population regulation of field populations and communities. This work began with models and studies of food limitation of deposit feeders that fed on a renewable resource, namely sediment associated microbes and algae. In more recent years I have focused on the dynamics of particulate organic matter supply and population responses.

Recently we have been working on an asexual oligochaete that undergoes a boom and bust cycle every summer, that appears to be related to the appearance and decline of a food base. We have shown (Cheng et al. 1993) that organic matter steadily declines in nutritional quality thorughout the spring and populations finally decline in the early summer. this is a general theme in intertidal mud flats dominated by surface and near surface-feeding deposit feeding annelids. We have recently discovered a behavioral-reproductive switch that appears when food is limited. This is a form that fails to bud and becomes a large active swimmer and is apparently a migratory individual. We are now doing spatial modeling to understand the implications of such an emigratory form.

Placing experimental cages in a mud flat at Flax Pond salt marsh

 

We have completed recently a field assay of emigration, using a device to estimate the proportion of Paranais litoralis that depart from the sediment. As found in the past, sediment-dwelling P. litoralis showed a strong peak in the spring, followed by a precipitous decline. The relative number of "swimmers" increased at or after the seasonal peak abundance of worms as predicted from previous laboratory discoveries. They are probably the first to demonstrate an ecological context, in terms of resources, for swimming from the sediment by soft-bottom benthos. We also have quantified for the first time, simultaneously, emigration and immigration (Junkins et al. 2006).

Our most recent efforts have also been directed toward extending laboratory experiments on food inputs to field situations. We completed a spatial sampling program that demonstrates that seasonal boom-bust cycles of annelids in Long Island salt marsh mud flats are spatially variable in time course, leading to strong spatial-temporal variation of cycles of surface feeding deposit feeders, such as the oligochaete Paranais litoralis and the polychaete Streblospio benedicti. Field manipulation experiments demonstrate that the system of surface feeders is food limited and that the mobile snail Ilyanassa obsoleta exerts negative effects on populations of deposit feeding annelids. Field experiments demonstrate that I. obsoleta populations move to local inputs of particulate organic detritus inputs, which in turn, tends to reduce population growth of surface deposit feeders. Thus, overall, there appears to be competition between the bottom-up input of food, which is spatially localized, and the top-down effect of the mobile consumer, Ilyanassa obsoleta.

 

Junkins, R., Kelaher, B., Levinton, J. S. 2006. Contributions of adult oligochaete emigration and immigration in a dynamic soft-sediment community. J. Exp. Mar. Biol. Ecol. 330: 208-220.

Levinton, J. S., Kelaher, B. P. 2004. Opposing organizing forces of deposit-feeding marine communities. J. Exp. Mar. Biol. Ecol. 300, 65-82.

Kelaher, B. P., Levinton, J.S. 2003. Variation in detrital-enrichment causes changes in spatio-temporal development of soft-sediment assemblages. Marine Ecology Progress Series.

Kelaher, B. P., Levinton, J. S., Hoch, J. M. 2003. Foraging by the mud snail, Ilyanassa obsoleta (Say), modulates spatial variation in benthic community structure. J. Exp. Mar. Biol. Ecol. 292:139-157.

Nilsson, P., J. S. Levinton, J. Kurdziel. 2000. Migration of a marine oligochaete: induction of dispersal and microhabitat choice. Mar. Ecol. Prog. Ser. 207: 89-96.

Nilsson, P., J.Kurdziel, J.S. Levinton. 1998. Heterogeneous population growth, parental effects and genotype- environment interactions of a marine oligochaete. Marine Biology, 130: 181-191.

Levinton, J.S. 1995. Bioturbators as ecosystem engineers: Population dynamics and material fluxes, pp. 29-36 IN C.G. Jones and J. H. Lawton, eds., Linking Species and Ecosystems, New York, Chapman and Hall

Cheng,I-J., J.S. Levinton, M. McCartney, D. Martinez, and M.J. Weissburg. 1993. A bioassay approach to seasonal variation in the nutritional value of sediment. Marine Ecology Progress Series, 94: 275-285.

Levinton, J.S., McCartney, M.M. 1991. The use of photosynthetic pigments as tracers of sources and fates of macrophyte organic matter in a sand flat. Marine Ecology - Progress Series, 78:87-96.

 

Thesis topics of most recent PhD students who have gotten their degrees in areas discussed above.

1. Daniel Martinez - study of senescence and life history in invertebrates, in relation to presence and absence of sexual reproduction. Now  Prof., Pomona College

2. Mike McCartney - study of male reproductive effort and its importance in varying hermaphroditic strategies in a bryozoan. Now Resarch Professor at Univ. Minnesota

3. Sean Craig - study of the importance of fusion in the biology of bryozoans. Now Professor, Cal. State at Humboldt

4. Marc Weissburg - study of foraging biology and optimal foraging in fiddler crabs. Now Prof. at Georgia Tech University

5. Josepha Kurdziel - study of the factors that select for male dimorphism in the amphipod Jassa marmorata, now Asst. Prof. at U. of Michigan

6. Michael Rosenberg - study using geomorphometrics and other approaches to understand morphological variation, functional morphology and phylogeny of fiddler crabs. now  Professor at Arizona State.

7. Bengt Allen - reproductive and physiological performance of the fiddler crab Uca pugilator, relating performace to thermal stress and food availability. now Assoc. Professor at California State University at Long Beach.

8. J. Matt Hoch - reproductive effort, fertilization success and morphological plasticity in acorn barnacles. now Associate Professor at Nova Southeastern University.

9. Chris Noto (coadvisor with Dr. Catherine Forster) - taphonomy and its influence on our understanding of dinosaur preservation and diversity patterns, now assistant professor at University of Wisconsin, Parkside.

10. Patrick Lyons - The evolution of mutualism between alpheid shrimp and gobiid fishes, now Assistant Professor, Valley College, California.

11. Abigail Cahill (BS Colgate University), Climate change and larval ecology and population genetics of slipper shells. now Assistant Professor Albion College, Michigan