Ecology and Evolution
Faculty research interests in the area of ecology and evolution include theoretical population biology (Desharnais Lab), bryophyte evolutionary ecology (Fisher Lab), evolutionary ecology of marine invertebrates (Krug Lab), conservation biology and ecology of tree squirrels (Muchlinski Lab), benthic marine ecology (Robles Lab), and evolutionary history of marine organisms (Torres Lab).
Theoretical Population Biology
 |
Contact: Robert A. Desharnais, Ph.D. Office: ASCB 323D, ext: 3-2056 Laboratory: ASCB 342, ext: 3-2033 E-mail: rdeshar@calstatela.edu Web: http://caldera.calstatela.edu/rdeshar | |
| Ventral view of an adult flour beetle, Tribolium castaneum. Populations of these insects are used as a laboratory model for testing ecological theory. |
Research Summary
Our research interests are in the area of theoretical and experimental population biology. We use of insect populations to test predictions of nonlinear population models, including phenomena such as chaos, the effects of stochasticity, and metapopulation synchrony. We are also working with the Robles laboratory on models of the dynamics of marine mussel beds. Our methods involve mathematical models, computer simulations, and laboratory population experiments with flour beetles.
| Representative Publications |
| Donahue, M.J., Desharnais, R.A., Robles, C.D., Arriola, P. 2011. Mussel bed boundaries as dynamic equilibria: thresholds, phase shifts, and alternative states. The American Naturalist (in press). |
| Robles, C.D., Desharnais, R.A., Garza, C., Donahue, M.J., and Martinez, C.A. 2009. Complex equilibria in the maintenance of boundaries: experiments with mussel beds. Ecology 90: 985-995. |
| Desharnais, R.A., Costantino, R.F., Cushing, J.M., Henson, S.M., Dennis, B, and King, A.A. 2006. Experimental support for the scaling rule of demographic stochasticity. Ecology Letters 9: 537-547. |
| Reuman, D.C., Desharnais, R.A., Costantino, R.F., Ahmad, O.S., and Cohen, J.E. 2006. Power spectra reveal the influence of stochasticity on nonlinear population dynamics. Proceedings of the National Academy of Sciences USA 103: 18860-18865. |
| Desharnais, R.A., Dennis, B., Cushing, J.M., Henson, S.M., and Costantino, R.F. 2001. Chaos and population control of insect outbreaks. Ecology Letters 4: 229-235. |
[top]
Bryophyte Evolutionary Ecology
 |
Contact: Kirsten Fisher, Ph.D. Office: ASCL 393, ext: 3-2089 Laboratory: ASCL 351, ext: 3-2085 E-mail: kfisher2@calstatela.edu Web: http://instructional1.calstatela.edu/kfisher2 | |
| Tropical moss, Calymperes tenerum, with asexual propagules. |
Research Summary
Our research interests include plant molecular systematics, phylogeography, and the use of phylogenetic trees for exploring evolutionary questions in general. In particular, we apply molecular phylogenetic methods to understanding cryptic diversity in mosses. We are investigating the potential link between physiological specialization and cryptic diversification in this group of plants, focusing on the desiccation tolerant model moss Syntrichia ruralis.
| Representative Publications |
| Fisher, K. 2008. Bayesian reconstruction of ancestral gene expression in the LEA families reveals propagule-derived desiccation tolerance in resurrection plants. American Journal of Botany 95: 506-515. |
| Fisher, K., Wall, D.P., Yip, K.L., and Mishler, B.D. 2007. Phylogeny of the Calymperaceae, with a rank-free systematic treatment. The Bryologist 110: 43-73. |
| Fisher, K. 2006. Rank-free monography: a practical example from the moss clade Leucophanella. Systematic Botany 31: 13-30. |
| La Farge, C., Mishler, B.D., Wheeler, J.A., Wall, D.P., Johannes, K., Schaffer, S., and Shaw, A.J. 2000. Phylogenetic relationships of the Haplolepideous mosses. The Bryologist 103: 257-276. |
[top]
Evolutionary Ecology of Marine Invertebrates
 |
Contact: Patrick Krug, Ph.D. Office: ASCL 314, ext: 3-2076 Laboratory: ASCL 325, ext: 3-2098 E-mail: pkrug@calstatela.edu Web: http://instructional1.calstatela.edu/pkrug/lab | |
| The Caribbean sea slug Elysia crispata stores chloroplasts from the algae it eats and can go months between meals, living off of photosynthesis performed by the hijacked plastids. |
Research Summary
Our lab studies the evolution of dispersal and habitat colonization by planktonic larvae of marine animals, aiming to identify factors that limit gene flow, set range limits, and promote local adaptation. We use herbivorous sea slugs as a model system to investigate the evolution of alternative larval strategies, and to study ecological speciation in the sea. Field studies focus on a dynamic range boundary in San Francisco Bay, examining physical and biological forces that allow two species to cyclically displace each other every year. We are also building a molecular phylogeny, or family tree, of algae-eating sea slugs to study the evolution of traits such as larval type and host use.
| Representative Publications |
| Smolensky, N., Romero, M., and Krug, P.J. 2009. Evidence for costs of mating and self-fertilization in a simultaneous hermaphrodite with hypodermic insemination, the opisthobranch Alderia willowi. Biological Bulletin 216: 188-199. |
| Krug, P.J., Riffell, J.A., and Zimmer, R.K. 2009. Endogenous signaling pathways and chemical communication between sperm and egg. Journal of Experimental Biology 212: 1092-1100. |
| Ellingson, R.A., and Krug, P.J. 2006. Evolution of poecilogony from planktotrophy: Cryptic speciation, phylogeography and larval development in the gastropod genus Alderia. Evolution 60: 2293-2310. |
| Botello, G. and Krug, P.J. 2006. Desperate larvae revisited: Age, energy and experience affect sensitivity to settlement cues in larvae of the gastropod Alderia sp. Marine Ecology Progress Series 312: 149-159. |
| Riffell, J.A., Krug, P.J., and Zimmer, R.K. 2004. The ecological and evolutionary consequences of sperm chemoattraction. Proceedings of the National Academy of Sciences USA 101: 4501-4506. |
[top]
Conservation Biology and Ecology of Tree Squirrels
 |
Contact: Alan Muchlinski, Ph.D. Office: ADM 710, ext: 3-3826 E-mail: amuchli@calstatela.edu Web: http://instructional1.calstatela.edu/amuchli | |
| Western gray squirrel, Sciurus griseus. The distribution of this species in Southern California is threatened by the expansion of the introduced eastern fox squirrel, Sciurus niger. |
Research Summary
We focus on the ecological and behavioral aspects of the interactions between the native western gray squirrel and the introduced eastern fox squirrel. Current projects involve the use of field studies along with Geographic Information System (GIS) software to develop Habitat Suitability Models for the two species.
| Representative Publications |
| King, J.L., Sue, M.C., and Muchlinski, A.E. 2010. Distribution of the eastern fox squirrel (Sciurus niger) in southern California. The Southwestern Naturalist 55:42-49. |
| Muchlinski, A.E., Stewart, G.R., King, J.L., and Lewis, S.A. 2009. Documentation of replacement of native western gray squirrels by introduced eastern fox squirrels. Bulletin Southern California Academy of Sciences 108:160-162. |
| Muchlinski, A.E., Baldwin, B.C., and Gramajo, R. 2000. Endotoxin elicits a febrile response in laboratory-maintained but not free-living California ground squirrels. Journal of Mammalogy, 81: 701-708. |
| Lee, B.Y., Padick, D.A., and Muchlinski, A.E. 2000. Season influences the magnitude of stress fever in the California ground squirrel. Comparative Biochemistry and Physiology - Part A 125: 325-330. |
| Muchlinski, A.E., Gramajo, R., and Garcia, C. 1999. Pre-existing bacterial infections, not stress fever, influenced previous studies which labeled Gerrhosaurus major an afebrile lizard species. Comparative Biochemistry and Physiology - Part A 124: 353-357. |
[top]
Benthic Marine Ecology
 |
Contact: Carlos Robles, Ph.D. Office: ASCB 323E, ext: 3-2067 Laboratory: ASCB 346, ext: 3-5661 E-mail: crobles@calstatela.edu Web: http://cea-crest.calstatela.edu/crobleswebsite2.htm | |
| Sea star, Pisaster ochraceus, attacking a marine mussel, Mytilus californianus. Size-dependent predator-prey interactions between these organisms lead to intertidal zonation. |
Research Summary
Our current work emphasizes experimental investigations of the mechanisms of intertidal zonation. We proposed that the lower boundary of a mussel bed falls at a shore level corresponding to an abrupt shift in equilibria—from an equilibrium maintaining a sparse population of small individuals below to a second maintaining a dense population of larger individuals above. The equilibria are a dynamic balance between rates of size-dependant predation and prey production (recruitment and growth). The shift from one equilibrium to another is forced by spatial variation in tidal submergence and wave energy, and as a result prey population structure (boundaries and size structure) varies greatly over large spatial scales in the intertidal landscape. This adjusted equilibrium hypothesis was expressed in a computer simulation model which allows us to consider other spatially structured mechanisms. The model stands as an alternative to the widely-held refuge theory, which maintains that dense zones of invertebrate prey form only on shore levels above the effective foraging range of the predators. Our on-going projects are field studies that address either the testing or further development of spatially explicit population models.
| Representative Publications |
| Robles, C.D., Desharnais, R.A., Garza, C., Donahue, M.J., and Martinez, C.A. 2009. Complex equilibria in the maintenance of boundaries: experiments with mussel beds. Ecology 90: 985-995. |
| Robles, C.D. 2007. Lobsters. In: Encyclopedia of Tide Pools and Rocky Shores. M.W. Denny and S.D. Gaines (eds), University of California Press, Berkeley. Pages 333-335. |
| Blakeway, D., Robles, C.D., Fuentes, D., and Qiu, H.L. 2004. Spatially extensive, high-resolution images of rocky shore communities. In Handbook of Scaling in Aquatic Ecology: Measurement, Analysis and Simulation, P. Strutton and L. Seuront (eds), CRC Press. Pages 109-124. |
| Donalson, D., Desharnais, R.A., Robles, C.D., and Nisbet, R. 2004. Spatial dynamics of a benthic community: applying multiple models to a single system. In Handbook of Scaling in Aquatic Ecology: Measurement, Analysis and Simulation, P. Strutton and L. Seuront (eds), CRC Press. Pages 429-444. |
| Robles, C. D. and R. A. Desharnais. 2002. History and current development of a paradigm of predation in rocky intertidal communities. Ecology 82: 1521-1536. |
[top]
Taxonomy & Evolution of Marine Ostracodes
 |
Contact: Elizabeth Torres, Ph.D. Office: ASCL 313, ext: 3-2179 Laboratory: ASCL 311, ext: 3-5856 E-mail: etorre11@calstatela.edu Web: http://www.calstatela.edu/faculty/etorre11/etorre11.htm | |
| Vargula tsujii is a cypridinid ostracod crustacean that lives off of the Pacific Coast of North America. It secretes a bright blue luminescence produced in the light organ (yellow vertical bar just below the compound eye). |
Research Summary
We use molecular methods and classic taxonomic approaches to understand phylogeny, diversity, and speciation in Caribbean cypridinid ostracode crustaceans. We are especially interested in the evolution of bioluminescence in cypridinids. Our genetic data have revealed several new species in the Caribbean, which we are in the process of describing. Students in our lab have also worked on other taxa, such as butterflies, Channel Island foxes, fox squirrels, marine snails, and bioluminescent fish.
| Representative Publications |
| Torres, E., and Morin, J.G. 2007. Vargula annecohenae, a new species of bioluminescent ostracode (Myodocopida: Cypridinidae) from Belize. Journal of Crustacean Biology 27: 649-659. |
| Torres, E., and Gonzalez, V.L. 2007. Molecular phylogeny of cypridinid ostracodes and the evolution of bioluminescence. In Proceedings of the 14th International Symposium on Bioluminescence and Chemiluminescence: Chemistry, Biology, and Applications. A.A. Szalay, P.J. Hill, L.J. Kricka, and P.E. Stanley (eds). New Jersey: World Scientific Publishing Company, pgs. 269-272. |
| Torres, E., and Cohen. A.C. 2005. Vargula morini, a new species of bioluminescent ostracode (Myodocopida: Cypridinidae) from Belize and an associated copepod (Copepoda:Siphonostomatoida:Nicothoidae). Journal of Crustacean Biology 2: 11-24. |
| Torres, E., Lees, D.C., Vane-Wright, R.I., Kremen, C., Leonard, J.A., and Wayne, R.K. 2001. Testing monophyly in a large radiation of Madagascan butterflies (Lepidoptera: Satyrinae: Mycalesidina) based on mitochondrial DNA data. Molecular Phylogenetics and Evolution 20: 460-473. |
[top]
Note: ADM = Administration Building, ASCL = Wallis Annenberg Integrated Science Complex-Wing A (La Kretz Hall), ASCB = Wallis Annenberg Integrated Science Complex-Wing B. When calling from off-campus, the area code and prefix for all telephone extensions is (323) 34X-XXXX.