Kurt Schwenk
Professor of Ecology and Evolutionary Biology (Ph.D., University of California, Berkeley)
Contents
Contact Information
Office: Pharmacy/Biology Building 600
Lab: BioPharm 410, 412
Office phone: (860) 486-0351
Lab phone: 860-486-4158
Fax: (860) 486-6364
Email: kurt.schwenk@uconn.edu
Mailing address:
Department of Ecology and Evolutionary Biology
University of Connecticut
75 N. Eagleville Road
Storrs, CT 06269-3043
Educational and Professional History
- B.A. (high honors) Oberlin College, studied with Warren F. Walker, Jr., and Jim Stewart (1977)
- Zookeeper (intern): Bronx Zoo (Herpetology) (1976)
- Zookeeper: Bronx Zoo (Mammalogy) (1977-1978)
- Ph.D. Dept. of Zoology (now within Integrative Biology), University of California, Berkeley, with Marvalee H. Wake (1984)
- Postdoctoral Research Associate, Instructor in Anatomy: Dept. of Oral Anatomy (now within Oral Biology), University of Illinois at Chicago College of Dentistry with Karen Hiiemae (deceased 2007) (1984-1987)
- NIH Postdoctoral Fellow, Lecturer on Biology: Museum of Comparative Zoology, Dept. or Organismic Biology, Harvard University with Fuzz Crompton (1987-1989)
- Assistant, Associate and Full Professor: Dept. of Ecology & Evolutionary Biology, University of Connecticut (1989-present)
- Curator of Mammalogy, EEB Biological Collections, University of Connecticut (1989-present)
- Chair, Division of Vertebrate Morphology (DVM), Society for Integrative and Comparative Biology (SICB) (2007-2009)
- Associate Editor, Evolution (2004-2006)
- Associate Editor, Journal of Comparative Zoology Part A: Ecological Genetics and Physiology (2006-present) (contact me if you have questions about submitting a manuscript; contributions on biomechanics and functional morphology welcome)
Related Links and Downloads
- My CV
- Schwenk Lab Page (under construction)
- My Classic Works in Evolutionary Biology pages: Introduction and Annotated List
- My Guide to Scientific Paper Citation Formatfor undergraduates
- PhD student Tobias Landberg's page
- PhD student Bill Ryerson's page
- Former PhD student Dr. Nirvana Filoramo's page
- Former PhD student Dr. Chuck Smith's page
- Collaborator, Gunter Wagner's page
- My brother John Schwenk's page (follow link to view some of my father's [George Schwenk] paintings)
Course Links
BIO 1102 Foundations of Biology
- -spring 2010
EEB 3273 Comparative Vertebrate Anatomy
- -next offered fall 2010
EEB 3254/5254 Mammalogy
- -NOTE: not offered until 2011 owing to sabbatical leave in 2009
Major Research Interests
- Phenotypic evolution
- Evolutionary constraint
- Evolutionary and functional morphology of vertebrates
- Evolutionary and functional morphology of feeding in tetrapod vertebrates, especially lizards
- Evolutionary and functional morphology of chemoreception in lizards and snakes
- Evolutionary and functional morphology of the vertebrate tongue
My research program is three-pronged: I pursue empirical studies related to the functional and evolutionary morphology of squamate feeding and chemoreception, and theoretical work related to phenotypic evolution and evolutionary constraint. Feeding and chemoreception are functionally and evolutionarily related in squamates owing to their shared use of a single, complex organ, the tongue. From a biomechanical point of view, optimization of the tongue for feeding function makes it less effective in (vomeronasal) chemoreception and vice versa. Thus, there is a classic functional (and evolutionary) trade-off between the two principal functions of the tongue. Phylogenetic character analysis reveals how each major clade of squamates has found a unique 'solution' to the problem of this trade-off. The dynamic nature of the evolutionary tension created by competing sources of selection pressure has led to my theoretical work on internal selection, functional integration, phenotypic stability and evolutionary constraint. Much of this work has been done in collaboration with Günter Wagner at Yale University. Although theoretical, the work is firmly grounded in my empirical work on squamate feeding and chemosensory systems, which have proven to be compelling model systems for approaching these broader issues.
Information for Prospective Graduate Students
Students in my laboratory develop their own, independent research programs under my supervision. Although I expect there to be some overlap or mutual interest in student projects, I do not require students to work in my specific research areas. Ideally students will incorporate elements of morphology, evolution and/or function into their projects. Purely ecological or conservation-related projects are discouraged (because they lie outside my areas of expertise), although these can be elements of a research program centered on the former topics. Although I am best able to supervise work on squamate reptiles, I am open to projects dealing with any vertebrate group. I principally do laboratory-based work, but recent graduate students have included significant field components in their research. Applications from potential doctoral students are preferred, but doing a Masters is also possible.
The Department of Ecology and Evolutionary Biology at UConn is very integrative and interactive, and there is a great deal of cross-fertilization among labs. The department comprises 30 full-time faculty, all of whom work in the general area of organismal biology. There are an additional 60+ biologists in our sister departments of Physiology and Neurobiology, and Molecular and Cell Biology - and this is not to mention a variety of wildlife biologists in the School of Agriculture, biomedical researchers in the School of Medicine, etc. Thus, there is virtually no area of expertise unavailable to students when they assemble their research advisory committees.
There are eight vertebrate biology faculty in the department (4 herpetology, 2 ornithology, 1 ichthyology, 1 mammalogy), and along with postdocs, graduate and undergraduate students, they constitute a very active and interactive research group. We have informal weekly meetings called 'vertlunch' in which we read and critique recent papers (and laugh a lot) and every Friday at 4:00 the Schwenk and Rubega labs (and others) meet for 'beermorph' in which - well, it's pretty self-explanatory. For those morphologists with a developmental bent, we also have weekly meetings of an 'evo-devo club' in which we read and discuss current literature. And this is not to mention, of course, the frequent graduate seminars on various topics offered by faculty in the department, as well as weekly departmental seminars and occasional 'Monday evening seminars' run by the EEB graduate students. All-in-all, a very active place where you can be intellectually challenged and exposed to a variety of viewpoints - often while drinking at the same time!
Before applying directly to the department for admission into the graduate program, you should contact me by email and describe your research interests and goals so that we can determine if there is an appropriate match. You should also explore the departmental web page to get as much information about EEB as you can. If you have any questions at all about the department or the University, don't hesitate to email me. I can also put you in touch with current graduate students if you would like to hear about the program from their perspectives.
Students accepted into the doctoral program are guaranteed 5 years of support (mostly by means of Teaching Assistantships). Support beyond 5 years is usually possible for students making good progress, but is not guaranteed. Masters students are guaranteed 2 years of support. The support package includes a tuition waiver and full health benefits.
NSF/SICB Initiative: Grand Challenges in Organismal Biology
At the January, 2009, annual meeting of the Society for Integrative and Comparative Biology (SICB) in Boston, William Zamer of the National Science Foundation challenged the Society to determine what the 'grand challenge questions' are for future work in organismal biology. As the largest comparative, organismal professional society in the country (and probably the world), SICB was called upon to organize organismal biologists to help shape future funding in the field by identifying integrative and forward-looking research arenas that would not only contribute to basic knowledge in organismal biology, but would also tie-in with interest-areas targeted by the Obama administration. SICB President Rich Satterlie called a series of meetings and discussions among the SICB Executive Committee, and on the basis of these discussions, a four-person subcommittee was appointed, with me as Chair, to produce a brief, initial document to be distributed among NSF staff immediately (as required by NSF's budget meeting schedule). This draft document has been expanded into a full-length manuscript that appeared in the first 2009 issue of the Sociey's journal, Integrative and Comparative Biology. Each subsequent issue of the journal will feature one or two additional 'perspective' pieces written by other organismal biologists aimed at targeting more specific topics. The aim of the documents posted here, as well as the forthcoming perspective essays, is to stimulate broader discussion in the field about future research initiatives, and novel, collaborative and synthetic research directions. SICB (and NSF) hopes that additional discussion will further develop and refine the 'grand challenges' in organismal biology. In the near future, face-to-face meetings are planned to broaden and extend the initiative, and these meetings, it is hoped, will lead to concrete advances and funding opportunities for organismal biology, an area that has been chronically underfunded for many years.
The 'grand challenges' initiative is presently in full swing. Additional essays on organismal biology are appearing regularly in ICB and a workshop was held at the 2010 annual SICB meeting in Seattle directed at devising ways to broaden participation in the program and to develop ideas and methods for implementation. In addition, I have been invited by the editor of BioScience to submit a short essay espousing my own ideas and opinions about implementing the 'grand challenges' program. This essay will be available for download here when available sometime early in 2010.
- You can download the preliminary 'grand challenges' NSF document HERE
- You can download a reprint of the published 'grand challenges' paper by Schwenk et al. (from Integrative and Comparative Biology) HERE
- You can download a reprint of the BioScience essay by Schwenk on strategies for implementing the 'grand challenges' program HERE (not yet available).
- You can link to the SICB website for further information and to post comments on a message board if you are a SICB member.
- For other questions/comments, please contact me directly: kurt.schwenk@uconn.edu
Lab Publications
Email for reprints not available here as pdfs: kurt.schwenk@uconn.edu
BOOKS:
Schwenk, K. (editor) (2000) Feeding: Form, Function and Evolution in Tetrapod Vertebrates. Academic Press, San Diego. xv + 537 pp.
Schwenk, K. and G. P. Wagner. Evolutionary Constraint (under consideration by Princeton Univ. Press). (in preparation)
EDITED COMPILATION:
Schwenk, K., and J. M. Starck (eds.) (2005) Integrative organismal biology: papers in honor of Professor Marvalee H. Wake. Zoology 108(4):261-356. LINK
PAPERS, BOOK CHAPTERS AND REVIEWS: (names in bold are current or former students)
Filoramo, N., and K. Schwenk. Tongue tips, tropotaxis and the mechanism of chemical delivery to the vomeronasal organs in fork-tongued squamates (Reptilia) (in preparation)
Schwenk, K., and N. Filoramo. The biomechanics of vomeronasal chemoreception in squamate reptiles (in preparation)
Schwenk, K. (2010) 'Grand challenges'—implementing the organismal agenda . BioScience (invited perspective/essay in preparation)
Schwenk, K., and G. P. Wagner (2010) EDITORIAL: Visualizing vertebrates: new methods in functional morpology. J. Exp. Zool. 313A.
Flores-Villela, O., C. A. Ríos-Muñoz, K. Schwenk, G. Zamudio-Varela and G. Magaña-Cota (2010) An unpublished manuscript of Alfredo Dugès related to the classification of lizards according to tongue morphology, circa 1898-1899. Archives of Natural History (in press, October)
Smith C. F., G. W. Schuett and K. Schwenk (2009) Plasma sex sterioids and mating season in wild-living copperheads (Agkistrodon contortrix) at the northeastern extreme of their range. Journal of Zoology (in press) PROOFS
Smith C. F., G. W. Schuett, R. L. Earley, and K. Schwenk. (2009) The spatial and reproductive ecology of copperheads, Agkistrodon contortrix (Serpentes: Viperidae), at the northeastern extreme of their range. Herpetological Monographs (in press)
Schwenk, K.*, D. Padilla*, G. Bakken* and R. Full* (2009) Grand challenges in organismal biology. Integrative and Comparative Biology 49:7-14. (*authorship equally shared)
Landberg T., J. D. Mailhot and E. L. Brainerd (2009). Lung ventilation during treadmill locomotion in a semi-aquatic turtle, Trachemys scripta. J. Exp. Zool. 311A. In press. PROOFS
Filoramo, N., and K. Schwenk (2009) The mechanism of chemical delivery to the vomeronasal organs in squamate reptiles: a comparative morphological approach. J. Exp. Zool. 311A:20-34.
Schwenk, K. (2008) Aristotle’s ghost. Wild River Review. October 2008 LINK. [Online reprint of Schwenk (2002)], Wild River Review home page
Sherbrooke, W. C.,* and K. Schwenk.* (2008) Horned lizards (Phrynosoma) incapacitate dangerous ant prey with mucus. J. Exp. Zool. 309A:447-459. (*authorship equally shared) (JEZA featured paper)
- SOME PRESS ON SHERBROOKE & SCHWENK (2008):
- Journal of Experimental Biology, 'Lizards incapacitate ants with mucus', by Stefan Pulver (see last page of pdf)
- ScienceNOW, 'How to eat a nasty ant', by Greg Miller LINK or pdf
- Natural History (12/08-1/09), 'How to Harvest a Harvester', by Graciela Flores
- Natural History (online version) LINK
- The Daily Planet, television segment, Discovery Channel (Canada). First broadcast 25 March 2009, approx. 6 min. (working on getting a clip posted)
Smith, C. F., K. Schwenk, R. L. Earley and G. W. Schuett (2008) Sexual size dimorphism of the tongue in a North American pitviper. Journal of Zoology 274:367-374.
Schwenk, K. (2008) Comparative anatomy and physiology of chemical senses in non-avian aquatic reptiles. In: Sensory Evolution on the Threshold. Adaptations in Secondarily Aquatic Vertebrates. J. G. M. Thewissen and S. Nummela (eds.). Univ. of California Press, Berkeley. Pp. 65-81.
Schwenk, K., and J. G. M. Thewissen (2008) Aquatic and semi-aquatic reptiles. In: Sensory Evolution on the Threshold. Adaptations in Secondarily Aquatic Vertebrates. J. G. M. Thewissen and S. Nummela (eds.). Univ. of California Press, Berkeley. Pp. 7-23.
Eisthen, H., and Schwenk, K. (2008) The chemical stimulus and its detection. In: Sensory Evolution on the Threshold. Adaptations in Secondarily Aquatic Vertebrates. J. G. M. Thewissen and S. Nummela (eds.). Univ. of California Press, Berkeley. Pp. 35-41.
Azizi, E., T. Landberg and R. J. Wassersug (2007) Vertebral function during tadpole locomotion. Zoology 110:290-297.
Schwenk, K. (2006) Evolution illustrated (Letter to the Editor). The Hartford Courant, 4 March:A9.
Schwenk, K.,and M. Rubega (2005) Diversity of vertebrate feeding systems. Pp. 1-41. In: Physiological and Ecological Adaptations to Feeding in Vertebrates. J. M. Starck and T. Wang (eds.). Science Publishers, Enfield, NH.
Schulp, A. S., E. W. A. Mulder and K. Schwenk (2005) Did mosasaurs have forked tongues? Neth. J. Geosci. 84:359-371.
Schwenk, K. , W. Korff and J. M. Starck (2005) Preface. Integrative organismal biology: papers in honor of Professor Marvalee H. Wake. Zoology 108:261-267.
Schwenk, K., and G. P. Wagner (2004) The relativism of constraints on phenotypic evolution. Pp. 390-408. In: Phenotypic Integration: Studying the Ecology and Evolution of Complex Phenotypes. M. Pigliucci & K. Preston (eds.). Oxford Univ. Press, Oxford.
Schwenk, K. (2004) REVIEWS OF: Introduction to Horned Lizards of North America, by Wade C. Sherbrooke, and Horned Lizards: The Book of Horny Toads, by Jane Manaster. Copeia 2004:190-192.
Schwenk, K. (2004) Leapin’ non-ophidian squamates! REVIEW OF: Lizards. Windows to the Evolution of Diversity, by E. R. Pianka and L. J. Vitt. Trends in Ecology and Evolution 19:357-358.
Landberg, T., J. Mailhot and E.L. Brainerd (2003) Lung ventilation during treadmill locomotion in a terrestrial turtle, Terrapene carolina. Journal of Experimental Biology 206:3391-3404.
Vitt, L. J., E. R. Pianka, W. E. Cooper and K. Schwenk (2003) History and the global ecology of squamate reptiles. American Naturalist 162:44-60.
Schwenk, K., and G. P. Wagner. (2003) Constraint. Pp. 52-61. In: Key Words and Concepts in Evolutionary Developmental Biology. B. K. Hall & W. M. Olson (eds.). Harvard University Press, Cambridge. URL or
Schwenk, K. (2002) Constraint. Pp. 196-199. In: Encyclopedia of Evolution, M. Pagel (ed.). Oxford Univ. Press, Oxford.
Azizi, E., and T. Landberg (2002) Effects of metamorphosis on the aquatic escape response of the two-lined salamander (Eurycea bislineata). Journal of Experimental Biology 205:841-849.
Schwenk, K. (2002) Aristotle’s ghost. Creative Nonfiction No.19:32-40 (Special Issue: “Diversity Dialogues”).
Schwenk, K. (2001) Extrinsic vs. intrinsic lingual muscles: a false dichotomy? Bull. Mus. Comp. Zool. (Harvard) 156:219-235.
Schwenk, K., and G. P. Wagner (2001) Function and the evolution of phenotypic stability: connecting pattern to process. American Zoologist 41:552-563.
Schwenk, K. (2001) Functional units and their evolution. Pp. 165-198. In: The Character Concept in Evolutionary Biology. G. P. Wagner (ed.). Academic Press, San Diego.
Nishikawa, K. C., and K. Schwenk (2001) Ingestion in amphibians and reptiles. In: Encyclopedia of Life Sciences. John Wiley & Sons, Ltd: Chichester [1] [doi:10.1038/npg.els.0001835] (pdf = 7 pp)
Schwenk, K. (2000) The apian way: from beehives to burrows, animal building sheds new light on biology. REVIEW OF: The Extended Organism. The Physiology of Animal-Built Structures, by J. Scott Turner. The New York Times Book Review, 10 Dec., p. 37. or URL
Schwenk, K. (2000) Preface. Pp. xiii-xv. In: Feeding: Form, Function and Evolution in Tetrapod Vertebrates. K. Schwenk (ed.). Academic Press, San Diego.
Schwenk, K. (2000) Tetrapod feeding in the context of vertebrate morphology. Pp. 3-20. In: Feeding: Form, Function and Evolution in Tetrapod Vertebrates. K. Schwenk (ed.). Academic Press, San Diego.
Schwenk, K. (2000) An introduction to tetrapod feeding. Pp. 21-61. In: Feeding: Form, Function and Evolution in Tetrapod Vertebrates. K. Schwenk (ed.). Academic Press, San Diego.
Schwenk, K. (2000) Feeding in lepidosaurs. Pp. 175-291. In: Feeding: Form, Function and Evolution in Tetrapod Vertebrates. K. Schwenk (ed.). Academic Press, San Diego.
Schwenk, K. (2000) A bibliography of turtle feeding. Pp. 169-171. In: Feeding: Form, Function and Evolution in Tetrapod Vertebrates. K. Schwenk (ed.). Academic Press, San Diego.
Wagner, G. P.,* and K. Schwenk* (2000) Evolutionarily Stable Configurations: functional integration and the evolution of phenotypic stability. Pp. 155-217. In: Evolutionary Biology, vol. 31. M. K. Hecht, R. J. MacIntyre & M. T. Clegg (eds.). Kluwer Academic/Plenum Press, New York. (*authorship equally shared)
Pigliucci, M., C. D. Schlichting, C. S. Jones and K. Schwenk (1996) Developmental reaction norms: the interactions among allometry, ontogeny and plasticity. Plant Species Biology 11:69-85.
Schwenk, K. (1998) REVIEW OF: Lizards, Vols. 1 & 2. By M. Rogner. Copeia 1998:1114-1116.
Schwenk, K. (1998) REVIEW OF: Comparative Osteological Examinations of Geckonids, Eublepharids and Uroplatids, by V. Wellborn (translated by A. P. Russell, A. M. Bauer & A. Deufel). Herpetological Translations No. 1. Breck Bartholomew, Bibliomania, Logan, Utah. Copeia 1998:259-260.
Schwenk, K. (1997) Snakes and the evolution of Harry Greene. REVIEW OF: Snakes. The Evolution of Mystery in Nature, by H. W. Greene. Natural History 106:8-9 (July/August).
Dial, B. E., and K. Schwenk (1996) Olfaction and predator detection in Coleonyx brevis (Squamata: Eublepharidae) with comments on the functional significance of buccal pulsing in geckos. J. Exp. Zool. 276:415-424.
Schwenk, K. (1996) REVIEW OF: Vertebrate Life, 4th ed., by F. H. Pough et al., Quart. Rev. Biol. 71:581-582.
Schwenk, K. (1995) REVIEW OF: The Lizard Man Speaks, by E. R. Pianka. Quart. Rev. Biol. 70:328-329.
Schwenk, K. (1995) Of tongues and noses: chemoreception in lizards and snakes. Trends in Ecology & Evolution 10:7-12.
Schwenk, K. (1995) A utilitarian approach to evolutionary constraint. Zoology 98:251-262.
Schwenk, K., and H. W. Greene (1995) No electrostatic sense in snakes. Nature 373:26.
Schwenk, K. (1995) The serpent's tongue. Natural History 104:48-55 (April).
Les, D. H., and K. Schwek (1995) Para-f***in-phyletic: a compromise category for classification. WARNING: SATIRIICAL REPRINT - PARENTAL DISCRETION ADVISED
Schwenk, K. (1994) Why snakes have forked tongues. Science 263:1573-1577.
Schwenk, K. (1994) Craniology: getting a head. REVIEW OF: The Skull, 3 vols. J. Hanken & B. K. Hall (eds.). Science 263:1779-1780.
Schwenk, K. (1994) Comparative biology and the importance of cladistic classification: a case study from the sensory biology of squamate reptiles. Biological J. Linnean Soc. 52:69-82.
Schwenk, K. (1994) Systematics and subjectivity: the phylogeny and classification of iguanian lizards reconsidered. Herpetological Review 25:53-57.
Schwenk, K., and D. B. Wake (1993) Prey processing in Leurognathus marmoratus and the evolution of form and function in desmognathine salamanders (Plethodontidae). Biol. J. Linn. Soc. 49:141-162.
Schwenk, K. (1993) Are geckos olfactory specialists? J. Zool., Lond. 229:289-302.
Schwenk, K. (1993) The evolution of chemoreception in squamate reptiles: a phylogenetic approach. Brain, Behavior and Evolution 41:124-137.
Schwenk, K. and G. C. Mayer (1991) Tongue display in anoles and its evolutionary basis. 4th Anolis Newsletter. J. Losos & G. Mayer (eds.). National Museum of Natural History (Smithsonian), Division of Amphibians and Reptiles, Washington, DC.
Schwenk, K. (1989) REVIEW OF: The Evolution of Vertebrate Design, by L. B. Radinsky. American Scientist 77:84.
Schwenk, K. (1988) Comparative morphology of the lepidosaur tongue and its relevance to squamate phylogeny. In: R. Estes & G. Pregill (eds.). Phylogenetic Relationships of the Lizard Families. Stanford Univ. Press, Stanford, 569-598.
Schwenk, K. and G. S Throckmorton (1989) Functional and evolutionary morphology of lingual feeding in squamate reptiles: phylogenetics and kinematics. J. Zool., Lond. 219:153-175.
Schwenk, K. and D. A. Bell (1988) A cryptic intermediate in the evolution of chameleon tongue projection. Experientia 44:697-700.
Schwenk, K. and H. W. Greene (1987) Water collection and drinking in Phrynocephalus helioscopus: a possible condensation mechanism. J. Herpetology 21:134-139.
Schwenk, K. (1986) Morphology of the tongue in the tuatara, Sphenodon punctatus (Reptilia: Lepidosauria), with comments on function and phylogeny. J. Morphology 188:129-156.
Wake, M. H. and K. Schwenk (1986) A preliminary report on the morphology and distribution of taste buds in gymnophiones, with comparison to other amphibians. J. Herpetology 20:254-256.
Schwenk, K. (1985) Occurrence, distribution and functional significance of taste buds in lizards. Copeia 1985:91-101.
Good, D. A., and K. Schwenk (1985) A new species of Abronia (Lacertilia: Anguidae) from Oaxaca, Mexico. Copeia 1985:135-141.
Schwenk, K. (1984) Evolutionary Morphology of the Lepidosaur Tongue. Ph.D. dissertation, University of California, Berkeley.
Houck, L., and K. Schwenk (1984) The potential for long-term sperm competition in a plethodontid salamander. Herpetologica 40:410-415.
Jaksic, F. M., and K. Schwenk (1983) Natural history observations on Liolaemus magellanicus, the southernmost lizard in the world. Herpetologica 39:457-461.
Bemis, W., K. Schwenk and M. H. Wake (1983) Morphology and function of the feeding apparatus in Dermophis mexicanus (Amphibia: Gymnophiona). Zool. J. Linn. Soc. 77:75-96.
Jaksic, F. M., H. W. Greene, K. Schwenk and R. L. Seib (1982) Predation upon reptiles in Mediterranean habitats of Chile, California, and Spain: a comparative analysis. Oecologia 53:152-159.
Schwenk, K., S. K. Sessions and D. M. Peccinini-Seale (1982) Karyotypes of the basiliscine lizards Corytophanes cristatus and Corytophanes hernandesii, with comments on the relationship between chromosomal and morphological evolution in lizards. Herpetologica 38:493-501.