Freeze Tolerance as an Overwintering Adaptation in Cope's Grey Treefrog (Hyla chrysoscelis) Jon P. Costanzo; Michael F. Wright; Richard E. Lee, Jr. Copeia, Vol. 1992, No. 2. (May 1, 1992), pp. 565-569. Stable URL: http://links.jstor.org/sici?sici=0045-8511%2819920501%293%3A1992%3A2%3C565%3AFTAAOA%3E2.0.CO%3B2-B Copeia is currently published by American Society of Ichthyologists and Herpetologists. Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available at http://www.jstor.org/about/terms.html. JSTOR's Terms and Conditions of Use provides, in part, that unless you have obtained prior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content in the JSTOR archive only for your personal, non-commercial use. Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained at http://www.jstor.org/journals/asih.html. Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printed page of such transmission. The JSTOR Archive is a trusted digital repository providing for long-term preservation and access to leading academic journals and scholarly literature from around the world. The Archive is supported by libraries, scholarly societies, publishers, and foundations. It is an initiative of JSTOR, a not-for-profit organization with a mission to help the scholarly community take advantage of advances in technology. For more information regarding JSTOR, please contact [email protected]. http://www.jstor.org Tue Jan 8 16:23:10 2008 SHORTER CONTRIBUTIONS: HERPETOLOGY chromosome homology, such as banding, is essays in honor of M. J. D. White. W. R. Atchley needed to further illuminate chromosome evo- and D. S. Woodruff (eds.). Cambridge Univ. Press, lution within the Xantusiidae. London, England. MACGREGOR,H. C., AND J. VARLEY.1988. Working with animal chromosomes. John Wiley and Sons, Acknowledgments.-This study would not have New York, New York. been possible without the help of the Museo OLMO,E. 1986. A. Reptilia, p. 1-100. In: Animal Nacional de Historia Natural de Cuba and the cytogenetics. Volume 4: Chordata 3. B. John (ed.). Universidad de La Habana, coorganizers (with Gebriider Borntraeger, Berlin, Germany. Pennsylvania State University) of the expedi- , AND G. ODIERNA.1980. Chromosomal evo- tion that obtained Cricosaura tjpica. Special lution and DNA of cordylid lizards. Herpetologica thanks to G. Silva and members of the expe- 36:311-316. dition. We thank A. Wynn for suggestions in PRESCH,W. 1988. Phylogenetic relationships of the karyotype preparation, G. Zug for cataloging Scincomorpha, p. 471-492. In: Phylogenetic rela- tionships of the lizard families. R. Estes and G. K. of specimens, L. R. Maxson for providing re- Pregill (eds.). Stanford Univ. Press, Stanford, Cal- search facilities, and S. W. Schaeffer for use of ifornia. equipment. Supported by a grant from the Na- SCHWENK,K. 1988. Comparative morphology of the tional Science Foundation (BSR-8906325 to lepidosaur tongue and its relevance to squamate SBH). phylogeny, p. 569-598. In: Phylogenetic relation- ships of the lizard families. R. Estesand G. K. Pregill (eds.). Stanford Univ. Press, Stanford, California. BEZY,R. L. 1972. Karyotypic variation and evolution CARLAANN HASSAND S. BLAIRHEDGES, De- of the lizards in the family Xantusiidae. Contr. Sci. partment of Biology, 208 Mueller Lab, Pennsyl- Nat. Hist. Mus. Los Angeles County 227: 1-29. vania State University, University Park, Pennsyl- -. 1984. Systematics of xantusiid lizards of the vania 16802. Accepted 1 April 1991. genusLepidophyma in northeastern Mexico. Ibid. 349: 1-16. BICKHAM,J. W. 1984. Patterns and modes of chro- mosomal evolution in reptiles, p. 13-40. In: Chro- mosomes in evolution of eukaryotic groups. Vol- ume 11. A. K. Sharma and A. Sharma (eds.). CRC Press, Boca Raton, Florida. CAPRIGLIONE,T. 1987. New data on karyotypes of some Scincidae. Caryologia 40: 109-1 14. Copria, 1992(2), pp. 565-569 O 1992 by the American Soclety of CROTHER,B. I.,M. M. MIYAMOTO, AND W. F. PRESCH. Ichthyologists and Herpetologists 1986. Phylogeny and biogeography of the lizard family Xantusiidae. Syst. Zool. 35:37-45. FREEZE TOLERANCE AS AN OVERWIN- DEWEESE,J. E., AND J. W. WRIGHT.1970. A prelim- TERING ADAPTATION IN COPE'S GREY inary karyological analysis of scincid lizards. Mam- TREEFROG (HYLA CHRYSOSCELZS).-Many malian Chromos. Newsl. 11:95-96. temperate zone ectotherms are confronted with ESTES,R., K. DE QUERIOZ,AND J. GAUTHIER.1988. severe environmental challenges during winter. Phylogenetic relationships within Squamata, p. 1 19- Aquatic forms usually are protected from freez- 281. In: Phylogenetic relationships of the lizard families. R. Estes and G. K. Pregill (eds.). Stanford ing temperatures owing to the high thermal Univ. Press, Stanford, California. buffering capacity of water. Terrestrial verte- GORMAN,G. C. 1970. Chromosomes and the system- brate ectotherms ugenerallv avoid extreme win- atics of the family Teiidae (Sauria, Reptilia). Copeia ter temperatures by hibernating within insulat- 1970:230-245. ed refugesu below the frostline: however, some -. 1973. The chromosomes of the Reptilia, a may be exposed to potentially lethal environ- t to taxonomic interpretation, p. 349-424. In: Cy- mental temperatures. Those overwintering totaxonomy and vertebrate evolution. A. B. Chi- above the frostline must survive either by ex- arelli and E. Capanna (eds.). Academic Press, Lon- tensive supercooling or by tolerating the for- don, England. mation of ice within body tissues. HEDGES,S. B., R. L. BEZY,AND L. R. MAXSON.1991. Phylogenetic relationships and biogeography of Deep and prolonged supercooling is a major xantusiid lizards inferred from mitochondria1 DNA overwintering adaptation of many terrestrial in- sequences. Mol. Biol. Evol. 8:767-780. vertebrates (Lee, 1989). However, the biophys- KING,M. 198 1. Chromosome change and speciation ical constraints of large body mass (i.e., water in lizards, p. 262-285. In: Evolution and speciation: volume) preclude this strategy for most verte- COPEIA, 1992, NO. 2 brate ectotherms (Costanzo et al., 1988; Cos- crickets and flesh fly larvae ad libitum. On 15 tanzo and Claussen, 1990). Manv, .~olar fishes Oct., the frogs were habituated to 15 C, 12:12 avoid freezing by supercooling, but these pro- (L:D) for 2 wk during which time food was with- duce specific antifreeze proteins that inhibit the held. Subsequently, the frogs were exposed to growth of ice crystals (DeVries, 1983). hibernative conditions [4 C, 0:24 (L:D)] until At least several species of amphibians and they were tested for freeze tolerance (3-8 Jan. reptiles survive the repeated freezing and thaw- 1990). ing of extracellular fluids. Natural freeze tol- Eight frogs, held individually within plastic erance has been conclusively demonstrated in (50 ml) centrifuge tubes, were cooled inside an four species of frogs: Rana syluatica (Lotshaw, insulatedjar submerged in a cold (-6.5 C) bath. 1977),Hjla crucifer, H. uersicolor (Schmid, 1982), The airspace in each tube was insulated with Pseudacris triseriata (Storey and Storey, 1986); plastic foam to reduce the rate of ice formation. two species of turtles: Chrysemys picta (Storey et A 30-gauge thermocouple positioned against al., 1988), Terrapene carolina (Costanzo and the abdomen provided a continuous recording Claussen, 1990);and one snake: Thamnophis sir- of body temperature on a data logger (OM 50 1- talis (Costanzo et al., 1988). Laboratory exper- C, Omega Electronics). iments involving freezing in other species, in- Ice formation in supercooled frogs was in- cluding toads (Storey and Storey, 1986), aquatic duced by briefly applying aerosol coolant to the frogs (Weigmann, 1929; Lotshaw, 1977; exterior of each tube. The onset of ice forma- Schmid, 1982), plethodontid and ambystomid tion was clearly indicated by the release of the salamanders (Storey and Storey, 1986; our un- latent heat of fusion. Freezing proceeded until publ. data), and lizards (Weigmann, 1929; Spel- the following criteria were met: (1) a minimum lerberg, 1972; Claussen et al., 1990), have re- of 24 hr had elapsed, and (2) body temperature sulted in death, irreparable injury, or had declined to -2.5 C or below. The frogs ecologically negligible survival rates. were then transferred to a cold room (4 C) and We hypothesized that Cope's gray treefrog allowed to thaw. Following a 3 d habituation (H. chr~soscelis)is tolerant of body freezing be- period they were transferred to 22 C and tested cause this species is similar to H. versicolor, a for recovery criteria. We judged that the frogs known freeze-tolerant form, in morphological, had recovered fully if they fed (caught and in- genetic, and ecophysiological characteristics gested live crickets), maintained normal body (Ralin, 1977). The two species differ primarily postures, and locomoted spontaneously. in chromosome compliment (H. chr~soscelisis The blood of nine additional frogs (collected diploid, whereas H. versicolor is tetraploid) and in Butler County, Ohio, during June 1990 and in the pulse frequency of mating calls (Ralin, exposed to hibernative conditions for 30 d) was 1977. 198 1). The H. chrvsoscelis-versicolor com- analyzed to determine whether glucose or glyc- plex is distributed widely over eastern North erol, cryoprotectants utilized by freeze-tolerant America and ranges from the Gulf Coast of the frogs (Storey, 1990),are mobilized by H. chrysos- United States to Manitoba and Nova Scotia, celis. Blood was obtained from six rapidly thawed Canada (Conant, 1975). Geographically these frogs previously frozen to -2.9 C (f0.1 C, SEM) species may be widely separated although they for 53.5 h and from three unfrozen (control) are sympatric over some parts of their ranges frogs; it was collected directly from the ventricle (Ralin, 1977). We investigated freeze tolerance and centrifuged to separate the plasma.