Geographic variation in the morphology of Crotalus horridus (Serpentes: Viperidae)

Herpetological Monographs

Volumn , Issue 20, 2006, Pages 1-63

  Allsteadt, John ^a,b   Savitzky, Alan H ^a   Petersen, Christopher E ^a,c   Naik, Dayanand N ^a  

^a OLD DOMINION UNIVERSITY   (United States)

^b Virginia Intermont College   (United States)

^c Naval Facilities Engineering Command   (United States)

Author keywords

Cluster analysis; Coloration; Crotalinae; Crotalus horridus; Discriminant function analysis; Geographic information system; Geographic variation; Morphological variation; Pattern; Principal component analysis; Scutellation; Serpentes; Taxonomic status; Viperidae

Indexed keywords

CROTALINAE; CROTALUS HORRIDUS; SERPENTES; VIPERIDAE;

EID: 33846203364     PISSN: 07331347     EISSN: None     Source Type: Book Series    
DOI: 10.1655/0733-1347(2007)20[1:gvitmo]2.0.co;2     Document Type: Article

References (123)

1. AHRENS, C. D. 1994. Meteorology Today: An Introduction to Weather, Climate, and the Environment, 5th edition. West Publishing Company, Saint Paul, Minnesota, U.S.A.
2. ALLSTEADT, J. 2003. Geographic variation in the morphology of Crotalus horridus (Serpentes: Viperidae). Ph.D. Dissertation, Old Dominion University, Norfolk, Virginia, U.S.A.
3. ANDERBERG, M. R. 1973. Cluster Analysis for Applications. Academic Press, New York, New York, U.S.A.
4. ASHTON, K. G. 2001a. Body size variation among mainland populations of the western rattlesnake (Crotalus viridis). Evolution 55:2523-2533.
5. -. 2001b. Are ecological and evolutionary rules being dismissed prematurely? Diversity and Distributions 7:289-295.
6. BARRY, R. C., AND R. J. CHORLEY. 1998. Atmosphere, Weather, and Climate, 7th edition. Routledge, New York, New York, U.S.A.
7. BLAIR, W. F. 1965. Amphibian speciation. Pp. 543-556. In H. E. Wright, Jr. and D. G. Frey (Eds.), The Quaternary of the United States: A Review Volume for the VII Congress of the International Association for Quaternary Research. Princeton University Press, Princeton, New Jersey, U.S.A.
8. BLANEY, R. M. 1971. Systematics of the common king-snake, Lampropeltis getulus. Ph.D. Dissertation, Louisiana State University, Baton Rouge, Louisiana, U.S.A.
9. BONNET, X., R. SHINE, G. NAULLEAU, AND C. THIBURCE. 2001. Plastic vipers: Influence of food intake on the size and shape of Gaboon vipers (Bitis gabonica). Journal of Zoology 255:341-351.
10. BRATTSTROM, B. H. 1954. The fossil pit-vipers (Reptilia: Crotalidae) of North America. Transactions of the San Diego Society of Natural History 12:31-46.
11. -. 1958. New records of Cenozoic amphibians and reptiles from California. Bulletin of the Southern California Academy of Sciences 57:5-13.
12. -. 1964. Evolution of the pit vipers. Transactions of the San Diego Society of Natural History 13:185-268.
13. -. 1965. Body temperatures of reptiles. American Midland Naturalist 73:376-422.
14. -. 1967. A succession of Pliocene and Pleistocene snake faunas from the high plains of the United States. Copeia 1967:188-202.
15. BROWN, C. W., AND C. H. ERNST. 1986. A study of variation of eastern timber rattlesnakes, Crotalus horridus Linnaeus (Serpentes: Viperidae). Brimleyana 12:57-74.
16. BROWN, W. S. 1991. Female reproductive ecology in a northern population of the timber rattlesnake, Crotalus horridus. Herpetologica 47:101-115.
17. -. 1993. Biology, Status, and Management of the Timber Rattlesnake (Crotalus horridus): A Guide for Conservation. Society for the Study of Amphibians and Reptiles, Herpetological Circular 22:1-78.
18. BROWN, W. S., D. W. PYLE, K. R. GREENE, AND J. B. FRIEDLAENDER. 1982. Movements and temperature relationships of timber rattlesnakes (Crotalus horridus) in northeastern New York. Journal of Herpetology 16:151-161.
19. BURBRINK, F. T. 2001. Systematics of the eastern ratsnake complex (Elaphe obsoleta). Herpetological Monographs 15:1-53.
20. BURBRINK, F. T., R. LAWSON, AND J. B. SLOWINSKI. 2000. Mitochondrial DNA phylogeography of the North American rat snake (Elaphe obsoleta): A critique of the subspecies concept. Evolution 54:2107-2114.
21. BUSHAR, L. M., H. K. REINERT, AND L. GELBERT. 1998. Genetic variation and gene flow within and between local populations of the timber rattlesnake, Crotalus horridus. Copeia 1998:411-422.
22. CADLE, J. E. 1987. Geographic distribution: Problems in phylogeny and zoogeography. Pp. 77-105. In R. A. Seigel, J. T. Collins, and S. S. Novak (Eds.), Snakes: Ecology and Evolutionary Biology. Macmillan Publishing Company, New York, U.S.A.
23. CAMIN, J. H., AND P. R. ERLICH. 1958. Natural selection in water snakes (Natrix sipedon L.) on islands in Lake Erie. Evolution 12:504-511.
24. CAMPBELL, J. A., AND W. W. LAMAR. 1989. The Venomous Reptiles of Latin America. Comstock Publishing Associates, Cornell University Press, Ithaca, New York, U.S.A.
25. CARROLL, R. L. 1988. Vertebrate Paleontology and Evolution. W. H. Freeman and Company, New York, New York, U.S.A.
26. CASTELLANO, S., A. MALHOTRA, AND R. S. THORPE. 1994. Within-island geographic variation of the dangerous Taiwanese snake, Trimeresurus stejnegeri, in relation to ecology. Biological Journal of the Linnean Society 52:365-375.
27. CHRISTMAN, S. P. 1980. Patterns of geographic variation in Florida snakes. Bulletin of the Florida State Museum, Biological Sciences 25:157-256.
28. CLARK, A. M., P. E. MOLER, E. E. POSSARDT, A. H. SAVITZKY, W. S. BROWN, AND B. W. BOWEN. 2003. Phylogeography of the timber rattlesnake (Crotalus horridus) based on mtDNA sequences. Journal of Herpetology 37:145-154.
29. CLARK, R. W. 2002. Diet of the timber rattlesnake, Crotalus horridus. Journal of Herpetology 36:494-499.
30. CONANT, R. 1998. A zoogeographical review of the amphibians and reptiles of southern New Jersey, with emphasis on the Pine Barrens. Pp. 467-488. In R. T. T. Forman (Ed.), Pine Barrens: Ecosystem and Landscape. Rutgers University Press, New Brunswick, New Jersey, U.S.A.
31. CONANT, R., AND J. T. COLLINS. 1991. A Field Guide to Reptiles and Amphibians: Eastern/Central North America, 3rd edition. Houghton Mifflin Company, Boston, Massachusetts, U.S.A.
32. CRACRAFT, J. 1989. Speciation and its ontology: The empirical consequences of alternative species concepts for understanding patterns and processes of differentiation. Pp. 28-59. In D. Otte and J. A. Endler (Eds.), Speciation and its Consequences. Sinauer Associates, Sunderland, Massachusetts, U.S.A.
33. CRUZ, F. B., L. A. FITZGERALD, R. E. ESPINOZA, AND J. A. SCHULTE, II. 2005. The importance of phylogenetic scale in tests of Bergmann's and Rapoport's rules: Lessons from a clade of South American lizards. Journal of Evolutionary Biology 18:1559-1574.
34. DELCOURT, H. R. 1979. Late Quaternary vegetational history of the eastern Highland Rim and adjacent Cumberland Plateau. Ecological Monographs 49:255-280.
35. DELCOURT, H. R., AND P. A. DELCOURT. 1991. Quaternary Ecology: A Paleoecological Perspective. Chapman and Hall, New York, New York, U.S.A.
36. DELCOURT, P. A., AND H. R. DELCOURT. 1987. Long-Term Forest Dynamics of the Temperate Zone: A Case Study of Late-Quaternary Forests in Eastern North America, Ecological Studies 63. Springer-Verlag, New York, New York, U.S.A.
37. -. 1993. Paleoclimates, paleovegetation, and paleofloras during the Late Quaternary. Pp. 71-94. In Flora of North America Editorial Committee (Eds.), Flora of North America, North of Mexico. Oxford University Press, New York, New York, U.S.A.
38. DESSAUER, H. C., AND F. H. POUGH. 1975. Geographic variation of blood proteins and the systematics of kingsnakes (Lampropeltis getulus). Comparative Biochemistry and Physiology 50B:9-12.
39. DILLER, L. V., AND R. L. WALLACE. 2002. Growth, reproduction, and survival in a population of Crotalus viridis oreganus in north central Idaho. Herpetological Monographs 16:26-45.
40. DOUGLAS, M. E., M. R. DOUGLAS, G. W. SCHUETT, L. W. PORRAS, AND A. T. HOLYCROSS. 2002. Phylogeography of the western rattlesnake (Crotalus viridis) complex, with emphasis on the Colorado Plateau. Pp. 11-50. In G. W. Schuett, M. Hoggren, M. E. Douglas, and H. W. Greene (Eds.), Biology of the Vipers. Eagle Mountain Publishing, Eagle Mountain, Utah, U.S.A.
41. ENDLER, J. A. 1977. Geographic Variation, Speciation, and Clines. Princeton University Press, Princeton, New Jersey, U.S.A.
42. ERNST, C. H. 1989. Snakes of Eastern North America. George Mason University Press, Fairfax, Virginia, U.S.A.
43. -. 1992. The Venomous Snakes of North America. Smithsonian Institution Press, Washington D. C., U.S.A.
44. ESRI. 1992-1999. ArcView, version 3.2. Environmental Systems Research Institute, Redlands, California.
45. ESRI. 1997. ArcUSA 1:2 M: A Comprehensive GIS Database for Use with ARC/INFO and ArcView, 1st edition. Environmental Systems Research Institute, Redlands, California.
46. EVERITT, B. S., S. LANDAU, AND M. LEESE. 2001. Cluster Analysis, 4th edition. Oxford University Press, New York, New York, U.S.A.
47. FITCH, H. S. 1940. Geographic variation in garter snakes of the species Thamnophis sirtalis in the Pacific Coast region of North America. American Midland Naturalist 26:570-592.
48. -. 1941. A biogeographical study of the ordinoides artenkreis of garter snakes (genus Thamnophis). University of California Publications in Zoology 44:1-150.
49. FOOTE, R., AND J. A. MACMAHON. 1977. Electrophoretic studies on rattlesnake (Crotalus and Sistrurus) venom: Taxonomic implications. Journal of Biochemistry and Physiology 57B:235-241.
50. FOX, W. W., C. GORDON, AND M. H. FOX. 1961. Morphological effects of low temperatures during the embryonic development of the garter snake, Thamnophis elegans. Zoologica 46:57-71.
51. GALLIGAN, J. H., AND W. A. DUNSON. 1979. Biology and status of timber rattlesnake (Crotalus horridus) populations in Pennsylvania. Biological Conservation 15:13-58.
52. GIBBONS, J. W. 1972. Reproduction, growth, and sexual dimorphism in the canebrake rattlesnake (Crotalus horridus atricaudatus). Copeia 1972:222-226.
53. GLOYD, H. K. 1935. The cane-brake rattlesnake. Copeia 1935:175-178.
54. -. 1940. The Rattlesnakes, Genera Sistrurus and Crotalus. Chicago Academy of Sciences Special Publications 4:1-266.
55. GLOYD, H. K., AND R. CONANT. 1990. Snakes of the Agkistrodon Complex: A Monographic Review. Society for the Study of Amphibians and Reptiles, Contributions to Herpetology 6:1-614.
56. GOULD, S. J., AND R. F. JOHNSTON. 1972. Geographic variation. Annual Review of Ecology and Systematics 3:457-498.
57. GOWER, J. C. 1967. A comparison of some methods of cluster analysis. Biometrics 23:623-637.
58. GRAHAM, R. W., AND E. L. LUNDELIUS, JR. 1984. Coevolutionary disequilibrium and Pleistocene extinctions. Pp. 223-249. In P. S. Martin and R. G. Klein (Eds.), Quaternary Extinctions: A Prehistoric Revolution. University of Arizona Press, Tucson, Arizona, U.S.A.
59. GREENE, H. W. 1997. Snakes: The Evolution of Mystery in Nature. University of California Press, Berkeley and Los Angeles, California, U.S.A.
60. HOLMAN, J. A. 1976. Paleoclimatic implications of "ecologically incompatible" herpetological species (late Pleistocene: southeastern United States). Herpetologica 32:290-295.
61. -. 1977. Upper Miocene snakes (Reptilia, Serpentes) from southeastern Nebraska. Journal of Herpetology 11:323-335.
62. -. 1979. A review of North American Tertiary snakes. Publications of the Museum, Michigan State University, Paleontological Series 1:203-206.
63. -. 1991. North American Pleistocene herpetofaunal stability and its impact on the interpretation of modern herpetofaunas: An overview. Illinois State Museum Scientific Papers 23:227-235.
64. -. 1995. Pleistocene Amphibians and Reptiles in North America. Oxford University Press, New York, New York, U.S.A.
65. JACKSON, J. F., W. INGRAM, III, AND H. W. CAMPBELL. 1976. The dorsal pigmentation pattern of snakes as an antipredator strategy: A multivariate approach. American Naturalist 110:1029-1053.
66. KHATTREE, R., AND D. N. NAIK. 2000. Multivariate Data Reduction and Discrimination with SAS Software. SAS Institute, Cary, North Carolina, U.S.A.
67. KING, R. B. 1989. Sexual dimorphism in snake tail length: Sexual selection, natural selection, or morphological constraint? Biological Journal of the Linnean Society 38:133-154.
68. -. 1993. Color-pattern variation in Lake Erie water snakes: Prediction and measurement of natural selection. Evolution 47:1819-1833.
69. KING, R. B., AND R. LAWSON. 1997. Microevolution in island water snakes: What processes influence color pattern differences in Lake Erie island and mainland water snakes? Bioscience 47:279-286.
70. KLAUBER, L. M. 1956. Rattlesnakes: Their Habits, Life Histories, and Influences on Mankind, Volumes 1 and 2. University of California Press, Berkeley and Los Angeles, California, U.S.A.
71. -. 1972. Rattlesnakes: Their Habits, Life Histories, and Influences on Mankind, Volumes 1 and 2, 2nd edition. University of California Press, Berkeley and Los Angeles, California, U.S.A.
72. KNIGHT, A., D. STYLER, S. PELIKAN, J. A. CAMPBELL, L. D. DENSMORE, III, AND D. P. MINDELL. 1993. Choosing among hypotheses of rattlesnake phylogeny: A best-fit rate test for DNA sequence data. Systematic Biology 42:356-367.
73. LEVITON, A. E., R. H. GIBBS, JR., E. HEAL, AND C. E. DAWSON. 1985. Standards in herpetology and ichthyology: Part 1. Standard symbolic codes for institutional resource collections in herpetology and ichthyology. Copeia 1985:802-832.
74. LUNDELIUS, E. L., R. W. GRAHAM, E. ANDERSON, J. GUILDAY, J. A. HOLMAN, D. W. STEADMAN, AND S. D. WEBB. 1983. Terrestrial vertebrate faunas. Pp. 311-353. In S. C. Porter (Ed.), Late Quaternary Environments of the United States, Volume 1, The Late Pleistocene. University of Minnesota Press, Minneapolis, Minnesota, U.S.A.
75. MACARTNEY, J. M., P. T. GREGORY, AND M. B. CHARLAND. 1990. Growth and sexual maturity of the western rattlesnake, Crotalus viridis, in British Columbia. Copeia 1990:528-542.
76. MADSEN, T., R. SHINE, J. LOMAN, AND T. HAAKANSSON. 1993. Determinants of mating success in male adders, Vipera berus. Animal Behaviour 45:491-499.
77. MALHOTRA, A., AND R. S. THORPE. 1991. Microgeographic variation in Anolis oculatus, on the island of Dominica, West Indies. Journal of Evolutionary Biology 4:321-335.
78. MARTIN, W. H. 1988. Life history of the timber rattlesnake. Catesbeiana 8:9-12.
79. -. 1992. The timber rattlesnake: Its distribution and natural history. Pp. 13-22. In T. F. Tyning (Ed.), Conservation of the Timber Rattlesnake in the Northeast. Massachusetts Audubon Society, Lincoln, Massachusetts, U.S.A.
80. -. 1993. Reproduction of the timber rattlesnake (Crotalus horridus) in the Appalachian mountains. Journal of Herpetology 27:133-143.
81. -. 2002. Life history constraints on the timber rattlesnake (Crotalus horridus) at its climatic limits. Pp. 285-306. In C. W. Schuett, M. Hoggren, M. E. Douglas, and H. W. Greene (Eds.), Biology of the Vipers. Eagle Mountain Publishing, Eagle Mountain, Utah, U.S.A.
82. MCQUITTY, L. L. 1966. Similarity analysis by reciprocal pairs for discrete and continuous data. Educational and Psychological Measurement 26:825-831.
83. MITCHELL, J. C. 1977. Geographic variation of Elaphe guttata (Reptilia: Serpentes) in the Atlantic Coastal Plain. Copeia 1977:33-41.
84. MORRISON, R. B. 1991. Introduction. Pp. 1-12. In R. B. Morrison (Ed.), Quaternary Nonglacial Geology: Conterminous U.S.: The Geology of North America, Volume K-2. The Geological Society of America, Boulder, Colorado, U.S.A.
85. MURPHY, R. W., J. FU, A. LATHROP, J. V. FELTHAM, AND V. KOVAC. 2002. Phylogeny of the rattlesnakes (Crotalus and Sistrurus) inferred from sequences of five mitochondrial DNA genes. Pp. 69-92. In C. W. Schuett, M. Hoggren, M. E. Douglas, and H. W. Greene (Eds.), Biology of the Vipers. Eagle Mountain Publishing, Eagle Mountain, Utah, U.S.A.
86. MURRAY, J. D., AND M. R. MYERSCOUGH. 1991. Pigmentation pattern formation on snakes. Journal of Theoretical Biology 149:339-360.
87. OSGOOD, D. W. 1978. Effects of temperature on the development of meristic characters in Natrix fasciata. Copeia 1978:33-47.
88. PARKINSON, C. L. 1999. Molecular systematics and biogeographical history of pitvipers as determined by mitochondrial ribosomal DNA sequences. Copeia 1999:576-586.
89. PARKINSON, C. L., J. A. CAMPBELL, AND P. T. CHIPPINDALE. 2002. Multigene phylogenetic analysis of pitvipers, with comments on their biogeography. Pp. 93-110. In G. W. Schuett, M. Hoggren, M. E. Douglas, and H. W. Greene (Eds.), Biology of the Vipers. Eagle Mountain Publishing, Eagle Mountain, Utah, U.S.A.
90. PEARSON, D., R. SHINE, AND R. How. 2002. Sex-specific niche partitioning and sexual size dimorphism in Australian pythons (Morelia spilota imbricata). Biological Journal of the Linnean Society 77:113-125.
91. PETERSON, C. R., A. R. GIBSON, AND M. E. DORCAS. 1993. Snake thermal ecology: The causes and consequences of body-temperature variation. Pp. 241-314. In R. A. Seigel and J. T. Collins (Eds.), Snakes: Ecology and Behavior. McGraw-Hill, New York, New York, U.S.A.
92. PISANI, G. R., J. T. COLLINS, AND S. R. EDWARDS. 1973. A re-evaluation of the subspecies of Crotalus horridus. Transactions of the Kansas Academy of Sciences 75:255-263.
93. POOK, C. E., W. WÜSTER, AND R. S. THORPE. 2000. Historical biogeography of the western rattlesnake (Serpentes: Viperidae: Crotalus viridis), inferred from mitochondrial DNA sequence information. Molecular Phylogenetics and Evolution 15:269-282.
94. POTTS, R., AND A. K. BEHRENSMEYER. 1992. Late Cenozoic terrestrial ecosystems. Pp. 419-541. In A. K. Behrensmeyer, J. D. Damuth, W. A. DiMichele, R. Potts, H.-D. Sues, and S. L. Wing (Eds.), Terrestrial Ecosystems through Time: Evolutionary Paleoecology of Terrestrial Plants and Animals. The University of Chicago Press, Chicago, Illinois, U.S.A.
95. QUERAL-REGIL, A., AND R. B. KING. 1998. Evidence for phenotypic plasticity in snake body size and relative head dimensions in response to amount and size of prey. Copeia 1998:423-429.
96. REED, R. N. 2003. Interspecific patterns of species richness, geographic range size, and body size among New World venomous snakes. Ecography 26:107-117.
97. REINERT, H. K., AND R. T. ZAPPALORTI. 1988. Timber rattlesnakes (Crotalus horridus) of the Pine Barrens: Their movement patterns and habitat preference. Copeia 1988:964-978.
98. RISER, J. A. M. 2001. Quaternary Geology and the Environment. Springer Verlag and Praxis Publishing, Berlin, Germany.
99. ROSS, H. H. 1965. Pleistocene events and insects. Pp. 583-596. In H. E. Wright, Jr. and D. G. Frey (Eds.), The Quaternary of the United States: A Review Volume for the VII Congress of the International Association for Quaternary Research. Princeton University Press, Princeton, New Jersey, U.S.A.
100. ROSSMAN, C. E. 1980. Ontogenetic changes in skull proportions of the diamondback water snake, Nerodia rhombifera. Herpetologica 36:42-46.
101. ROSSMAN, D. A. 1962. Thamnophis proximus (Say), a valid species of garter snake. Copeia 1962:741-748.
102. -. 1963. The colubrid snake genus Thamnophis: A revision of the sauritus group. Bulletin of the Florida State Museum, Biological Sciences 7:99-178.
103. ROSSMAN, D. A., N. B. FORD, AND R. A. SEIGEL. 1996. The Garter Snakes: Evolution and Ecology. University of Oklahoma Press, Norman, Oklahoma, U.S.A.
104. SAS INSTITUTE. 1989. SAS/STAT User's Guide, Volumes 1 and 2, version 6, 4th edition. SAS Institute, Cary, North Carolina, U.S.A.
105. -. 2000. Base SAS software for personal computers, version 8.01. SAS Institute, Cary, North Carolina, U.S.A.
106. SAVITZKY, A. H. 1980. The role of venom delivery strategies in snake evolution. Evolution 34:1194-1204.
107. SHARMA, S. 1996. Applied Multivariate Techniques. John Wiley and Sons, New York, New York, U.S.A.
108. SHINE, R. 1993. Sexual dimorphism in snakes. Pp. 49-86. In R. A. Seigel and J. T. Collins (Eds.), Snakes: Ecology and Behavior. McGraw-Hill, New York, New York, U.S.A.
109. -. 1994. Sexual size dimorphism in snakes revisited. Copeia 1994:326-346.
110. SITES, J. W. JR., AND J. R. DIXON. 1982. Geographic variation in Sceloporus variabilis, and its relationship to S. teapensis. (Sauria: Iguanidae). Copeia 1982:14-27.
111. SNEATH, P. H. A., AND R. R. SOKAL. 1973. Numerical Taxonomy: The Principles and Practice of Numerical Classification. W. H. Freeman and Company, San Francisco, California, U.S.A.
112. SOKAL, R. R., AND C. D. MICHENER. 1958. A statistical method for evaluating systematic relationships. University of Kansas Science Bulletin 38:1409-1438.
113. SORENSON, T. 1948. A method of establishing groups of equal amplitude in plant sociology based on similarity of species content and its application to analyses of the vegetation on Danish Commons. Biologiske Skrifter 5:1-34.
114. THOMAS, R. A. 1974. Geographic variation in Elaphe guttata (Linnaeus) (Serpentes: Colubridae). M.S. Thesis, Texas A & M University, College Station, Texas, U.S.A.
115. THORPE, R. S., AND M. BAEZ. 1987. Geographic variation within an island: Univariate and multivariate contouring of scalation, size, and shape of the lizard Gallotia galloti. Evolution 41:256-268.
116. THORPE, R. S., R. P. BROWN, A. MALHOTRA, AND W. WÜSTER. 1991. Geographic variation and population systematics: Distinguishing between ecogenetics and phylogenetics. Bolletini di Zoologia 58:329-335.
117. THORPE, R. S., A. MALHOTRA, H. BLACK, J. C. DALTRY, AND W. WÜSTER. 1995. Relating geographic pattern to phylogenetic process. Philosophical Transactions of the Royal Society of London B 349:61-68.
118. THORPE, R. S., R. P. BROWN, M. DAY, A. MALHOTRA, D. P. MCGREGOR, AND W. WÜSTER. 1994. Testing ecological and phylogenetic hypotheses in microevolutionary studies. Pp. 189-206. In P. Eggleton and R. Vane-Wright (Eds.), Phylogenetics and Ecology. Academic Press, London, U.K.
119. UNITED STATES FISH AND WILDLIFE SERVICE. 1999. Endangered and Threatened Wildlife and Plants. 50 CFR 17.11 and 17.12. Department of the Interior, Washington, D. C., U.S.A.
120. AN DEVENDER, T. R., AND R. CONANT. 1990. Pleistocene forests and copperheads in the eastern United States, and the historical biogeography of New World Agkistrodon. Pp. 601-614. In H. K. Gloyd and R. Conant (Eds.), Snakes of the Agkistrodon Complex: A Monographic Review. Society for the Study of Amphibians and Reptiles, Contributions to Herpetology, 6:1-614.
121. WARD, J. H. 1963. Hierarchical grouping to optimize an objective function. Journal of the American Statistical Association 58:236-244.
122. WILLIAMS, K. L. 1978. Systematics and natural history of the American milk snake, Lampropeltis triangulum. Milwaukee Public Museum Publications in Biology and Geology 2:1-258.
123. WÜSTER, W., M. G. SALOMĀO, J. A. QUIJADA-MASCAREÑAS, R. S. THORPE, BBBSP. 2002. Origins and evolution of the South American pitviper fauna: Evidence from mitochondrial DNA sequence analysis. Pp. 111-128. In C. W. Schuett, M. Hoggren, M. E. Douglas, and H. W. Greene (Eds.), Biology of the Vipers. Eagle Mountain Publishing. Eagle Mountain, Utah, U.S.A.