Sexual signal evolution outpaces ecological divergence during electric fish species radiation

American Naturalist

Volumn 176, Issue 3, 2010, Pages 335-356

  Arnegard, Matthew E ^a,i   McIntyre, Peter B ^b   Harmon, Luke J ^c   Zelditch, Miriam L ^d   Crampton, William G R ^e   Davis, Justin K ^e   Sullivan, John P ^f   Lavoué, Sébastien ^g   Hopkins, Carl D ^h  

^a UNIVERSITY OF BRITISH COLUMBIA   (Canada)

^b UNIVERSITY OF WISCONSIN MADISON   (United States)

^c UNIVERSITY OF IDAHO   (United States)

^d UNIVERSITY OF MICHIGAN   (United States)

^e UNIVERSITY OF CENTRAL FLORIDA   (United States)

^f Cornell University Museum of Vertebrates ^*  (United States)

^g DEPARTMENT OF LIFE SCIENCES   (United Kingdom)

^h Department of Obstetrics Gynecology   (United States)

ⁱ Fred Hutchinson Cancer Research Center   (United States)

Author keywords

Electric organ discharge; Key innovation; Private communication channel; Sexual selection; Speciation

Indexed keywords

ADAPTIVE RADIATION; DIVERGENCE; HETEROGENEITY; INNOVATION; MATING SUCCESS; RESOURCE SCARCITY; SEXUAL SELECTION; SIGNAL; SPECIES FLOCK; TELEOST;

ANIMAL; ANIMAL COMMUNICATION; ARTICLE; BODY SIZE; ELECTRIC FISH; EVOLUTION; FEMALE; MALE; MATE CHOICE; PHYSIOLOGY; REGRESSION ANALYSIS; SPECIES DIFFERENCE; SPECIES DIFFERENTIATION;

ANIMAL COMMUNICATION; ANIMALS; BODY SIZE; ELECTRIC FISH; EVOLUTION; FEMALE; GENETIC SPECIATION; MALE; MATING PREFERENCE, ANIMAL; REGRESSION ANALYSIS; SPECIES SPECIFICITY; BIOLOGICAL EVOLUTION;

MORMYRIDAE; PARAMORMYROPS; PISCES;

EID: 77955629232     PISSN: 00030147     EISSN: None     Source Type: Journal    
DOI: 10.1086/655221     Document Type: Article

References (119)

1. Allender, C. J., O. Seehausen, M. E. Knight, G. F. Turner, and N. Maclean. 2003. Divergent selection during speciation of Lake Malawi cichlid fishes inferred from parallel radiations in nuptial coloration. Proceedings of the National Academy of Sciences of the USA 100:14074-14079.
2. Alves-Gomes, J., and C. D. Hopkins. 1997. Molecular insights into the phylogeny of mormyriform fishes and the evolution of their electric organs. Brain, Behavior, and Evolution 49:324-351.
3. Arnegard, M. E., and B. A. Carlson. 2005. Electric organ discharge patterns during group hunting by a mormyrid fish. Proceedings of the Royal Society B: Biological Sciences 272:1305-1314.
4. Arnegard, M. E., and C. D. Hopkins. 2003. Electric signal variation among seven bluntsnouted Brienomyrus species (Teleostei: Mormyridae) from a riverine species flock in Gabon, Central Africa. Environmental Biology of Fishes 67:321-339.
5. Arnegard, M. E., and A. S. Kondrashov. 2004. Sympatric speciation by sexual selection alone is unlikely. Evolution 58:222-237.
6. Arnegard, M. E., S. M. Bogdanowicz, and C. D. Hopkins. 2005. Multiple cases of striking genetic similarity between alternate electric fish signal morphs in sympatry. Evolution 59:324-343.
7. Arnegard, M. E., B. S. Jackson, and C. D. Hopkins. 2006. Timedomain signal divergence and discrimination without receptor modification in sympatric morphs of electric fishes. Journal of Experimental Biology 209:2182-2198.
8. Arnqvist, G., M. Edvardsson, U. Friberg, and T. Nilsson. 2000. Sexual conflict promotes speciation in insects. Proceedings of the National Academy of Sciences of the USA 97:10460-10464.
9. Baier, B. 2008. Effect of conductivity changes on the stability of electric signal waveforms in dwarf stonebashers (Mormyridae; Pollimyrus castelnaui, P. marianne). Journal of Comparative Physiology A 194:915-919.
10. Barraclough, T. G., P. H. Harvey, and S. Nee. 1995. Sexual selection and taxonomic diversity in passerine birds. Proceedings of the Royal Society B: Biological Sciences 259:211-215.
11. Bass, A. H. 1986a. Electric organs revisited: evolution of a vertebrate communication and orientation organ. Pages 13-70 in T. H. Bullock and W. Heiligenberg, eds. Electroreception. Wiley, New York.
12. Bass, A. H., and C. D. Hopkins. 1983. Hormonal control of sexual differentiation: changes in electric organ discharge waveform. Science 220:971-974.
13. Bell, C. C., J. Bradbury, and C. J. Russell. 1976. The electric organ of a mormyrid as a current and voltage source. Journal of Comparative Physiology 110:65-88.
14. Blomberg, S. P., T. Garland Jr., and A. R. Ives. 2003. Testing for phylogenetic signal in comparative data: behavioral traits are more labile. Evolution 57:717-745.
15. Bookstein, F. L. 1986. Size and shape spaces for landmark data in two dimensions. Statistical Science 1:181-222.
16. -. 1997. Landmark methods for forms without landmarks: morphometrics of group differences in outline shape. Medical Image Analysis 1:97-118.
17. Boul, K. E., W. C. Funk, C. R. Darst, D. C. Cannatella, and M. J. Ryan. 2007. Sexual selection drives speciation in an Amazonian frog. Proceedings of the Royal Society B: Biological Sciences 274:399-406.
18. Bradbury, J. W., and S. L. Vehrencamp. 1998. Principles of animal communication. Sinauer, Sunderland, MA.
19. Candolin, U. 2003. The use of multiple cues in mate choice. Biological Reviews 78:575-595.
20. Caputi, A. A., B. A. Carlson, and O. Macadar. 2005. Electric organs and their control. Pages 410-451 in T. H. Bullock, C. D. Hopkins, A. N. Popper, and R. R. Fay, eds. Electroreception. Springer, New Yo r k.
21. Carlson, B. A. 2002. Electric signaling behavior and the mechanisms of electric organ discharge production in mormyrid fish. Journal of Physiology Paris 96:405-419.
22. Cherry, L. M., S. M. Case, J. G. Kunkel, J. S. Wyles, and A. C. Wilson. 1982. Body shape metrics and organismal evolution. Evolution 36:914-933.
23. Coyne, J. A., and H. A. Orr. 2004. Speciation. Sinauer, Sunderland, MA.
24. Crampton, W. G. R., J. K. Davis, N. R. Lovejoy, and M. Pensky. 2008. Multivariate classification of animal communication signals: a simulation-based comparison of alternative signal processing procedures using electric fishes. Journal of Physiology Paris 102:304-321.
25. Eldredge, N., J. N. Thompson, P. M. Brakefield, S. Gavrilets, D. Jablonski, J. B. C. Jackson, R. E. Lenski, B. S. Lieberman, M. A. McPeek, and W. Miller III. 2005. The dynamics of evolutionary stasis. Paleobiology 31 (suppl.): 133-145
26. Elias, D. O., E. A. Hebets, and R. R. Hoy. 2006a. Female preference for complex/novel signals in a spider. Behavioral Ecology 17:765-771.
27. Elias, D. O., E. A. Hebets, R. R. Hoy, W. P. Maddison, and A. C. Mason. 2006b. Regional seismic song differences in sky island populations of the jumping spider Habronattus pugillis Griswold (Araneae, Salticidae). Journal of Arachnology 34:545-556.
28. Endler, J. A. 1992. Signals, signal conditions, and the direction of evolution. American Naturalist 139 (suppl.): S125-S153.
29. Eschmeyer, W. N. 2010. Catalog of fishes. California Academy of Sciences, San Francisco. http://research.calacademy.org/ichthyology/catalog/fishcatmain. asp.
30. Felsenstein, J. 1985. Phylogenies and the comparative method. American Naturalist 125:1-15.
31. Feulner, P. G. D., F. Kirschbaum, V. Mamonekene, V. Ketmaier, and R. Tiedemann. 2007. Adaptive radiation in African weakly electric fish (Teleostei: Mormyridae: Campylomormyrus): a combined molecular and morphological approach. Journal of Evolutionary Biology 20:403-414.
32. Feulner, P. G. D., F. Kirschbaum, and R. Tiedemann. 2008. Adaptive radiation in the Congo River: an ecological speciation scenario for African weakly electric fish (Teleostei; Mormyridae; Campylomormyrus). Journal of Physiology Paris 102:340-346.
33. Feulner, P. G. D., M. Plath, J. Engelmann, F. Kirschbaum, and R. Tiedemann. 2009a. Electrifying love: electric fish use speciesspecific discharge for mate recognition. Biology Letters 5:225-228.
34. Fry, B. 2006. Stable isotope ecology. Springer, New York.
35. Genner, M. J., G. F. Turner, S. Barker, and S. J. Hawkins. 1999. Niche segregation among Lake Malawi cichlid fishes? evidence from stable isotope signatures. Ecology Letters 2:185-190.
36. Gerhardt, H. C. 1999. Reproductive character displacement and other sources of selection on acoustic communication systems. Pages 515-534 in M. D. Hauser and M. Konishi, eds. The design of animal communication. MIT Press, Cambridge, MA.
37. Gerhardt, H. C., and F. Huber. 2002. Acoustic communication in insects and anurans: common problems and diverse solutions. University of Chicago Press, Chicago.
38. Gingerich, P. D. 1993. Quantification and comparison of evolutionary rates. American Journal of Science 293-A: 453-478.
39. Grant, P. R., and B. R. Grant. 2008. How and why species multiply: the radiation of Darwin's finches. Princeton University Press, Princeton, NJ.
40. Green, W. D. K. 1996. The thin-plate spline and images with curving features. Pages 79-87 in K. V. Mardia, C. A. Gill, and I. L. Dryden, eds. Image fusion and shape variability. University of Leeds Press, Leeds.
41. Hanika, S., and B. Kramer. 2000. Electrosensory prey detection in the African sharptooth catfish, Clarias gariepinus (Clariidae), of the weakly electric mormyrid fish, the bulldog (Marcusenius macrolepidotus). Behavioral Ecology and Sociobiology 48:218-228.
42. Hebets, E. A. 2008. Seismic signal dominance in the multimodal courtship display of the wolf spider Schizocosa stridulans Stratton 1991. Behavioral Ecology 19:1250-1257.
43. Helland, I. P., C. Harrod, J. Freyhof, and T. Mehner. 2008. Coexistence of a pair of pelagic planktivorous coregonid fishes. Evolutionary Ecology Research 10:373-390.
44. Hendry, A. P., and M. T. Kinnison. 1999. The pace of modern life: measuring rates of contemporary microevolution. Evolution 53:1637-1653.
45. Herfeld, S., and P. Moller. 1998. Effects of 17 α- methyltestosterone on sexually dimorphic characters in the weakly discharging electric fish, Brienomyrus niger (Günther, 1866) (Mormyridae): electric organ discharge, ventral body wall indentation, and anal-fin ray bone expansion. Hormones and Behavior 34:303-319.
46. Hoeinghaus, D. J., and S. C. Zeug. 2008. Can stable isotope ratios provide for community-wide measures of trophic structure? comment. Ecology 89:2353-2357.
47. Hopkins, C. D. 1973. Lightning as background noise for communication among electric fish. Nature 242:268-270.
48. -. 1980. Evolution of electric communication channelsof mormyrids. Behavioral Ecology and Sociobiology 7:1-13.
49. -. 1986. Behavior of Mormyridae. Pages 527-576 in T. H. Bullock and W. Heiligenberg, eds. Electroreception. Wiley, New York.
50. -. 1999. Design features for electric communication. Journal of Experimental Biology 202:1217-1228.
51. -. 2010. Electroreception. Pages 384-387 in E. B. Goldstein, ed. Encyclopedia of perception. Sage, Thousand Oaks, CA.
52. Hopkins, C. D., and A. H. Bass. 1981. Temporal coding of species recognition signals in an electric fish. Science 212:85-87.
53. Hopkins, C. D., S. Lavoué, and J. P. Sullivan. 2007. Mormyridae. Pages 219-334 in M. L. J. Stiassny, G. G. Teugels, and C. D. Hopkins, eds. Poissons d'eaux douces et saumâtres de basse Guinée, ouest de l'Afrique centrale (The fresh and brackish water fishes of Lower Guinea, west-central Africa). IRD, Paris.
54. Hubbell, S. P. 2001. The unified neutral theory of biodiversity and biogeography. Princeton University Press, Princeton, NJ.
55. Kawasaki, M. 2005. Physiology of tuberous electrosensory systems. Pages 154-194 in T. H. Bullock, C. D. Hopkins, A. N. Popper, and R. R. Fay, eds. Electroreception. Springer, New York.
56. Kazancioǧlu, E., T. J. Near, H. Reinhold, and P. C. Wainwright. 2009. Influence of sexual selection and feeding functional morphology on diversification rate of parrotfishes (Scaridae). Proceedings of the Royal Society B: Biological Sciences 276:3439-3446.
57. Kingston, T., and S. J. Rossiter. 2004. Harmonic-hopping in Wallacea's bats. Nature 429:654-657.
58. Kirkpatrick, M., and S. L. Nuismer. 2004. Sexual selection can constrain sympatric speciation. Proceedings of the Royal Society B: Biological Sciences 271:687-693.
59. Lavoué, S., and J. P. Sullivan. 2004. Simultaneous analysis of five molecular markers provides a well-supported phylogenetic hypothesis for the living bony-tongue fishes (Osteoglossomorpha: Teleostei). Molecular Phylogenetics and Evolution 33:171-185.
60. Lavoué, S., R. Bigorne, G. Lecointre, and J. F. Agnèse. 2000. Phylogenetic relationships of mormyrid electric fishes (Mormyridae, Teleostei) inferred from cytochrome b sequences. Molecular Phylogenetics and Evolution 14:1-10.
61. Lavoué, S., J. P. Sullivan, and C. D. Hopkins. 2003. Phylogenetic utility of the first two introns of the S7 ribosomal protein gene in African electric fishes (Mormyroidea: Teleostei) and congruence with other molecular markers. Biological Journal of the Linnean Society 78:273-292.
62. Lavoué, S., C. D. Hopkins, and A. Kamdem Toham. 2004. The Petrocephalus (Pisces, Osteoglossomorpha, Mormyridae) of Gabon, Central Africa, with the description of a new species. Zoosystema 26:511-535.
63. Lavoué, S., J. P. Sullivan, M. E. Arnegard, and C. D. Hopkins. 2008a. Differentiation of morphology, genetics and electric signals in a region of sympatry between sister species of African electric fish (Mormyridae). Journal of Evolutionary Biology 21:1030-1045.
64. Lavoué, S., M. E. Arnegard, J. P. Sullivan, and C. D. Hopkins. 2008b. Petrocephalus of Odzala offer insights into evolutionary patterns of signal diversification in the Mormyridae, a family of weakly electrogenic fishes from Africa. Journal of Physiology Paris 102:322-339.
65. Lerman, A. 1965. On rates of evolution of unit characters and character complexes. Evolution 19:16-25.
66. Losos, J. B. 2009. Lizards in an evolutionary tree: ecology and adaptive radiation of anoles. University of California Press, Berkeley.
67. Losos, J. B., and R. E. Ricklefs. 2009. Adaptation and diversification on islands. Nature 457:830-836.
68. Losos, J. B., T. R. Jackman, A. Larson, K. de Queiroz, and L. Rodríguez-Schettino. 1998. Contingency and determinism in replicated adaptive radiations of island lizards. Science 279:2115-2118.
69. Lovette, I. J., E. Bermingham, and R. E. Ricklefs. 2002. Clade-specific morphological diversification and adaptive radiation in Hawaiian songbirds. Proceedings of the Royal Society B: Biological Sciences 269:37-42.
70. MacArthur, R. H. 1958. Population ecology of some warblers of northeastern coniferous forests. Ecology 39:599-619.
71. Machnik, P., and B. Kramer. 2008. Female choice by electric pulse duration: attractiveness of the males' communication signal assessed by female bulldog fish, Marcusenius pongolensis (Mormyridae, Teleostei). Journal of Experimental Biology 211:1969-1977.
72. Mahalanobis, P. C. 1936. On the generalized distance in statistics. Proceedings of the National Institute of Sciences of India 2:49-55.
73. Mallat, S. 1999. A wavelet tour of signal processing. Academic Press, San Diego, CA.
74. Marrero, C., and K. O. Winemiller. 1993. Tube-snouted gymnotiform and mormyriform fishes: convergence of a specialized foraging mode in teleosts. Environmental Biology of Fishes 38:299-309.
75. Masta, S. E., and W. P. Maddison. 2002. Sexual selection driving diversification in jumping spiders. Proceedings of the National Academy of Sciences of the USA 99:4442-4447.
76. Matthews, B., K. B. Marchinko, D. I. Bolnick, and A. Mazumder. 2010. Specialization of trophic position and habitat use by sticklebacks in an adaptive radiation. Ecology 91:1025-1034.
77. McClure, M. M., P. B. McIntyre, and A. R. McCune. 2006. Notes on the natural diet and habitat of eight danionin fishes, including the zebrafish Danio rerio. Journal of Fish Biology 68:1-18.
78. McIntyre, P. B., and A. S. Flecker. 2006. Rapid turnover of tissue nitrogen of primary consumers in tropical freshwaters. Oecologia (Berlin) 148:12-21.
79. McKinnon, J. S., S. Mori, B. K. Blackman, L. David, D. M. Kingsley, L. Jamieson, J. Chou, and D. Schluter. 2004. Evidence for ecology's role in speciation. Nature 429:294-298.
80. Mendelson, T. C., and K. L. Shaw. 2005. Rapid speciation in an arthropod. Nature 433:375-376.
81. Moller, P. 1995. Electric fishes: history and behavior. Chapman & Hall, New York.
82. Neter, J., and W. Wasserman. 1974. Applied linear statistical models: regression, analysis of variance, and experimental designs. Irwin, Homewood, IL.
83. Nosil, P., and L. Harmon. 2009. Niche dimensionality and ecological speciation. Pages 127-154 in R. K. Butlin, J. R. Bridle, and D. Schluter, eds. Speciation and patterns of diversity. Cambridge University Press, Cambridge.
84. Otte, D. 1994. The crickets of Hawaii: origin, systematics and evolution. Orthopterists' Society/Academy of Natural Sciences of Philadelphia, Philadelphia.
85. Parent, C. E., and B. J. Crespi. 2009. Ecological opportunity in adaptive radiation of Galápagos endemic land snails. American Naturalist 174:898-905.
86. Partan, S. R., and P. Marler. 2005. Issues in the classification of multimodal communication signals. American Naturalist 166:231-245.
87. Pezzanite, B., and P. Moller. 1998. A sexually dimorphic basal analfin ray expansion in the weakly discharging electric fish Gnathonemus petersii. Journal of Fish Biology 53:638-644.
88. Podos, J. 2001. Correlated evolution of morphology and vocal signal structure in Darwin's finches. Nature 409:185-188.
89. Podos, J., and A. P. Hendry. 2006. The biomechanics of ecological speciation. Pages 301-321 in A. Herrel, T. Speck, and N. P. Rowe, eds. Ecology and biomechanics: a mechanical approach to the ecology of animals and plants. CRC, Boca Raton, FL.
90. Post, D. M. 2002. Using stable isotopes to estimate trophic position: models, methods, and assumptions. Ecology 83:703-718.
91. Pouyaud, L., Sudarto, and G. G. Teugels. 2003. The different colour varieties of the Asian arowana Scleropages formosus (Osteoglossidae) are distinct species: morphologic and genetic evidences. Cybium 27:287-305.
92. Price, J. J., N. R. Friedman, and K. E. Omland. 2007. Song and plumage evolution in the New World orioles (Icterus) show similar lability and convergence in patterns. Evolution 61:850-863.
93. Price, T. 1998. Sexual selection and natural selection in bird speciation. Philosophical Transactions of the Royal Society B: Biological Sciences 353:251-260.
94. R Core Development Team. 2009. R, version 2.9.0. R Foundation for Statistical Computing, Vienna. http://www.r-project.org/.
95. Ricklefs, R. E. 2007. Estimating diversification rates from phylogenetic information. Trends in Ecology & Evolution 22:601-610.
96. Ritchie, M. G. 2007. Sexual selection and speciation. Annual Review of Ecology, Evolution, and Systematics 38:79-102.
97. Rohlf, F. J., and D. Slice. 1990. Extensions of the Procrustes method for the optimal superimposition of landmarks. Systematic Zoology 39:40-59.
98. Rundell, R. J., and T. D. Price. 2009. Adaptive radiation, nonadaptive radiation, ecological speciation and nonecological speciation. Trends in Ecology & Evolution 24:394-399.
99. Rundle, H. D., L. N. Nagel, J. W. Boughman, and D. Schluter. 2000. Natural selection and parallel speciation in sympatric sticklebacks. Science 287:306-308.
100. Sanderson, M. J. 2003. r8s: inferring absolute rates of molecular evolution and divergence times in the absence of a molecular clock. Bioinformatics 19:301-302.
101. Schluter, D. 2000. The ecology of adaptive radiation. Oxford University Press, New York.
102. Schoener, T. W. 1989. The ecological niche. Pages 79-113 in J. M. Cherrett, ed. Ecological concepts: the contribution of ecology to an understanding of the natural world. Blackwell Scientific, Oxford.
103. Seehausen, O. 2009. Progressive levels of trait divergence along a "speciation transect" in the Lake Victoria cichlid fish Pundamilia. Pages 155-176 in R. K. Butlin, J. R. Bridle, and D. Schluter, eds. Speciation and patterns of diversity. Cambridge University Press, Cambridge.
104. Seehausen, O., Y. Terai, I. S. Magalhaes, K. L. Carleton, H. D. J. Mrosso, R. Miyagi, I. van der Sluijs, et al. 2008. Speciation through sensory drive in cichlid fish. Nature 455:620-626.
105. Servedio, M. R., and M. A. F. Noor. 2003. The role of reinforcement in speciation: theory and data. Annual Review of Ecology, Evolution, and Systematics 34:339-364.
106. Simpson, G. G. 1953. The major features of evolution. Columbia University Press, New York.
107. Stoddard, P. K. 1999. Predation enhances complexity in the evolution of electric fish signals. Nature 400:254-256.
108. Streelman, J. T., and P. D. Danley. 2003. The stages of vertebrate evolutionary radiation. Trends in Ecology & Evolution 18:126-131.
109. Sullivan, J. P., and C. D. Hopkins. 2004. A new Stomatorhinus (Osteoglossomorpha: Mormyridae) from the Ivindo River, Gabon, west central Africa. Zootaxa 847:1-23.
110. Sullivan, J. P., S. Lavoué, and C. D. Hopkins. 2000. Molecular systematics of the African electric fishes (Mormyroidea: Teleostei) and a model for the evolution of their electric organs. Journal of Experimental Biology 203:665-683.
111. -. 2002. Discovery and phylogenetic analysis of a riverine species flock of African electric fishes (Mormyridae: Teleostei). Evolution 56:597-616.
112. Sullivan, J. P., S. Lavoué, M. E. Arnegard, and C. D. Hopkins. 2004. AFLPs resolve phylogeny and reveal mitochondrial introgression within a species flock of African electric fish (Mormyroidea: Teleostei). Evolution 58:825-841.
113. von der Emde, G., S. Schwarz, L. Gomez, R. Budelli, and K. Grant. 1998. Electric fish measure distance in the dark. Nature 395:890-894.
114. Winemiller, K. O., and A. Adite. 1997. Convergent evolution of weakly electric fishes from floodplain habitats in Africa and South America. Environmental Biology of Fishes 49:175-186.
115. Wong, R. Y., and C. D. Hopkins. 2007. Electrical and behavioral courtship displays in the mormyrid fish Brienomyrus brachyistius. Journal of Experimental Biology 210:2244-2252.
116. Xu-Friedman, M. A., and C. D. Hopkins. 1999. Central mechanisms of temporal analysis in the knollenorgan pathway of mormyrid electric fish. Journal of Experimental Biology 202:1311-1318.
117. Yang, Z. 1994. Maximum likelihood phylogenetic estimation from DNA sequences with variable rates over sites: approximate methods. Journal of Molecular Evolution 39:306-314.
118. Zakon, H. H. 1988. The electroreceptors: diversity in structure and function. Pages 813-850 in J. Atema, R. R. Fay, A. N. Popper, and W. N. Tavolga, eds. Sensory biology of aquatic animals. Springer, New York.
119. Zwickl, D. J. 2006. Genetic algorithm approaches for the phylogenetic analysis of large biological sequence datasets under the maximum likelihood criterion. PhD diss. University of Texas, Austin. http://www.zo.utexas.edu/ faculty/antisense/garli/Garli.html.