Abstract
The Pyrenean newt (Calotriton asper) is a morphologically diversified species endemic to the Pyrenean mountains (Western Europe) that inhabits fast running streams and mountain lakes. Given its high morphological diversity, the species has been subdivided into at least ten different taxa, subsequently treated by most authors as local forms. Herein, we examined the electrophoretic patterns produced by 20 presumptive allozyme loci in specimens of seven populations distributed over the entire geographic range of the species. Sixteen loci were monomorphic across the sampling area and only four loci were polymorphic. No diagnostic alleles of any population or population set were detected. The average number of alleles per locus was found to be extremely low, between 1.1 and 1.2 ± 0.1. Genetic divergence among populations was minimal, with a maximum divergence of Nei 78 = 0.031. No correlation was shown between genetic and geographic distances (Mantel test: r = -0.29, t = -1.1, p = 0.13). Fst values were low, as would be expected for a nonfragmented population. Estimated gene flow among populations was high, with a Nm = 1.01. Cytochrome b mtDNA sequences from the two populations furthest apart only differed in a single position. According to these genetic/morphological discrepancies, we interpret the observed morphological diversification of C. asper as a product of rapid morphological change under local selection pressure, in response to population specific ecological conditions. The implication of our findings for conservation efforts is that we need to preserve the unique evolutionary processes occurring in single populations or small groups of populations, even if the populations involved cannot be taxonomically differentiated.References
Accordi, F., Grassi-Milano, E. & Gallo, V.P. (1984) The adrenal gland of Euproctus (Urodela, Salamandridae), comparison of three species and phylogenetic inferences. Journal of Anatomy, 139, 209–214.
Alcobendas, M., Dopazo, H. & Alberch, P. (1996) Geographic variation in allozymes of populations of Salamandra salamandra exhibiting distinc reproductive modes. Journal of Evolutionary Biology, 9, 83–102.
Arano, B., Arntzen, J.W., Herrero, P. & García-París, M. (1991) Genetic differentiation among Iberian populations of the Alpine newt, Triturus alpestris. Amphibia-Reptilia, 12, 409–421.
Barbadillo, L.J., García-París, M. & Sanchiz, B. (1997) Orígenes y relaciones evolutivas de la herpetofauna ibérica. In: Pleguezuelos, J.M. (Ed.). Distribución y biogeografía de los anfibios y reptiles en España y Portugal. Monografías de Herpetología Vol 3. Universidad de Granada-Asociación Herpetológica Española, pp. 47–100.
Boscá, E. (1918) Una nueva forma de Anfibio urodelo (Molge bolivari). Boletín de la Real Sociedad Española de Historia Natural, 18, 58–61.
Boulenger, G. (1917) Les batraciens Urodèles rapportés au genre Euproctus, leurs rapports ethologiques et phylogeniques. Comptes rendus de l'Académie des Sciences, 164, 709–712, 801–805.
Buckley, D., Alcobendas, M., García-París, M. & Wake, M. (2007) Heterochrony, cannibalism, and the evolution of viviparity in Salamandra salamandra. Evolution and Development, 9(1), 105–115.
Buckley, D., Arano, B., Herrero, P., Llorente, G.A. & Esteban, M. (1994) Moroccan water frogs vs. Rana perezi: allozymes studies show up their differences. Zoologica Poloniae, 39(3-4), 393–401.
Caballero, A. (1994) Developments in the prediction of effective population size. Heredity, 73, 657–679.
Caccone A., Milinkovitch, M.C., Sbordoni, V. & Powell, J.R. (1996) Mitochondrial DNA rates and biogeography in European newts (Genus Euproctus). Systematic Biology, 46(1), 126–144.
Campeny, R., Montori, A. & Llorente, G.A. (1984) Nota preliminar sobre la permanencia de caracters larvaris en individus adults d'una població d'Euproctus asper. Bulletin de la Societat Catalana de Ictiologia i Herpetologia, 9, 43–45.
Campeny, R., Montori, A. & Llorente, G.A. (1986) Nuevos datos sobre la permanencia de caracteres larvarios en individuos adultos de una población de tritón pirenaico (Euproctus asper) en el Valle de Arán. Doñana Acta Vertebrata, 13, 170–174.
Carranza, S. & Amat, F. (2005) Taxonomy, biogeography and evolution of Euproctus (Amphibia: Salamandridae), with the resurrection of the genus Calotriton and the description of a new endemic species from the Iberian Peninsula. Zoological Journal of the Linnean Society, 145, 555–582.
Chapman, D.G. (1951) Some properties of the hypergeometric distribution with applications to zoological censuses. University of California Publications on Statistics. 1. 131-160.
Clergue-Gazeau, M. & Martínez-Rica, J.P. (1978) Les différents biotopes de l'urodèle pyrénéen, Euproctus asper. Bulletin de la Société d’ Histoire Naturelle de Toulouse, 114, 461–471.
Crandall, K.A., Bininda-Emonds, O.R.P., Mace, G.M. & Wayne, R.K. (2000) Considering evolutionary processes in conservation biology: returning to the original meaning of "evolutionarily significant units". Trends in Ecology and Evolution, 15(7), 290–295.
Crnobrnja, J. & Kalezic, M.L. (1990) The organization of the genetic variation in the Crested newt (Triturus cristatus complex) from Yugoslavia. Genetika, 22, 133–146.
Despax, R. (1923) Contribution à l'étude anatomique et biologique des Batraciens Urodeles du groupe des Euproctes et spécialement de l'Euprocte des pyrénées Triton (Euproctus) asper. Bulletin de la Société d’ Histoire Naturelle de Toulouse, 51, 185–440.
Dugès, A. (1852) Recherches zoologiques sur les urodeles de France. Annales de Sciences Naturelles, Zoologie, Série 3, 17, 253–272.
Duméril, A.M.C. Bibron, G. & Duméril, A.H. (1854) Erpétologie générale ou Histoire Naturelle complète des Reptiles. 9, 1–440, atlas, 1–24, pls., 1–108. Roret. París.
Fraser, D.J. & Bernatchez, L. (2001) Adaptative evolutionary conservation: towards a unified concept for defining conservation units. Molecular Ecology, 10, 2741–2752.
García-París, M., Alcobendas, M., Buckley, D. & Wake, D.B. (2003) Dispersal of viviparity across contact zones in Iberian populations of fire salamanders (Salamandra) inferred from discordance of genetic and morphological traits. Evolution, 57, 129–143.
García-París M. & Jockusch E.L. (1999) A mitochondrial DNA perspective on the evolution of Iberian Discoglossus (Amphibia: Anura). Journal of Zoology, 248, 209–218.
García-París, M., Montori, M. & Herrero, P. (2004) Amphibia, Lissamphibia. Fauna Ibérica, vol. 24, Museo Nacional de Ciencias Naturales, CSIC, Madrid, pp. 1–640.
Gasser, F. (1973) Cartographie des proteines sèriques de l'Urodèle pyrénéen. Euproctus asper (Dugès). Stabilité de l'aire de répartition de l'espèce. Comparative Biochemistry and Physiology, 45B, 419–443.
Gasser, F. & Clergue-Gazeau, M. (1981) Les proteines sèriques de l'urodèle Euproctus asper (Dugès). Elements de différentiation génétique dans les prepyrénées espagnols. Vie et Milieu, 31, 297–302.
Hartl, D.L. & Clark, A.G. (1989) Principles of Population Genetics. 2nd Ed. Sinauer Associates Inc., Sunderland, MA.
Larson, A., Wake, D.B. & Yanev, K.P. (1984) Measuring gene flow among populations having high levels of genetic fragmentations. Genetics, 106, 293–308.
Levene, H. (1949) On a matching problem arising in genetics. Annals of Mathematical Statistics, 20, 91–94.
Llorente, G.A., Montori, A., Santos, X. & Carretero, M.A. (1995) Atlas dels amfibis i rèptils de Catalunya i Andorra. El Brau, Figueres, pp. 1–191.
Mantel, N. & Valand, R.S. (1970) A technique for nonparametric multivariate analysis. Biometrics, 26, 547–558.
Martín, C. (1986) Morfología y registro fósil de Euproctus asper. Actas del Primer Congreso Nacional de Herpetología - Segunda Reunió General de la SCIH, Benicassim., SCIH, Barcelona, pp. 72. 114pp.
Martínez-Rica, J.P. (1980) Algunos datos sobre las poblaciones meridionales del tritón pirenaico Euproctus asper Dugés. Studia Oecologica, 2, 135–154.
Martínez-Solano, I. Alcobendas, M., Buckley, D. & García-París, M. (2005) Molecular characterization of the endangered Salamandra salamandra almanzoris (Caudata, Salamandridae). Annales Zoologici Fennici, 42, 57–68.
Mertens, R. & Wermuth, H. (1960) Die Amphibien und Reptilien Europas. Waldemar Kramer, Frankfurt am Main.
Montori, A. (1988) Estudio sobre la biología y ecología del tritón pirenaico Euproctus asper (Dugès, 1852) en la Cerdanya. Tesis doctoral, Universitat de Barcelona, Barcelona.
Montori, A. (1990) Skeletochronological results in the pyrenean newt Euproctus asper (Dugès, 1852) from one prepyrenean population. Annales des Sciences Naturelles, Zoologie, Série 13, 11, 209–211.
Montori, A. (1997) Trophic segregation between the Brown Trout (Salmo trutta) and the Pyrenean newt (Euproctus asper). In: Herpetologia Bonnensis, 1997. Bohme, W. Bischoff, W. & Ziegler, T. (Eds). Bonn, pp. 273–278.
Montori, A. & Campeny, R. (1992) Situación actual de las poblaciones de tritón pirenaico Euproctus asper en el macizo del Montseny. Boletín de la Asociación Herpetológica Española, 2, 10–12.
Montori, A. & Herrero, P. (2004) Caudata. In: García-París, M., Montori, A., Herrero, P. (Eds.) Amphibia, Lissamphibia. Fauna Ibérica, vol. 24, Museo Nacional de Ciencias Naturales, CSIC, Madrid, pp. 43–275
Montori, A., Llorente, G.A., Santos, X. & Carretero, M.A. (2002) Euproctus asper. In: Pleguezuelos, J.M., Márquez, R. & Lizana, M. (Eds.) Atlas y libro rojo de los anfibios y reptiles de España. Dirección General de la Conservación de la Naturaleza-Asociación Herpetológica Española, Madrid, pp. 48–50.
Montori, A., Tierno De Figueroa, J.M. & Santos, X. (2006) The diet of the Brown Trout Salmo trutta (L.) during the reproductive period: size-related and sexual effects. International Review of Hydrobiology, 91(5), 438–450.
Montori, A., Llorente, G.A. & Richter-Boix, A. (2008) Habitat features affecting the small-scale distribution and longitudinal migration patterns of Calotriton asper in a Pre-Pyrenean population. Amphibia-Reptolia, 29. 371-381.
Moritz, C. (2002) Strategies to protect biological diversity and the processes that sustain it. Systematic Biology, 51, 238–254.
Nei, M. (1975) Molecular Population Genetics and Evolution. North-Holland Publishers, Amsterdam.
Nei, M. (1978) Estimation of average heterozygosity and genetic distance from small number of individuals. Genetics, 89, 583–590.
Ragghianti, M. & Wake, D.B. (1986) Genetic variation and its evolutionary implications in the Italian newt, Triturus italicus. Herpetologica, 42, 206–214.
Rohlf, R.-J. (1993) NTSYS-pc. Numerical Taxonomy and Multivariate Analysis System, Version 1.8. Exeter Software, Setauket, NY.
Ryder, O.A. (1986) Species conservation and systematics: the dilemma of subespecies. Trends in Ecology and Evolution, 1, 9–10.
Salvador, A. (1974) Guía de los anfibios y reptiles españoles. Instituto Nacional para la Conservación de la Naturaleza (ICONA), Madrid. pp 1–282.
Sbordoni, V., Cobolli, M., De Mattaeis, E., Allegrucci, G., Cesaroni, D., Caccone, A. & Carpareto, G.M. (1982) Orologi molecolari e paleogeografia: congruenza ta stime geocronologiche e datazioni elettroforetiche della divergenza nelle specie del genere Euproctus (Caudata, Salamandridae). Bolletino di Zoologia, 49, suppl., p. 170.
Serra-Cobo, J., Uiblein, F.T. & Martínez-Rica, J.P. (2000) Variation in sexual dimorphism between two populations of the Pyrenean salamander Euproctus asper from ecologically different mountain sites. Belgian Journal of Zoology, 130(1), 39–45.
Slatkin, M. (1985) Rare alleles as indicators of gene flow. Evolution, 39, 53–65.
Swofford, D.L. & Selander, R.B. (1989) Biosys-1: A Computer Program for the Analysis of Allelic Variation in Population Genetics and Biochemical Systematics, Release 1.7, Illinois Natural History Survey, Chicago.
Thorn, R. (1968) Les salamandres d'Europe, d'Asie et d'Afrique du Nord. Paul Lechevalier. Paris. pp. 1–373.
Weir, B.S. (1990) Intraespecific differentiation. In: Hillis, D.M. & Moritz, C. (Eds.). Molecular Systematics. Sinauer Associates Inc., Sunderland, MA
Wolterstorff, W. (1925) Über mehrere Lokalformen des Pyreneenmolches Euproctus asper Dugès. Abhandlungen und Berichte für Naturkunde und Vorgeschichte, 4, 61–76.
Wright, S. (1943) Isolation by distance. Genetics, 28, 114–138.
Wright, S. (1978) Evolution and the Genetics of Populations. Vol. 4. Variability In and Among Natural Populations. University of Chicago Press, Chicago.