Conservation genetics of an endemic mountaintop salamander with an extremely limited range

Abstract

Montane regions can promote allopatric speciation and harbor unique species with small ranges. The southern Appalachians are a biodiversity hotspot for salamanders, and several montane endemics occur in the region. Here, we present the first DNA sequence data for Plethodon sherando, a terrestrial salamander recently discovered in the Blue Ridge Mountains of Virginia. We sequenced two mitochondrial regions (cyt-b and CO1) from salamanders at reference sites near the center of P. sherando’s range and from two contact zones where P. sherando populations are replaced by Plethodon cinereus, the Northern Red-Backed salamander. We then used these sequence data to examine divergence and hybridization between the two taxa. We found P. sherando and P. cinereus morphotypes from contact zones to be reciprocally monophyletic and highly divergent (~17%). P. sherando exhibited very low sequence diversity (π = 0.0010) as compared to P. cinereus from the same locations (π = 0.0096). Salamander morphology in the contact zone was as distinct as morphology at reference sites, and discriminant function analysis based on morphology successfully classified 98% of salamanders to their mitochondrial lineage. Phylogenetic analysis of cyt-b sequences showed P. sherando to be sister to Plethodon serratus (the Southern Red-Backed salamander) rather than P. cinereus or any nearby mountaintop endemics. Our results suggest that P. sherando is a distinct lineage that is not subject to substantial introgression from P. cinereus and that may have a history of geographic isolation. Given its limited range (<80 km2), we believe P. sherando should merit a conservation status similar to that of other mountaintop salamanders in the region.

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References

  1. Adams DC (2004) Character displacement via aggressive interference in Appalachian salamanders. Ecology 85:2664–2670

    Article  Google Scholar 

  2. Adams DC, West ME, Collyer ML (2007) Location-specific sympatric morphological divergence as a possible response to species interactions in West Virginia Plethodon salamander communities. J Anim Ecol 76:289–295

    PubMed  Article  Google Scholar 

  3. Anderson E, Maldonado-Ocampo J (2010) A regional perspective on the diversity and conservation of the tropical Andean fishes. Conserv Biol 25:30–39

    PubMed  Article  Google Scholar 

  4. Arif S, Wicknick JA, Adams DC (2007) Bioclimatic modeling, morphology, and behavior reveal alternative mechanisms regulating the distributions of two parapatric salamander species. Evol Ecol Res 9:843–854

    Google Scholar 

  5. Babik W, Branicki W, Crnobnja-Isailović J, Cogălniceanu D, Sas I, Olgun K, Poyarkov NA, Garcia-País M, Arntzen JW (2005) Phylogeography of two European newt species—discordance between mtDNA and morphology. Mol Ecol 14:2475–2491

    PubMed  Article  CAS  Google Scholar 

  6. Bensasson D, Zhang D-X, Hartl DL, Hewitt GM (2001) Mitochondrial pseudogenes: evolution’s misplaced witnesses. Trends Ecol Evol 16:314–321

    PubMed  Article  Google Scholar 

  7. Cabe P, Hanlon T, Aldrich M, Connors L, Marsh D (2007) Fine-scale population differentiation and gene flow in a terrestrial salamander (Plethodon cinereus) living in continuous habitat. Heredity 98:53–60

    PubMed  Article  CAS  Google Scholar 

  8. Carpenter D, Jung R, Sites J (2001) Conservation genetics of the endangered Shenandoah Salamander (Plethodon shenandoah, Plethodontidae). Anim Conserv 4:111–119

    Article  Google Scholar 

  9. Chan C, Ballantyne K, Aikman H, Fastier D, Daugherty C, Chambers G (2006) Genetic analysis of interspecific hybridization in the world’s only Forbes’ parakeet (Cyanoramphus forbesi) natural population. Conserv Genet 7:493–506

    Article  CAS  Google Scholar 

  10. Colliard C, Sicilia A, Turrisi G, Arculeo M, Perrin N, Stöck M (2010) Strong reproductive barriers in a narrow hybrid zone of west-mediterranean green toads (Bufo viridis subgroup) with Plio-Pleistocene divergence. BMC Evol Biol 10:232

    PubMed  Article  Google Scholar 

  11. Connors LM, Cabe PR (2003) Isolation of dinucleotide microsatellite loci from red-backed salamanders (Plethodon cinereus). Mol Ecol Notes 3:131–133

    Article  CAS  Google Scholar 

  12. Degnan JH, Rosenberg NA (2009) Gene tree discordance, phylogenetic inference, and the multispecies coalescent. Trends Ecol Evol 24:332–340

    PubMed  Article  Google Scholar 

  13. Drummond AJ, Rambaut A (2007) BEAST: Bayesian evolutionary analysis sampling trees. BMC Evol Biol 7:214

    PubMed  Article  Google Scholar 

  14. Duellman WE, Sweet SS (1999) Distribution patterns of amphibians in the Nearctic region of North America. In: Duellman WE (ed) Patterns of distribution of amphibians. Johns Hopkins Univ. Press, Baltimore, pp 31–109

    Google Scholar 

  15. Felsenstein J (1993) PHYLIP (Phylogeny Inference Package) version 3.5c. Distributed by the author. Department of Genetics, University of Washington, Seattle

  16. Fraley C, Raftery AE (2006) MCLUST version 3 for R: normal mixture modeling and model-based clustering. Technical report. Department of Statistics, University of Washington, Seattle

  17. Gilman SE, Urban MC, Tewksbury J, Gilchrist GW, Holt RD (2010) A framework for community interactions under climate change. Trends Ecol Evol 25:325–331

    PubMed  Article  Google Scholar 

  18. Harpending RC (1994) Signature of ancient population growth in a low-resolution mitochondrial DNA mismatch distribution. Hum Biol 66:591–600

    PubMed  CAS  Google Scholar 

  19. Hastie T, Tibshirani R, Friedman JH (2001) Elements of statistical learning. Springer, New York

    Google Scholar 

  20. Hebert PDN, Penton EH, Burns JM, Janzen DH, Hallwachs W (2004) Ten species in one: DNA barcoding reveals cryptic species in the neotropical skipper butterfly Astraptes fulgerator. PNAS 101:14812–14817

    PubMed  Article  CAS  Google Scholar 

  21. Hegde SG, Nason JD, Clegg JM, Ellstrand NC (2006) The evolution of California’s wild radish has resulted in the extinction of its progenitors. Evolution 60:1187–1197

    PubMed  Google Scholar 

  22. Highton R (1995) Speciation in Eastern North American salamanders of the genus Plethodon. Annu Rev Ecol Syst 26:579–600

    Article  Google Scholar 

  23. Highton R (1998) Frequency of hybrids between introduced and native populations of the salamander Plethodon jordani in their first generation of sympatry. Herpetologica 54:143–153

    Google Scholar 

  24. Highton R (1999) Geographic protein variation and speciation in the salamanders of the Plethodon cinereus group with the description of two new species. Herpetologica 55:43–90

    Google Scholar 

  25. Highton R (2004) A new species of woodland salamander of the Plethodon cinereus group from the Blue Ridge Mountains of Virginia. Jeffersoniana 14:1–22

    Google Scholar 

  26. Highton R, Worthington R (1967) A new salamander of the genus Plethodon from Virginia. Copeia 1967:617–626

    Article  Google Scholar 

  27. Huelsenbeck JP, Ronquist F (2001) MRBAYES: Bayesian inference of phylogeny. Bioinformatics 17:754–755

    PubMed  Article  CAS  Google Scholar 

  28. Jaeger RG, Forester DC (1993) Social behavior of plethodontid salamanders. Herpetologica 49:163–175

    Google Scholar 

  29. Johnson JA, Dunn PO, Bouzat JL (2007) Effects of recent population bottlenecks on reconstructing the demographic history of prairie chickens. Mol Ecol 16:2203–2222

    PubMed  Article  CAS  Google Scholar 

  30. Kleindorfer S, Chapman TW, Winkler H, Sulloway FJ (2006) Adaptive divergence in contiguous populations of Darwin’s Small Ground Finch (Geospiza fuliginosa). Evol Ecol Res 8:357–372

    Google Scholar 

  31. Knowles L (2001) Did the Pleistocene glaciations promote divergence? Tests of explicit refugial models in montane grasshopprers. Mol Ecol 10:691–701

    PubMed  Article  CAS  Google Scholar 

  32. Kozak K, Wiens J (2006) Does niche conservatism promote speciation? A case study in North American salamanders. Evolution 60:2604–2621

    PubMed  Google Scholar 

  33. Kozak KH, Wiens JJ (2010) Niche conservatism drives elevational diversity patterns in Appalachian salamanders. Am Nat 176:40–54

    PubMed  Article  Google Scholar 

  34. LaSorte F, Jetz W (2010) Projected range contractions of montane biodiversity under global warming. Proc R Soc B Biol Sci 277:3401–4310

    Article  Google Scholar 

  35. Lawler JJ, Shafer SL, White D, Kareiva P, Maurer EP, Blaustein AR, Bartlein PJ (2009) Projected climate-induced faunal change in the Western Hemisphere. Ecology 90:588–597

    PubMed  Article  Google Scholar 

  36. Lovett JC (1998) Continuous change in Tanzanian moist forest tree communities with elevation. J Trop Ecol 14:719–722

    Article  Google Scholar 

  37. Mallet J (2005) Hybridization as an invasion of the genome. Trends Ecol Evol 20:229–237

    PubMed  Article  Google Scholar 

  38. Mallet J, Beltrán M, Neukirchen W, Linares M (2007) Natural hybridization in heliconiine butterflies: the species boundary as a continuum. BMC Evol Biol 7:28

    PubMed  Article  Google Scholar 

  39. Marsh D, Page RB, Hanlon TJ, Corritone R, Little EE, Seifert DE, Cabe PR (2008) Effects of roads on patterns of genetic differentiation in red-backed salamanders, Plethodon cinereus. Conserv Genet 9:603–613

    Article  Google Scholar 

  40. McCain CM (2005) Elevational gradients in diversity of small mammals. Ecology 86:366–372

    Article  Google Scholar 

  41. Milanovich J, Peterman W, Nibbelink N, Maerz J (2010) Project loss of a salamander diversity hotspot as a consequence of project global climate change. PLoS ONE 5:e12189

    PubMed  Article  Google Scholar 

  42. Moritz C, Patton JL, Conroy CJ, Parra JL, White GC et al (2008) Impact of a century of climate change on small-mammal communities in Yosemite National Park, USA. Science 322:261–264

    PubMed  Article  CAS  Google Scholar 

  43. Mueller R (2006) Evolutionary rates, divergence dates, and the performance of mitochondrial genes in Bayesian phylogenetic analysis. Syst Biol 55:289–300

    PubMed  Article  Google Scholar 

  44. Myers N, Mittermeier R, Mittermeier C, Fonseca G, Kent J (2000) Biodiversity hotspots for conservation priorities. Nature 403:853–858

    PubMed  Article  CAS  Google Scholar 

  45. Pauley T (2007) Revised notes on the range of the Cheat Mountain Salamander, Plethodon nettingi. Proc W Va Acad Sci 79:16–21

    Google Scholar 

  46. Petranka JW (1998) Salamanders of the United States and Canada. Smithsonian Institution Press, Washington

    Google Scholar 

  47. Posada D (2008) jModelTest: phylogenetic model averaging. Mol Biol Evol 25:1253–1256

    PubMed  Article  CAS  Google Scholar 

  48. Rhymer J, Simberloff D (1996) Extinction by hybridization and introgression. Annu Rev Ecol Syst 27:83–109

    Article  Google Scholar 

  49. Rissler LJ, Smith WH (2010) Mapping amphibian contact zones and phylogeographic break hotspots across the United States. Mol Ecol 19:5404–5416

    PubMed  Article  Google Scholar 

  50. Ronquist F, Huelsenbeck JP (2003) MRBAYES 3: Bayesian phylogenetic inference under mixed models. Bioinformatics 19:1572–1574

    PubMed  Article  CAS  Google Scholar 

  51. Rozas J, Sanchez-DelBarrio JC, Messeguer X, Rozas R (2003) DnaSP, DNA polymorphism analyses by the coalescent and other methods. Bioinformatics 19:2496–2497

    PubMed  Article  CAS  Google Scholar 

  52. Schneider S, Excoffier L (1999) Estimation of past demographic parameters from the distribution of pairwise differences when the mutation rates vary among sites: application to human mitochondrial DNA. Genetics 152:1079–1089

    PubMed  CAS  Google Scholar 

  53. Smith MA, Poyarkov NA, Hebert PDN (2008) CO1 DNA barcoding amphibians: take the chance, meet the challenge. Mol Ecol Resour 8:235–246

    PubMed  Article  CAS  Google Scholar 

  54. Steele C, Carstens BC, Storfer A, Sullivan J (2005) Testing hypotheses of speciation timing in Dicamptodon copei and Dicamptodon aterrimus (Caudata: Dicamptodontidae). Mol Phylogenet Evol 36:90–100

    PubMed  Article  Google Scholar 

  55. Szymura JM, Uzzell T, Spolsky C (2000) Mitochondrial DNA variation in the hybridizing fire-bellied toads, Bombina bombina and B. variegata. Mol Ecol 9:891–899

    PubMed  Article  CAS  Google Scholar 

  56. Tamura K, Dudley J, Nei M, Kumar S (2007) MEGA4: molecular evolutionary genetics analysis (MEGA) software version 4.0. Mol Biol Evol 24:1596–1599

    PubMed  Article  CAS  Google Scholar 

  57. Terborgh J (1977) Bird species diversity on an Andean elevational gradient. Ecology 58:1007–1019

    Article  Google Scholar 

  58. United States Forest Service (2011) George Washington National Forest plan revision. http://www.fs.fed.us/. Accessed 11 November 2011

  59. Weisrock D, Kozak H, Larson A (2005) Phylogeographic analysis of mitochondrial gene flow and introgression in the salamander, Plethodon shermani. Mol Ecol 14:1457–1472

    PubMed  Article  CAS  Google Scholar 

  60. Wiens J, Engstrom T, Chippindale P (2006) Rapid diversification, incomplete isolation, and the “speciation clock” in North American Salamanders (genus Plethodon): testing the hybrid swarm hypothesis of rapid radiation. Evolution 60:2585–2603

    PubMed  CAS  Google Scholar 

  61. Wilson R, Gutiérrez D, Gutiérrez J, Monserrat V (2007) An elevational shift in butterfly species richness and composition accompanying recent climate change. Glob Change Biol 3:1873–1887

    Article  Google Scholar 

  62. Xu T, Abbot R, Milne R, Mao K, Du F, Wu G, Ciren Z, Miehe G, Liu J (2010) Phylogeography and allopatric divergence of cypress species (Cupressus L.) in the Qinghai-Tibetan Plateau and adjacent regions. BMC Evol Biol 10:194

    PubMed  Article  Google Scholar 

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Acknowledgments

We thank Shane Ramee and members of the 2009 Field Herpetology class for help with collecting salamanders. Briana Gregory and Woodrow Friend assisted with DNA extractions and Jennifer Schieltz and Caroline Bovay contributed to the GIS analysis. We thank Richard Highton, Nadia Ayoub, and two anonymous reviewers for helpful comments on earlier drafts of this manuscript. This research was covered by Virginia state collection permit #33510 and IACUC animal care and use permit DM0109. Financial support for this study was provided by the U.S. Forest Service, a Howard Hughes Medical Institute award to Washington & Lee University under the Undergraduate Science Education Program, and an H. F. Lenfest grant to D Marsh.

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Correspondence to David M. Marsh.

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Bayer, C.S.O., Sackman, A.M., Bezold, K. et al. Conservation genetics of an endemic mountaintop salamander with an extremely limited range. Conserv Genet 13, 443–454 (2012). https://doi.org/10.1007/s10592-011-0297-7

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Keywords

  • Plethodon sherando
  • Big Levels salamander
  • Plethodon cinereus
  • mtDNA
  • Phylogeography
  • Population genetics