Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

Testing Nested Phylogenetic and Phylogeographic Hypotheses in the Plethodon vandykei Species Group

Bryan C. Carstens, Angela L. Stevenson, Jeremiah D. Degenhardt and Jack Sullivan
Systematic Biology
Vol. 53, No. 5 (Oct., 2004), pp. 781-792
Stable URL: http://www.jstor.org/stable/4135364
Page Count: 12
  • Download ($42.00)
  • Cite this Item
Testing Nested Phylogenetic and Phylogeographic Hypotheses in the Plethodon vandykei Species Group
Preview not available

Abstract

Mesic forests in the North American Pacific Northwest occur in two disjunct areas: along the coastal and Cascade ranges of Oregon, Washington, and British Columbia as well as the Northern Rocky Mountains of Idaho, Montana, and British Columbia. Over 150 species or species complexes have disjunct populations in each area, and a priori hypotheses based on phytogeography and geology potentially explain the disjunction via either dispersal or vicariance. Here, we test these hypotheses in the disjunct salamander complex Plethodon vandykei and P. idahoensis by collecting genetic data (669 bp of Cyt b) from 262 individuals. Maximum likelihood analysis indicated reciprocal monophyly of these species, supporting the ancient vicariance hypothesis, whereas parametric bootstrap and Bayesian hypothesis testing allow rejection of the dispersal hypothesis. The coalescent estimate of the time since population divergence (estimated using MDIV) is $3.75 \times 10^6$ years, and the 95% credibility interval of this value overlaps with the geological estimate of vicariance, but not the hypothesized dispersal. These results are congruent with the pattern seen in other mesic forest amphibian lineages and suggest disjunction in amphibians may be a concerted response to a geological/climatological event. Within P. idahoensis, we tested the corollary hypothesis of an inland Pleistocene refugium in the Clearwater drainage with nested clade analysis and coalescent estimates of population growth rate (g). Both analyses support post-Pleistocene expansion from the Clearwater refugium. We corroborated this result by calculating Tajima's D and mismatch distribution within each drainage, showing strong evidence for recent population expansion within most drainages. This work demonstrates the utility of statistical phylogeography and contributes two novel analytical tools: tests of stationarity with respect to topology in the Bayesian estimation, and the use of coalescent simulations to test the significance of the population growth-rate parameter.

Page Thumbnails

  • Thumbnail: Page 
781
    781
  • Thumbnail: Page 
782
    782
  • Thumbnail: Page 
783
    783
  • Thumbnail: Page 
784
    784
  • Thumbnail: Page 
785
    785
  • Thumbnail: Page 
786
    786
  • Thumbnail: Page 
787
    787
  • Thumbnail: Page 
788
    788
  • Thumbnail: Page 
789
    789
  • Thumbnail: Page 
790
    790
  • Thumbnail: Page 
791
    791
  • Thumbnail: Page 
792
    792