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Species boundaries, phylogeography and conservation genetics of the red-legged frog (Rana aurora/drytonii) complex

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Species boundaries, phylogeography and conservation genetics of the red-legged frog (Rana aurora/drytonii) complex. Presented by: Chris Burton & Matt Meyer. Presentation Overview. Introduction – Matt Materials and Methods – Chris Results – Chris Discussion and Implications - Matt.

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Species boundaries, phylogeography and conservation genetics of the red-legged frog (Rana aurora/drytonii) complex

Presented by: Chris Burton & Matt Meyer

presentation overview
Presentation Overview
  • Introduction – Matt
  • Materials and Methods – Chris
  • Results – Chris
  • Discussion and Implications - Matt
r aurora
R. Aurora
  • Originally classified as two distinct species: R. aurora (Northern red-legged frog) and R. draytonii (California red-legged frog)
  • Reclassified R. aurora as a single polytypic species with two subspecies, R. a. aurora & R. a. draytonii
  • Currently R. a. aurora and R. a. draytonii are conspecific subspecies

R. a. aurora

R. a. draytonii

r aurora4
R. aurora
  • Once widespread in Sierra Nevada and San Joaquin Valley
  • Currently only 6 known, recently discovered, populations still in existence in these areas
  • R. a. draytonnii – threatened under US Endangered Species Act. – Enormous economic and ecological consequences
  • Mark Twain’s – “The Celebrated Jumping Frog of Calaveras County”

Restricted to Pacific Coast of North America from southern British Columbia to northern Mexico.

  • Broad Zone of Intergradation – several hundred kilometers in northern California

materials and methods
Materials and Methods


  • 108 Specimen from six taxa
  • Sample 50 sites that span the range of aurora and draytonii – (1 to 4 from each site)
  • Included three outgroup taxa
    • R. boylii
    • R. muscosa
    • R. catesbeiana
molecular methods
Molecular Methods
  • DNA was extracted
  • Primers were developed to amplify a fragment of cytochrome b mtDNA from all taxa
  • Species specific Primers
      • cytb1-ra
      • cytb1-rm
      • cytb1-rb
      • cytb2-ra
  • Individual were sequenced in both directions
  • Sequences ranged from 297 to 397bp (most ~ 350bp)
  • Parsimony analysis was ran on both short and full fragments
  • Likelihood analysis used MODELTEST for a common 287bp fragment
  • Bootstrap proportions (BP) were used to asses the strength of the trees
  • Parametric bootstrapping used to test a prior hypthesis of relationships
  • 47of 107 sequnces were unique
  • All individuals showed low frequency of guanine. – f(G)=0.15
  • Optimal Model selection HKY+G



  • Several well supported clades
  • Demonstrate a sister-group between aurora and cascadae
  • aurora and cascadae are not a monophyletic group
bootstrap likelihood of subset of unique sequences
Bootstrap Likelihood of Subset of Unique Sequences
  • 15 sequences – 3 of each major group
  • Show monophyly of individual taxon and the monophyly of aurora and cascadea clade
parametric bootstrap analysis
Parametric Bootstrap Analysis
  • Test Hypothesis that Rana a. aurora and R. a. draytonii are sister taxa
  • Search for a model tree, with aurora + draytonii forming an exclusive clade
the aurora draytonii contact zone
The aurora/draytonii contact zone
  • Sample effort was supplemented
    • To approximate the width of the contact zone
    • To identify biogeographical barriers
  • Found that the two over lap over a several-km region
  • Pure aurora found from Big River north
  • Pure draytonii from Mills Creek south
  • In between both were found
  • Breeding dynamics or restriction of overlap zone can not be determined due to only one or a few indiviuals being sequenced per site
  • However, mtDNA contact zone can be determined to be narrow with no obvious barriers to gene flow
discussion and conclusions
Discussion and Conclusions
  • mtDNA data supports the separate species hypothesis based on:
      • Relatively deep differentiation and reciprocal monophyly of aurora and draytonii
      • The sister group relationship of aurora and cascadae and the exclusion of draytonii
  • Assuming the data reflects the correct order of speciation:
      • Split 1 – between northern (aurora & cascadae) and southern frogs (draytonii)
      • Split 2 – between coast range (aurora) and interior cascade mountains (cascadae)
  • Past studies have shown two distinct phylogeographical splits along the Pacific Coast in California
    • North/South break
    • Northern California break
  • These phylogeographic boundaries relatively coincide with the north and south ends of the aurora and draytonii contact zone
  • Data reflects history of species, not just mitochondrion
species conservation implications
Species Conservation / Implications
  • As a result of the data, many of the population that were thought to be intergrades are not.
    • draytonii (protected species) extends farther north
    • Confirmation with nuclear markers could result in a conservation status adjustment
  • Single draytonii population in southern California
    • Only 3 adult males
    • Captive breeding
    • Data suggests more closely related to distant draytonii populations rather than closest ones