Lunglessness in Plethodontid Salamanders is Consistent with the Hypothesis of a Mountain Stream Origin: A Response to Ruben and Boucot

Beachy, Christopher K.; Bruce, Richard C.

doi:10.1086/285360

Cited by 42 publications

(30 citation statements)

References 33 publications

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“…A large molecular dataset was interpreted as either challenging (2) or supporting (3) this idea. The origin of lunglessness also has been debated (16,(31)(32)(33)(34), and an analysis in the context of geologic history favored an Appalachian origin but did not reject a western North American or eastern Asian origin (16). We combined a robust phylogenetic hypothesis for all Holarctic genera, divergence time estimates, paleographic reconstructions, and a biodiversity analysis to examine the ''Out of Appalachia'' hypothesis.…”

Section: Resultsmentioning

confidence: 99%

Rapid diversification and dispersal during periods of global warming by plethodontid salamanders

Vieites

Min

Wake

2007

Proc. Natl. Acad. Sci. U.S.A.

207

235

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A phylogeny and timescale derived from analyses of multilocus nuclear DNA sequences for Holarctic genera of plethodontid salamanders reveal them to be an old radiation whose common ancestor diverged from sister taxa in the late Jurassic and underwent rapid diversification during the late Cretaceous. A North American origin of plethodontids was followed by a continentalwide diversification, not necessarily centered only in the Appalachian region. The colonization of Eurasia by plethodontids most likely occurred once, by dispersal during the late Cretaceous. Subsequent diversification in Asia led to the origin of Hydromantes and Karsenia, with the former then dispersing both to Europe and back to North America. Salamanders underwent rapid episodes of diversification and dispersal that coincided with major global warming events during the late Cretaceous and again during the Paleocene-Eocene thermal optimum. The major clades of plethodontids were established during these episodes, contemporaneously with similar phenomena in angiosperms, arthropods, birds, and mammals. Periods of global warming may have promoted diversification and both inter-and transcontinental dispersal in northern hemisphere salamanders by making available terrain that shortened dispersal routes and offered new opportunities for adaptive and vicariant evolution.historical biogeography ͉ paleogeography ͉ Plethodontidae dispersal ͉ salamander phylogeny ͉ phylogeny P lethodontidae, the most speciose family of salamanders, is also the most differentiated in morphology, ecology, and behavior. The family includes Ϸ68% of the extant described species of caudate amphibians (1). New analyses of mtDNA, nuclear DNA, and morphology (2-6) have achieved consensus on many aspects of phylogenetic relationships, but unresolved conflicts remain. The disjunct and highly asymmetric Holarctic distribution of the family, with Ϸ98% of the species in the Americas and a few in the Mediterranean region, has long been a biogeographic puzzle (7-9), with the debate centered on the timing and route of colonization of Eurasia (reinvigorated with the recent discovery of Karsenia, the first East Asian plethodontid; ref. 10

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Section: Resultsmentioning

confidence: 99%

Rapid diversification and dispersal during periods of global warming by plethodontid salamanders

Vieites

Min

Wake

2007

Proc. Natl. Acad. Sci. U.S.A.

207

235

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“…Small size is not concomitant with the evolution of loss of lungs in Atretochoana; its large size, hypervascularization of the skin and skeletomuscular modifications appear to be an entirely different response to selection. Wilder & Dunn (1920), Dunn (1926), Wake (1966) and Beachy & Bruce (1992) all concluded that plethodontid stream dwellers lost their lungs as a rheotropic adaptation for larvae in the cool, fast-flowing mountain brook habitats of Appalachia. Conversely, Ruben & Boucot (1989) stated that plethodontid ancestors probably reduced head size and concomitantly lung development during their evolution in the Mesozoic of Appalachia, then a warm, low-elevation, non-montane region.…”

Section: Discussionmentioning

confidence: 99%

A new lungless caecilian (Amphibia: Gymnophiona) from Guyana

Wake

Donnelly

2009

Proc. R. Soc. B.

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We report the discovery of a single specimen of a small, terrestrial, lungless caecilian, the second known taxon of lungless caecilians. It differs from all other caecilians in lacking open external nares, and from the large aquatic lungless species described by Nussbaum & Wilkinson (Nussbaum, R. A. & Wilkinson, M. 1995 Proc. R. Soc. Lond. B 261, 331 -335) in having no significant skull modifications. All modifications are of 'soft morphology' (covered external nares and choanae, lung and pulmonary vessel loss, etc.). A new genus and species are described to accommodate this form. Aspects of its skull and visceral morphology are described and considered in terms of the possible life history and evolution of the species, and compared with those of other lungless amphibians.

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“…A direct-developing plethodontid ancestor (Fig. 3a) necessitates reevaluation of several hypotheses, including a stream origin for the clade and the ecological causes of lung loss (29)(30)(31)(32)(33)(34)(35).…”

Section: Different Levels Of Nodal Support Among Partitioning Strategmentioning

confidence: 99%

Morphological homoplasy, life history evolution, and historical biogeography of plethodontid salamanders inferred from complete mitochondrial genomes

Mueller

Macey

Jaekel

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

234

243

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The evolutionary history of the largest salamander family (Plethodontidae) is characterized by extreme morphological homoplasy. Analysis of the mechanisms generating such homoplasy requires an independent molecular phylogeny. To this end, we sequenced 24 complete mitochondrial genomes (22 plethodontids and two outgroup taxa), added data for three species from GenBank, and performed partitioned and unpartitioned Bayesian, maximum likelihood, and maximum parsimony phylogenetic analyses. We explored four dataset partitioning strategies to account for evolutionary process heterogeneity among genes and codon positions, all of which yielded increased model likelihoods and decreased numbers of supported nodes in the topologies (Bayesian posterior probability >0.95) relative to the unpartitioned analysis. Our phylogenetic analyses yielded congruent trees that contrast with the traditional morphology-based taxonomy; the monophyly of three of four major groups is rejected. Reanalysis of current hypotheses in light of these evolutionary relationships suggests that (i) a larval life history stage reevolved from a direct-developing ancestor multiple times; (ii) there is no phylogenetic support for the ''Out of Appalachia'' hypothesis of plethodontid origins; and (iii) novel scenarios must be reconstructed for the convergent evolution of projectile tongues, reduction in toe number, and specialization for defensive tail loss. Some of these scenarios imply morphological transformation series that proceed in the opposite direction than was previously thought. In addition, they suggest surprising evolutionary lability in traits previously interpreted to be conservative.partitioned Bayesian analysis ͉ larvae ͉ tongues ͉ tail autotomy ͉ digits M ore than two-thirds of the 522 species of salamanders are members of Plethodontidae (http:͞͞amphibiaweb.org), a clade that exhibits both extreme long-term stasis and great adaptive diversity in life history, ecology, and morphology. Morphological evolution in plethodontids is characterized by extensive homoplasy (1). Previous studies examining the causes of this homoplasy identify recurrent morphological transformations and address both their outcomes, or derived character states, and their necessary ancestral preconditions (2, 3). Two plethodontid features figure prominently in shaping morphological evolution: lunglessness, a synapomorphy for the clade, and direct development, present in three of the four major groups.No well supported molecular phylogenetic hypothesis exists for plethodontids. As a consequence, all analyses of morphological homoplasy are based on phylogenies constructed from many of these same homoplastic characters (4). We present a molecular phylogenetic hypothesis for plethodontids based on 27 complete mitochondrial genomes, 24 of which were sequenced for this study. We explore four strategies for partitioning our dataset in a Bayesian phylogenetic framework and compare those results to maximum parsimony (MP) and maximum likelihood (ML) results. Our mitochondrial phylo...

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Lunglessness in Plethodontid Salamanders is Consistent with the Hypothesis of a Mountain Stream Origin: A Response to Ruben and Boucot

Cited by 42 publications

References 33 publications

Rapid diversification and dispersal during periods of global warming by plethodontid salamanders

Rapid diversification and dispersal during periods of global warming by plethodontid salamanders

A new lungless caecilian (Amphibia: Gymnophiona) from Guyana

Morphological homoplasy, life history evolution, and historical biogeography of plethodontid salamanders inferred from complete mitochondrial genomes

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