Molecular Systematics of Plethodon and Aneides (Caudata: Plethodontidae: Plethodontini): Phylogenetic Analysis of an Old and Rapid Radiation

Mahoney, Meredith J.

doi:10.1006/mpev.2000.0880

Cited by 27 publications

(22 citation statements)

References 59 publications

(113 reference statements)

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“…Recent work on higher-level plethodontid relationships shows that Plethodon is monophyletic with respect to other Highton and Larson 1979;Mahoney 2001;Chippindale et al 2004). …”

Section: Sampling Of Taxamentioning

confidence: 99%

Rapid Diversification, Incomplete Isolation, and the "Speciation Clock" in North American Salamanders (Genus Plethodon): Testing the Hybrid Swarm Hypothesis of Rapid Radiation

2006

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The history of life has been marked by several spectacular radiations, in which many lineages arise over a short period of time. A possible consequence of such rapid splitting in the recent past is that the intrinsic barriers that prevent gene flow between many species may have too little time to develop fully, leading to extensive hybridization among recently evolved lineages. The salamander genus Plethodon in eastern North America has been proposed as a possible example of this scenario, but without explicit statistical tests. In this paper, we present a nearly comprehensive phylogeny for the 45 extant species of eastern Plethodon, based on DNA sequences of mitochondrial (two genes, 1335 base pairs) and nuclear genes (two genes, up to 3481 base pairs). We then use this phylogeny to examine rates and patterns of diversification and hybridization. We find significantly rapid diversification within the glutinosus species group. Examining patterns of natural hybridization in light of the phylogeny shows considerable hybridization within this clade, including introgression between species that are morphologically distinct and distantly related. Reproductive isolation increases over time and may be very weak among the most recently diverged species. These results suggest that the origin of species and the evolution of intrinsic reproductive isolating mechanisms, rather than being synonymous, may be decoupled in some cases (i.e., rapid origin of lineages outstrips the “;speciation clock”). In contrast to the conclusions of a recent review of adaptive radiation and hybridization, we suggest that extensive hybridization sometimes may be a consequence, rather than a cause, of rapid diversification.

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“…Recent work on higher-level plethodontid relationships shows that Plethodon is monophyletic with respect to other Highton and Larson 1979;Mahoney 2001;Chippindale et al 2004). …”

Section: Sampling Of Taxamentioning

confidence: 99%

Rapid Diversification, Incomplete Isolation, and the "Speciation Clock" in North American Salamanders (Genus Plethodon): Testing the Hybrid Swarm Hypothesis of Rapid Radiation

2006

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“…Many species are endemic to the Appalachian Highlands, where they are among the most abundant and ecologically important vertebrates in forest ecosystems (Davic & Welsh 2004). Despite ancient histories of evolutionary separation (Highton & Larson 1979;Maxson et al 1979;Mahoney 2001), species of Plethodon exhibit extreme morphological stasis (Wake et al 1983;Larson 1984;Carr 1996;Adams & Rohlf 2000), suggesting low rates of adaptive phenotypic evolution relative to other plethodontid taxa (García-París et al 2000;Parra-Olea et al 2004;Kozak et al 2005). Geographic patterns of genetic variation are described for hundreds of natural populations and the geographic limits of many morphologically cryptic species are well known (Highton 1995).…”

Section: Introductionmentioning

confidence: 99%

Rapid lineage accumulation in a non-adaptive radiation: phylogenetic analysis of diversification rates in eastern North American woodland salamanders (Plethodontidae:Plethodon)

2005

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Adaptive radiations have served as model systems for quantifying the build-up of species richness. Few studies have quantified the tempo of diversification in species-rich clades that contain negligible adaptive disparity, making the macroevolutionary consequences of different modes of evolutionary radiation difficult to assess. We use mitochondrial-DNA sequence data and recently developed phylogenetic methodologies to explore the tempo of diversification of eastern North American Plethodon, a species-rich clade of woodland salamanders exhibiting only limited phenotypic disparity. Lineage-through-time analysis reveals a high rate of lineage accumulation, 0.8 species per million years, occurring 11-8 million years ago in the P. glutinosus species group, followed by decreasing rates. This high rate of lineage accumulation is exceptional, comparable to the most rapid of adaptive radiations. In contrast to classic models of adaptive radiation where ecological niche divergence is linked to the origin of species, we propose that phylogenetic niche conservatism contributes to the rapid accumulation of P. glutinosus-group lineages by promoting vicariant isolation and multiplication of species across a spatially and temporally fluctuating environment. These closely related and ecologically similar lineages persist through longperiods of evolutionary time and form strong barriers to the geographic spread of their neighbours, producing a subsequent decline in lineage accumulation. Rapid diversification among lineages exhibiting long-term maintenance of their bioclimatic niche requirements is an under-appreciated phenomenon driving the build-up of species richness.

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“…Geographic patterns of genetic variation have been described across hundreds of populations and geographic boundaries of many cryptic species have been studied (e.g., Tilley and Schwertdfeger 1981;Karlin and Guttman 1986;Highton et al 1989;Highton 1995Highton , 1997Highton , 1999Tilley and Mahoney 1996;Bonett 2000;Highton and Peabody 2000;Tilley 2000;Mead et al 2001;Anderson and Tilley 2003;Weisrock et al 2005;Weisrock and Larson 2006). In addition, recent phylogenetic analyses provide a robust framework for identifying extant sister species (Mahoney 2001;Rissler and Taylor 2003;Chippindale et al 2004;Kozak et al 2005Kozak et al , 2006Wiens et al 2006). Finally, the availability of thousands of georeferenced sampling locations in natural history museums permits rigorous quantification of potential climatic factors limiting species' geographic distributions.…”

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confidence: 99%

Does Niche Conservatism Promote Speciation? A Case Study in North American Salamanders

2006

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Abstract. Recent speciation research has generally focused on how lineages that originate in allopatry evolve intrinsic reproductive isolation, or how ecological divergence promotes nonallopatric speciation. However, the ecological basis of allopatric isolation, which underlies the most common geographic mode of speciation, remains poorly understood and largely unstudied. Here, we explore the ecological and evolutionary factors that promote speciation in Desmognathus and Plethodon salamanders from temperate eastern North America. Based on published molecular phylogenetic estimates and the degree of geographic range overlap among extant species, we find strong evidence for a role for geographic isolation in speciation. We then examine the relationship between climatic variation and speciation in 16 sister-taxon pairs using geographic information system maps of climatic variables, new methods for modeling species' potential geographic distributions, and data on geographic patterns of genetic variation. In contrast to recent studies in tropical montane regions, we found no evidence for parapatric speciation along climatic gradients. Instead, many montane sister taxa in the Appalachian Highlands inhabit similar climatic niches and seemingly are allopatric because they are unable to tolerate the climatic conditions in the intervening lowlands. This temporal and spatial-ecological pattern suggests that niche conservatism, rather than niche divergence, plays the primary role in promoting allopatric speciation and montane endemism in this species-rich group of vertebrates. Our results demonstrate that even the relatively subtle climatic differences between montane and lowland habitats in eastern North America may play a key role in the origin of new species.

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Molecular Systematics of Plethodon and Aneides (Caudata: Plethodontidae: Plethodontini): Phylogenetic Analysis of an Old and Rapid Radiation

Cited by 27 publications

References 59 publications

Rapid Diversification, Incomplete Isolation, and the "Speciation Clock" in North American Salamanders (Genus Plethodon): Testing the Hybrid Swarm Hypothesis of Rapid Radiation

Rapid Diversification, Incomplete Isolation, and the "Speciation Clock" in North American Salamanders (Genus Plethodon): Testing the Hybrid Swarm Hypothesis of Rapid Radiation

Rapid lineage accumulation in a non-adaptive radiation: phylogenetic analysis of diversification rates in eastern North American woodland salamanders (Plethodontidae:Plethodon)

Does Niche Conservatism Promote Speciation? A Case Study in North American Salamanders

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