Discordant mtDNA and cpDNA phylogenies indicate geographic speciation and reticulation as driving factors for the diversification of the genus Picea

Abstract

The phylogeny of the genus Picea was investigated by sequencing three loci from the paternally inherited chloroplast genome (trnK, rbcL and trnTLF) and the intron 2 of the maternally transmitted mitochondrial gene nad1 for 35 species. Significant topological differences were found between the trnK tree and the rbcL and trnTLF phylogenetic trees, and between cpDNA and mtDNA phylogenies. None of the phylogenies matched morphological classifications. The mtDNA phylogeny was geographically more structured than cpDNA phylogenies, reflecting the different inheritance of the two cytoplasmic genomes in the Pinaceae and their differential dispersion by seed only and seed and pollen, respectively. Most North American taxa formed a monophyletic group on the mtDNA tree, with topological patterns suggesting geographic speciation by range fragmentation or by dispersal and isolation. Similar patterns were also found among Asian taxa. Such a trend towards geographic speciation is anticipated in other Pinaceae genera with similar life history, autecology and reproductive system. Incongruences between organelle phylogenies suggested the occurrence of mtDNA capture by invading cpDNA. Incongruences between cpDNA partitions further suggested heterologous recombination presumably also linked to ancient reticulate evolution. Whilst cpDNA appears potentially valuable for molecular taxonomy and systematics purposes, these results emphasize the reduced value of cpDNA to infer vertical descent and the speciation history for plants with paternal transmission and high dispersal of their chloroplast genome.

Range-wide chloroplast and mitochondrial DNA imprints reveal multiple lineages and complex biogeographic history for Douglas-fir

“…Such vicariance factors have been shown to be crucial for the diversification of widely distributed North American forest conifers in their major subspecific lineages (Gérardi et al 2010;Godbout et al 2005Godbout et al , 2008Jaramillo-Correa et al 2009). In addition, this evolutionary trend is in line with the recognition of vicariance and geographical/allopatric speciation as a major cause for the birth of new species in the Pinaceae (Bouillé et al 2011;Perron et al 2000). Thus, the geographically well-defined major intraspecific lineages and varieties of Douglas-fir likely reflect an intermediate stage of speciation potentially leading towards the formation of new species.…”

Origins of Plant Diversity in the California Floristic Province

“…Brewer spruce (Picea breweriana; Pinaceae), endemic to the Klamath Ranges and long regarded as a paleoendemic with closest relatives in Asia, was resolved as sister to all other sampled spruces, based on cpDNA, or as sister to northern Asian Picea obovata, outside the North American clade, based on mitochondrial DNA (mtDNA), also in keeping with relict status (Bouillé et al 2011). Incense cedar (Calocedrus decurrens; Cupressaceae), which ranges to central western Oregon but is otherwise within the CA-FP, is known from fossils outside its current range in the Pacific Northwest and was estimated from an nrDNA phylogeny to have diverged from a common ancestor with all other living, Asian taxa of Calocedrus at ∼25.2 Ma, putatively because of vicariance; fossils of the genus also occur in Alaska, Asia, and Europe from as early as the lower Eocene (Chen et al 2009).…”

Chromosome banding in <i>Picea</i> IV. Comparative karyotype analysis of fluorescent band patterns in 25 taxa

“…Several classification systems of genus Picea were proposed by taxonomists such as Mayr (1890) and Liu (1982) based on vegetative and reproductive structures, and a revision recognized two sections each with two subsections (Farjon 1990(Farjon , 2001(Farjon , 2010) (see Table 1 in Bouillé et al 2011). These taxonomical treatments were somewhat complex and difficult to compare with the species alignment based on the CMA-band pattern.…”

“…These taxonomical treatments were somewhat complex and difficult to compare with the species alignment based on the CMA-band pattern. Recently several molecular phylogenetic studies were performed in Picea (Ran et al 2006, Bouillé et al 2011, Lockwood et al 2013. The molecular phylogenetic relationship (Fig.…”