TY - JOUR
T1 - A new phylogeny for the genus Picea from plastid, mitochondrial, and nuclear sequences
AU - Lockwood, Jared D.
AU - Aleksić, Jelena M.
AU - Zou, Jiabin
AU - Wang, Jing
AU - Liu, Jianquan
AU - Renner, Susanne S.
N1 - Funding Information:
We thank U. Pietzarka at the Tharandt Botanical Garden, B. Jaquish at the Kalamalka Research Station, and M. Tollefsrud at the Norwegian Forest and Landscape Institute for samples; M. Silber for assistance in the laboratory; B. LePage for discussion of fossils; B. Moore for a matrix of past continental connection probabilities; and G. Holman, A. Klein, and C. Campbell for information on Picea accessions sampled in earlier studies. Financial support came from the Ecology, Evolution, and Systematics program of Munich University, the Ministry of Education and Science of the Republic of Serbia (Research Grant 173030 to JA), and the National Natural Science Foundation of China (Research Grant 30930072 to LJQ) and the Key Project of International Collaboration Program, the Ministry of Science and Technology of China (Research Grant 2010DFB63500 to LJQ).
PY - 2013/12
Y1 - 2013/12
N2 - Studies over the past ten years have shown that the crown groups of most conifer genera are only about 15-25. Ma old. The genus Picea (spruces, Pinaceae), with around 35 species, appears to be no exception. In addition, molecular studies of co-existing spruce species have demonstrated frequent introgression. Perhaps not surprisingly therefore previous phylogenetic studies of species relationships in Picea, based mostly on plastid sequences, suffered from poor statistical support. We therefore generated mitochondrial, nuclear, and further plastid DNA sequences from carefully sourced material, striking a balance between alignability with outgroups and phylogenetic signal content. Motif duplications in mitochondrial introns were treated as characters in a stochastic Dollo model; molecular clock models were calibrated with fossils; and ancestral ranges were inferred under maximum likelihood. In agreement with previous findings, Picea diverged from its sister clade 180 million years ago (Ma), and the most recent common ancestor of today's spruces dates to 28. Ma. Different from previous analyses though, we find a large Asian clade, an American clade, and a Eurasian clade. Two expansions occurred from Asia to North America and several between Asia and Europe. Chinese P. brachytyla, American P. engelmannii, and Norway spruce, P. abies, are not monophyletic, and North America has ten, not eight species. Divergence times imply that Pleistocene refugia are unlikely to be the full explanation for the relationships between the European species and their East Asian relatives. Thus, northern Norway spruce may be part of an Asian species complex that diverged from the southern Norway spruce lineage in the Upper Miocene, some 6. Ma, which can explain the deep genetic gap noted in phylogeographic studies of Norway spruce. The large effective population sizes of spruces, and incomplete lineage sorting during speciation, mean that the interspecific relationships within each of the geographic clades require further studies, especially based on genomic information and population genetic data.
AB - Studies over the past ten years have shown that the crown groups of most conifer genera are only about 15-25. Ma old. The genus Picea (spruces, Pinaceae), with around 35 species, appears to be no exception. In addition, molecular studies of co-existing spruce species have demonstrated frequent introgression. Perhaps not surprisingly therefore previous phylogenetic studies of species relationships in Picea, based mostly on plastid sequences, suffered from poor statistical support. We therefore generated mitochondrial, nuclear, and further plastid DNA sequences from carefully sourced material, striking a balance between alignability with outgroups and phylogenetic signal content. Motif duplications in mitochondrial introns were treated as characters in a stochastic Dollo model; molecular clock models were calibrated with fossils; and ancestral ranges were inferred under maximum likelihood. In agreement with previous findings, Picea diverged from its sister clade 180 million years ago (Ma), and the most recent common ancestor of today's spruces dates to 28. Ma. Different from previous analyses though, we find a large Asian clade, an American clade, and a Eurasian clade. Two expansions occurred from Asia to North America and several between Asia and Europe. Chinese P. brachytyla, American P. engelmannii, and Norway spruce, P. abies, are not monophyletic, and North America has ten, not eight species. Divergence times imply that Pleistocene refugia are unlikely to be the full explanation for the relationships between the European species and their East Asian relatives. Thus, northern Norway spruce may be part of an Asian species complex that diverged from the southern Norway spruce lineage in the Upper Miocene, some 6. Ma, which can explain the deep genetic gap noted in phylogeographic studies of Norway spruce. The large effective population sizes of spruces, and incomplete lineage sorting during speciation, mean that the interspecific relationships within each of the geographic clades require further studies, especially based on genomic information and population genetic data.
KW - Fossil calibrations
KW - Historical biogeography
KW - Mitochondrial nad introns
KW - Molecular clocks
KW - North American spruces
KW - Secondary structure-based alignment
KW - Stochastic Dollo model
UR - http://www.scopus.com/inward/record.url?scp=84884592869&partnerID=8YFLogxK
U2 - 10.1016/j.ympev.2013.07.004
DO - 10.1016/j.ympev.2013.07.004
M3 - Article
C2 - 23871916
AN - SCOPUS:84884592869
SN - 1055-7903
VL - 69
SP - 717
EP - 727
JO - Molecular Phylogenetics and Evolution
JF - Molecular Phylogenetics and Evolution
IS - 3
ER -