Phylogenetic analyses of the harvest mouse,Micromys minutus (Rodentia: Muridae) based on the complete mitogenome sequences

Harvest Mouse (Micromys minutus) has a very wide range of distribution in Asia and Europe. However, the phylogenetic relationship of M. minutus is still uncertain. In this study, we determined the complete mitochondrial (mt) genome sequences of M. minutus, and used the complete mitochondrial genome sequences constructed the phylogenetic tree of Muroidea. The size of the genome is 16,232 bp in length and has a base composition of 33.6% A, 29.1% T, 24.8% C, and 12.5% G. The mitogenome structure was similar to that of typical vertebrate and other rodents' mitochondrial genomes, includes 13 protein-coding genes, 2 rRNA genes (12S rRNA and 16S rRNA), 22 tRNA genes, and 1 control region. We suggested a new initiation codon for ND5 (NADH dehydrogenase subunit), which has been never reported in the mitochondrial genome of vertebrate. The ML and BI phylogenetic trees, which based on the combination of the 12 protein-coding genes, supported strongly that the genus Micromys was represent an early offshoot within the Muridae with high support values (BI = 1.00, ML = 100).     

The mitogenomes of three beetles (Coleoptera: Polyphaga: Cucujiformia): New gene rearrangement and phylogeny

The mitochondrial genome (mitogenome) has been extensively used for studying phylogenetic relationships at different taxonomic levels. Several molecular analyses have been performed, but the phylogenetic relationships among infraorders in Polyphaga have not been well resolved. In this work, three nearly complete mitogenomes of Coleoptera, Sitophilus oryzae, Oryzaephilus surinamensis and Callosobruchus chinensis, were determined. The O. surinamensis and S. oryzae mitogenomes harbor gene content typical of other Polyphaga mitogenomes, while a gene rearrangement (trnQ) was found in the C. chinensis mitogenome. The mitogenomes of these three Coleoptera species each consist of approximately 13 protein-coding genes, 22 tRNA genes, two rRNA genes and one A + T-rich region. Phylogenetic analysis within Polyphaga was carried out based on mitochondrial data. The phylogenetic results within Polyphaga support the basal position of Cyphon sp., which belonged to Scirtoidea, Elateriformia. Within Cucujiformia, monophyletic Curculionoidea, Chrysomeloidea and Tenebrionoidea were confirmed.     

Complete mitochondrial genome sequence of the Himalayan Griffon,Gyps himalayensis (Accipitriformes: Accipitridae): Sequence,structure, and phylogenetic analyses

This is the first study to describe the mitochondrial genome of the Himalayan Griffon, Gyps himalayensis, which is an Old World vulture belonging to the family Accipitridae and occurring along the Himalayas and the adjoining Tibetan Plateau. Its mitogenome is a closed circular molecule 17,381 bp in size containing 13 protein‐coding genes, 22 tRNA coding genes, two rRNA‐coding genes, a control region (CR), and an extra pseudo‐control region (CCR) that are conserved in most Accipitridae mitogenomes. The overall base composition of the G. himalayensis mitogenome is 24.55% A, 29.49% T, 31.59% C, and 14.37% G, which is typical for bird mitochondrial genomes. The alignment of the Accipitridae species control regions showed high levels of genetic variation and abundant AT content. At the 5′ end of the domain I region, a long continuous poly‐C sequence was found. Two tandem repeats were found in the pseudo‐control regions. Phylogenetic analysis with Bayesian inference and maximum likelihood based on 13 protein‐coding genes indicated that the relationships at the family level were (Falconidae + (Cathartidae + (Sagittariidae + (Accipitridae + Pandionidae))). In the Accipitridae clade, G. himalayensis is more closely related to Aegypius monachus than to Spilornis cheela. The complete mitogenome of G. himalayensis provides a potentially useful resource for further exploration of the taxonomic status and phylogenetic history of Gyps species.     

Complete mitogenome sequence of black carp (<Emphasis Type="Italic">Mylopharyngodon piceus</Emphasis>) and its use for molecular phylogeny of leuciscine fishes

The black carp Mylopharyngodon piceus (Cyprinidae), native to eastern Asian, is a large, commercially important fish, and has been introduced to many other countries for variable reasons. In this study, the complete mitochondrial genome sequences from three specimens of black carp were first determined and were used to evaluate the sister relationship between black carp and grass carp (Ctenopharyngodon idellus). Two individuals had a mitogenome of 16,609 bp, while the other was 16,611 bp in length. Similar to most vertebrates, the black carp contains the same gene order and an identical number of genes or regions, including 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes, and 1 putative control region. Phylogenetic analyses using three different computational algorithms (Maximum Parsimony, Maximum Likelihood, and Bayesian analysis) revealed two distinct clades in subfamily Leuciscinae. However, the sister taxonomic relationship of black carp and grass carp was not observed using sequences of nearly complete mitochondrial genomes, which suggests more nuclear gene markers are needed to resolve the phylogenetic relationship between black carp and grass carp.     

The complete mitogenome of the hydrothermal vent crab Gandalfus yunohana (Crustacea: Decapoda: Brachyura): a link between the Bythograeoidea and Xanthoidea

Yang, J.‐S., Nagasawa, H., Fujiwara, Y., Tsuchida, S. & Yang, W.‐J. The complete mitogenome of the hydrothermal vent crab Gandalfus yunohana (Crustacea: Decapoda: Brachyura): a link between the Bythograeoidea and Xanthoidea. —Zoologica Scripta, 39, 621–630. Metazoan mitochondrial genomes (mitogenomes) are often used for all‐level phylogenetic analyses and evolution modelling. Although mitochondrial fragments facilitate studying the occurrence and dispersal of hydrothermal‐vent species, few complete mitogenomes have been determined for comprehensive analyses. We determined the complete nucleotide sequence of the bythograeid crab Gandalfus yunohana. The G. yunohana mitogenome is 15 567 bp in length and with an AT content of 69.9%. A putative control region of 625 bp was identified due to its position (between rrnS and trnI) and AT richness (72.8%), which exhibits high similarity with that of the Australian giant crab Pseudocarcinus gigas. The mitochondrial gene order is identical to the typical brachyuran mode. Codon usage, nucleotide composition and bias are well conserved as the Brachyura. Phylogenetic analyses from protein‐coding genes indicated its closest relationship with P. gigas. All the results support the close evolution distance between the Bythograeoidea and Xanthoidea, which might imply the possible origin that the only superfamily of vent crabs underwent. The G. yunohana mitogenome exhibits highly conserved characteristics with those of other decapods, especially its close relative brachyurans. A recent origin rather than the relic fauna was suggested. The present study will supply considerable data of use for both genomics and evolutionary research on hydrothermal vent ecosystems.     

Complete mitochondrial genome of Spilosoma lubricipedum (Noctuoidea: Erebidae) and implications for phylogeny of noctuid insects

Mitochondrial genomes (mitogenomes) have been widely used for studies on phylogenetic relationships and molecular evolutionary biology. Here, the complete mitogenome sequence of Spilosoma lubricipedum (Noctuoidea: Erebidae: Arctiinae) was determined (total length 15,375 bp) and phylogenetic analyses S. lubricipedum were inferred from available noctuid sequence data. The mitogenome of S. lubricipedum was found to be highly A + T-biased (81.39%) and exhibited negative AT- and GC-skews. All 13 protein-coding genes (PCGs) were initiated by ATN codons, except for cox1 with CGA. All tRNAs exhibited typical clover-leaf secondary structures, except for trnS1. The gene order of the S. lubricipedum mitogenome was trnM-trnI-trnQ-nad2. The A + T-rich region of S. lubricipedum contained several conservative features common to noctuid insects. Phylogenetic analysis within Noctuoidea was carried out based on mitochondrial data. Results showed that S. lubricipedum belonged to Erebidae and the Noctuoidea insects could be divided into five well-supported families (Notodontidae + (Erebidae + (Nolidae + (Euteliidae + Noctuidae)))).     

Characterization and phylogenetic analysis of the complete mitogenome of a rare cavefish, <Emphasis Type="Italic">Sinocyclocheilus multipunctatus</Emphasis> (Cypriniformes: Cyprinidae)

The genus Sinocyclocheilus is a representative group of cave creatures. However, genetic studies on Sinocyclocheilus are rare. The primary objective of this study was to explore the structure and feature of the complete mitochondrial genome of S. multipunctatus, and reconstruct the mitogenomic phylogeny of Sinocyclocheilus. The mitochondrial DNA of S. multipunctatus was amplified by overlapping PCR fragments. The mitogenome was assembled by the SeqMan and annotated using MitoAnnotator. The phylogenetic tree was established using the Bayesian inference and Maximum likelihood methods. The mitogenome of S. multipunctatus is a typical circular molecule of 16,586 bp with base composition A (31.25%), T (25.90%), G (16.35%), and C (26.50%), and consists of 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNAs) genes, two ribosomal RNAs, and a 931 bp control region. Phylogenetic analysis reveals two clades in the Sinocyclocheilus with robust support. S. multipunctatus is close to a newly discovered cavefish, S. ronganensis. We obtained and described the complete mitogenome of S. multipunctatus, and investigated its phylogenetic status, which may provide a valuable resource for future phylogenetic analyses and population genetic studies in Sinocyclocheilus.     

The complete mitochondrial genome of Eriocheir japonica sinensis (Decapoda: Varunidae) and its phylogenetic analysis

The complete mitochondrial genome (mitogenome) can provide novel insights into understanding the mechanisms underlying mitogenome evolution. In this study, the complete mitogenome of Eriocheir japonica sinensis (Decapoda: Varunidae) was determined to be 16,378 bp, including 13 protein-coding genes (PCGs), two rRNA genes, 22 tRNA genes and a D-loop region. The AT skew of the E. j. sinensis mitogenome was slightly negative (−0.016), indicating a higher number of T compared with A nucleotides. The nucleotide composition of the mitogenome was also biased toward A + T nucleotides (71.6%). All PCGs were initiated by ATN codons. Eight of the 13 PCGs harbored the incomplete termination codon by T, or TA. All other tRNA genes displayed a typical clover-leaf structure of mitochondrial tRNA. The D-loop region of the E. j. sinensis mitogenome was 918 bp in length. Based on 13 PCGs, phylogenetic analysis confirmed the placement of E. j. sinensis within the Varunidae.     

Complete mitochondrial DNA sequences of the Nile tilapia (<Emphasis Type="Italic">Oreochromis niloticus</Emphasis>) and Blue tilapia (<Emphasis Type="Italic">Oreochromis aureus</Emphasis>): genome characterization and phylogeny applications

Cichlid fishes have played an important role in evolutionary biology and aquaculture industry. Nile tilapia (Oreochromis niloticus), blue tilapia (Oreochromis aureus) and Mozambique tilapia (Oreochromis mossambicus), the useful models in studying evolutionary biology within Cichlid fishes, are also mainly cultured species in aquaculture with great economic importance. In this paper, the complete nucleotide sequence of the mitochondrial genome for O. niloticus and O. aureus were determined and phylogenetic analyses from mitochondrial protein-coding genes were conducted to explore their phylogenetic relationship within Cichlids. The mitogenome is 16,625 bp for O. niloticus and 16,628 bp for O. aureus, containing the same gene order and an identical number of genes or regions with the other Cichlid fishes, including 13 protein-coding genes, two rRNA genes, 22 tRNA genes and one putative control region. Phylogenetic analyses using three different computational algorithms (maximum parsimony, maximum likelihood and Bayesian method) show O. niloticus and O. mossambicus are closely related, and O. aureus has remotely phylogenetic relationship from above two fishes.     

The complete mitochondrial genome sequences of <Emphasis Type="Italic">Chelodina rugosa</Emphasis> and <Emphasis Type="Italic">Chelus fimbriata</Emphasis> (Pleurodira: Chelidae): implications of a common absence of initiation sites (O<Subscript>L</Subscript>) in pleurodiran turtles

Within the order Testudines, while phylogenetic analyses have been performed on the suborder Cryptodira with complete mitochondrial genomes (mitogenomes), mitogenomic information from another important suborder Pleurodira has been inadequate. In the present study, complete mitochondrial DNA (mtDNA) sequences of two chelid turtles Chelodina rugosa and Chelus fimbriata were firstly determined, the lengths of which were 16,582 and 16,661 bp respectively. As the typical vertebrate mitogenome, both mtDNAs consist of 13 protein coding genes, 2 ribosomal RNAs (rRNAs), 22 transfer RNAs (tRNAs), and a long noncoding region (control region, CR). However, the initiation sites for light-strand replication (O_L), which has been identified in all reported Cryptodire mitogenomes, were not found in the putative position of the two chelid turtles and African helmeted turtle Pelomedusa subrufa. The results suggested that the absence of mitogenomic initiation sites (O_L) could be a characteristic of Pleurodira. Phylogenetic relationships of chelid turtles and other turtles were reconstructed using the reported mitogenomes. Both maximum likelihood (ML) and Bayesian inference (BI) analyses suggested the monophyly of Pleurodira and Cryptodira as well as a sister group relationship between the two chelid turtles with strong statistical support. This phylogenetic framework was also utilized to estimate divergence dates among lineages using relaxed-clock methods combined with fossil evidence. Divergence estimates revealed that genus Chelodina diverged from genus Chelus in Late Cretaceous (~83 million years ago (mya)), and the time is consistent with the vicariance of the fragments which was caused by Gondwana split.     

The complete nucleotide sequence of the mitochondrial genome of <Emphasis Type="Italic">Phthonandria atrilineata</Emphasis> (Lepidoptera: Geometridae)

Using long-polymerase chain reaction (Long-PCR) method, we determined the complete nucleotide sequence of the mitochondrial genome (mitogenome) of Phthonandria atrilineata. The complete mtDNA from P. atrilineata was 15,499 base pairs in length and contained 13 protein-coding genes (PCGs), 2 rRNA genes, 22 tRNA genes, and a control region. The P. atrilineata genes were in the same order and orientation as the completely sequenced mitogenomes of other lepidopteran species. The nucleotide composition of P. atrilineata mitogenome was biased toward A + T nucleotides (81.02%), and the 13 PCGs show different A + T contents that range from 73.25% (cox1) to 92.12% (atp8). Phthonandria had the canonical set of 22 tRNA genes, that fold in the typical cloverleaf structure described for metazoan mt tRNAs, with the unique exception of trnS(AGN). The phylogenetic relationships were reconstructed with the concatenated sequences of the 13 PCGs of the mitochondrial genome, which confirmed that P. atrilineata is most closely related to the superfamily Bombycoidea.     

The first complete mitogenome of Picumnus innominatus (Aves,Piciformes, Picidae) and phylogenetic inference within the Picidae

The avian family Picidae, which is nearly global in distribution, contains the piculets (Picumninae and Nesoctitinae), the woodpeckers (Picinae), and the wrynecks (Jynginae). However, the phylogenetic relationships within the Picidae remain obscure for most genera. In the present study, the complete mitochondrial genome of Picumnus innominatus was determined and described, which was the first complete mitogenome reported in the Picumnus. The circular mitogenome of P. innominatus was 17,180 bp in size and consisted of 13 protein-coding genes (PCGs), 22 tRNAs, 2 rRNA genes, a control region (CR), and a noncoding region. The gene order and arrangement of the P. innominatus mitogenome were identical to other mitogenomes of the Picidae. Moreover, strikingly large tandem repeats were found in the noncoding region of the P. innominatus mitogenome, which have not yet been covered in other picid species to date. At the family level (Picidae), the highest dN/dS ratio was detected for the ND1 gene (1.38726) among 13 PCGs, indicating that positive selection was powerful for this gene. Bayesian and Maximum Likelihood phylogenetic analyses based on the combination of 12S rRNA and CYTB gene supported strongly that the Picumninae is monophyletic.     

Evolution of fragmented mitochondrial ribosomal RNA genes inChlamydomonas

The fragmented mitochondrial ribosomal RNAs (rRNAs) of the green algaeChlamydomonas eugametos andChlamydomonas reinhardtii are discontinuously encoded in subgenic modules that are scrambled in order and interspersed with protein coding and tRNA genes. The mitochondrial rRNA genes of these two algae differ, however, in both the distribution and organization of rRNA coding information within their respective genomes. The objectives of this study were (1) to examine the phylogenetic relationships between the mitochondrial rRNA gene sequences ofC. eugametos andC. reinhardtii and those of the conventional mitochondrial rRNA genes of the green alga,Prototheca wickerhamii, and land plants and (2) to attempt to deduce the evolutionary pathways that gave rise to the unusual mitochondrial rRNA gene structures in the genusChlamydomonas. Although phylogenetic analysis revealed an affiliation between the mitochondrial rRNA gene sequences of the twoChlamydomonas taxa to the exclusion of all other mitochondrial rRNA gene sequences tested, no specific affiliation was noted between theChlamydomonas sequences andP. wickerhamii or land plants. Calculations of the minimal number of transpositions required to convert hypothetical ancestral rRNA gene organizations to the arrangements observed forC. eugametos andC. reinhardtii mitochondrial rRNA genes, as well as a limited survey of the size of mitochondrial rRNAs in other members of the genus, lead us to propose that the last common ancestor ofChlamydomonas algae contained fragmented mitochondrial rRNA genes that were nearly co-linear with conventional rRNA genes.     

The complete mitochondrial genome of Pardosa pusiola (Araneae,Lycosidae) and its phylogenetic implications

The mitochondrial genome (mitogenome) is useful for identification and phylogenetic analyses among arthropods, but there are no sufficient mitogenome data for wolf spiders. To enrich the mitogenome database of wolf spiders, the complete mitogenome of Pardosa pusiola was sequenced by high-throughput sequencing. It is 14,284 bp, comprising 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), two ribosomal RNA genes (rRNAs), and a control region (CR). It represents a high bias toward A and T nucleotides with an A + T content of 76.49%. The mitogenome exhibited a negative AT skew (−0.13) and a positive GC skew (0.32). Most PCGs started with ATN codons and ended with TAA, TAG, or an incomplete T. In addition, most tRNAs had aberrant secondary structures with the absence of DHU arm or TΨC arm. Analysis performed with CREx software demonstrated that large-scale rearrangements of tRNAs were observed in the mitogenome of P. pusiola as compared with the putative ancestral mitogenome. The Bayesian inference (BI) and maximum likelihood (ML) phylogenetic trees based on the 13 PCGs of 25 spiders had the same topology, which could be presented as (Araneidae + (Agelenidae + (Dictynidae + Desidae)) + (Salticidae + (Thomisidae + (Oxyopidae + (Pisauridae + Lycosidae))))). This study offers a useful genetic resource for the taxonomy and phylogeny of spiders.     

Prospects on the evolutionary mitogenomics of plants: A case study on the olive family (Oleaceae)

The mitogenome is rarely used to reconstruct the evolutionary history of plants, contrary to nuclear and plastid markers. Here, we evaluate the usefulness of mitochondrial DNA for molecular evolutionary studies in Oleaceae, in which cases of cytoplasmic male sterility (CMS) and of potentially contrasted organelle inheritance are known. We compare the diversity and the evolution of mitochondrial and chloroplast genomes by focusing on the olive complex and related genera. Using high‐throughput techniques, we reconstructed complete mitogenomes (ca. 0.7 Mb) and plastomes (ca. 156 kb) for six olive accessions and one Chionanthus. A highly variable organization of mitogenomes was observed at the species level. In olive, two specific chimeric genes were identified in the mitogenome of lineage E3 and may be involved in CMS. Plastid‐derived regions (mtpt) were observed in all reconstructed mitogenomes. Through phylogenetic reconstruction, we demonstrate that multiple integrations of mtpt regions have occurred in Oleaceae, but mtpt regions shared by all members of the olive complex derive from a common ancestor. We then assembled 52 conserved mitochondrial gene regions and complete plastomes of ten additional accessions belonging to tribes Oleeae, Fontanesieae and Forsythieae. Phylogenetic congruence between topologies based on mitochondrial regions and plastomes suggests a strong disequilibrium linkage between both organellar genomes. Finally, while phylogenetic reconstruction based on plastomes fails to resolve the evolutionary history of maternal olive lineages in the Mediterranean area, their phylogenetic relationships were successfully resolved with complete mitogenomes. Overall, our study demonstrates the great potential of using mitochondrial DNA in plant phylogeographic and metagenomic studies.     

Characterization of the complete mitogenome of Trachylophus sinensis (Coleoptera: Cerambycidae: Cerambycinae), the type species of Trachylophus and its phylogenetic implications

Complete mitochondrial genomes (mitogenomes) have long been proved as reliable markers for phylogenetic reconstruction among diverse animal groups, especially benefited from recent rapid development of sequencing techniques. However, the mitogenomes of many important clades remain poorly represented, which restricted the understanding of macroscale evolutionary history of these groups. Here, we sequenced and characterized the complete mitogenome of Trachylophus sinensis, a type species of the Trachylophus genus, which also represents the first sequenced mitogenome in this genus. The complete circular mitogenome was 15,746 bp in length, containing 37 typical genes and one noncoding AT-rich control region. The nucleotide composition of the mitogenome was highly A + T biased, accounting for 70.07 % of the whole mitogenome with a slightly positive AT skewness (0.106). The 13 Protein coding genes (PCGs) used ATN as their start codons, except nad1 which used TTG. All tRNA genes were predicted with a characteristic cloverleaf secondary structure except trnS1^(AGN), whose dihydrouridine (DHU) arm was replaced by a simple loop. Phylogenetic analyses recovered Cerambycinae as a monophyletic group with high node supports and the sister relationship between T. sinensis and Nadezhdiella cantori. However, we found that deeper nodes showed not strong support, which may be caused by limited taxa sampling in our study. More mitogenomes should be sequenced representing various taxonomic levels, especially closely related species, which will enhance our understanding of phylogenetic relationships among Cerambycinae.     

Complete mitochondrial genome sequence of the Indian pipistrelle Pipistrellus coromandra (Vespertilioninae)

We characterized the complete mitogenome of Pipistrellus coromandra (Indian pipistrelle) for comparative analysis of mitogenomes and for resolving the phylogenetic relationship of four tribes in the subfamily Vespertilioninae. The mitogenome size of P. coromandra was 17,153?bp, with a control region and a typical set of 37 mitochondrial genes. The nucleotide composition of the P. coromandra mitogenome showed an AT bias with a nucleotide composition of 33.5% A, 30.7% T, 13.3% G, and 22.5% C. The mitochondrial protein-coding genes in P. coromandra use the standard start codon (ATN), two stop codons (TAA and AGA), and two incomplete stop codons (TA- and T--). The intertribal relationship of four tribes was highly resolved from the phylogenetic analysis of mitogenome sequences.     

Mitochondrial Genome of Prasinophyte Alga Pyramimonas parkeae

Prasinophytes are a paraphyletic assemblage of nine heterogeneous lineages in the Chlorophyta clade of Archaeplastida. Until now, seven complete mitochondrial genomes have been sequenced from four prasinophyte lineages. Here, we report the mitochondrial genome of Pyramimonas parkeae, the first representative of the prasinophyte clade I. The circular‐mapping molecule is 43,294 bp long, AT rich (68.8%), very compact and it comprises two 6,671 bp long inverted repeat regions. The gene content is slightly smaller than the gene‐richest prasinophyte mitochondrial genomes. The single identified intron is located in the cytochrome c oxidase subunit 1 gene (cox1). Interestingly, two exons of cox1 are encoded on the same strand of DNA in the reverse order and the mature mRNA is formed by trans‐splicing. The phylogenetic analysis using the data set of 6,037 positions assembled from 34 mtDNA‐encoded proteins of 48 green algae and plants is not in compliance with the branching order of prasinophyte clades revealed on the basis of 18S rRNA genes and cpDNA‐encoded proteins. However, the phylogenetic analyses based on all three genomic elements support the sister position of prasinophyte clades Pyramimonadales and Mamiellales.     

A mitogenome of the Chevrier's field mouse (Apodemus chevrieri) and genetic variations inferred from the cytochrome b gene

The Chevrier's field mouse (Apodemus chevrieri) is an endemic species to China and is an important pest in agriculture and human diseases. In this study, the complete mitochondrial genome of this species was sequenced and its size was 16,298 bases (accession no.: HQ896683). The mitogenome structure was similar compared with other reported rodent mitochondrial genomes and includes 13 protein-coding genes, 2 rRNA genes (12S rRNA and 16S rRNA), 22 tRNA genes, and 1 control region. This was the first complete mitogenome sequenced in genus Apodemus. The phylogenetic analyses based on the sequences of 12 heavy-strand protein-coding genes demonstrated that A. chevrieri clustered together with genus Mus. Additionally, extremely high haplotype and nucleotide diversities (h=0.978, π=2.6%) were observed based on 44 mitochondrial cytochrome b (cyt b) gene sequences. This suggests adaptive divergence of this species to a variety of living habitats and potential refuges in the eastern margin of the Hengduan Mountains during the Quaternary ice ages. No population expansions or genetic bottlenecks were observed in demographic analyses. The phylogenetic analysis of cyt b sequences and haplotypes revealed a genetic differentiation between north and south populations. The divergence between north clade and south clade occurred probably in the middle Pleistocene 1.1815 million years ago (Mya) (95% highest posterior density 2.3189-0.2737 Mya), which was congruent with the periods of the most tense uplift events in the Tibetan Plateau.     

Dynamic evolution of eukaryotic mitochondrial and nuclear genomes: a case study in the gourmet pine mushroom Tricholoma matsutake

Fungi, as eukaryotic organisms, contain two genomes, the mitochondrial genome and the nuclear genome, in their cells. How the two genomes evolve and correlate to each other is debated. Herein, taking the gourmet pine mushroom Tricholoma matsutake as an example, we performed comparative mitogenomic analysis using samples collected from diverse locations and compared the evolution of the two genomes. The T. matsutake mitogenome encodes 49 genes and is rich of repetitive and non-coding DNAs. Six genes were invaded by up to 11 group I introns, with one cox1 intron cox1P372 showing presence/absence dynamics among different samples. Bioinformatic analyses suggested limited or no evidence of mitochondrial heteroplasmy. Interestingly, hundreds of mitochondrial DNA fragments were found in the nuclear genome, with several larger than 500 nt confirmed by PCR assays and read count comparisons, indicating clear evidence of transfer of mitochondrial DNA into the nuclear genome. Nuclear DNA of T. matsutake showed a higher mutation rate than mitochondrial DNA. Furthermore, we found evidence of incongruence between phylogenetic trees derived from mitogenome and nuclear DNA sequences. Together, our results reveal the dynamic genome evolution of the gourmet pine mushroom.