Search Results (179)

Cetaceans are artiodactyls adapted to live in the marine environment, and this group includes whales, dolphins, and porpoises. Although mitochondrial nucleotide diversity has been reported separately for many cetacean groups, the proportion of deleterious mutations in these populations is unknown. Furthermore, a comparison of mitogenomic diversities across all cetaceans is also lacking. To investigate this, we conducted a comparative genomic analysis of 2244 mitochondrial genomes from 65 populations across 32 cetacean species. We observed a 78-fold variation in mitogenomic diversity among cetacean populations, suggesting a large difference in genetic diversity. We used the ratio of nonsynonymous-to-synonymous diversities (dN/dS) to measure the proportion of deleterious mutations in the mitochondrial exomes. The dN/dS ratio showed a 22-fold difference between the cetacean population. Based on genetic theories, the large differences observed in the two measures could be attributed to differences in the effective sizes of the cetacean populations. Typically, small populations have low heterozygosity and a high dN/dS ratio, and the reverse is true for large populations. This was further confirmed by the negative correlation observed between heterozygosity and dN/dS ratios of cetacean populations. While our analysis revealed similarities in mitogenomic diversity between the endangered and least-concern cetacean species, the dN/dS ratio of the former was found to be higher than that of the latter. The findings of this study are useful for identifying the relative magnitude of reductions in the population sizes of different cetacean species. This will help conservation management efforts prioritise the use of limited resources, time, and effort to protect the cetacean populations that need immediate attention. Full article

Mitochondrial genomes play a central role in fungal physiology and adaptation, yet their evolutionary dynamics during domestication remain poorly understood. Here, we performed a comparative mitogenomic and gene-expression analysis of three Pleurotus ostreatus dikaryotic strains differing in origin and degree of adaptation to laboratory conditions: the long-term commercial strain dkN001, the laboratory-maintained wild isolate dkF515, and the recently collected wild strain dkN009. High-throughput Illumina sequencing enabled complete assembly of circular mitochondrial genomes, revealing substantial size variation among strains, where the dkN001 strain exhibited the second smallest mitogenome reported for the genus Pleurotus. Comparative analyses showed >99% sequence identity between wild isolates and ~95% identity relative to the commercial strain. Variations in genome size among strains were associated with intron dynamics in the cox1 and rnl genes, as well as intron loss predominantly in the commercial strain dkN001, consistent with mitochondrial genome streamlining during domestication. Expression profiling of mitochondrial protein-coding genes (PCGs) under multiple culture conditions revealed conserved transcriptional responses in dkN001 and dkF515 that contrasted sharply with those of dkN009. The differences observed, which affected components of the electron transport chain, suggested shifts in energy metabolism associated with long-term laboratory maintenance. Therefore, our results demonstrate that domestication in P. ostreatus involves both structural remodelling of the mitogenome and changes in regulation of mitochondrial PCGs, highlighting the importance of mitonuclear interactions in fungal adaptation to controlled environments. Full article

Background. Eriobotrya seguinii (Lév.) Cardot ex Guillaumin (Rosaceae, Maleae) is native to China and inhabits various altitudes within the subtropical biome of the Yunnan-Guizhou Plateau. The complexity of the plant mitogenome has impeded a systematic description of this species, leading to a limited understanding of its evolutionary position. Methods. In this study, we constructed, annotated, characterized, and compared the complete E. seguinii mitogenome with previously reported Eriobotrya japonica. Results. The E. seguinii mitogenome exhibited a typical circular architecture, spanning 372,899 bp in length, with a GC content of 46%, making it the smallest and highest GC content of any known Eriobotrya species. It encodes 71 unique genes, comprising 47 protein-coding genes, 20 transfer RNA (tRNA) genes, and 4 ribosomal RNA (rRNA) genes. The genome contains rich repetitive sequences, with mononucleotides, A/T bias, and forward and palindromic repeats being the most prevalent. The predominant codons were GCU (Ala) and UAU (Tyr), with frequencies of 1.54 and 1.53, respectively. Thirteen genes (atp9, atp6, atp1, rps14, sdh4, sdh3, rps12, rnaseH, nad1, nad6, nad7, rpl16, and mttB) demonstrated high Pi values, ranging from 0.84 to 1. The evolutionary lineage of E. seguinii was explored using mitogenome data from 19 genera within the Rosaceae family, revealing that Eriobotrya species are monophyletic and closely related to E. japonica (MN481990). Conclusions. Understanding the mitogenome characteristics of E. seguinii enhances our understanding of its genesis and classification based on mitochondrial genome data. This study provides additional evidence for future research on the evolutionary relationships among species in the Rosaceae family. Full article

The dung beetle family Geotrupidae (Scarabaeoidea) plays a vital ecological role in nutrient cycling and soil health, yet the scarcity of complete mitochondrial genome (mitogenome) data has hindered phylogenetic and comparative studies within this family. Here, we sequenced, assembled, and annotated the first complete mitogenomes of Geotrupes stercorarius and Phelotrupes auratus, collected from the Qinghai–Tibetan Plateau. Comparative analysis of these two novel mitogenomes with eight existing mitogenomes revealed conserved architectural features across Geotrupidae, such as gene arrangement, tRNA secondary structures, and small intergenic spacers. Nucleotide composition was largely conserved, though marked divergence occurred at the third codon positions. Substantial structural variation was observed in non-coding regions, particularly in the control region and the nad2-trnW spacer. Evolutionary analyses indicated strong purifying selection across all protein-coding genes, with no evidence of widespread positive selection linked to high-altitude adaptation. Phylogenetic reconstruction consistently recovered the relationships (Bolboceratinae, (Lethrinae, Geotrupinae)), with Anoplotrupes and Geotrupes forming sister genera within Geotrupinae. This study provides additional mitogenomic resources and a well-supported phylogenetic framework for Geotrupidae, resolving key taxonomic uncertainties and establishing a basis for future evolutionary and ecological research. Full article

Butidae is a family of teleost fishes with diverse morphological and ecological adaptations, including the marbled goby (Oxyeleotris marmorata), a large species of high economic value in Southeast and East Asia. The previous mitogenomic studies on cultured populations of O. marmorata from non-native habitats have provided limited insights into genetic divergence, structural variation, and evolutionary relationships. Hence, this study presented the complete mitochondrial genome of O. marmorata from its native habitat in Indonesia, providing structural characterization, assessment of genetic diversity, and matrilineal phylogenetic analysis. The circular mitogenome was 16,525 bp, comprising 37 genes and a non-coding control region (CR). The gene organization and strand distribution were conserved among Oxyeleotris species, with 28 genes on the heavy strand and nine on the light strand, and a pronounced A+T compositional bias. The comparative analyses of O. marmorata (from both native and cultured habitats) and Oxyeleotris lineolata mitogenomes revealed minor variations in intergenic spacers, gene overlaps, protein-coding gene (PCGs) lengths, and codon usage patterns. Conversely, the nonsynonymous and synonymous substitution ratios observed in species of the family Butidae and its closest related family (Eleotridae) indicate strong purifying selection in the present dataset. Notably, the ATG was the predominant start codon, whereas the COI gene utilized GTG, and amino acid composition analysis demonstrated high frequencies of arginine, leucine, and serine. Most transfer RNAs retained the canonical cloverleaf secondary structure except for trnS1, which lacked a functional dihydrouridine arm, whereas the CR contained four conserved sequence blocks with variable nucleotide motifs and no detectable tandem repeats. The haplotype analysis of native (Indonesia) and introduced populations (China) highlighted three haplotypes with high diversity (Hd = 1.0000) and substantial nucleotide variation (π = 0.6667). The genetic divergence across 13 PCGs was gene-specific, with COI and ND5 showing the highest variation, while ND4L and ATP8 were highly conserved. The phylogenetic analyses based on concatenated 13 PCGs using both Bayesian Inference and Maximum Likelihood methods revealed that Oxyeleotris forms a monophyletic clade and is closely related to Bostrychus sinensis. In addition, the broader phylogenetic framework inferred the matrilineal relationships within the family Butidae and its closest related family, Eleotridae. This study also recommends expanding analyses to include the mitogenomes of the remaining 17 Oxyeleotris species, together with comprehensive genomic data, to further elucidate their genetic architecture, evolutionary history, and ecological adaptability across diverse aquatic ecosystems. Full article

Background: A comprehensive temporal analysis of mtDNA haplogroup variation across Lithuanian history remains limited. This study investigates the mtDNA variation landscape during the Iron Age by comparing newly reported Iron Age individual mtDNA data with the new data from present-day Lithuanians. Methods: Remains of individuals from the Iron Age Lithuania (n = 101) were processed using standard protocols for ancient DNA processing. For the present-day Lithuanians (n = 279), whole mitogenomes were sequenced. Thirty-six polymorphic sites within the Hypervariable Region I were used for haplogroup assignment, phylogenetic and population genetic analyses. Results: Fifteen distinct haplogroups in the Iron Age and the present-day Lithuanians were identified. Haplogroup R0/H remained the most frequent across time. Haplogroups U, T, and N were prominent in the Iron Age. Haplogroups M and D were introduced after the Iron Age. Phylogenetic and population genetic analyses revealed greater mtDNA diversity in the present-day Lithuanians. Significant difference in molecular variance was observed during the Iron Age. Barring the Viking period, the Iron Age mtDNA variation matched the present-day Lithuanian and European populations. Conclusions: Our study showed that mtDNA variation over time remained stable with some random fluctuations and gained more diversity in the present-day Lithuanians. Full article

Callicarpa americana L. is a member of the Lamiaceae family with important ornamental and medicinal value. Although the chloroplast genome of Lamiaceae has been extensively studied, its mitochondrial genome remains unreported, limiting a comprehensive understanding of the phylogeny and genome evolution of Lamiaceae. In this study, the complete mitochondrial genome of C. americana was successfully assembled for the first time. The genome is 499,565 bp in length, showing a complex multi-branched closed-loop structure that contains 37 protein-coding genes, 23 tRNA genes, and 4 rRNA genes. The difference in mitochondrial genome size is relatively large compared to Orobanchaceae species, but the difference in GC content is not obvious. The expansion of genome size was mainly due to the accumulation of non-coding regions and repetitive sequences. Meanwhile, two pairs of long repetitive sequences (LR3 and LR5) mediated homologous recombination. The mitogenome was also identified; there were a total of 494 C-to-U RNA editing sites in protein-coding genes. In addition, 42 mitochondrial plastid DNA fragments (MTPTs) were detected, with a total length of 21,464 bp, accounting for 4.30% of the genome. Repeat sequence analysis showed that tetranucleotide SSR was the most abundant repeat type in the mitochondria of Lamiaceae. Phylogenetic analysis based on the alignment of 32 protein-coding gene sequences showed that Callicarpa is sister to the other eight species of Lamiaceae. This work fills an important gap by presenting the first complete mitochondrial genome of C. americana, providing an important data resource for further understanding the structural evolution, dynamic recombination mechanism, and phylogeny of the mitochondrial genome of Lamiaceae. Full article

The genus Takydromus (grass lizards) represents a diverse and ecologically significant group of lacertid lizards widely distributed across East and Southeast Asia. However, phylogenetic relationships within the genus remain contentious, primarily due to limited molecular data and inconsistent results from previous studies based on single or few mitochondrial genes. This study aimed to (1) sequence and characterize the complete mitogenome of T. intermedius; (2) perform a comparative analysis of mitogenomic features across the genus; and (3) reconstruct a robust phylogeny to clarify intra-generic evolutionary relationships. The mitogenome of T. intermedius was 18,770 bp in size and contained the typical set of 37 genes. Comparative analyses revealed characteristic features including AT-richness, strand asymmetry, and considerable length variation in the control region attributable to tandem repeats. The ATP8 gene showed the highest nucleotide diversity, and all protein-coding genes were found to be under strong purifying selection. Phylogenetic trees were reconstructed from a concatenated dataset of 13 protein-coding genes and two rRNA genes using both maximum likelihood and Bayesian inference methods. The resulting phylogeny strongly supported the monophyly of Takydromus and resolved several species relationships; however, it did not support the recognition of Platyplacopus as a distinct subgenus. Moreover, our mitogenomic analysis strongly validates the forest-grassland ecological speciation hypothesis and the southern–northern lineage division in Takydromus. Our study provides valuable mitogenomic resources and underscores the utility of complete mitochondrial genomes in elucidating phylogenetic relationships within Takydromus. These findings lay a solid foundation for future taxonomic and evolutionary studies, although expanded species sampling is needed to fully understand the genus’s diversification history. Full article

The genus Phylloporus (Boletaceae, Boletales) is a group of ectomycorrhizal fungi, distinguished from other members of Boletaceae by its unique lamellate hymenophore. Although some molecular data exist for this genus, its mitogenomic characteristics remain poorly understood. In our study, we sequenced, assembled, and annotated the complete mitogenomes of eight species representing seven major subclades of Boletaceae collected in Jiangxi Province, China, with a focus on four Phylloporus species. We found that Phylloporus mitogenomes are circular, ranging in size from 35,117 bp to 38,908 bp, and contain 14–15 core protein-coding genes (PCGs), 24–28 tRNA genes, and 2 rRNA genes. Our comparative analysis revealed that Phylloporus species share many features, such as gene content, gene length, tRNA repertoire, and gene order, while Boletaceae as a whole shows a lot of diversity. Codon usage patterns are quite similar across the family. The Ka/Ks ratios of most 15 core PCGs were less than 1, suggesting these genes have been preserved through purifying selection over time. By using Bayesian inference (BI) and maximum likelihood (ML) methods and combining 28 other mitotic genomes in the NCBI database, our phylogenetic analysis produced highly consistent and well-supported trees (BPP ≥ 0.98, BS ≥ 71). It is noted that this family is divided into seven subfamilies, which is consistent with previous taxonomic studies. Altogether, our findings shed light on the unique features of Phylloporus and its connections to other members of Boletaceae. These findings not only provide valuable insights into the taxonomy, phylogeny, genetic diversity, and resource conservation of Boletaceae but also serve as a valuable genomic resource for future research. Full article

Representatives of the family Moinidae (Crustacea: Cladocera) are well-adapted to life in temporary waters. Different species are characteristic of the Arid Belt of Eurasia. We aimed to compare the moinid species composition and genetic diversity found in Djibouti (with extreme and uniform environments) with neighboring Ethiopia (a relatively large country with diverse environmental conditions). Any cladocerans were found in only four localities in Djibouti from Ecoregion 527 (Western Red Sea Drainages) according to Abell et al. (2008). The moinids belonged to two taxa: M. cf. micrura and M. heilongjiangensis. In Ethiopia, moinids were found in 28 water bodies from four other Ecoregions (522, 525, 526 and 528). They belonged to M. micrura and M. belli. A genetic study based on full mitogenomes, sequences of the mitochondrial COI and nuclear ITS1 loci demonstrated that M. micrura from Djibouti and Ethiopia belong to distant lineages. Our genetic analysis revealed a very contrasting moinid fauna in two neighboring countries of the African Horn: there was no single haplotype, clade or even species sharing these territories. We have revealed unexpectedly small genetic distances between Chinese (type locality) and Djiboutian populations of M. heilongjiangensis; the question of the invasive status of the latter could therefore be raised. Moreover, the status of M. micrura populations from the Rift Valley also needs to be checked; they could be non-indigenous, as they belong to “European” M. micrura s. str. Finally, we have demonstrated that M. cf. micrura is not a monophyletic clade. Full article

Corydalinae (dobsonfly) is one of the subfamilies of the megalopteran family Corydalidae. Species of Corydalinae are some of the largest freshwater insects in the world. Comparative analyses of mitochondrial genomes in Corydalinae were conducted. The evolutionary rates of 13 PCGs of fifty species in Corydalinae were estimated. The total PCGs of Corydalinae exhibited negative AT bias, ranging from −0.1810 to −0.1408. The Ka/Ks ratio of total PCGs in Corydalinae ranged from 0.1011 (Protohermes) to 0.1673 (Chloroniella). Phylogenetic analysis of Corydalinae was conducted using mitogenomes. Positive selection analyses, conducted based on the Corydalinae phylogenetic topology, revealed potential positively selected sites in the genera Acanthacorydalis, Corydalus, Neoneuromus, Nevromus, and Protohermes. These genera were distributed in areas characterized by marked seasonality and pronounced annual thermal amplitude variations. The observed divergence in potential positive selection sites and evolutionary rates might be attributed to differential adaptive evolution in response to climatic factors, potentially reflecting distinct molecular mechanisms underlying species-specific adaptation to rapid environmental shifts. Full article

The number of known mitochondrial genomes in Buprestidae is limited, especially in Chrysochroinae, which seriously hinders the phylogenetic study of this family. The mitogenomes of Capnodis miliaris, Lamprodila cupreosplendens, Sphenoptera insidiosa and Philocteanus rubroaureus were sequenced, assembled and annotated in this study. The mitogenomes of these four species are typical circular double-stranded DNA molecules, containing 13 protein-coding genes (PCGS), 22 transfer RNA genes (tRNAs), 2 ribosomal RNA genes (rRNAs), and a control region (CR). The total lengths of these four mitogenomes are moderate, ranging from 15,778 bp to 16,230 bp. Additionally, their A + T content ranges from 68.76% to 73.47%, showing positive AT-skew values ranging from 0.098 to 0.181. Relative Synonymous Codon Usage (RSCU) analysis indicated that TTT (Phe), ATT (Ile), TCT (Ser2), and TTA (Leu2) are the most frequently used codons. The gene arrangement of four mitogenomes is consistent with the previously reported Buprestidae mitogenomes. Most of the PCGs use ATN as the start codon, with TAA as the stop codon or an incomplete stop codon T-. Phylogenetic trees were constructed based on the PCGs and rRNAs using both maximum-likelihood and Bayesian inference methods. The phylogenetic results showed that Julodinae, Polycestinae, Buprestinae and Agrilinae are monophyletic groups, and Chrysochroinae is a paraphyletic group. As the number of Buprestidae mitogenomes used for polyogenetic analysis increases, the topology of phylogenetic tree shows differences compared to previous studies. Full article

Background: Thrushes (family Turdidae) are ecologically important passerine birds widely distributed across the Northern Hemisphere. However, the phylogenetic placement of several East Asian congeners, including Turdus pallidus, remains insufficiently resolved due to the limited resolution of partial mitochondrial or nuclear markers used in previous studies. Methods: In this work, we sequenced and annotated the complete mitochondrial genome of T. pallidus (16,739 bp) using high-throughput Illumina sequencing. The mitogenome exhibited the typical circular architecture and contained 37 genes (13 protein-coding genes, 22 tRNAs, and 2 rRNAs), with an overall GC content of 47.32%. Results: Most protein-coding genes initiated with the standard ATG codon, although lineage-specific deviations such as GTG in COX1 and ND2 were identified, and incomplete stop codons (T– or TA–) were observed, consistent with post-transcriptional polyadenylation. The 22 tRNA genes displayed typical cloverleaf secondary structures, except for trnS(AGN), which lacked a DHU arm, while rRNA genes were 977 bp (12S, 48.52% GC) and 1590 bp (16S, 44.65% GC), showing conserved stem regions but variable loop regions. Codon usage analysis revealed a strong bias toward A/T-ending codons, with a total of 3798 codons and an effective number of codons (ENC) of ~40, indicating moderate codon bias shaped by both mutational pressure and translational selection. Comparative analysis of evolutionary rates demonstrated that conserved genes such as COX1 and CYTB are suitable for resolving deeper relationships, whereas rapidly evolving genes like ATP8 provide resolution among closely related taxa. Conclusions: Phylogenetic reconstructions based on 13 mitochondrial protein-coding genes robustly supported the monophyly of Turdidae and recovered T. pallidus as most closely related to T. obscurus. Overall, this study provides a novel mitogenomic resource for T. pallidus, enhances phylogenetic resolution within Turdus, and underscores the value of complete mitochondrial genomes for molecular identification, conservation management, and avian evolutionary studies. Full article

Background/Objectives: Sepiella japonica is a highly adaptable cephalopod with an advanced nervous system and complex reproductive behavior, capable of reproducing two to three generations annually depending on water temperature. However, the absence of a complete genome assembly has limited molecular investigations of its unique biological characteristics. This study aimed to perform a genome survey of female and male S. japonica, systematically characterize and compare key genomic characteristics. Methods: Quality-filtered short reads enabled K-mer-based estimation of genome size, heterozygosity, repeat content, and GC content; generation of draft genome assemblies, SSR identification from the draft assemblies, complete mitogenome assemblies and annotations with ML phylogeny based on 13 concatenated PCGs, and PSMC-based demographic inference. Results: The estimated genome sizes were 4317 Mb (female) and 4222 Mb (male), with revised estimates of 4310 Mb and 4215 Mb, respectively. K-mer analysis revealed heterozygosity rates of 0.85% (female) and 0.77% (male) and repeat content of 76.05% (female) and 75.91% (male). The assembled genome sizes were 4197 Mb for females (N50: 508 bp) and 4206 Mb for males (N50: 511 bp); the GC content was 34.15% for both genomes. Deduplicated data showed GC content of 35.16% (female) and 35.27% (male). Microsatellite analysis revealed that mononucleotide repeats were the most abundant simple sequence repeat motif. The mitochondrial genome sequences measured 16,729 bp for the female genome and 16,725 bp for the male genome. Conclusions: This study provides fundamental data for subsequent high-quality whole-genome assembly and comparative analysis of female and male genomes. Full article

The genus Quercus is an ecological keystone and economically vital component of Northern Hemisphere forests. While genomic studies have advanced our understanding of its nuclear and chloroplast genomes, the mitochondrial genomes of oaks remain less explored due to their complex evolutionary dynamics, which include extreme size variation, frequent rearrangements, and recurrent horizontal gene transfer. This study presents the assembly, annotation, and comparative analysis of mitogenomes from three closely related Asian oaks—Q. engleriana, Q. kongshanensis, and Q. tungmaiensis—using PacBio HiFi sequencing. The assemblies revealed distinct structural organizations: the Q. engleriana and Q. kongshanensis mitogenomes each comprised one circular contig and one linear contig, whereas the Q. tungmaiensis mitogenome comprised one circular contig and two linear contigs. Comparative analyses revealed variations in codon usage bias, simple sequence repeats, and predicted RNA editing sites. Notably, RNA editing in rps12 was uniquely observed in Q. kongshanensis. Mitochondrial targeting of plastid transcripts constituted 1.39%, 1.79%, and 2.24% of the mitogenomes, respectively. Phylogenetic reconstruction based on mitochondrial PCGs robustly resolved Q. kongshanensis and Q. tungmaiensis as sister species, with all three forming a distinct clade separate from other Quercus species. This study provides comprehensive mitogenomic resources essential for elucidating Quercus evolutionary biology and supporting germplasm development. Full article