Complete Chloroplast Genome Sequence of Fagus longipetiolata Seemen (Fagaceae): Genome Structure, Adaptive Evolution, and Phylogenetic Relationships

Fagus longipetiolata Seemen is a deciduous tree of the Fagus genus in Fagaceae, which is endemic to China. In this study, we successfully sequenced the cp genome of F. longipetiolata, compared the cp genomes of the Fagus genus, and reconstructed the phylogeny of Fagaceae. The results showed that the cp genome of F. longipetiolata was 158,350 bp, including a pair of inverted repeat (IRA and IRB) regions with a length of 25,894 bp each, a large single-copy (LSC) region of 87,671 bp, and a small single-copy (SSC) region of 18,891 bp. The genome encoded 131 unique genes, including 81 protein-coding genes, 37 transfer RNA genes (tRNAs), 8 ribosomal RNA genes (rRNAs), and 5 pseudogenes. In addition, 33 codons and 258 simple sequence repeats (SSRs) were identified. The cp genomes of Fagus were relatively conserved, especially the IR regions, which showed the best conservation, and no inversions or rearrangements were found. The five regions with the largest variations were the rps12, rpl32, ccsA, trnW-CCA, and rps3 genes, which spread over in LSC and SSC. The comparison of gene selection pressure indicated that purifying selection was the main selective pattern maintaining important biological functions in Fagus cp genomes. However, the ndhD, rpoA, and ndhF genes of F. longipetiolata were affected by positive selection. Phylogenetic analysis revealed that F. longipetiolata and F. engleriana formed a close relationship, which partially overlapped in their distribution in China. Our analysis of the cp genome of F. longipetiolata would provide important genetic information for further research into the classification, phylogeny and evolution of Fagus.

Comparative and Phylogenetic Analysis of Complete Plastomes among Aristidoideae Species (Poaceae)

Aristidoideae is a subfamily in the PACMAD clade of family Poaceae, including three genera, Aristida, Stipagrostis, and Sartidia. In this study, the plastomes of Aristida adscensionis and Stipagrostis pennata were newly sequenced, and a total of 16 Aristidoideae plastomes were compared. All plastomes were conservative in genome size, gene number, structure, and IR boundary. Repeat sequence analysis showed that forward and palindrome repeats were the most common repeat types. The number of SSRs ranged from 30 (Sartidia isaloensis) to 54 (Aristida purpurea). Codon usage analysis showed that plastome genes preferred to use codons ending with A/T. A total of 12 highly variable regions were screened, including four protein coding sequences (matK, ndhF, infA, and rpl32) and eight non-coding sequences (rpl16-1-rpl16-2, ccsA-ndhD, trnY-GUA-trnD-GUC, ndhF-rpl32, petN-trnC-GCA, trnT-GGU-trnE-UUC, trnG-GCC-trnfM-CAU, and rpl32-trnL-UAG). Furthermore, the phylogenetic position of this subfamily and their intergeneric relationships need to be illuminated. All Maximum Likelihood and Bayesian Inference trees strongly support the monophyly of Aristidoideae and each of three genera, and the clade of Aristidoideae and Panicoideae was a sister to other subfamilies in the PACMAD clade. Within Aristidoideae, Aristida is a sister to the clade composed of Stipagrostis and Sartidia. The divergence between C4 Stipagrostis and C3 Sartidia was estimated at 11.04 Ma, which may be associated with the drought event in the Miocene period. Finally, the differences in carbon fixation patterns, geographical distributions, and ploidy may be related to the difference of species numbers among these three genera. This study provides insights into the phylogeny and evolution of the subfamily Aristidoideae.

Whole genome based insights into the phylogeny and evolution of the Juglandaceae

Background The walnut family (Juglandaceae) contains commercially important woody trees commonly called walnut, wingnut, pecan and hickory. Phylogenetic relationships and diversification within the Juglandaceae are classic and hot scientific topics that have been elucidated by recent fossil, morphological, molecular, and (paleo) environmental data. Further resolution of relationships among and within genera is still needed and can be achieved by analysis of the variation of chloroplast, mtDNA, and nuclear genomes. Results We reconstructed the backbone phylogenetic relationships of Juglandaceae using organelle and nuclear genome data from 27 species. The divergence time of Juglandaceae was estimated to be 78.7 Mya. The major lineages diversified in warm and dry habitats during the mid-Paleocene and early Eocene. The plastid, mitochondrial, and nuclear phylogenetic analyses all revealed three subfamilies, i.e., Juglandoideae, Engelhardioideae, Rhoipteleoideae. Five genera of Juglandoideae were strongly supported. Juglandaceae were estimated to have originated during the late Cretaceous, while Juglandoideae were estimated to have originated during the Paleocene, with evidence for rapid diversification events during several glacial and geological periods. The phylogenetic analyses of organelle sequences and nuclear genome yielded highly supported incongruence positions for J. cinerea, J. hopeiensis, and Platycarya strobilacea. Winged fruit were the ancestral condition in the Juglandoideae, but adaptation to novel dispersal and regeneration regimes after the Cretaceous-Paleogene boundary led to the independent evolution of zoochory among several genera of the Juglandaceae. Conclusions A fully resolved, strongly supported, time-calibrated phylogenetic tree of Juglandaceae can provide an important framework for studying classification, diversification, biogeography, and comparative genomics of plant lineages. Our addition of new, annotated whole chloroplast genomic sequences and identification of their variability informs the study of their evolution in walnuts (Juglandaceae).

Complete Mitochondrial Genome of Phoneutria Boliviensis (Araneae, Ctenidae): New Insights Into the Phylogeny and Evolution of Spider

Spiders are the most abundant land predators and megadiverse on earth. In recent years, the mitochondrial genome has been sequenced, mainly for ecological and commercial purposes, reporting some level of rearrangements in this genome. However, there is poor genetic information in several taxonomic families of spiders. The aim of this study was to obtain the sequence of the complete genome of Phoneutria boliviensis and, based on this, extract the mitogenomes of other species of the family Ctenidae from published transcriptomes to perform a comparative study among spider species to determine the relationship between the level of mitochondrial rearrangement and its possible relationship with molecular variability in spiders. Complete mitochondrial genomes of eighteen spiders (including nine Ctenidae species) were obtained by two different methodologies (sequencing and transcriptome extraction). Fifty-eight spider mitochondrial genomes were downloaded from the NCBI database for gene order analysis. After verifying the annotation of each mitochondrial gene, a phylogeny and gene order, analysis from 76 spider mitochondrial genomes was obtained. Our results show a high rate of annotation error in the mitochondrial genomes of spiders published in databases, which could lead to false phylogenetic relationships. Moreover, to provide new mitochondrial genomes in spiders by two different methodologies to obtain them, our analysis identifies six different mitochondrial architectures among all spiders. Translocation or tandem duplication random loss (TDRL) events in tRNA genes were identified to explain the evolution of the spider mitochondrial genome. In addition, our findings provide new insights into spider mitochondrial evolution.

The development of tick taxonomy and systematics in Australia and Papua New Guinea through the works of five late 20th century contributors and with comments on the place of Australasia in the study of the phylogeny and evolution of the ticks

The largely unique fauna of ticks in Australia and Papua New Guinea (PNG) has been studied for 250 years. Here, we briefly review the early stages of tick taxonomy in the region, then focus on the activities of five people who contributed much to our knowledge of ticks in Australasia during the second half of the 20th century: F.H.S Roberts, David H. Kemp, Douglas E. Moorhouse, Nixon Wilson and Harry Hoogstraal. We provide biographical notes on each and collated publication lists for Roberts, Kemp and Moorhouse. We recognize three eras of tick taxonomy in Australia. First, an era that we refer to as “colonial tick taxonomy”, where ticks were sent from the European colonies to taxonomists in Europe. Second, a brief but significant era that we refer to as “endemic tick taxonomy” defined by the works of F.H.S. Roberts. Thirdly, a final phase of “colonial taxonomy” where ticks were described by workers in the USA. In PNG there has been no phase of endemic tick taxonomy and, while Australian workers are once again describing new tick species, in PNG the USA continues to make the most significant contributions. Through this work, we now see Australasia as one of the “theatres of evolution” of Bothriocroton and Archaeocroton, the Amblyomma-like ticks without eyes. We briefly discuss the current hypotheses for the theatre of evolution of the Ixodida, consider the 22 genus and subgenus-level entities of the Prostriata (Ixodinae) as provisional biological entities, and provide observations on tick phylogenetics and future research. Finally, we outline additional genetic evidence, from a recent whole-transcriptome study, for the two clades of the subfamily Ixodinae (Prostriata), the Australasian Ixodes and all other Ixodes.