Differentiation of the dragonfly genus Davidius (Odonata: Gomphidae) in Japan inferred from mitochondrial and nuclear gene genealogies

The genetic differentiation of a cricket (Velarifictorus micado) with two modes of life cycle in East Asia after the middle Pleistocene and the invasion origin of the United States of America

The cricket Velarifictorus micado is widely distributed in East Asia and colonized the United States of America (the USA) in 1959. It has two life cycles: egg and nymph diapause. We aimed to investigate the biogeographic boundary between them and determine when and why V. micado diverged. Mitochondrial fragments including COI and CytB were used for haplotype network, demographic analysis, and divergence time estimation in individuals of East Asia. We selected several samples from the USA to find out the colonization origin. The haplotype network indicated there were three lineages based on COI, NE lineage (the egg diapause and mainly distributed in the northern regions), SE lineage (the egg diapause and mainly distributed in the southern regions), and SN lineage (the nymph diapause and mainly distributed in the southern regions). The molecular chronograms indicated that the first divergence of V. micado into two main lineages, NE and southern lineages (SE and SN), was essentially bounded by the Yangtze River. It occurred around ~0.79 Ma (95% HPD: 1.13-0.46 Ma) in the Middle Pleistocene Transition. This was followed by the divergence of the southern lineage into two sublineages, SE and SN lineage, occurred around ~0.50 Ma (95% HPD: 0.71-0.25 Ma), corresponding to the time of development of glaciers in various parts of the Qinghai-Tibet Plateau (QTP) (0.73-0.46 Ma). SE lineage might originate from southwestern China based on the comparison between the haplotype network based on COI and CytB. Our study suggested that divergences of lineages have twice co-occurred with tendency of cooling climatic in Asia after the Mid-Pleistocene, and the life-history strategy may play an important role in lineage diversification. Additionally, our results indicated that the USA populations were revealed at least twice separate Asian invasions. These both belonged to the egg diapause, which might provide a new perspective for invasion control.

Dispersal versus vicariance in the Aegean: combining molecular and morphological phylogenies of eastern Mediterranean Dendarus (Coleoptera: Tenebrionidae) sheds new light on the phylogeography of the Aegean area

The Aegean archipelago, as an ‘evolutionary laboratory of nature’, is an ideal model for research in phylogeography. In this area, the darkling beetles of the genus Dendarus (distributed from Morocco to the Caucasus) exhibit a high level of diversity with 36 species, 27 of which are island endemics. However, their taxonomy is complex and unstable, having undergone continuous revision to address extensive morphological and ecological plasticity. Here, we examine the phylogenetic relationships of 23 species from Greece and Turkey, using mitochondrial and nuclear DNA sequences and 61 morphological characters, to unveil their phylogeny in the Aegean. This helps to clarify phylogeographic scenarios and historical processes that shaped the observed patterns. The analyses reveal 13 distinct lineages with several para- and polyphyletic cases that correspond to three major phylogroups [south/south-east Aegean (D. foraminosus complex, D. rhodius, D. sporadicus, D. wettsteini); central to north Aegean, Turkey and mainland Greece (D. crenulatus, D. moesiacus group, D. sinuatus complex, D. stygius) and mainland Greece (D. messenius, D. paganettii)], indicating the need for further taxonomic re-evaluation. Lineage topology and phylogeography suggest a spatial and temporal sequence of geographic isolation, following either a vicariant or a dispersal model coincident with major palaeogeographic separations in the Aegean.

Genetic diversity of the families Aeshnidae, Gomphidae and Libellulidae through COI gene from South China

Adult dragonflies (Anisoptera) were collected from different localities of South China covering eight provinces. Representative sequences were sixty-one, including 16 species, 11 genera and three families (Aeshnidae, Gomphidae and Libellulidae), under cytochrome oxidase subunit I (COI) gene. After alignment of sequences by BioEdit v6, genetic interaction and divergence were computed by MEGA 7 whereas all the indices of genetic diversity were calculated by DnaSP v5 software. Phylogenetic trees were constructed through Neighbor-Joining method under Jukes-Cantor model, and all species of respective families were assembled with each other into individual groups. Maximum divergence was observed by Trithemis genus (18.69%), followed by Orthetrum genus (18.16%), whereas a minimum value of divergence was noted for Pantala genus (0.31%). On the other hand, maximum genetic diversity was recorded for Orthetrum genus up to 142 mutations, followed by Trithemis genus (126 mutations), while the minimum value (two mutations) was observed for Pantala genus. Genetic diversity for overall and Libellulidae family sequences was much higher, up to 404 mutations and 344 mutations, respectively. Current results suggest a high diversity of odonates in the South China region and results are valuable in gaining a total obligation of the diversity of Asian odonates and conservation measures of this insect group.

Genetic interaction and diversity of the families Libellulidae and Gomphidae through COI gene from China and Pakistan

A total of 300 dragonflies (Odonata) were collected from six different localities of China and Pakistan. Sixty seven representative samples were selected to sequence their mitochondrial cytochrome oxidase subunit I (COI). An examination of the resultant sequences identified 21 different dragonfly species, belonging to 15 distinct genera, two families, Libellulidae and Gomphidae. Sequence alignment was executed using Clustal-W in BioEdit v6. The phylogenetic tree was constructed through Neighbor-joining method by using Jukes-Cantor model, and genetic divergence was calculated via Kimura 2-parameter using MEGA7, while Genetic diversity was calculated by DnaSP v5. The maximum genetic divergence was observed for Crocothemis servilia, at 20.49%, followed by Libellulidae sp. with 22.30% while minimum divergence (0.82%) was observed for Melligomphus ardens. Likewise, a significant genetic diversity was observed for all species. However, Crocothemis servilia species presented maximum value (176 mutations) followed by Libellulidae spp. (150 mutations), whereas minimum value (3 mutations) was observed by Orthetrum testaceum. Interestingly, the diversity of C. servilia, all of which are collected from a single location of China, is much higher than those from Pakistan, which were collected from 5 different places with a spatial distance exceeding 500 Kms. Our results are useful in gaining a full appreciation of the global diversity of dragonflies and the development of conservation measures of this insect.

Postglacial range shift and demographic expansion of the marine intertidal snail Batillaria attramentaria

To address the impacts of past climate changes, particularly since the last glacial period, on the history of the distribution and demography of marine species, we investigated the evolutionary and demographic responses of the intertidal batillariid gastropod, Batillaria attramentaria, to these changes, using the snail as a model species in the northwest Pacific. We applied phylogeographic and divergence population genetic approaches to mitochondrial COI sequences from B. attramentaria. To cover much of its distributional range, 197 individuals collected throughout Korea and 507 publically available sequences (mostly from Japan) were used. Finally, a Bayesian skyline plot (BSP) method was applied to reconstruct the demographic history of this species. We found four differentiated geographic groups around Korea, confirming the presence of two distinct, geographically subdivided haplogroups on the Japanese coastlines along the bifurcated routes of the warm Tsushima and Kuroshio Currents. These two haplogroups were estimated to have begun to split approximately 400,000 years ago. Population divergence analysis supported the hypothesis that the Yellow Sea was populated by a northward range expansion of a small fraction of founders that split from a southern ancestral population since the last glacial maximum (LGM: 26,000-19,000 years ago), when the southern area became re-submerged. BSP analyses on six geographically and genetically defined groups in Korea and Japan consistently demonstrated that each group has exponentially increased approximately since the LGM. This study resolved the phylogeography of B. attramentaria as a series of events connected over space and time; while paleoceanographic conditions determining the connectivity of neighboring seas in East Asia are responsible for the vicariance of this species, the postglacial sea-level rise and warming temperatures have played a crucial role in rapid range shifts and broad demographic expansions of its populations.

Contrasting genetic structure of closely related giant water bugs: phylogeography of Appasus japonicus and Appasus major (Insecta: Heteroptera, Belostomatidae)

Appasus japonicus and A. major, two belostomatid species of the giant water bug found in parts of East Asia, have very similar morphological characteristics and ecological niches, and also overlapping habitats. However, the results of our previous published study utilizing molecular phylogenetic analyses of mitochondrial and nuclear DNA revealed extensive genetic differences, which indicated that the possibility of inter-specific hybridization was extremely unlikely. We collected A. japonicus and A. major from the Japanese Archipelago, Korean Peninsula, and Russian Far East, and conducted molecular analyses of mitochondrial DNA COI and 16S rRNA to compare phylogenetic relationships between these species. Three major clades were recognized within A. japonicus. Specimens from the Korean population constituted a monophyletic clade, and were a sister group of the western region of the Japanese Archipelago. The Eastern Japanese clade was clearly differentiated. Four major clades were recognized within A. major. Specimens from the Japanese and Korean populations revealed two distinct monophyletic clades. Significant differentiation was clearly observed between their genetic structures. Furthermore, the results of mismatch distribution and Bayesian skyline plot analyses suggested the possibility of a bottleneck effect or founder effect in two of the A. major clades. Collectively, these results demonstrated both similarities and differences in these two species even though their distribution widely overlaps in East Asia, with their morphological characteristics and ecological niches being very similar. These differences in genetic structures are considered to be due to their evolutionary history.

Distinct genetic clades of Malaysian Copera damselflies and the phylogeny of platycnemine subfamilies

The phylogenetic relationships of some taxa in the Platycnemidinae at the species and generic levels have been investigated. Phylogenetic trees were generated from both individual mitochondrial encoded COI, COII, 16S rDNA and nuclear encoded 28S rDNA and also combined sequences; these data indicate that the component taxa of the genus Copera belong to two distinct genetic clades - the marginipes group and the annulata group. There was no distinct genetic difference between the red-legged and yellow-legged morphs of C. vittata. Molecular data showed that the annulata group is considered a member of the genus Platycnemis, as originally proposed. The genus Coeliccia, a member of the subfamily Calicnemiinae (Platycnemididae), is not grouped with the Platycnemidinae. The Disparoneurinae of the 'Protoneuridae' showed a closer relationship to the Platycnemidinae than the Calicnemiinae. The dataset supports the placement of the Disparoneurinae as a subfamily of the Platycnemididae. This resolves the monophyly of Platycnemididae.

Morphometric and molecular analyses of the sand fly species Lutzomyia shannoni (Diptera: Psychodidae: Phlebotominae) collected from seven different geographical areas in the southeastern United States

A morphometric and molecular study of adult male and female Lutzomyia shannoni (Dyar 1929) collected at seven different locations within the southeastern United States was conducted to assess the degree of divergence between the grouped specimens from each location. The collection locations were as follows: Fort Bragg, NC; Fort Campbell, KY; Fort Rucker, AL; Ossabaw Island, GA; Patuxent National Wildlife Research Refuge, MD; Suwannee National Wildlife Refuge, FL; and Baton Rouge, LA. Forty males and forty females from each location were analyzed morphometrically from 54 and 49 character measurements, respectively. In addition, the molecular markers consisting of the partial cytochrome c oxidase subunit I (from 105 sand flies: 15 specimens/collection site) and the partial internal transcribed spacer 2 (from 42 sand flies: six specimens/collection site) were compared. Multivariate analyses indicate that the low degree of variation between the grouped specimens from each collection site prevents the separation of any collection site into an entity that could be interpreted as a distinct population. The molecular analyses were in concordance with the morphometric study as no collection location grouped into a separate population based on the two partial markers. The grouped specimens from each collection site appear to be within the normal variance of the species, indicating a single population in the southeast United States. It is recommended that additional character analyses of L. shannoni based on more molecular markers, behavioral, ecological, and physiological characteristics, be conducted before ruling out the possibility of populations or a cryptic species complex within the southeastern United States.

Revisiting the insect mitochondrial molecular clock: the mid-Aegean trench calibration

Phylogenetic trees in insects are frequently dated by applying a "standard" mitochondrial DNA (mtDNA) clock estimated at 2.3% My(-1), but despite its wide use reliable calibration points have been lacking. Here, we used a well-established biogeographic barrier, the mid-Aegean trench separating the western and eastern Aegean archipelago, to estimate substitution rates in tenebrionid beetles. Cytochrome oxidase I (cox1) for six codistributed genera across 28 islands (444 individuals) on both sides of the mid-Aegean trench revealed 60 independently coalescing entities delimited with a mixed Yule-coalescent model. One representative per entity was used for phylogenetic analysis of mitochondrial (cox1, 16S rRNA) and nuclear (Mp20, 28S rRNA) genes. Six nodes marked geographically congruent east-west splits whose separation was largely contemporaneous and likely to reflect the formation of the mid-Aegean trench at 9-12 Mya. Based on these "known" dates, a divergence rate of 3.54% My(-1) for the cox1 gene (2.69% when combined with the 16S rRNA gene) was obtained under the preferred partitioning scheme and substitution model selected using Bayes factors. An extensive survey suggests that discrepancies in mtDNA substitution rates in the entomological literature can be attributed to the use of different substitution models, the use of different mitochondrial gene regions, mixing of intraspecific with interspecific data, and not accounting for variance in coalescent times or postseparation gene flow. Different treatments of these factors in the literature confound estimates of mtDNA substitution rates in opposing directions and obscure lineage-specific differences in rates when comparing data from various sources.