Beringia Research Articles

Species Diversity, Host Association, and Evolutionary History of Cronartium: An Important Global Fungal Pathogen to Trees.

Pine stem rust, the most damaging and widespread forest disease occurring in pine trees in the Northern Hemisphere, is primarily caused by Cronartium species (Pucciniales, Melampsorineae). While the phylogenetic relationships of major Cronartium species have been largely elucidated, there is limited understanding of their species diversity and the evolutionary processes shaping their distribution patterns. In this work, we performed broad sampling and sequencing of Cronartium taxa in China together with additional sequence data and other accessions in NCBI to investigate the diversification and to estimate the divergence time of major evolutionary events in this genus. Molecular dating analysis suggested that the divergence of the genus Cronartium probably was around 91.78 Ma during the Upper Cretaceous. It is believed that Cronartium species may have originated in Asia and North America, with intercontinental dispersals occurring primarily during the Middle Eocene, Middle Miocene, and Pliocene. These dispersal events likely took place through the North Atlantic Land Bridge, the De Geer Route, and the Bering Land Bridge, and subsequently diverged through sporadic dispersal and vicariance events. Furthermore, our analysis of host associations revealed that the diversification of Cronartium species was correlated with their telial-hosts, and some species may have experienced host jump events, indicating a complex interplay between host specificity and pathogen-host interaction during Cronartium evolution.

A footworm in the door: revising Onchocerca phylogeny with previously unknown cryptic species in wild North American ungulates

Onchocerca is an important genus of vector-borne filarial nematodes that infect both humans and animals worldwide. Many Onchocerca spp., most of medical and veterinary health relevance, are the focus of a variety of diagnostic and molecular research. However, despite the importance of these parasites, there is growing evidence of previously unexplored genetic diversity of these nematodes, particularly among wild ungulate hosts in North America. These understudied parasites prevent us from comprehending the evolutionary history of the genus Onchocerca, monitoring potential One Health threats, and improving our filarioid diagnostic capabilities. In order to fill these knowledge gaps, we identified five uncharacterized Onchocerca lineages and compared them with other well-known filarioid species using single and concatenated gene regions (i.e., nd5, cox1, 12S, 18S, 28S, hsp70, MyoHC, rbp1). Phylogenetic analyses revealed that the novel Onchocerca lineages of wild North American ungulates segregate into two clades. One clade comprised Onchocerca lineages II, IV, and V and other species found mainly in domestic animals and humans, and the second comprised Onchocerca lineages I and III and other species from a variety of hosts including cervids, bovids, and equids. The formation of two clearly separate clades supports the idea of at least two independent expansion events of ancestral Onchocerca spp. into the North American continent via the Bering land bridge. Cophylogenetic analysis shows evidence of ancestral Onchocerca spp. of Bovidae host-switching to wild Cervidae and giving rise to the novel Onchocerca spp. Lastly, pairwise analysis confirms informative molecular markers of diagnostic relevance in both mitochondrial and nuclear gene regions of filarioid nematodes. The overall information provides greater context to the genus Onchocerca and emphasizes the need to discover, characterize, and monitor neglected parasites, especially those of wildlife origin.

A new neoceratopsian (Ornithischia, Ceratopsia) from the Lower Cretaceous Ohyamashimo Formation (Albian), southwestern Japan

AbstractThe herbivorous dinosaur clade Ceratopsia flourished in the northern hemisphere during the Late Jurassic to Late Cretaceous. Previous palaeobiogeographic studies have suggested that their initial diversification occurred in Asia, with early‐branching neoceratopsians extending their geographical range to North America sometime during the Barremian to Albian. However, the specific timing and mode of their dispersal from Asia to North America remains unknown. Here we describe a new, early‐branching neoceratopsian, Sasayamagnomus saegusai gen. et sp. nov., from the Albian Ohyamashimo Formation in southwestern Japan, representing the easternmost fossil record of ceratopsians in Asia. Sasayamagnomus exhibits three diagnostic features in the jugal, squamosal and coracoid, respectively, and also has a unique combination of characters in the lacrimal. Our phylogenetic analysis indicates that Sasayamagnomus forms a clade with Aquilops americanus, one of the earliest neoceratopsians from North America, followed by the sister taxon Auroraceratops rugosus from China. The present time‐calibrated phylogenetic tree indicates that the immigration of neoceratopsians from Asia to North America occurred during the latest Aptian or early Albian, refining the previously suggested timeframe. This aligns with fragmentary neoceratopsian fossil records from the Lower Cretaceous of North America and the initial formation of the Bering land bridge. Furthermore, the simultaneous occurrence of global warming (which enabled the development of extensive forests in the Arctic region) and the emergence of the Bering land bridge during the Aptian–Albian, probably played a crucial role in facilitating the immigration of neoceratopsians from Asia to North America.

Extended haplotype with rs41524547-G defines the ancestral origin of SCA10.

Spinocerebellar ataxia type 10 (SCA10) is a rare autosomal dominant ataxia caused by a large expansion of the (ATTCT)n repeat in ATXN10. SCA10 was described in Native American and Asian individuals which prompted a search for an expanded haplotype to confirm a common ancestral origin for the expansion event. All patients with SCA10 expansions in our cohort share a single haplotype defined at the 5'-end by the minor allele of rs41524547, located ~35kb upstream of the SCA10 expansion. Intriguingly, rs41524547 is located within the miRNA gene, MIR4762, within its DROSHA cleavage site and just outside the seed sequence for mir4792-5p. The world-wide frequency of rs41524547-G is less than 5% and found almost exclusively in the Americas and East Asia-a geographic distribution that mirrors reported SCA10 cases. We identified rs41524547-G(+) DNA from the 1000 Genomes/International Genome Sample Resource and our own general population samples and identified SCA10 repeat expansions in up to 25% of these samples. The reduced penetrance of these SCA10 expansions may be explained by a young (pre-onset) age at sample collection, a small repeat size, purity of repeat units, or the disruption of miR4762-5p function. We conclude that rs41524547-G is the most robust at-risk SNP allele for SCA10, is useful for screening of SCA10 expansions in population genetics studies and provides the most compelling evidence to date for a single, prehistoric origin of SCA10 expansions sometime prior to or during the migration of individuals across the Bering Land Bridge into the Americas.

Phylogeny and biogeography of the wingless orthopteran family Rhaphidophoridae

Cave crickets (Rhaphidophoridae) are insects of an ancient and wingless lineage within Orthoptera that are distributed worldwide except in Antarctica, and each subfamily has a high level of endemicity. Here, we show the comprehensive phylogeny of cave crickets using multi-gene datasets from mitochondrial and nuclear loci, including all extant subfamilies for the first time. We reveal phylogenetic relationships between subfamilies, including the sister relationship between Anoplophilinae and Gammarotettiginae, based on which we suggest new synapomorphies. Through biogeographic analyses based on divergence time estimations and ancestral range reconstruction, we propose novel hypotheses regarding the biogeographic history of cave crickets. We suggest that Gammarotettiginae in California originated from the Asian lineage when Asia and the Americas were connected by the Bering land bridge, and the opening of the western interior seaway affected the division of Ceuthophilinae from Tropidischiinae in North America. We estimate that Rhaphidophoridae originated at 138 Mya throughout Pangea. We further hypothesize that the loss of wings in Rhaphidophoridae could be the result of their adaptation to low temperatures in the Mesozoic era.

Biogeographic history of Pterocarya (Juglandaceae) inferred from phylogenomic and fossil data

AbstractPterocarya (Juglandaceae) is disjunctly distributed in East Asia and the Caucasus region today, but its fossils are widely distributed in the Northern Hemisphere. We first inferred phylogeny with time estimation of Pterocarya under node‐dating (ND) based on plastomes of all eight extant species and tip‐dating (TD) based on plastomes and 69 morphological characters of 19 extant and extinct species, respectively. We compared the biogeographical reconstructions on the timetrees from ND and TD, respectively, and then compiled 83 fossil records and 599 current occurrences for predicting the potential distributions for the past and the future. The most recent comment ancestor of Pterocarya is inferred in East Asia at 40.46 Ma (95% highest posterior density [HPD]: 28.04–54.86) under TD and 26.81 Ma (95% HPD: 23.03–33.12) under ND. The current distribution was attributed to one dispersal and one vicariant event without fossils, but as many as six dispersal, six vicariant, and 11 local extinction events when considering fossils. Pterocarya migrated between East Asia and North America via the Bering Land Bridge during the early Oligocene and the early Miocene periods. With the closure of Turgai Strait, Pterocarya dispersed between East Asia and Europe through the Miocene. The potential distribution analyses indicated that Pterocarya preferred warm temperate regions across the Northern Hemisphere since the Oligocene, but the drastic temperature decline caused its extinction in high latitudes. Except for Pterocarya fraxinifolia and Pterocarya stenoptera, suitable habitats for this genus are predicted to contract by 2070 due to climate change.

Discovery of a Nearctic vicariant bumblebee (Hymenoptera: Apidae) in Eurasia uncovers secondary trans-Beringian exchanges of insect faunas

Repeated emergence and disappearance of the Bering Land Bridge during the Quaternary triggered multiple faunal exchanges between northeast Asia and North America. Older (Early to Middle Pleistocene) dispersal events through the bridge followed by its submergence often lead to the vicariant origin of sister species, whose allopatric ranges are currently separated by the Bering Strait. Among bumblebees, examples of these pairs include Bombus balteatus Dahlbom 1832 – B. kirbiellus Curtis 1835, B. pyrrhopygus Friese 1902 – B. polaris Curtis 1835, and B. hyperboreus Schönherr 1809 – B. natvigi Richards 1931. However, integrative taxonomic analyses of new bumblebee samples from hard-to-reach areas of the Chukotka Peninsula (Russian Far East) reveal that the Nearctic B. kirbiellus is present at the north-eastern margin of Asia and that its Asian specimens share the COI haplotype with populations from Alaska. Although B. kirbiellus originated as a Nearctic relative of B. balteatus and was thought to be an endemic to North America, there was a Late Pleistocene (or more recent) expansion of this species from Alaska to Chukotka. Our findings indicate the possibility of secondary expansion of vicariant species through the Beringia during the Last Glacial Maximum or via a more recent migration event across the Bering Strait.

Population genetic structure of the provincially endangered mainland Eastern Moose (<i>Alces americanus americanus</i>) in Nova Scotia, Canada

Eastern Moose (Alces americanus americanus (Clinton, 1822)) on mainland Nova Scotia (MNS) are declining and experience limited immigration across the Isthmus of Chignecto from the larger population in neighbouring New Brunswick. Provincially Endangered, the recovery strategy for MNS Moose involves mitigating various threats that may lead to local extirpation. We examine genetic diversity of MNS Moose using microsatellite markers and mitochondrial (mtDNA) control region sequences. Genetic similarities with the Alces a. americana population in New Brunswick and the introduced Northwestern Moose (Alces americanus andersoni (= Alces alces andersoni) Peterson, 1952) population on Cape Breton Island are also analysed. Observed heterozygosity for microsatellites for MNS Moose was low and there was also evidence of limited gene flow between Nova Scotia and New Brunswick across the narrow Isthmus of Chignecto that connects these provinces. Consistent with relatively recent colonization of North America by Moose dispersing across the Bering Land Bridge <15 000 years ago, mtDNA haplotypes of MNS Moose were identical or extremely similar to haplotypes found across North America. However, mtDNA diversity was lower in Nova Scotia and New Brunswick than in more central regions of the species’ range. Active measures to maintain habitat that promote connectivity across the Isthmus of Chignecto would likely be valuable for Moose in terms of maintaining genetic variation in the region and reducing inbreeding.

Phylogeny And Historical Biogeography Of The Order Pandanales

Reconstruction of the dispersal history and formation of modern ranges of various taxa is one of the actual problems of modern biogeography. Molecular genetic biogeography based on the analysis of phylogenetic relationships of taxa of different levels began to develop actively at the end of the XX century. Currently, this method is the most objective and represents the basis for reconstruction of scenarios of the origin and dispersal of various groups of plants. Due to recent transformation of views on the phylogenetic relationships of Pandanales, the reconstruction of tracks and modes of dispersal of representatives of the order Pandanales becomes an actual task. Representatives of all 5 families of Pandanales sensu APG IV were selected for the study and two cladograms were constructed. Based on the molecular-genetic cladistic method the region of hypothetical origin and probable dispersal scenarios of the families of the order Pandanales were determined. The order Pandanales is treated as originated in Laurasia and its differentiation began on the territory of Tibet. Dispersal of the representatives of the basal family Velloziaceae took place by long-distance transport via the Bering Land Bridge to South America (approximately 115 Mya). Velloziaceae dispersed in the New World vicariously in South America, then it was distributed to sub-Atlantic Africa by long-distance transport, and finally also vicariously to the east, south and north of the continent. It is shown, that the modern range of the representatives of rest Pandanales is the result of both types of dispersal – vicariously and long-distance transport.

Biogeographic analysis based on phylogenomic data supports multiple ancient dispersals that facilitated the eastern Asia–North America–Mexico disjunction in the subfamily Linnaeoideae (Caprifoliaceae)

AbstractThe small subfamily Linnaeoideae of Caprifoliaceae exhibits a disjunct distribution in Eurasia and North America, including Mexico, with most taxa occurring in eastern Asia or Mexico and the monospecific Linnaea Gronov. ex L. having a circumboreal to north temperate distribution. We sampled 17 of the 20 species representing all Linnaeoideae genera and used nuclear (target enrichment) and complete plastome sequence data to reconstruct the phylogeny. Our results show strong topological conflicts between nuclear and plastid data, especially concerning Dipelta Maxim. and Diabelia Landrein, supporting hybridization events complicating the deep diversification. Nuclear data were used for divergence time estimation and ancestral area reconstruction. The divergence time between the Mexican Vesalea M. Martens & Galeotti and the Linnaea clade was dated to 39.5 Ma, with a 95% highest posterior density of 28.2 Ma (mid‐Oligocene) to 45.2 Ma (mid‐Eocene). Reconstructed ancestral areas support a widespread common ancestor of Linnaea plus Vesalea in Mexico and at least another area (eastern Asia, North America, or Europe). The biogeographic analysis, including fossils, supports the ancestral range of Linnaeoideae to be widespread in central and western China + Europe + Mexico, or eastern and northern Asia + central and western China + Mexico, or central and western China + North America + Mexico. The North Atlantic and/or the Bering land bridges may be important in the widespread distribution across continents in the Northern Hemisphere. Our study highlights the importance of utilizing fossils in biogeographic inferences andusing data from different genomes while reconstructing deep and shallow phylogenies of organisms.

Past climate cooling and orogenesis of the Hengduan Mountains have influenced the evolution of Impatiens sect. Impatiens (Balsaminaceae) in the Northern Hemisphere

BackgroundImpatiens sect. Impatiens is distributed across the Northern Hemisphere and has diversified considerably, particularly within the Hengduan Mountains (HDM) in southwest China. Yet, the infra-sectional phylogenetic relationships are not well resolved, largely due to limited taxon sampling and an insufficient number of molecular markers. The evolutionary history of its diversification is also poorly understood. In this study, plastome data and the most complete sampling to date were used to reconstruct a robust phylogenetic framework for this section. The phylogeny was then used to investigate its biogeographical history and diversification patterns, specifically with the aim of understanding the role played by the HDM and past climatic changes in its diversification.ResultsA stable phylogeny was reconstructed that strongly supported both the monophyly of the section and its division into seven major clades (Clades I-VII). Molecular dating and ancestral area reconstruction suggest that sect. Impatiens originated in the HDM and Southeast China around 11.76 Ma, after which different lineages dispersed to Northwest China, temperate Eurasia, and North America, mainly during the Pliocene and Pleistocene. An intercontinental dispersal event from East Asia to western North America may have occurred via the Bering Land Bridge or Aleutian Islands. The diversification rate was high during its early history, especially with the HDM, but gradually decreased over time both within and outside the HDM. Multiple linear regression analysis showed that the distribution pattern of species richness was strongly associated with elevation range, elevation, and mean annual temperature. Finally, ancestral niche analysis indicated that sect. Impatiens originated in a relatively cool, middle-elevation area.ConclusionsWe inferred the evolutionary history of sect. Impatiens based on a solid phylogenetic framework. The HDM was the primary source or pump of its diversity in the Northern Hemisphere. Orogeny and climate change may have also shaped its diversification rates, as a steady decrease in the diversification rate coincided with the uplift of the HDM and climate cooling. These findings provide insights into the distribution pattern of sect. Impatiens and other plants in the Northern Hemisphere.

Phylogenetic relationships and biogeography in Hedysarum (Hedysareae, Fabaceae) with a focus on Central Asian taxa

AbstractCentral Asia, especially the Tian‐Shan and Pamir‐Alay, is a biodiversity hotspot for Hedysarum (Fabaceae) with a high number of endemic species. However, to date, studies of the genus Hedysarum based on molecular data have included only a few species distributed in this region. To fill this gap, we analysed 110 Hedysarum species, 36 of which were from the Tian‐Shan and Pamir‐Alay Mountains of Central Asia. We performed phylogenetic analyses, divergence time estimates, and biogeographic analyses using both the internal transcribed spacers of nuclear ribosomal DNA (nrDNA ITS) and three plastid DNA (cpDNA) sequences (trnL‐trnF, matK, psbA‐trnH). Our phylogenetic analysis grouped the species of Hedysarum into three sections: H. sect. Hedysarum, sect. Multicaulia, and sect. Stracheya, which are largely consistent with previous phylogenetic classifications. Accordingly, most of the Central Asian species we studied (28 spp.) were placed in H. subsect. Crinifera within H. sect. Multicaulia. Our divergence time and biogeographic analyses indicate that Hedysarum likely originated in West Asia and/or East Asia during the Early Miocene or Middle Miocene and subsequently dispersed to adjacent areas of Eurasia, as well as North America via the Bering Land Bridge. The likely area of origin for H. sect. Multicaulia is West Asia, while East Asia appears to be the center of origin for H. sect. Hedysarum and sect. Stracheya. In addition, we suggest that the rapid radiation of the species of H. subsect. Crinifera occurred in the Tian‐Shan and Pamir‐Alay Mountains, as well as the Turkish‐Iranian Plateau, and that geological and climatic changes were the main causes of speciation in Hedysarum.

Liverworts of Magadan: Life on the Edge of Beringia

Magadan Province, located on the southwestern edge of Greater Beringia, combines various floristic elements in its flora, including Beringian and circum-boreal species. The geographic position and habitat diversity of Magadan Province predicts its liverwort flora is one of the richest hemiarctic floras in Asia. The distribution of species throughout the region is uneven, and while its southern part shows close connections with the suboceanic floras of Kamchatka, the middle and central parts are clearly related to the floras of Chukotka, where the Beringian land bridge directly lies in the past. The wide distribution of basic rocks here leads to the existence of a significant complex of basiphylous taxa. A total of 214 taxa (including 205 species and nine varieties) are reported in the present paper. The study of liverworts of Magadan Province should be continued and several new additions to the floral list are highly likely.

Origins of cryophilous lineages and the role of Beringia: evidence from the cosmopolitan angiosperm genus Stellaria L. (Caryophyllaceae)

Abstract The cosmopolitan angiosperm genus Stellaria L. (Caryophyllaceae) occurs across the Arctic and is most diverse in the high southern Asian mountains, including presence at the most extreme latitudinal and elevational limits of vascular plants. Using the primary fossil record and double digest restriction site-associated DNA sequencing data, we estimated divergence times of Stellaria and relatives across the Caryophyllaceae. We then used ancestral area and ancestral state reconstructions to interpret the biogeographical history of the group. We found that Stellaria originated in the Miocene and gave rise to repeated New World lineages, mostly from temperate Old World regions and probably via Bering Land Bridges. Circumboreal lineages were recovered of recent, Pleistocene origin and several might have originated in southerly mountains of both the Old World and the New World before subsequently colonizing the Arctic. Ancestral state reconstruction of inhabitance of cold vs. temperate climates and of wet vs. dry habitats revealed repeated evolutionary transitions across these extremes by members of the genus worldwide. Our study, which samples nearly all species within a diverse and cosmopolitan lineage of flowering plants, recovers a group characterized by niche lability and helps to support prior findings of temperate origins of many cryophilous plant lineages. Pre-adaptation to cold might have been a prerequisite for colonization of the Arctic.

Evidence for the evolutionary history and diversity of fossil sweetgums: leaves and associated capitate reproductive structures of Liquidambar from the Eocene of Hainan Island, South China

AbstractExtant species of Liquidambar L. exhibit a disjunct distribution between western and eastern Asia and eastern North America to Central America, with the highest species diversity being in China. In this study, two new species of Liquidambar are described from the Eocene of Hainan Island, South China: L. hainanensis on basis of the leaf fossils, and L. ovoidea based on compressions of infructescences. The co‐occurrences of L. hainanensis leaves, associated infructescences of L. ovoidea and dispersed pantoporate pollen grains have the combination of morphological features peculiar to the genera Liquidambar and former Semiliquidambar and Altingia. This is considered further palaeobotanical justification for the placement of these three genera into a single genus, Liquidambar, proposed earlier based on molecular markers. Our data provide evidence for the occurrence of an ancestral polymorphic group of Liquidambar species (L. maomingensis with associated capitate infructescences, L. bella, L. hainanensis and L. ovoidea) during the Eocene in South China, and corroborate the view that South China could have been a centre of Liquidambar speciation during the Eocene. The morphological similarity of L. hainanensis leaves to those of the extant species L. orientalis from Western Asia and the North American L. styraciflua may support the importance of both the North Atlantic Land Bridge and the Bering Land Bridge for the dispersal of Liquidambar. Analysis of fossil species of Liquidambar from eastern Asia also contributes to further understanding of patterns in the taxonomic diversity and evolutionary history of this genus.

Molecular phylogenetics and biogeography reveal the origin of cherries (Prunus subg. Cerasus, Rosaceae)

Abstract Cherries (subg. Cerasus) belong to Prunus s.l. (Rosaceae) and are widely distributed in temperate and subtropical regions of the Northern Hemisphere. Given its ornamental and edible functions, it is a hugely preferred germplasm resource for human societies. However, the interspecific phylogenetic relationships, divergence times, and routes of this subgenus remain unclear. To reveal its enigmatic and intricate evolutionary history, we newly sequenced 12 subg. Cerasus species, reconstructed the plastome phylogeny with 24 previously published subg. Cerasus species. This study supports that subg. Cerasus split into five clades, among which P. mahaleb is the basal group of subg. Cerasus; P. campanulata is genetically distantly related to P. cerasoides and is not recommended for treatment as a variety of the latter; P. subhirtella is involved in the speciation of P. yedoensis. Molecular dating and ancestral area reconstructions infer that subg. Cerasus originated in the Eastern Mediterranean–Central Asia before 11.57 Mya (95% HPD = 5.34–19.1 Mya) and subsequently spread into the Qinghai-Tibetan Plateau (QTP) and adjacent regions. The first dispersal event of modern subg. Cerasus was facilitated by ‘out-of-QTP’, colonizing North America across the Bering Land Bridge and re-dispersing into Europe from the Late Miocene to Pliocene and forming the initial distribution pattern of extant subg. Cerasus in the Pliocene; The end of the Quaternary glacial period witnessed a second dispersal event, and core subg. Cerasus population diversity flourished radially in its separate refugia during the Late Pleistocene.

Ultraconserved elements improve resolution of marmot phylogeny and offer insights into biogeographic history

Marmots (Marmota spp.) comprise a lineage of large-bodied ground squirrels that diversified rapidly in the Pleistocene, when the planet quickly transitioned to a drier, colder, and highly seasonal climate—particularly at high latitudes. Fossil evidence indicates the genus spread from North America, across Beringia, and into the European Alps over the course of only a few million years, beginning in the late Pliocene. Marmots are highly adapted to survive long and severely cold winters, and this likely favored their expansion and diversification over this time period. Previous phylogenetic studies have identified two major subgenera of marmots, but the timing of important speciation events and some species relationships have been difficult to resolve. Here we use ultraconserved elements and mitogenomes, with samples from all 15 extant species, to more precisely retrace how and when marmots came to inhabit a vast Holarctic range. Our results indicate marmots arose in North America in the Early Miocene (∼16.3 Ma) and dispersed across the Bering Land Bridge in the Pliocene (∼3–4 Ma); in addition, our fossil-calibrated timeline is suggestive of the rise and spread of open grasslands as being particularly important to marmot diversification. The woodchuck (M. monax) and the Alaska marmot (M. broweri) are found to be more closely related to the Eurasian species than to the other North American species. Paraphyly is evident in the bobak marmot (M. bobak) and the hoary marmot (M. caligata), and in the case of the latter the data are highly suggestive of a second, cryptic species in the Cascade Mountains of Washington.

Orthoptera of Northeast Asia and Northwest America.

An annotated list of 42 species in 26 genera and four families of Orthoptera recorded from Beringia (Northeast Yakutia, Chukotka, Magadan region, and Kamchatka in Russia, Alaska in USA, Yukon and the Northwestern Territories in Canada) is given. The distribution of species is clarified. The exchange of orthopteran faunas between Asia and America by the Bering Land Bridge in Pleistocene was strongly limited. The only three species, Tetrix subulata (Linnaeus, 1761), Melanoplus frigidus (Boheman, 1846), and Stethophyma grossum (Linnaeus, 1758), are recorded from both Asian and American parts. The orthopteran fauna of Beringia is not original. Majority of Beringian species are widespread throughout either Asia or North America. There are only four endemic grasshoppers, namely two Asian subspesies, Melanoplus frigidus kamtchatkae (Sjosted, 1935) and Aeropedellus variegatus gelidus Mistshenko, 1951, and two American species, A. arcticus Hebard, 1935 and Bruneria yukonensis Vickery, 1969. Composition of the regional faunas is briefly discussed. The monotypic genus Bohemanella Ramme, 1951 is again considered as a synonym of Melanoplus Stål, 1873, where a type species of the former genus, Melanoplus frigidus (Boheman, 1846) comb. resurr., forming its own species group.

Phylogenomics revealed migration routes and adaptive radiation timing of Holarctic malaria mosquito species of the Maculipennis Group

BackgroundPhylogenetic analyses of closely related species of mosquitoes are important for better understanding the evolution of traits contributing to transmission of vector-borne diseases. Six out of 41 dominant malaria vectors of the genus Anopheles in the world belong to the Maculipennis Group, which is subdivided into two Nearctic subgroups (Freeborni and Quadrimaculatus) and one Palearctic (Maculipennis) subgroup. Although previous studies considered the Nearctic subgroups as ancestral, details about their relationship with the Palearctic subgroup, and their migration times and routes from North America to Eurasia remain controversial. The Palearctic species An. beklemishevi is currently included in the Nearctic Quadrimaculatus subgroup adding to the uncertainties in mosquito systematics.ResultsTo reconstruct historic relationships in the Maculipennis Group, we conducted a phylogenomic analysis of 11 Palearctic and 2 Nearctic species based on sequences of 1271 orthologous genes. The analysis indicated that the Palearctic species An. beklemishevi clusters together with other Eurasian species and represents a basal lineage among them. Also, An. beklemishevi is related more closely to An. freeborni, which inhabits the Western United States, rather than to An. quadrimaculatus, a species from the Eastern United States. The time-calibrated tree suggests a migration of mosquitoes in the Maculipennis Group from North America to Eurasia about 20–25 million years ago through the Bering Land Bridge. A Hybridcheck analysis demonstrated highly significant signatures of introgression events between allopatric species An. labranchiae and An. beklemishevi. The analysis also identified ancestral introgression events between An. sacharovi and its Nearctic relative An. freeborni despite their current geographic isolation. The reconstructed phylogeny suggests that vector competence and the ability to enter complete diapause during winter evolved independently in different lineages of the Maculipennis Group.ConclusionsOur phylogenomic analyses reveal migration routes and adaptive radiation timing of Holarctic malaria vectors and strongly support the inclusion of An. beklemishevi into the Maculipennis Subgroup. Detailed knowledge of the evolutionary history of the Maculipennis Subgroup provides a framework for examining the genomic changes related to ecological adaptation and susceptibility to human pathogens. These genomic variations may inform researchers about similar changes in the future providing insights into the patterns of disease transmission in Eurasia.

Evaluating species boundaries using coalescent delimitation in pine-killing Monochamus (Coleoptera: Cerambycidae) sawyer beetles

Plant-feeding beetle species are diverse and often individually highly variable. Accurate classifications can be difficult to establish yet are essential for study of evolutionary patterns and processes. Molecular data are key to further characterizing morphologically difficult groups and defining genus and species boundaries.Monochamus Dejean species are ecologically and economically significant, and in coniferous forests they vector the nematode that causes Pine Wilt Disease. This study uses nuclear and mitochondrial genes to test the monophyly and relationships of Monochamus and applies coalescent methods to further delimit the conifer-feeding species.Monochamus has also included approximately 120 Old World species associated with diverse angiosperm tree species. We sample from these additional morphologically diverse species to determine their placement in the Lamiini. Through supermatrix and coalescent methods, the higher-level relationships of Monochamus show that conifer-feeders are a monophyletic group that includes the type species and has split into Nearctic and Palearctic clades. Molecular dating indicates a single dispersal of conifer-feeders to North America over the second Bering Land Bridge circa 5.3 Ma. All other Monochamus sampled fall in different parts of the Lamiini tree. Small-bodied angiosperm-feeding Monochamus group with the monotypic genus Microgoes Casey. The African Monochamus subgenera sampled are distantly related to the conifer-feeding clade.The multispecies coalescent delimitation methods BPP and STACEY delimit 17 conifer-feeding Monochamus species for a total of 18 species, and supports the retention of all current species. An interrogation with nuclear gene allele phasing reveals that unphased data can be unreliable for accurate delimitations and divergence times. The delimited species are discussed with integrative evidence, highlighting real-world challenges in recognizing the completion of speciation.