Multiple refugia from penultimate glaciations in East Asia demonstrated by phylogeography and ecological modelling of an insect pest

Sex pheromone biosynthesis in the Oriental fruit moth Grapholita molesta involves Δ8 desaturation

The Oriental fruit moth Grapholita molesta is distributed throughout temperate regions and considered to be a pest in peach production and other high-value fruit crops in the rose family. Insecticide treatment has led to resistance development, but the use of sex pheromones in pest management has shown great promise. We investigated the pheromone biosynthesis pathway in G. molesta with the aim of elucidating pheromone evolution in the Olethreutinae subfamily of moths and harnessing pathway genes in biotechnological production of sex pheromone for use in pest management. In vivo labelling experiments suggested that an uncommon Δ8 fatty acyl desaturase is involved in sex pheromone biosynthesis. CRISPR/Cas9 knock-out of the highly expressed candidate desaturase gene Gmol_CPRQ almost completely blocked the production of Δ8 pheromone components in vivo. Heterologous expression of Gmol_CPRQ protein in yeast- or Sf9 insect cells, however, failed to demonstrate the expected Δ8 desaturase activity. Instead, Δ9 desaturase activity was observed. Co-expression in the yeast system of the electron donor, cytochrome b5, from G. molesta still produced only Δ9 desaturase activity. We suggest that Gmol_CPRQ is intimately involved in pheromone production in vivo, via an unknown reaction mechanism that may possibly involve another co-factor that is absent in the yeast and Sf9 expression systems, or depend on its subcellular site of activity. Solving this puzzle will shed further light on pheromone biosynthesis in the family Tortricidae and will be required for successful biotechnological production of fatty acids and pheromones requiring Δ8 desaturation.

Plastome data provides new insights into population differentiation and evolution of Ginkgo in the Sichuan Basin of China

BACKGROUND

Ginkgo biloba L., an iconic living fossil, challenges traditional views of evolutionary stasis. While nuclear genomic studies have revealed population structure across China, the evolutionary patterns reflected in maternally inherited plastomes remain unclear, particularly in the Sichuan Basin - a potential glacial refugium that may have played a crucial role in Ginkgo's persistence.

RESULTS

Analysis of 227 complete plastomes, including 81 newly sampled individuals from the Sichuan Basin, revealed three distinct maternal lineages differing from known nuclear genome patterns. We identified 170 sequence variants and extensive RNA editing (235 sites) with a bias toward hydrophobic amino acid conversions, suggesting active molecular evolution. A previously undocumented haplotype (IIA2), predominant in western Sichuan Basin populations, showed close genetic affinity with rare refugial haplotypes. Western populations exhibited higher haplotypic diversity and distinctive genetic structure, supporting the basin's role as both glacial refugium and corridor for population expansion. Ancient trees (314-784 years) provided evidence for interaction between natural processes and historical human dispersal in shaping current genetic patterns.

CONCLUSIONS

Our findings demonstrate substantial genetic diversity within Sichuan Basin Ginkgo populations and reveal dynamic molecular evolution through plastome variation and RNA editing patterns, challenging the notion of evolutionary stasis in this living fossil. This study provides crucial genomic resources for understanding Ginkgo's evolution and informs conservation strategies for this endangered species.

Climate change effect on the widely distributed Palearctic plant bug species (Insecta: Heteroptera: Miridae)

Insects are poikilothermic organisms and temperature increase usually accelerates their development rates, population and distribution area growth. Therefore, it is assumed that global warming can be beneficial for the pests and other widespread species at least in the relatively cool temperate zones. However, climate change's effect on the widespread species in the Palearctic remains poorly studied. This work was performed on three plant bug species (Insecta: Heteroptera: Miridae), at present inhabiting Europe and Asia. Liocoris tripustulatus is known from the Western Palearctic, Lygocoris pabulinus occupies the territories from Western Europe to South Asia, Lygus punctatus is distributed from Northern Europe to the Far East. In this paper, it is tested whether temperature rise is positively connected with the area of preferred climatic conditions for those species, and explores the particular climatic variables which can be limiting for the distribution of those species. Maxent software was used for the environmental niche modeling and to find the variables with significant contribution to the climatic models for the studied species. Based on those models, areas with preferred climatic conditions over different periods were calculated in QGIS. Principal component analysis and logistic regression were performed to find the variables highly contributing to the differences between the species. The results contradict the assumption that temperature growth alone can be a predictor for the widespread species and pest distribution range change. All species differ in suitable climatic conditions and their area dynamics in time, and the temperature affects each species differently. Only Liocoris tripustulatus might significantly expand its distribution area by 2070 due to the climate change. The areas in Asia and above the polar circle will be more suitable by that time for all three species than now. However, conditions in Europe might be less suitable for Lygocoris pabulinus and Lygus punctatus in the future. Both, temperature and precipitation variables, can be important for shaping distribution of Liocoris tripustulatus and Lygocoris pabulinus. Mean annual temperature and temperature in winter, most probably, limit the distribution of at least Liocoris tripsutulatus and Lygus punctatus, but changes in this variable affect those two species differently.

Sympatric diversity pattern driven by the secondary contact of two deeply divergent lineages of the soybean pod borer Leguminivora glycinivorella

The soybean pod borer, Leguminivora glycinivorella (Matsumura), is an important tortricid pest species widely distributed in most parts of China and its adjacent regions. Here, we analyzed the genetic diversity and population differentiation of L. glycinivorella using diverse genetic information including the standard cox1 barcode sequences, mitochondrial genomes (mitogenomes), and single-nucleotide polymorphisms (SNPs) from genotyping-by-sequencing. Based on a comprehensive sampling (including adults or larvae of L. glycinivorella newly collected at 22 of the total 30 localities examined) that covers most of the known distribution range of this pest, analyses of 543 cox1 barcode sequences and 60 mitogenomes revealed that the traditionally recognized and widely distributed L. glycinivorella contains two sympatric and widely distributed genetic lineages (A and B) that were estimated to have diverged ∼1.14 million years ago during the middle Pleistocene. Moreover, low but statistically significant correlations were recognized between genetic differentiation and geographic or environmental distances, indicating the existence of local adaptation to some extent. Based on SNPs, phylogenetic inference, principal component analysis, fixation index, and admixture analysis all confirm the two divergent sympatric lineages. Compared with the stable demographic history of Lineage B, the expansion of Lineage A had possibly made the secondary contact of the two lineages probable, and this process may be driven by the climate fluctuation during the late Pleistocene as revealed by ecological niche modeling.

Synergistic effects of Pleistocene geological and climatic events on complex phylogeographic history of widespread sympatric species of Megaloptera in East Asia

Unraveling the phylogeographic histories of species remains a key endeavor for comprehending the evolutionary processes contributing to the rich biodiversity and high endemism found in East Asia. In this study, we explored the phylogeographic patterns and demographic histories of three endemic fishfly and dobsonfly species ( Neochauliodes formosanus, Protohermes costalis, and Neoneuromus orientalis) belonging to the holometabolan order Megaloptera. These species, which share a broad and largely overlapping distribution, were analyzed using comprehensive mitogenomic data. Our findings revealed a consistent influence of vicariance on the population isolation of Neoc. formosanus and P. costalis between Hainan, Taiwan, and the East Asian mainland during the early Pleistocene, potentially hindering subsequent colonization of the later diverged Neon. orientalis to these islands. Additionally, we unveiled the dual function of the major mountain ranges in East Asia, serving both as barriers and conduits, in shaping the population structure of all three species. Notably, we demonstrated that these co-distributed species originated from Southwest, Southern, and eastern Central China, respectively, then subsequently migrated along multi-directional routes, leading to their sympatric distribution on the East Asian mainland. Furthermore, our results highlighted the significance of Pleistocene land bridges along the eastern coast of East Asia in facilitating the dispersal of mountain-dwelling insects with low dispersal ability. Overall, this study provides novel insight into the synergistic impact of Pleistocene geological and climatic events in shaping the diversity and distribution of aquatic insects in East Asia.

Identifying a potentially invasive population in the native range of a species: The enlightenment from the phylogeography of the yellow spotted stink bug, Erthesina fullo (Hemiptera: Pentatomidae)

The yellow spotted stink bug (YSSB), Erthesina fullo (Thunberg, 1783) is an important Asian pest that has recently successfully invaded Europe and an excellent material for research on the initial stage of biological invasion. Here, we reported the native evolutionary history, recent invasion history, and potential invasion threats of YSSB for the first time based on population genetic methods [using double digest restriction-site associated DNA (ddRAD) data and mitochondrial COI and CYTB] and ecological niche modelling. The results showed that four lineages (east, west, southwest, and Hainan Island) were established in the native range with a strong east-west differentiation phylogeographical structure, and the violent climate fluctuation might cause population divergence during the Middle and Upper Pleistocene. In addition, land bridges and monsoon promote dispersal and directional genetic exchanging between island populations and neighboring continental populations. The east lineage (EA) was identified as the source of invasion in Albania. EA had the widest geographical distribution among all other lineages, with a star-like haplotype network with the main haplotype as the core. It also had a rapid population expansion history, indicating that the source lineage might have stronger diffusion ability and adaptability. Our findings provided a significant biological basis for fine tracking of invasive source at the lineage or population level and promote early invasion warning of potential invasive species on a much subtler lineage level.

Shared phylogeographic patterns and environmental responses of co-distributed soybean pests: Insights from comparative phylogeographic studies of Riptortus pedestris and Riptortus linearis in the subtropics of East Asia

Comparative phylogeographic studies of closely related species sharing co-distribution areas can elucidate the role of shared historical factors and environmental changes in shaping their phylogeographic pattern. The bean bugs, Riptortus pedestris and Riptortus linearis, which both inhabit subtropical regions in East Asia, are recognized as highly destructive soybean pests. Many previous studies have investigated the biological characteristics, pheromones, chemicals and control mechanisms of these two pests, but few studies have explored their phylogeographic patterns and underlying factors. In this study, we generated a double-digest restriction site-associated DNA sequencing (ddRAD-seq) dataset to investigate phylogeographic patterns and construct ecological niche models (ENM) for both Riptortus species. Our findings revealed similar niche occupancies and population genetic structures between the two species, with each comprising two phylogeographic lineages (i.e., the mainland China and the Indochina Peninsula clades) that diverged approximately 0.1 and 0.3 million years ago, respectively. This divergence likely resulted from the combined effects of temperatures variation and geographical barriers in the mountainous regions of Southwest China. Further demographic history and ENM analyses suggested that both pests underwent rapid expansion prior to the Last Glacial Maximum (LGM). Furthermore, ENM predicts a northward shift of both pests into new soybean-producing regions due to global warming. Our study indicated that co-distribution soybean pests with overlapping ecological niches and similar life histories in subtropical regions of East Asia exhibit congruent phylogeographic and demographic patterns in response to shared historical biogeographic drivers.

Phylogeographic Pattern of the Assassin Bug Sycanus bifidus Inferred from Mitochondrial Genomes and Nuclear Genes

The assassin bug Sycanus bifidus has a wide distribution across southern China. This study explored its distribution and evolution by analyzing mitochondrial and nuclear ribosomal RNA genes, revealing how Pleistocene climate and geological changes shaped its phylogeography. We identified two main clades, A and B, that diverged in the Middle Pleistocene. Hainan Island's populations form a unique group within Clade A, suggesting that the Qiongzhou Strait served as a dispersal corridor during glaciation. Rising sea levels likely separated the Hainan population afterward. Ecological niche modeling showed that both populations have been viable since the last interglacial period, with demographic analyses indicating possible expansions during the Middle and Late Pleistocene, driven by favorable climates. This study highlights the significant effects of Pleistocene sea-level and climatic changes on the distribution and evolution of S. bifidus in China.

Ancient DNA reveals genetic admixture in China during tiger evolution

The tiger (Panthera tigris) is a charismatic megafauna species that originated and diversified in Asia and probably experienced population contraction and expansion during the Pleistocene, resulting in low genetic diversity of modern tigers. However, little is known about patterns of genomic diversity in ancient populations. Here we generated whole-genome sequences from ancient or historical (100-10,000 yr old) specimens collected across mainland Asia, including a 10,600-yr-old Russian Far East specimen (RUSA21, 8× coverage) plus six ancient mitogenomes, 14 South China tigers (0.1-12×) and three Caspian tigers (4-8×). Admixture analysis showed that RUSA21 clustered within modern Northeast Asian phylogroups and partially derived from an extinct Late Pleistocene lineage. While some of the 8,000-10,000-yr-old Russian Far East mitogenomes are basal to all tigers, one 2,000-yr-old specimen resembles present Amur tigers. Phylogenomic analyses suggested that the Caspian tiger probably dispersed from an ancestral Northeast Asian population and experienced gene flow from southern Bengal tigers. Lastly, genome-wide monophyly supported the South China tiger as a distinct subspecies, albeit with mitochondrial paraphyly, hence resolving its longstanding taxonomic controversy. The distribution of mitochondrial haplogroups corroborated by biogeographical modelling suggested that Southwest China was a Late Pleistocene refugium for a relic basal lineage. As suitable habitat returned, admixture between divergent lineages of South China tigers took place in Eastern China, promoting the evolution of other northern subspecies. Altogether, our analysis of ancient genomes sheds light on the evolutionary history of tigers and supports the existence of nine modern subspecies.

Impacts of Quaternary glaciation, geological history and geography on animal species history in continental East Asia: A phylogeographic review

Continental East Asia has a mild Pleistocene climate and a complex recent geological history. Phylogeographic studies of animals over the last 30 years have produced several distinctive patterns. Glaciation refugia are numerous and are not restricted to any particular regions. Most of them are localized and species-specific, although several large refugia, for example the mountains of SW China, are shared by multiple species and have refugia-within-refugia. Furthermore, postglaciation range expansion events vary greatly in time, scale and direction. Large-scale south-to-north post-LGM expansions are few and mostly occurred in the northern regions. Additionally, several unique geographic features, including the three-step terrain of China and the northern arid belt, have significant impacts on many species histories. Overall, the impacts of Pleistocene glaciations, particularly the LGM, on species history vary drastically from nondetectable to significant. The impacts are the least for species from the southwestern region and are most dominant for species from the north. Geological events play a more significant role in shaping species history than Pleistocene climatic changes. Phylogeographic patterns among animals species are highly consistent with those of plants. Future phylogeographic endeavour in East Asia should be hypothesis-driven and seek processes that underlie common patterns. The wide use of genomic data allow accurate estimates of historical population processes and exploration of older history beyond the Pleistocene.

Phylogeography and Genetic Structure of the Bush Cricket Decma fissa (Orthoptera, Tettigoniidae) in Southern China

Decma fissa is the most widely distributed species of the genus Decma occuring in southern China. This study presents the first phylogeographic work of D. fissa based on COI, Cytb and ITS sequence. We examined genetic diversity with ITS and mitochondrial sequence respectively, and phylogenetic work was based on the mitochondrial data. A high-level genetic diversity was revealed based on mitochondrial data but a low-level diversity was shown with ITS sequence. For the mitochondrial data, divergence time analysis displayed five lineages. Based on the Mantel test, geographic and genetic distances among D. fissa populations revealed a significant positive correlation. Bayesian skyline plot (BSP) analyses implied that none of three major lineages of D. fissa was seemingly affected by the last glacial maximum (LGM, 0.015-0.025 Mya). Ecological niche modeling was used to predict the distribution of D. fissa in four periods (LGM, Mid-Holocene, current and 2070) in China. Analysis of the ancestral area reconstruction indicated that D. fissa occurred in the South China area.

Climatic oscillation promoted diversification of spinous assassin bugs during Pleistocene glaciation

Insect speciation is among the most fascinating topics in evolutionary biology; however, its underlying mechanisms remain unclear. Allopatric speciation represents one of the major types of speciation and is believed to have frequently occurred during glaciation periods, when climatic oscillation may have caused suitable habitats to be fragmented repeatedly, creating geographical isolation among populations. However, supporting evidence for allopatric speciation of insects in East Asia during the Pleistocene glaciation remains lacking. We aim to investigate the effect of climatic oscillation during the Pleistocene glaciation on the diversification pattern and evolutionary history of hemipteran insects and to test the hypothesis of Pleistocene species stability using spinous assassin bugs Sclomina (Hemiptera: Reduviidae), a small genus widely distributed in southern China but was later found to have cryptic species diversity. Here, using the whole mitochondrial genome (mitogenome) and nuclear ribosomal RNA genes, we investigated both interspecific and intraspecific diversification patterns of spinous assassin bugs. Approximate Bayesian computation, ecological niche modeling, and demographic history analyses were also applied to understand the diversification process and driven factors. Our data suggest that the five species of Sclomina are highly diverged, despite three of them currently being cryptic. Speciation occurred during the Pleistocene when suitable distribution areas were possibly fragmented. Six phylogeographic groups in the type species S. erinacea were identified, among which two groups underwent expansion during the early Last Glacial Period and after Last Glacier Maximum. Our analyses suggest that this genus may have experienced climate-driven habitat fragmentation and postglacial expansion in the Pleistocene, promoting allopatric speciation and intraspecific diversification. Our results reveal underestimated species diversity in a small insect group and illustrate a remarkable example of allopatric speciation of insects in East Asia promoted by Pleistocene climatic oscillations. These findings provide important insights into the speciation processes and aid the conservation of insect species diversity.

Population genomic signatures of the oriental fruit moth related to the Pleistocene climates

The Quaternary climatic oscillations are expected to have had strong impacts on the evolution of species. Although legacies of the Quaternary climates on population processes have been widely identified in diverse groups of species, adaptive genetic changes shaped during the Quaternary have been harder to decipher. Here, we assembled a chromosome-level genome of the oriental fruit moth and compared genomic variation among refugial and colonized populations of this species that diverged in the Pleistocene. High genomic diversity was maintained in refugial populations. Demographic analysis showed that the effective population size of refugial populations declined during the penultimate glacial maximum (PGM) but remained stable during the last glacial maximum (LGM), indicating a strong impact of the PGM rather than the LGM on this pest species. Genome scans identified one chromosomal inversion and a mutation of the circadian gene Clk on the neo-Z chromosome potentially related to the endemicity of a refugial population. In the colonized populations, genes in pathways of energy metabolism and wing development showed signatures of selection. These different genomic signatures of refugial and colonized populations point to multiple impacts of Quaternary climates on adaptation in an extant species.

Lack of Genetic Structure Among Populations of Striped Flea Beetle Phyllotreta striolata (Coleoptera: Chrysomelidae) Across Southern China

The striped flea beetle (SFB) Phyllotreta striolata (Fabricius) (Coleoptera: Chrysomelidae) is a major pest of cruciferous vegetables in southern China. The population diversity and genetic structure of SFB are unknown. Here, we assembled a draft genome for the SFB and characterized the distribution of microsatellites. Then, we developed 12 novel microsatellite markers across the genome. We used a segment of the cox1 gene and newly developed microsatellite markers to genotype the genetic diversity of SFB across southern China. There were 44 mitochondrial haplotypes in the SFB populations, with haplotype 2 as the most widespread. The population genetic differentiation was very low, indicated by FST-values (<0.05 except for Guangxi population with other populations based on cox1), high gene flow (4.10 and 44.88 of cox1 and microsatellite, respectively) and Principal Coordinate Analysis across all populations. Mantel test showed genetic distance in SFB was significantly associated with geographic distance based on microsatellites (R2 = 0.2373, P = 0.014) while result based on cox1 (R2 = 0.0365, P = 0.155) showed no significant difference. The phylogenetic analysis did not find any geographically related clades among all haplotypes. Analyses based on microsatellites showed a lack of population genetic structure among all populations. Our study provides a foundation for the future understanding of the ecology and evolution of SFB and its management.

Global phylogeography and invasion history of the spotted lanternfly revealed by mitochondrial phylogenomics

Biological invasion has been a serious global threat due to increasing international trade and population movements. Tracking the source and route of invasive species and evaluating the genetic differences in their native regions have great significance for the effective monitoring and management, and further resolving the invasive mechanism. The spotted lanternfly Lycorma delicatula is native to China and invaded South Korea, Japan, and the United States during the last decade, causing severe damages to the fruits and timber industries. However, its global phylogeographic pattern and invasion history are not clearly understood. We applied high-throughput sequencing to obtain 392 whole mitochondrial genome sequences from four countries to ascertain the origin, dispersal, and invasion history of the spotted lanternfly. Phylogenomic analyses revealed that the spotted lanternfly originated from southwestern China, diverged into six phylogeographic lineages, and experienced northward expansion across the Yangtze River in the late Pleistocene. South Korea populations were derived from multiple invasions from eastern China and Japan with two different genetic sources of northwestern (Loess Plateau) and eastern (East Plain) lineages in China, whereas the each of Japan and the United States had only one. The United States populations originated through single invasive event from South Korea, which served as a bridgehead of invasion. The environmental conditions, especially the distribution of host Ailanthus trees, and adaptability possibly account for the rapid spread of the spotted lanternfly in the native and introduced regions.

A transcriptomic variation map provides insights into the genetic basis of Pinus massoniana Lamb. evolution and the association with oleoresin yield

BACKGROUND

Masson pine (Pinus massoniana Lamb.), the dominant native coniferous species in southern China, is commercially important for supplying timber and oleoresin. However, knowledge of the genetic variability of masson pine germplasm is still limited. In this study, the genetic diversity and population structure of masson pine germplasm were assessed using 204 wild accessions from 10 main distribution regions using 94,194 core single-nucleotide polymorphisms (SNPs) obtained from transcriptome sequencing data.

RESULTS

The average expected heterozygosity was 0.2724, implying abundant genetic diversity within masson pine germplasm. Analysis of molecular variance (AMOVA) revealed that 3.29% of the variation was sourced from genetic differentiation. Structure analysis identified two geographically distinct groups. Discriminant analysis of principal components (DAPC) showed that one of those groups was further divided into two clusters. Sichuan and Chongqing provenance is the geographical origin, which diffused outward along two different lines. Oleoresin yield is reflected in the evolution of the two groups, and exhibits two different trends along the two lines of diffusion. The oleoresin yield may be associated with the genes of chitinase, CYP720B, cytochrome P450, ABC transporter, and AP2/ethylene-responsive transcription factor (ERF) based on SNPs and expression.

CONCLUSIONS

SNP markers from transcriptome sequencing are highly capable of evaluating genetic diversity within different species, as well as the genetic control of objective traits. The functions of these genes will be verified in future studies, and those genes strongly associated with oleoresin yield will be used to improve yields by means of early genotype selection and genetic engineering.

Impact of the Mid-Pleistocene Revolution and Anthropogenic Factors on the Dispersion of Asian Black-Spined Toads (Duttaphrynus melanostictus)

Divergence-time estimation critically improves the understanding of biogeography processes underlying the distribution of species, especially when fossil data is not available. We hypothesise that the Asian black-spined toad, Duttaphrynus melanostictus, expanded into the Eastern Indomalaya following the Quaternary glaciations with the subsequent colonisation of new landscapes during the Last Glacial Maximum. Divergence dating inferred from 364 sequences of mitochondrial tRNAGly ND3 supported the emergence of a common ancestor to the three D. melanostictus clades around 1.85 (±0.77) Ma, matching with the Lower to Mid-Pleistocene transition. Duttaphrynus melanostictus then dispersed into Southeast Asia from the central Indo-Pacific and became isolated in the Southern Sundaic and Wallacea regions 1.43 (±0.10) Ma through vicariance as a result of sea level oscillations. The clade on the Southeast Asian mainland then colonised the peninsula from Myanmar to Vietnam and expanded towards Southeastern China at the end of the Mid-Pleistocene Revolution 0.84 (±0.32) Ma. Population dynamics further highlight an expansion of the Southeast Asian mainland population towards Taiwan, the Northeastern edge of the species' range after the last interglacial, and during the emergence of the Holocene human settlements around 7000 BP. Thus, the current divergence of D. melanostictus into three segregated clades was mostly shaped by Quaternary glaciations, followed by natural dispersion events over land bridges and accelerated by anthropogenic activities.

Strong genetic differentiation among populations of Cheirotonus gestroi (Coleoptera: Euchiridae) in its native area sheds lights on species conservation

The long-armed scarab (Cheirotonus gestroi) is an endangered large insect in southwestern China and neighboring countries; however, limited information is available regarding its population genetics, hindering conservation efforts. Therefore, we investigated the population genetic structure and evolutionary history of C. gestroi in southwestern China. Twenty-five haplotypes were obtained from 47 specimens across five populations. The Dawei Mountain (DWS) population differed from other populations by a high genetic distance. Population structure analysis generated three distinct clades, corresponding to Hengduan Mountains (HM), Ailao Mountains (AM), and Dawei Mountains (DM), and high-level genetic diversity was found in two HM populations. Collectively, the strong genetic differentiation among populations might be due to limited gene flow, geographical isolation, and habitat fragmentation. Therefore, while developing a conservation strategy, HM, AM, and DM groups should be defined as separate management units. Additionally, the DWS population should be given priority protection due to its uniqueness and low genetic diversity.

Sky islands as foci for divergence of fig trees and their pollinators in southwest China

The dynamics of populations and their divergence over time have shaped current levels of biodiversity and in the case of the "sky islands" of mountainous southwest (SW) China have resulted in an area of exceptional botanical diversity. Ficus tikoua is a prostrate fig tree subendemic to the area that displays unique intraspecific diversity, producing figs typical of different pollination modes in different parts of its range. By combining climate models, genetic variation in populations of the tree's obligate fig wasp pollinators and distributions of the different plant phenotypes, we examined how this unusual situation may have developed. We identified three genetically distinct groups of a single Ceratosolen pollinator species that have largely parapatric distributions. The complex topography of the region contributed to genetic divergence among the pollinators by facilitating geographical isolation and providing refugia. Migration along elevations in response to climate oscillations further enhanced genetic differentiation of the three pollinator groups. Their distributions loosely correspond to the distributions of the functionally significant morphological differences in the male figs of their host plants, but postglacial expansion of one group has not been matched by spread of its associated plant phenotype, possibly due to a major river barrier. The results highlight how interplay between the complex topography of the "sky island" complex and climate change has shaped intraspecies differentiation and relationships between the plant and its pollinator. Similar processes may explain the exceptional botanical diversity of SW China.

Identification of winter moth (Operophtera brumata) refugia in North Africa and the Italian Peninsula during the last glacial maximum

Numerous studies have shown that the genetic diversity of species inhabiting temperate regions has been shaped by changes in their distributions during the Quaternary climatic oscillations. For some species, the genetic distinctness of isolated populations is maintained during secondary contact, while for others, admixture is frequently observed. For the winter moth (Operophtera brumata), an important defoliator of oak forests across Europe and northern Africa, we previously determined that contemporary populations correspond to genetic diversity obtained during the last glacial maximum (LGM) through the use of refugia in the Iberian and Aegean peninsulas, and to a lesser extent the Caucasus region. Missing from this sampling were populations from the Italian peninsula and from North Africa, both regions known to have played important roles as glacial refugia for other species. Therefore, we genotyped field-collected winter moth individuals from southern Italy and northwestern Tunisia-the latter a region where severe oak forest defoliation by winter moth has recently been reported-using polymorphic microsatellite. We reconstructed the genetic relationships of these populations in comparison to moths previously sampled from the Iberian and Aegean peninsulas, the Caucasus region, and western Europe using genetic distance, Bayesian clustering, and approximate Bayesian computation (ABC) methods. Our results indicate that both the southern Italian and the Tunisian populations are genetically distinct from other sampled populations, and likely originated in their respective refugium during the LGM after diverging from a population that eventually settled in the Iberian refugium. These suggest that winter moth populations persisted in at least five Mediterranean LGM refugia. Finally, we comment that outbreaks by winter moth in northwestern Tunisia are not the result of a recent introduction of a nonnative species, but rather are most likely due to land use or environmental changes.

Phylogeography of the Assassin Bug Sphedanolestes impressicollis in East Asia Inferred From Mitochondrial and Nuclear Gene Sequences

The assassin bug, Sphedanolestes impressicollis (Hemiptera: Reduviidae), is widely distributed in East Asia. It is an ideal model for evaluating the effects of climatic fluctuation and geographical events on the distribution patterns of East Asian reduviids. Here, we used two mitochondrial genes and one nuclear gene to investigate the phylogeographic pattern of the assassin bug based on comprehensive sampling in China, Japan, South Korea, Vietnam, and Laos. High levels of genetic differentiation were detected among the geographic populations classified into the northern and southern groups. A significant correlation was detected between genetic and geographical distances. The East China Sea land bridge served as a “dispersal corridor” during Pleistocene glaciation. The estimated divergence time indicated that the northern group may have separated from the eastern Chinese populations when the sea level rapidly rose during the “Ryukyu Coral Sea Stage” and the East China Sea land bridge was completely submerged. Demographic history and ecological niche modeling suggested that appropriate climatic conditions may have accounted for the rapid spread across the Korean Peninsula and Japan during the late Pleistocene. Our study underscores the pivotal roles of the Pleistocene sea level changes and climatic fluctuations in determining the distribution patterns of East Asian reduviids.