Influence of global warming on forest coleopteran communities with special reference to ambrosia and bark beetles

Forest insect pests are one of the major disturbance factors in forest ecosystems and their outbreaks are expected to be more severe under the influence of global warming. Coleopterans are dominant among forest insects and their ecological functions include general detritivores, dead wood feeders, fungivores, herbivores, live wood feeders and predators. Ambrosia and bark beetles contribute to ecological succession of forests and, therefore, ecological functions of forests can be changed in response to their outbreaks. Mountain pine beetle (MPB) outbreaks are the most dramatic example of changes in the ecological functions of forest due to the outbreak of a forest insect pest altered by global warming. Composition of coleopteran species varies with latitude. However, composition of functional groups is consistent with latitude which indicates that resources available to beetles are consistent. In coleopteran communities, ambrosia and bark beetles can become dominant due to increases of dead or stressed trees due to the warming climate. This can also induce changes in the ecological functions of coleopterans, i.e. selective force to displace trees that have lower ecological fitness due to temperature increase. Therefore, recent increases in the density ambrosia and bark beetles offer a chance to study ecological processes in forests under the influence of global warming.     

Patterns of functional enzyme activity in fungus farming ambrosia beetles

ABSTRACT: INTRODUCTION: In wood-dwelling fungus-farming weevils, the so-called ambrosia beetles, wood in the excavated tunnels is used as a medium for cultivating fungi by the combined action of digging larvae (which create more space for the fungi to grow) and of adults sowing and pruning the fungus. The beetles are obligately dependent on the fungus that provides essential vitamins, amino acids and sterols. However, to what extent microbial enzymes support fungus farming in ambrosia beetles is unknown. Here we measure (i) 13 plant cell-wall degrading enzymes in the fungus garden microbial consortium of the ambrosia beetle Xyleborinus saxesenii, including its primary fungal symbionts, in three compartments of laboratory maintained nests, at different time points after gallery foundation and (ii) four specific enzymes that may be either insect or microbially derived in X. saxesenii adult and larval individuals. RESULTS: We discovered that the activity of cellulases in ambrosia fungus gardens is relatively small compared to the activities of other cellulolytic enzymes. Enzyme activity in all compartments of the garden was mainly directed towards hemicellulose carbohydrates such as xylan, glucomannan and callose. Hemicellulolytic enzyme activity within the brood chamber increased with gallery age, whereas irrespective of the age of the gallery, the highest overall enzyme activity were detected in the gallery dump material expelled by the beetles. Interestingly endo-beta-1,3(4)-glucanase activity capable of callose degradation was identified in whole-body extracts of both larvae and adult X. saxesenii, whereas endo-beta-1,4-xylanase activity was exclusively detected in larvae. CONCLUSION: Similar to closely related fungi associated with bark beetles in phloem, the microbial symbionts of ambrosia beetles do not degrade cellulose. Instead, their enzyme activity is directed mainly towards comparatively more easily accessible hemicellulose components of the ray-parenchyma cells in the wood xylem. Furthermore, the detection of xylanolytic enzymes exclusively in larvae and not in adults indicates that larvae (pre-) digest plant cell wall structures exclusively in larvae (which feed on fungus colonized wood) and not in adults (which feed only on fungi). This implies that in X. saxesenii and likely also in many other ambrosia beetles, adults and larvae do not compete for the same food within their nests - in contrast, larvae increase colony fitness by facilitating enzymatic wood degradation and fungus cultivation.     

Species diversity estimation of ambrosia and bark beetles in temperate mixed forests in Japan based on host phylogeny and specificity

Understandings of the effect of host plant phylogeny on the structure of herbivore assemblage is useful for estimating global species richness of herbivores. Here we test the relationship between host plant phylogeny and two assemblages including ambrosia beetle assemblage that have been considered to be the lowest host specificity among plant-dependent guilds. These results of local scale were used for estimating regional species richness by extrapolating to the number of plant order and species in Japan. The estimated numbers were compared with the numbers of described species in Japan. Tree trunks of 17 plant species representing 17 orders of all major lineages of Japanese tree flora were exposed for collecting wood boring beetle species. A total of 12 ambrosia and four bark beetle species were collected. Similarity of both ambrosia and bark beetle assemblages showed a significant negative trend with phylogenetic distance between focal host plant species. The regression model for this relationship was well fit by a linear model whereas previous studies used a semi-log model, which suggests a difference in mechanism of host utilization with host taxonomic levels. Our results showed a broader host range of ambrosia beetle assemblage in temperate forest than to a comparable study in tropical rainforests. Species richness estimated is lower than the described species in Japan, suggesting the need for more samples along the altitudinal gradients for accurate estimation for the Japanese fauna.     

DNA barcoding of bark and ambrosia beetles reveals excessive NUMTs and consistent east‐west divergence across Palearctic forests

A comprehensive DNA barcoding library is very useful for rapid identification and detection of invasive pest species. We tested the performance of species identification in the economically most damaging group of wood‐boring insects – the bark and ambrosia beetles – with particular focus on broad geographical sampling across the boreal Palearctic forests. Neighbour‐joining and Bayesian analyses of cytochrome oxidase I (COI) sequences from 151 species in 40 genera revealed high congruence between morphology‐based identification and sequence clusters. Inconsistencies with morphological identifications included the discovery of a likely cryptic Nearctic species of Dryocoetes autographus, the possible hybrid origin of shared mitochondrial haplotypes in Pityophthorus micrographus and P. pityographus, and a possible paraphyletic Xyleborinus saxeseni. The first record of Orthotomicus suturalis in North America was confirmed by DNA barcoding. The mitochondrial data also revealed consistent divergence across the Palearctic or Holarctic, confirmed in part by data from the large ribosomal subunit (28S). Some populations had considerable variation in the mitochondrial barcoding marker, but were invariant in the nuclear ribosomal marker. These findings must be viewed in light of the high number of nuclear insertions of mitochondrial DNA (NUMTs) detected in eight bark beetle species, suggesting the possible presence of additional cryptic NUMTs. The occurrence of paralogous COI copies, hybridization or cryptic speciation demands a stronger focus on data quality assessment in the construction of DNA barcoding databases.     

Attraction of ambrosia and bark beetles to coast live oaks infected by Phytophthora ramorum

1 Sudden oak death is caused by the apparently introduced oomycete, Phytophthora ramorum. We investigated the role of bark and ambrosia beetles in disease progression in coast live oaks Quercus agrifolia. 2 In two Marin County, California sites, 80 trees were inoculated in July 2002 with P. ramorum and 40 were wounded without inoculation. Half of the trees in each group were sprayed with the insecticide permethrin [cyclopropanecarboxylic acid, 3‐(2,2‐dichloroethenyl)‐2,2‐dimethyl‐(3‐phenoxyphenyl) methyl ester] to prevent ambrosia and bark beetle attacks, and then were sprayed twice per year thereafter. After each treatment, sticky traps were placed on only the permethrin‐treated trees. Beetles were collected periodically in 2003. 3 Inoculated trees accounted for 95% of all beetles trapped. The ambrosia beetles Monarthrum scutellare and Xyleborinus saxeseni and the western oak bark beetle Pseudopityophthorus pubipennis were the most abundant of the seven species trapped. 4 Permethrin treatment delayed initiation of beetle attacks and significantly reduced the mean number of attacks per tree. Beetles did not attack any wounded or noncankered inoculated trees. 5 Trees with larger cankers trapped more beetles early in the disease. Once permethrin lost effectiveness, the number of beetle entrance tunnels was a more reliable predictor of subsequent trap catch than was canker size. 6 Beetles were initially attracted to P. ramorum cankers in response to kairomones generated in the host‐pathogen interaction. After beetles attacked the permethrin‐treated trees, aggregation pheromones most probably were the principal factor in beetle colonization behaviour.     

Ophiostomatoid fungi associated with hardwood-infesting bark and ambrosia beetles in Poland: Taxonomic diversity and vector specificity

Fungi in the orders Ophiostomatales and Microascales (Ascomycota), often designated as ophiostomatoid fungi, are frequent associates of scolytine bark and ambrosia beetles that colonize hardwood and coniferous trees. Several species, e.g., Ophiostoma novo-ulmi, are economically damaging pathogens of trees. Because little is known regarding the ophiostomatoid fungi in Europe, we have explored the diversity of these fungi associated with hardwood-infesting beetles in Poland. This study aims to clarify the associations between fungi in the genera Ambrosiella, Graphium (Microascales), Graphilbum, Leptographium, Ophiostoma and Sporothrix (Ophiostomatales) and their beetle vectors in hardwood ecosystems. Samples associated with 18 bark and ambrosia beetle species were collected from 11 stands in Poland. Fungi were isolated from adult beetles and galleries. Isolates were identified based on morphology, DNA sequence comparisons for five gene regions (ITS, LSU, ßT, TEF 1-α, and CAL) and phylogenetic analyses. In total, 36 distinct taxa were identified, including 24 known and 12 currently unknown species. Several associations between fungi and bark and ambrosia beetles were recorded for the first time. In addition, associations between Dryocoetes alni, D. villosus, Hylesinus crenatus, Ernoporus tiliae, Pteleobius vittatus and ophiostomatoid fungi were reported for the first time, and Sporothrix eucastanea was reported for the first time outside of the USA. Among the species of Ophiostomatales, 14 species were in Ophiostoma s. l., two species were in Graphilbum, nine species were in Sporothrix, and seven species were in Leptographium s. l. Among the species of Microascales, three species were in Graphium, and one was in Ambrosiella. Twenty taxa were present on the beetles and in the galleries, twelve only on beetles, and four only in galleries. Bark and ambrosia beetles from hardwoods appear to be regular vectors, with ophiostomatoid fungi present in all the beetle species. Most ophiostomatoid species had a distinct level of vector/host specificity, although Ophiostoma quercus, the most frequently encountered species, also had the greatest range of beetle vectors and tree hosts. Plant pathogenic O. novo-ulmi was found mainly in association with elm-infesting bark beetles (Scolytus multistriatus, S. scolytus, and P. vittatus) and occasionally with H. crenatus on Fraxinus excelsior and with Scolytus intricatus on Quercus robur.     

The evolution of mating systems in bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae)

The extraordinary array of mating systems in the Scolytidae and Platypodidae has been largely overlooked by researchers interested in the evolution of sexual behaviour. This paper provides the first overview of reproductive behaviour in this important and widespread group, known to most biologists only by the reputations of tree-killing taxa. Referred to generally as ‘bark beetles’, these insects chew egg tunnels inside a variety of (usually dead) plant tissues, though most species are either phloeophagous (breeding in the inner bark of woody plants) or xylomycetophagous (all stages feeding on mutualistic fungi growing on sapwood or heartwood). In most species, permanent records of many aspects of reproductive behaviour are etched in the host; in many, engravings reveal female fecundity, eggs sired per male, hatching success, and offspring survivorship. Each gallery arm represents a good portion of a given female's lifetime reproduction, but in many species females commonly re-emerge to reproduce in one or two additional sites. In most species of bark beetles, each female initiates her own gallery, to be joined later by a male. These monogynous gallery systems are associated with mating systems defined by how long males stay with females: in a few species, males seldom if ever join females under the bark; in the vast majority of species, males stay for part or all of the oviposition period then leave to seek other mates; and a few groups exhibit permanent monogamy, in that both sexes die in their only gallery system. While these patterns emerge from an overview of the world scolytid fauna, the length of male residency has seldom been quantified, and the costs and benefits associated with male mating strategies have not been measured for any bark beetle. Male-initiated monogyny is uncommon in Scolytidae, though the rule in Platypodidae; all instances of which I am aware are summarized from a phylogenetic perspective. Inbreeding polygyny with highly biased sex ratios has arisen at least seven times in Scolytidae. These taxa are usually characterized by males being dwarfed, flightless, and uncommon. Sex determination is known for only a few examples, but both haplodiploidy and diplodiploidy have been reported. Multiple origins of harem polygyny (otherwise rare in invertebrates) add an exciting dimension to the comparative and experimental study of scolytid mating systems. In harem polygynous taxa, males initiate gallery construction. I summarize what little can be learned from the literature about the fine structure of harem polygynous mating systems in bark beetles, and the problem of measuring reproductive success. Data on the nature of harem polygyny in Pityophthorus lautus are presented, illustrating (a) the fluidity of harems; (b) that average eggs laid per gallery arm is relatively unaffected by harem size, but strongly influenced by resource quality; (c) that male egg-gain is strongly correlated with territory quality (a consequence of (b) above); and (d) the temporal patterning of immigration and emigration and its effects on gallery system sex ratios. The second half of this paper is a discussion of the evolution of bark and ambrosia beetle mating Mating systems, emphasizing sexual selection and the role of resources. Male, residence is interpreted as postcopulalory guarding—preventing sexual liaisons with wandering males. Operational sex ratio, encounter rate, synchrony of breeding, ejaculate competition, and spatiotemporal distribution of resources are discussed as evolutionary forces moulding scolytid and platypodid male postmating behaviour. The nature of male male competition is reviewed. The paucity of information on male behaviour in gallery systems is mentioned; whether or not males significantly aid females is not known. Three hypotheses are presented for why females re-emerge, a feature which strongly affects operational sex ratios. Finally, I summarize features of bark beetle existence predisposing them to the evolution of post-inseminative guarding. Male-initiated monogyny presents a puzzle. I propose that most uncontested examples can be explained by monogyny re-evolving from (male-initiated) harem polygyny, and I present an argument for the evolution of harem polygyny leading to the development of male gallery initiation. The evolution of harem polygyny in birds and mammals has attracted considerable attention. The Verner Willson Orians polygyny threshold model is discussed with respect to bark beetles in general and P. lautus in particular. Resource quality is a major factor in P. lautus harem dynamics: the cost to females of joining harems is apparently slight compared to benefits accrued from moving into sites with higher quality inner bark. Female-biased adult sex ratios have been suggested to lead to harem polygyny, and literature and original data pertinent to this hypothesis are examined. The geometric constraints model, based on the polygyny threshold concept but tailored to bark beetles, is proposed to account for the failure of most species to evolve harem polygyny, and testable predictions are derived that interrelate breeding systems, habitat quality, and progeny size. The evolution of Inbreeding is briefly covered, and two routes to inbreeding polygyny are suggested.     

Potential impact of global warming on deciduous oak dieback caused by ambrosia fungus Raffaelea sp. carried by ambrosia beetle Platypus quercivorus (Coleoptera: Platypodidae) in Japan

Deciduous oak dieback in Japan has been known since the 1930s, but in the last ten years epidemics have intensified and spread to the island's western coastal areas. The symbiotic ambrosia fungus Raffaelea sp. is the causal agent of oak dieback, and is vectored by Platypus quercivorus (Murayama). This is the first example of an ambrosia beetle fungus that kills vigorous trees. Mortality of Quercus crispula was approximately 40% but much lower for associated species of Fagaceae, even though each species had a similar number of beetle attacks. It is likely that other oaks resistant to the fungus evolved under a stable relationship between the tree, fungus and beetle during a long evolutionary process. Quercus crispula was probably not part of this coevolution. This hypothesis was supported by the fact that P. quercivorus showed the least preference for Q. crispula yet exhibited highest reproductive success in this species. Therefore, P. quercivorus could spread more rapidly in stands with a high composition of Q. crispula. The present oak dieback epidemic in Japan probably resulted from the warmer climate that occurred from the late 1980s which made possible the fateful encounter of P. quercivorus with Q. cripsula by allowing the beetle to extend its distribution to more northerly latitudes and higher altitudes. Future global warming will possibly accelerate the overlapping of the distributions of P. quercivorus and Q. crispula with the result that oak dieback in Q. crispula will become more prevalent in Japan.     

Molecular systematics reveals the origins of subsociality in tortoise beetles (Coleoptera,Chrysomelidae, Cassidinae)

Subsocial behaviour is known to occur in at least 19 insect orders and 17 families of Coleoptera. Within the leaf beetle family, Chrysomelidae, extended maternal care is reported in only 2 of 15 subfamilies: Cassidinae and Chrysomelinae. Although the emergence of subsociality in insects has received much attention, extensive analyses on the evolution of this behaviour based on phylogenetic approaches are missing. Subsociality is recorded in 33 species of tortoise beetles belonging to the tribes Mesomphaliini and Eugenysini. A molecular phylogenetic reconstruction of these tribes and the remaining five Neotropical tribes of cassidine tortoise beetles was used to investigate the evolution of maternal care and to elucidate the phylogenetic relationships among Neotropical cassidine tribes. A phylogeny was constructed using 90 species and three loci from both mitochondrial and nuclear genes (COI, CAD and 28S). Bayesian inference and maximum likelihood analyses based on a concatenated dataset recovered two independent origins, with no evidence of reversal to solitary behaviour. One origin comprises three Mesomphaliini genera tightly associated with Convolvulaceae, and the other consists of the genus Eugenysa Chevrolat (Eugenysini), a small clade embedded within a group feeding exclusively on Asteraceae. A previous hypothesis suggesting dual origins on different host plants was confirmed, whereas other hypotheses based on a phylogenetic reconstruction of Cassidinae could not be sustained. Our analysis also revealed that the tribe Mesomphaliini is a monophyletic taxon if Eugenysini is included, and for this reason, we re-establish synonymy of both tribes. We also provide nine new records of subsociality for tortoise beetles species.     

Adaptive traits of bark and ambrosia beetle-associated fungi

A phenotype is the expression of interactions between species genotype and environment. We quantified the contributions of ecological and phylogenetic associations to phenotypic variation in Geosmithia fungi. Geosmithia are symbiotic beetle-associated saprotrophs with a range of life histories and host specificities, including obligate nutritional beetle mutualists (ambrosia fungi) and phytopathogens. We hypothesized that: (1) species phenotypes are better explained by their ecology than by their phylogenetic relationships; (2) niche specialization was accompanied by enzymatic capability losses; and (3) ambrosia Geosmithia species have higher nutritional quality and antibiotic capabilities than species with facultative symbioses. Our results confirmed that long-term co-evolved specialists have reduced metabolic breadth in comparison to generalists. Phytopathogenic G. morbida produces unique enzyme suites with affinity to ligno-cellulose. Mycelia of ambrosia fungi contain large amounts of oleic fatty acid with nutritive and possibly allelopathic function. Overall, our results indicate that Geosmithia ecology have greater effect on species phenotype than their phylogenetic relationships.     

When ontogeny reveals what phylogeny hides: gain and loss of horns during development and evolution of horned beetles

How ecological, developmental and genetic mechanisms interact in the genesis and subsequent diversification of morphological novelties is unknown for the vast majority of traits and organisms. Here we explore the ecological, developmental, and genetic underpinnings of a class of traits that is both novel and highly diverse: beetle horns. Specifically, we focus on the origin and diversification of a particular horn type, those protruding from the pronotum, in the genus Onthophagus, a particularly speciose and morphologically diverse genus of horned beetles. We begin by documenting immature development of nine Onthophagus species and show that all of these species express pronotal horns in a developmentally transient fashion in at least one or both sexes. Similar to species that retain their horns to adulthood, transient horns grow during late larval development and are clearly visible in pupae. However, unlike species that express horns as adults, transient horns are resorbed during pupal development. In a large number of species this mechanisms allows fully horned pupae to molt into entirely hornless adults. Consequently, far more Onthophagus species appear to possess the ability to develop pronotal horns than is indicated by their adult phenotypes. We use our data to expand a recent phylogeny of the genus Onthophagus to explore how the widespread existence of developmentally transient horns alters our understanding of the origin and dynamics of morphological innovation and diversification in this genus. We find that including transient horn development into the phylogeny dramatically reduces the number of independent origins required to explain extant diversity patters and suggest that pronotal horns may have originated only a few times, or possibly only once, during early Onthophagus evolution. We then propose a new and previously undescribed function for pronotal horns during immature development. We provide histological as well as experimental data that illustrate that pronotal horns are crucial for successful ecdysis of the larval head capsule during the larval-to-pupal molt, and that this molting function appears to be unique to the genus Onthophagus and absent in the other scarabaeine genera. We discuss how this additional function may help explain the existence and maintenance of developmentally transient horns, and how at least some horn types of adult beetles may have evolved as exaptations from pupal structures originally evolved to perform an unrelated function.     

Molecular phylogeny reveals a core clade of Rhytismatales

Rhytismatales (Leotiomycetes, Pezizomycotina, Ascomycota) are an order of mostly plant-associated ascomycetes with a global distribution. Well known taxa include the Rhytisma tar spots on Acer spp. and several needle-cast pathogens in genera Lophodermium and Meloderma. Critical studies are lacking at all taxonomic ranks from order to species, and in particular the genus taxonomy in the order has been criticized for being unnatural. We used nuclear LSU and mitochondrial SSU sequences in Bayesian phylogenetic analyses to define a core clade of Rhytismatales sensu stricto. Some of the genera traditionally placed within the Rhytismatales, Ascodichaena, Marthamyces, Mellitiosporium, Potebniamyces, Propolis and Pseudophacidium, are shown to be phylogenetically distinct, all related to various other taxa at present placed in the polyphyletic Helotiales. Within the core clade only Cudonia, Spathularia and Terriera are supported as monophyletic. The large genera Coccomyces, Hypoderma and Lophodermium all are polyphyletic as are a few smaller genera. The traditionally used characters of ascoma and spore shape are shown to be unreliable for the delimitation of monophyletic genera but in some cases can be useful when combined with other characters. In this study we provide 72 new nrLSU and 64 new mtSSU sequences. Together with publicly available sequences data for 103 specimens representing 91 species of Rhytismatales are now available. Despite this taxon sampling intensity is still too low to propose an alternative generic taxonomy.     

Molecular phylogeny of Entomobrya (Collembola: Entomobryidae) from China: Color pattern groups and multiple origins

Highly diversified colorations among springtails (Collembola) have been widely used for species diagnosis, but their phylogenetic significance is poorly known. We addressed this issue in the largest Entomobryinae genus Entomobrya, which possesses variable color patterns among species. The relationships within the genus and to other genera have also rarely been studied. Based on material mainly from China, we have conducted a multilocus phylogeny and topology tests with likelihood and Bayesian algorithms, and accordingly demonstrated the non-monophyly of Chinese Entomobrya. The division of five clades, including Entomobrya and several related genera, coincided well with five types of colorations, respectively. Further analyses of divergence time and historical biogeography revealed that Chinese Entomobrya originated mainly from Palearctic (northern and western) China in the Paleocene and Eocene. This study highlights the great phylo? genetic values as well as taxonomic uses of coloration in Chinese Entomobrya. Multiple phylogenetic and biogeographic origins of Entomobrya imply its complicated relationships with both scaled and unsealed genera of Entomobryinae.     

Host specificity of ambrosia and bark beetles (Col., Curculionidae: Scolytinae and Platypodinae) in a New Guinea rainforest

Abstract.  1. Bark and ambrosia beetles are crucial for woody biomass decomposition in tropical forests worldwide. Despite that, quantitative data on their host specificity are scarce.
2. Bark and ambrosia beetles (Scolytinae and Platypodinae) were reared from 13 species of tropical trees representing 11 families from all major lineages of dicotyledonous plants. Standardised samples of beetle-infested twigs, branches, trunks, and roots were taken from three individuals of each tree species growing in a lowland tropical rainforest in Papua New Guinea.
3. A total of 81 742 beetles from 74 species were reared, 67 of them identified. Local species richness of bark and ambrosia beetles was estimated at 80–92 species.
4. Ambrosia beetles were broad generalists as 95% of species did not show any preference for a particular host species or clade. Similarity of ambrosia beetle communities from different tree species was not correlated with phylogenetic distances between tree species. Similarity of ambrosia beetle communities from individual conspecific trees was not higher than that from heterospecific trees and different parts of the trees hosted similar ambrosia beetle communities, as only a few species preferred particular tree parts.
5. In contrast, phloeophagous bark beetles showed strict specificity to host plant genus or family. However, this guild was poor in species (12 species) and restricted to only three plant families (Moraceae, Myristicaceae, Sapindaceae).
6. Local diversity of both bark and ambrosia beetles is not driven by the local diversity of trees in tropical forests, since ambrosia beetles display no host specificity and bark beetles are species poor and restricted to a few plant families.     

Molecular phylogeny of rootworms and related galerucine beetles (Coleoptera: Chrysomelidae)

The Galerucinae (Coleoptera: Chrysomelidae) sensu stricto (true galerucines) comprise a large assemblage of diverse phytophagous beetles containing over 5000 described species. Together with their sister taxon, the flea beetles, which differ from true galerucines by having the hind femora usually modified for jumping, the Galerucinae sensu lato comprises over 13 000 described species and is the largest natural group within the Chrysomelidae. Unlike the flea beetles, for which robust hierarchical classification schemes have not been erected, an existing taxonomic structure exists for the true galerucines, based mostly on the works of the late John Wilcox. In the most recent taxonomic list of the Galerucinae sensu stricto, five tribes were established comprising 29 sections housing 488 genera. The majority of the diversity within these tribes is found within the tribe Luperini, in which two genera, Monolepta and Diabrotica, are known to contain over 500 described species. Here, we extend the work from previous phylogenetic studies of the Galerucinae by analysing four amplicons from three gene regions (18S and 28S rRNA; COI) representing 249 taxa, providing the largest phylogenetic analysis of this taxon to date. Using two seven‐state RNA models, we combine five maximum likelihood models (RNA + DNA for the rRNAs; three separate DNA models for the COI codon positions) for these partitions and analyse the data under likelihood using Bayesian inference. The results of these two analyses are compared with those from equally weighted parsimony. Instead of choosing the results from one optimality criterion over another, either based on statistical support, tree topology or philosophical predisposition, we elect to draw attention to the similar results produced by all three analyses, illustrating the robustness of the data to these different analytical methods. In general, the results from all three analyses are consistent with each other and previous molecular phylogenetic reconstructions for Galerucinae, except that increased taxon sampling for several groups, namely the tribes Hylaspini and Oidini, has improved the phylogenetic position of these taxa. As with previous analyses, under‐sampled taxa, such as the Old World Metacyclini and all sections of the subtribe Luperina, continue to be unstable, with the few taxa representing these groups fluctuating in their positions based on the implemented optimality criterion. Nonetheless, we report here the most comprehensive phylogenetic estimation for the Galerucinae to date.     

Genus-level phylogeny of snakes reveals the origins of species richness in Sri Lanka

Snake diversity in the island of Sri Lanka is extremely high, hosting at least 89 inland (i.e., non-marine) snake species, of which at least 49 are endemic. This includes the endemic genera Aspidura, Balanophis, Cercaspis, Haplocercus, and Pseudotyphlops, which are of uncertain phylogenetic affinity. We present phylogenetic evidence from nuclear and mitochondrial loci showing the relationships of 40 snake species from Sri Lanka (22 endemics) to the remaining global snake fauna. To determine the phylogenetic placement of these species, we create a molecular dataset containing 10 genes for all global snake genera, while also sampling all available species for genera with endemic species occurring in Sri Lanka. Our sampling comprises five mitochondrial genes (12S, 16S, cyt-b, ND2, and ND4) and five nuclear genes (BDNF, c-mos, NT3 RAG-1, and RAG-2), for a total of up to 9582 bp per taxon. We find that the five endemic genera represent portions of four independent colonizations of Sri Lanka, with Cercaspis nested within Colubrinae, Balanophis in Natricinae, Pseudotyphlops in Uropeltidae, and that Aspidura + Haplocercus represents a distinct, ancient lineage within Natricinae. We synonymize two endemic genera that render other genera paraphyletic (Haplocercus with Aspidura, and Cercaspis with Lycodon), and discover that further endemic radiations may be present on the island, including a new taxon from the blindsnake family Typhlopidae, suggesting a large endemic radiation. Despite its small size relative to other islands such as New Guinea, Borneo, and Madagascar, Sri Lanka has one of the most phylogenetically diverse island snake faunas in the world, and more research is needed to characterize the island’s biodiversity, with numerous undescribed species in multiple lineages.     

大步甲的分子系统与进化模式

大步甲主要分布于北半球,全世界大约有1000余种。因大步甲后翅退化,不能飞行,其移动能力和扩散范围都受到很大程度的限制,因此,容易产生地理隔离和遗传分化,从而成为研究物种分化和生物多样化的好材料。近年来,通过对大步甲分子系统的详细研究,不仅很大程度上解明了大步甲各分类群间的系统发育关系,而且对大步甲的系统演化过程和形态进化模式也有了较深的理解,获得了很多重要的见解。在此做一个简单的综述。