DNA barcoding confirms polyphagy in a generalist moth,Homona mermerodes(Lepidoptera: Tortricidae)

Argyrotaeniasocoromaensis sp. nov. (Lepidoptera, Tortricidae), a sexually dimorphic micromoth with polyphagous larvae from the arid Andes of northern Chile

Argyrotaeniasocoromaensissp. nov. (Lepidoptera, Tortricidae, Tortricinae, Archipini) from the arid Andes of northern Chile is described and illustrated. Adults are sexually dimorphic, with differences in wing size, shape and pattern. The larvae feed on Steviaphilippiana Hieron. (Asteraceae) and Lupinusoreophilus Phil. (Fabaceae). Genetic distance between DNA barcodes of male and female adults reared from larvae collected on the two hosts was 0-0.2% (K2P). The discovery of A.socoromaensissp. nov. represents the first record of the genus Argyrotaenia Stephens, 1852 and the tribe Archipini for the Chilean fauna of Tortricidae.

Species delimitation in asexual insects of economic importance: The case of black scale (Parasaissetia nigra), a cosmopolitan parthenogenetic pest scale insect

Asexual lineages provide a challenge to species delimitation because species concepts either have little biological meaning for them or are arbitrary, since every individual is monophyletic and reproductively isolated from all other individuals. However, recognition and naming of asexual species is important to conservation and economic applications. Some scale insects are widespread and polyphagous pests of plants, and several species have been found to comprise cryptic species complexes. Parasaissetia nigra (Nietner, 1861) (Hemiptera: Coccidae) is a parthenogenetic, cosmopolitan and polyphagous pest that feeds on plant species from more than 80 families. Here, we implement multiple approaches to assess the species status of P. nigra, including coalescence-based analyses of mitochondrial and nuclear genes, and ecological niche modelling. Our results indicate that the sampled specimens of P. nigra should be considered to comprise at least two ecotypes (or "species") that are ecologically differentiated, particularly in relation to temperature and moisture. The presence of more than one ecotype under the current concept of P. nigra has implications for biosecurity because the geographic extent of each type is not fully known: some countries may currently have only one of the biotypes. Introduction of additional lineages could expand the geographic extent of damage by the pest in some countries.

Finding hot singles: matching males to females in dimorphic spiders (Araneidae: Micrathena) using phylogenetic placement and DNA barcoding

Many orb-weaving spiders exhibit remarkable sexual dimorphism, hampering the matching of males and females in taxonomic studies. This is the case for the spiny Micrathena spiders, a species-rich Neotropical genus with 27% of its species known from a single sex. In this paper we document several undescribed Micrathena specimens, and test whether they belong to some of those incompletely known species. In order to do so, we: (1) tested the phylogenetic position of males and their putative females using a previous morphological dataset; (2) calculated genetic distances among individuals based on a fragment of the mitochondrial gene cytochrome c oxidase subunit I; and (3) examined their geographical distributions. These approaches, isolated or in combination, allowed us to identify and describe the previously unknown males of M. embira Levi, M. reimoseri Mello-Leitão, M. exlinae Levi, M. miles Simon, M. spinulata F.O. Pickard-Cambridge, M. yanomami Magalhães & Santos and M. cornuta (Taczanowski), and the female of M. beta di Caporiacco. We found that the males previously associated with M. bicolor (Keyserling), M. cornuta and M. lata Chickering had been incorrectly matched with females. The latter actually belongs to a hitherto unnamed species, herein described as Micrathena perfida, sp. nov. New geographical data are given for these and other Micrathena species. Our study highlights the importance of using different sources of data for matching the sexes in diverse groups with strong sexual dimorphism. http://zoobank.org/urn:lsid:zoobank.org:urn:lsid:zoobank.org:pub:AFEDA522-D0B4-4902-A747-9721DEED8B89

DNA barcoding, microarrays and next generation sequencing: recent tools for genetic diversity estimation and authentication of medicinal plants

DNA barcoding, microarray technology and next generation sequencing have emerged as promising tools for the elucidation of plant genetic diversity and its conservation. They are proving to be immensely helpful in authenticating the useful medicinal plants for herbal drug preparations. These newer versions of molecular markers utilize short genetic markers in the genome to characterize the organism to a particular species. This has the potential not only to classify the known and yet unknown species but also has a promising future to link the medicinally important plants according to their properties. The newer trends being followed in DNA chips and barcoding pave the way for a future with many different possibilities. Several of these possibilities might be: characterization of unknown species in a considerably less time than usual, identification of newer medicinal properties possessed by the species and also updating the data of the already existing but unnoticed properties. This can assist us to cure many different diseases and will also generate novel opportunities in medicinal drug delivery and targeting.

The spatial and temporal distributions of arthropods in forest canopies: uniting disparate patterns with hypotheses for specialisation

Arguably the majority of species on Earth utilise tropical rainforest canopies, and much progress has been made in describing arboreal assemblages, especially for arthropods. The most commonly described patterns for tropical rainforest insect communities are host specificity, spatial specialisation (predominantly vertical stratification), and temporal changes in abundance (seasonality and circadian rhythms). Here I review the recurrent results with respect to each of these patterns and discuss the evolutionary selective forces that have generated them in an attempt to unite these patterns in a holistic evolutionary framework. I propose that species can be quantified along a generalist-specialist scale not only with respect to host specificity, but also other spatial and temporal distribution patterns, where specialisation is a function of the extent of activity across space and time for particular species. When all of these distribution patterns are viewed through the paradigm of specialisation, hypotheses that have been proposed to explain the evolution of host specificity can also be applied to explain the generation and maintenance of other spatial and temporal distribution patterns. The main driver for most spatial and temporal distribution patterns is resource availability. Generally, the distribution of insects follows that of the resources they exploit, which are spatially stratified and vary temporally in availability. Physiological adaptations are primarily important for host specificity, where nutritional and chemical variation among host plants in particular, but also certain prey species and fungi, influence host range. Physiological tolerances of abiotic conditions are also important for explaining the spatial and temporal distributions of some insect species, especially in drier forest environments where desiccation is an ever-present threat. However, it is likely that for most species in moist tropical rainforests, abiotic conditions are valuable indicators of resource availability, rather than physiologically limiting factors. Overall, each distribution pattern is influenced by the same evolutionary forces, but at differing intensities. Consequently, each pattern is linked and not mutually exclusive of the other distribution patterns. Most studies have examined each of these patterns in isolation. Future work should focus on examining the evolutionary drivers of these patterns in concert. Only then can the relative strength of resource availability and distribution, host defensive phenotypes, and biotic and abiotic interactions on insect distribution patterns be determined.

Comparative studies on species identification of Noctuoidea moths in two nature reserve conservation zones (Beijing, China) using DNA barcodes and thin-film biosensor chips

Rapid and accurate identification of species is required for the biological control of pest Noctuoidea moths. DNA barcodes and thin-film biosensor chips are two molecular approaches that have gained wide attention. Here, we compare these two methods for the identification of a limited number of Noctuoidea moth species. Based on the commonly used mitochondrial gene cytochrome c oxidase I (the standard DNA barcode for animal species), 14 probes were designed and synthesized for 14 species shared by two national nature reserves in Beijing and Hebei, China. Probes ranged in length from 18 to 27 bp and were designed as mismatch probes to guarantee that there were at least three base differences between the probe and nontarget sequences. The results on the chip could be detected by the naked eye without needing special equipment. No cross-hybridizations were detected although we tested all probes on the 14 target and 24 nontarget Noctuoidea species. The neighbour-joining tree of the 38 species based on COI sequences gave 38 highly supported independent groups. Both DNA barcoding and thin-film biosensor chips, based on the COI gene, are able to accurately identify and discriminate the 14 targeted moth species in this study. Because of its speed, high accuracy and low cost, the thin-film biosensor chip is a very practical means of species identification. Now, a more comprehensive chip will be developed for the identification of additional Noctuoidea moths for pest control and ecological protection.

Integration of DNA barcoding into an ongoing inventory of complex tropical biodiversity

Inventory of the caterpillars, their food plants and parasitoids began in 1978 for today's Area de Conservacion Guanacaste (ACG), in northwestern Costa Rica. This complex mosaic of 120 000 ha of conserved and regenerating dry, cloud and rain forest over 0-2000 m elevation contains at least 10 000 species of non-leaf-mining caterpillars used by more than 5000 species of parasitoids. Several hundred thousand specimens of ACG-reared adult Lepidoptera and parasitoids have been intensively and extensively studied morphologically by many taxonomists, including most of the co-authors. DNA barcoding - the use of a standardized short mitochondrial DNA sequence to identify specimens and flush out undisclosed species - was added to the taxonomic identification process in 2003. Barcoding has been found to be extremely accurate during the identification of about 100 000 specimens of about 3500 morphologically defined species of adult moths, butterflies, tachinid flies, and parasitoid wasps. Less than 1% of the species have such similar barcodes that a molecularly based taxonomic identification is impossible. No specimen with a full barcode was misidentified when its barcode was compared with the barcode library. Also as expected from early trials, barcoding a series from all morphologically defined species, and correlating the morphological, ecological and barcode traits, has revealed many hundreds of overlooked presumptive species. Many but not all of these cryptic species can now be distinguished by subtle morphological and/or ecological traits previously ascribed to 'variation' or thought to be insignificant for species-level recognition. Adding DNA barcoding to the inventory has substantially improved the quality and depth of the inventory, and greatly multiplied the number of situations requiring further taxonomic work for resolution.

Contrasting genetic structure of rear edge and continuous range populations of a parasitic butterfly infected by Wolbachia

BACKGROUND

Climatic oscillations are among the long-term factors shaping the molecular features of animals and plants and it is generally supposed that the rear edges (i.e., the low-latitude limits of distribution of any given specialised species) situated closer to glacial refugia are vital long-term stores of genetic diversity. In the present study, we compared the genetic structure of several populations of an endangered and obligate myrmecophilous butterfly (Maculinea arion) from two distinct and geographically distant parts of its European distribution (i.e., Italy and Poland), which fully represent the ecological and morphological variation occurring across the continent.

RESULTS

We sequenced the COI mitochondrial DNA gene (the 'barcoding gene') and the EF-1α nuclear gene and found substantial genetic differentiation among M. arion Italian populations in both markers. Eleven mtDNA haplotypes were present in Italy. In contrast, almost no mtDNA polymorphisms was found in the Polish M. arion populations, where genetic differentiation at the nuclear gene was low to moderate. Interestingly, the within-population diversity levels in the EF-1α gene observed in Italy and in Poland were comparable. The genetic data did not support any subspecies divisions or any ecological specialisations. All of the populations studied were infected with a single strain of Wolbachia and our screening suggested 100% prevalence of the bacterium.

CONCLUSIONS

Differences in the genetic structure of M. arion observed in Italy and in Poland may be explained by the rear edge theory. Although we were not able to pinpoint any specific evolutionarily significant units, we suggest that the Italian peninsula should be considered as a region of special conservation concern and one that is important for maintaining the genetic diversity of M. arion in Europe. The observed pattern of mtDNA differentiation among the populations could not be explained by an endosymbiotic infection.

Mitochondrial pseudogenes in insect DNA barcoding: differing points of view on the same issue

Molecular tools have been used in taxonomy for the purpose of identification and classification of living organisms. Among these, a short sequence of the mitochondrial DNA, popularly known as DNA barcoding, has become very popular. However, the usefulness and dependability of DNA barcodes have been recently questioned because mitochondrial pseudogenes, non-functional copies of the mitochondrial DNA incorporated into the nuclear genome, have been found in various taxa. When these paralogous sequences are amplified together with the mitochondrial DNA, they may go unnoticed and end up being analyzed as if they were orthologous sequences. In this contribution the different points of view regarding the implications of mitochondrial pseudogenes for entomology are reviewed and discussed. A discussion of the problem from a historical and conceptual perspective is presented as well as a discussion of strategies to keep these nuclear mtDNA copies out of sequence analyzes.

Insects on plants: explaining the paradox of low diversity within specialist herbivore guilds

Classical niche theory explains the coexistence of species through their exploitation of different resources. Assemblages of herbivores coexisting on a particular plant species are thus expected to be dominated by species from host-specific guilds with narrow, coexistence-facilitating niches rather than by species from generalist guilds. Exactly the opposite pattern is observed for folivores feeding on trees in New Guinea. The least specialized mobile chewers were the most species rich, followed by the moderately specialized semiconcealed and exposed chewers. The highly specialized miners and mesophyll suckers were the least species-rich guilds. The Poisson distribution of herbivore species richness among plant species in specialized guilds and the absence of a negative correlation between species richness in different guilds on the same plant species suggest that these guilds are not saturated with species. We show that herbivore assemblages are enriched with generalists because these are more completely sampled from regional species pools. Herbivore diversity increases as a power function of plant diversity, and the rate of increase is inversely related to host specificity. The relative species diversity among guilds is thus scale dependent, as the importance of specialized guilds increases with plant diversity. Specialized insect guilds may therefore comprise a larger component of overall diversity in the tropics (where they are also poorly known taxonomically) than in the temperate zone, which has lower plant diversity.

Pheromone production, male abundance, body size, and the evolution of elaborate antennae in moths

The males of some species of moths possess elaborate feathery antennae. It is widely assumed that these striking morphological features have evolved through selection for males with greater sensitivity to the female sex pheromone, which is typically released in minute quantities. Accordingly, females of species in which males have elaborate (i.e., pectinate, bipectinate, or quadripectinate) antennae should produce the smallest quantities of pheromone. Alternatively, antennal morphology may be associated with the chemical properties of the pheromone components, with elaborate antennae being associated with pheromones that diffuse more quickly (i.e., have lower molecular weights). Finally, antennal morphology may reflect population structure, with low population abundance selecting for higher sensitivity and hence more elaborate antennae. We conducted a phylogenetic comparative analysis to test these explanations using pheromone chemical data and trapping data for 152 moth species. Elaborate antennae are associated with larger body size (longer forewing length), which suggests a biological cost that smaller moth species cannot bear. Body size is also positively correlated with pheromone titre and negatively correlated with population abundance (estimated by male abundance). Removing the effects of body size revealed no association between the shape of antennae and either pheromone titre, male abundance, or mean molecular weight of the pheromone components. However, among species with elaborate antennae, longer antennae were typically associated with lower male abundances and pheromone compounds with lower molecular weight, suggesting that male distribution and a more rapidly diffusing female sex pheromone may influence the size but not the general shape of male antennae.

Host tracking or cryptic adaptation? Phylogeography of Pediobius saulius (Hymenoptera, Eulophidae), a parasitoid of the highly invasive horse-chestnut leafminer

Classical biological control is often advocated as a tool for managing invasive species. However, accurate evaluations of parasitoid species complexes and assessment of host specificity are impeded by the lack of morphological variation. Here, we study the possibility of host races/species within the eulophid wasp Pediobius saulius, a pupal generalist parasitoid that parasitize the highly invasive horse-chestnut leaf-mining moth Cameraria ohridella. We analysed the population genetic structure, host associations and phylogeographic patterns of P. saulius in Europe using the COI mitochondrial gene. This marker strongly supports a division into at least five highly differentiated parasitoid complexes, within two of which clades with differing degrees of host specialization were found: a Balkan clade that mainly (but not only) attacks C. ohridella and a more generalist European group that attacks many hosts, including C. ohridella. The divergence in COI (up to 7.6%) suggests the existence of cryptic species, although this is neither confirmed by nuclear divergence nor morphology. We do not find evidence of host tracking. The higher parasitism rates observed in the Balkans and the scarcity of the Balkan–Cameraria haplotypes out of the Balkans open the possibility of using these Balkan haplotypes as biological control agents of C. ohridella elsewhere in Europe.

Joining inventory by parataxonomists with DNA barcoding of a large complex tropical conserved wildland in northwestern Costa Rica

Background

The many components of conservation through biodiversity development of a large complex tropical wildland, Area de Conservacion Guanacaste (ACG), thrive on knowing what is its biodiversity and natural history. For 32 years a growing team of Costa Rican parataxonomists has conducted biodiversity inventory of ACG caterpillars, their food plants, and their parasitoids. In 2003, DNA barcoding was added to the inventory process.

Methodology/Principal Findings

We describe some of the salient consequences for the parataxonomists of barcoding becoming part of a field biodiversity inventory process that has centuries of tradition. From the barcoding results, the parataxonomists, as well as other downstream users, gain a more fine-scale and greater understanding of the specimens they find, rear, photograph, database and deliver. The parataxonomists also need to adjust to collecting more specimens of what appear to be the “same species” – cryptic species that cannot be distinguished by eye or even food plant alone – while having to work with the name changes and taxonomic uncertainty that comes with discovering that what looked like one species may be many.

Conclusions/Significance

These career parataxonomists, despite their lack of formal higher education, have proven very capable of absorbing and working around the additional complexity and requirements for accuracy and detail that are generated by adding barcoding to the field base of the ACG inventory. In the process, they have also gained a greater understanding of the fine details of phylogeny, relatedness, evolution, and species-packing in their own tropical complex ecosytems. There is no reason to view DNA barcoding as incompatible in any way with tropical biodiversity inventory as conducted by parataxonomists. Their year-round on-site inventory effort lends itself well to the sampling patterns and sample sizes needed to build a thorough barcode library. Furthermore, the biological understanding that comes with barcoding increases the scientific penetrance of biodiversity information, DNA understanding, evolution, and ecology into the communities in which the parataxonomists and their families are resident.

Guild-specific patterns of species richness and host specialization in plant-herbivore food webs from a tropical forest

1. The extent to which plant-herbivore feeding interactions are specialized is key to understand the processes maintaining the diversity of both tropical forest plants and their insect herbivores. However, studies documenting the full complexity of tropical plant-herbivore food webs are lacking. 2. We describe a complex, species-rich plant-herbivore food web for lowland rain forest in Papua New Guinea, resolving 6818 feeding links between 224 plant species and 1490 herbivore species drawn from 11 distinct feeding guilds. By standardizing sampling intensity and the phylogenetic diversity of focal plants, we are able to make the first rigorous and unbiased comparisons of specificity patterns across feeding guilds. 3. Specificity was highly variable among guilds, spanning almost the full range of theoretically possible values from extreme trophic generalization to monophagy. 4. We identify guilds of herbivores that are most likely to influence the composition of tropical forest vegetation through density-dependent herbivory or apparent competition. 5. We calculate that 251 herbivore species (48 of them unique) are associated with each rain forest tree species in our study site so that the ∼200 tree species coexisting in the lowland rain forest community are involved in ∼50,000 trophic interactions with ∼9600 herbivore species of insects. This is the first estimate of total herbivore and interaction number in a rain forest plant-herbivore food web. 6. A comprehensive classification of insect herbivores into 24 guilds is proposed, providing a framework for comparative analyses across ecosystems and geographical regions.

ISFG: recommendations regarding the use of non-human (animal) DNA in forensic genetic investigations

The use of non-human DNA typing in forensic science investigations, and specifically that from animal DNA, is ever increasing. The term animal DNA in this document refers to animal species encountered in a forensic science examination but does not include human DNA. Non-human DNA may either be: the trade and possession of a species, or products derived from a species, which is contrary to legislation; as evidence where the crime is against a person or property; instances of animal cruelty; or where the animal is the offender. The first instance is addressed by determining the species present, and the other scenarios can often be addressed by assigning a DNA sample to a particular individual organism. Currently there is little standardization of methodologies used in the forensic analysis of animal DNA or in reporting styles. The recommendations in this document relate specifically to animal DNA that is integral to a forensic science investigation and are not relevant to the breeding of animals for commercial purposes. This DNA commission was formed out of discussions at the International Society for Forensic Genetics 23rd Congress in Buenos Aires to outline recommendations on the use of non-human DNA in a forensic science investigation. Due to the scope of non-human DNA typing that is possible, the remit of this commission is confined to animal DNA typing only.

Population genetics of ecological communities with DNA barcodes: an example from New Guinea Lepidoptera

Comparative population genetics of ecological guilds can reveal generalities in patterns of differentiation bearing on hypotheses regarding the origin and maintenance of community diversity. Contradictory estimates of host specificity and beta diversity in tropical Lepidoptera (moths and butterflies) from New Guinea and the Americas have sparked debate on the role of host-associated divergence and geographic isolation in explaining latitudinal diversity gradients. We sampled haplotypes of mitochondrial cytochrome c oxidase I from 28 Lepidoptera species and 1,359 individuals across four host plant genera and eight sites in New Guinea to estimate population divergence in relation to host specificity and geography. Analyses of molecular variance and haplotype networks indicate varying patterns of genetic structure among ecologically similar sympatric species. One-quarter lacked evidence of isolation by distance or host-associated differentiation, whereas 21% exhibited both. Fourteen percent of the species exhibited host-associated differentiation without geographic isolation, 18% showed the opposite, and 21% were equivocal, insofar as analyses of molecular variance and haplotype networks yielded incongruent patterns. Variation in dietary breadth among community members suggests that speciation by specialization is an important, but not universal, mechanism for diversification of tropical Lepidoptera. Geographically widespread haplotypes challenge predictions of vicariance biogeography. Dispersal is important, and Lepidoptera communities appear to be highly dynamic according to the various phylogeographic histories of component species. Population genetic comparisons among herbivores of major tropical and temperate regions are needed to test predictions of ecological theory and evaluate global patterns of biodiversity.

To speciate, or not to speciate? Resource heterogeneity, the subjectivity of similarity, and the macroevolutionary consequences of niche-width shifts in plant-feeding insects

Coevolutionary studies on plants and plant-feeding insects have significantly improved our understanding of the role of niche shifts in the generation of new species. Evolving plant lineages essentially constitute moving islands and archipelagoes in resource space, and host shifts by insects are usually preceded by colonizations of novel resources. Critical to hypotheses concerning ecological speciation is what happens immediately before and after colonization attempts: if an available plant is too similar to the current host(s), it simply will be incorporated into the existing diet, but if it is too different, it will not be colonized in the first place. It thus seems that the probability of speciation is maximized when alternative hosts are at an 'intermediate' distance in resource space. In this review, I wish to highlight the possibility that resource similarity and, thus, the definition of 'intermediate', are subjective concepts that depend on the herbivore lineage's tolerance to dietary variation. This subjectivity of similarity means that changes in tolerance can either decrease or increase speciation probabilities depending on the distribution of plants in resource space: insect lineages with narrow tolerances are likely to speciate by 'island-hopping' on young, species-rich plant groups, whereas more generalized lineages could speciate by shifting among resource archipelagoes formed by higher plant taxa. Repeated and convergent origins of traits known to broaden or to restrict host-plant use in multiple different insect groups provide opportunities for studying how tolerance and resource heterogeneity may interact to determine speciation rates.

DNA barcoding of the endemic New Zealand leafroller moth genera, Ctenopseustis and Planotortrix

Molecular techniques such as DNA barcoding have become popular in assisting species identification especially for cryptic species complexes. We have analysed data from a 468-bp region of the mitochondrial cytochrome oxidase subunit I (COI) gene from 200 specimens of 12 species of endemic New Zealand leafroller moths (Tortricidae) from the genera Planotortrix and Ctenopseustis to assess whether the DNA barcoding region can distinguish these species. Among the 200 sequences analysed, 72 haplotypes were recovered, with each genus forming a separate major clade. Maximum likelihood phylogenetic methods were used to test whether species fell into reciprocally monophyletic clades. The optimal phylogeny showed that four species within the genus Ctenopseustis (C. obliquana, C. herana, C. filicis and C. fraterna) and three within Planotortrix (P. octo, P. excessana and P. avicenniae) are polyphyletic. Shimodaira-Hasegawa tests rejected a null hypothesis of monophyly for the species C. obliquana, C. herana, P. octo and P. excessana. Comparisons of within and between species levels of sequence divergence for the same set of seven species showed cases where maximum levels of within-species divergence were greater than some levels of between-species divergence. DNA barcoding using this region of the COI gene is able to distinguish the two genera and some species within each genus; however, many species cannot be identified using this method. Finally, we discuss the possible reasons for this polyphyly, including incomplete lineage sorting, introgression, horizontal gene transfer and incorrect taxonomy.

Low beta diversity of herbivorous insects in tropical forests

Recent advances in understanding insect communities in tropical forests have contributed little to our knowledge of large-scale patterns of insect diversity, because incomplete taxonomic knowledge of many tropical species hinders the mapping of their distribution records. This impedes an understanding of global biodiversity patterns and explains why tropical insects are under-represented in conservation biology. Our study of approximately 500 species from three herbivorous guilds feeding on foliage (caterpillars, Lepidoptera), wood (ambrosia beetles, Coleoptera) and fruit (fruitflies, Diptera) found a low rate of change in species composition (beta diversity) across 75,000 square kilometres of contiguous lowland rainforest in Papua New Guinea, as most species were widely distributed. For caterpillars feeding on large plant genera, most species fed on multiple host species, so that even locally restricted plant species did not support endemic herbivores. Large plant genera represented a continuously distributed resource easily colonized by moths and butterflies over hundreds of kilometres. Low beta diversity was also documented in groups with differing host specificity (fruitflies and ambrosia beetles), suggesting that dispersal limitation does not have a substantial role in shaping the distribution of insect species in New Guinea lowland rainforests. Similar patterns of low beta diversity can be expected in other tropical lowland rainforests, as they are typically situated in the extensive low basins of major tropical rivers similar to the Sepik-Ramu region of New Guinea studied here.