Phylogeny of Agrodiaetus Hübner 1822 (Lepidoptera: Lycaenidae) inferred from mtDNA sequences of COI and COII and nuclear sequences of EF1-alpha: karyotype diversification and species radiation

Phylogenetic Structure Revealed through Combining DNA Barcodes with Multi-Gene Data for Agrodiaetus Blue Butterflies (Lepidoptera, Lycaenidae)

The need for multi-gene analysis in evolutionary and taxonomic studies is generally accepted. However, the sequencing of multiple genes is not always possible. For various reasons, short mitochondrial DNA barcodes are the only source of molecular information for some species in many genera, although multi-locus data are available for other species of the same genera. In particular, such situation exists in the species-rich butterfly subgenus Polyommatus (Agrodiaetus). Here, we analyzed the partitioning of this subgenus into species groups by using three data sets. The first data set was represented by short mitochondrial DNA barcodes for all analyzed samples. The second and third data sets were represented by a combination of short mitochondrial DNA barcodes for part of the taxa with longer mitochondrial sequences COI + tRNA-Leu + COII (data set 2) and with longer mitochondrial COI + tRNA-Leu + COII and nuclear 5.8S rDNA + ITS2 + 28S rDNA sequences (data set 3) for the remaining species. We showed that the DNA barcoding approach (data set 1) failed to reveal the phylogenetic structure, resulting in numerous polytomies in the tree obtained. Combined analysis of the mitochondrial and nuclear sequences (data sets 2 and 3) revealed the species groups and the position within these species groups, even for the taxa for which only short DNA barcodes were available.

Integrative analysis reveals cryptic speciation linked to habitat differentiation within Albanian populations of the anomalous blues (Lepidoptera, Lycaenidae, Polyommatus Latreille, 1804)

The Balkan Peninsula is one of the greatest hotspots for biodiversity in Europe. While the region has been investigated thoroughly, some parts remain understudied and may still harbour undiscovered diversity, even in well-studied organisms such as Lepidoptera. Here we investigated the group of the so-called anomalous blue butterflies, also known as 'brown complex' of the subgenus Agrodiaetus Hübner, 1822 including the taxa of the entire Polyommatusaroaniensis (Brown, 1976) species complex. This species complex is distributed in the southern part of the Balkan Peninsula and known to be represented by three closely related allopatric species, differentiated by their chromosome numbers (n) and mitochondrial (mt) DNA. These are P.aroaniensis sensu stricto (Southern Greece, Peloponnese, n=47-48; mt haplogroup aroa1), P.timfristos Lukhtanov, Vishnevskaya et Shapoval, 2016 (Central Greece, Attika, n=38, aroa2) and P.orphicus Kolev, 2005 (North-Eastern Greece, Southern Bulgaria, n=41-42, orph1). Based on an analysis of chromosomal, molecular and morphological markers, we demonstrate that a fourth taxon of this species complex exists in Albania. This taxon possesses the mt haplogroup aroa3, which is the most differentiated within the entire P.aroaniensis species complex, and the karyotype (n=42-43), which differs by one fixed chromosome fission from P.orphicus. The Albanian taxon seems to be ecologically specialised (habitat on dark-coloured, ophiolitic substrate soils) and differs in colouration (wing reflectance) from the others taxa of the P.aroaniensis species group. Based on the evidence here presented and following the current view of the taxonomy of the group, we propose considering the Albanian taxon as a new species, here described as Polyommatuslurae sp. nov. At the contact zone between the new species and P.orphicus, in addition to typical ones, we detected specimens with haplogroup orph2, karyotype n=43 and intermediate morphology, which seem to represent P.lurae × P.orphicus hybrids.

Sympatric occurrence of deeply diverged mitochondrial DNA lineages in Siberian geometrid moths (Lepidoptera: Geometridae): cryptic speciation, mitochondrial introgression, secondary admixture or effect of Wolbachia?

The divergent sympatric mitochondrial lineages within traditionally recognized species present a challenge regularly faced by taxonomists and evolutionary biologists. We encountered this problem when studying the Siberian geometrid moths, Alcis deversata and Thalera chlorosaria. Within each of these species we found two deeply diverged mitochondrial lineages that demonstrated a level of genetic differentiation exceeding the standard interspecific DNA barcode threshold. Using analyses of nuclear genes, morphology, ecological preferences and Wolbachia endosymbionts, we tested five hypotheses that might explain the mitochondrial pattern observed: cryptic speciation, ancestral polymorphism, interspecific mitochondrial introgression, secondary admixture of allopatrically evolved populations and an effect of intracellular Wolbachia endosymbionts. We demonstrate that in A. deversata and Th. chlorosaria the mitochondrial differences are not correlated with differences in nuclear genes, morphology, ecology and Wolbachia infection status, thus not supporting the hypothesis of cryptic species and an effect of Wolbachia. Mitochondrial introgression can lead to a situation in which one species has both its own mitochondrial lineage and the lineage obtained from another species. We found this situation in the species pair Alcis repandata and Alcis extinctaria. We conclude that the mitochondrial heterogeneity in A. deversata and Th. chlorosaria is most likely to be attributable to the secondary admixture of allopatrically evolved populations.

DNA barcodes combined with multi-locus data of representative taxa can generate reliable higher-level phylogenies

Taxa are frequently labeled incertae sedis when their placement is debated at ranks above the species level, such as their subgeneric, generic, or subtribal placement. This is a pervasive problem in groups with complex systematics due to difficulties in identifying suitable synapomorphies. In this study, we propose combining DNA barcodes with a multilocus backbone phylogeny in order to assign taxa to genus or other higher-level categories. This sampling strategy generates molecular matrices containing large amounts of missing data that are not distributed randomly: barcodes are sampled for all representatives, and additional markers are sampled only for a small percentage. We investigate the effects of the degree and randomness of missing data on phylogenetic accuracy using simulations for up to 100 markers in 1000-tips trees, as well as a real case: the subtribe Polyommatina (Lepidoptera: Lycaenidae), a large group including numerous species with unresolved taxonomy. Our simulation tests show that when a strategic and representative selection of species for higher-level categories has been made for multigene sequencing (approximately one per simulated genus), the addition of this multigene backbone DNA data for as few as 5–10% of the specimens in the total data set can produce high-quality phylogenies, comparable to those resulting from 100% multigene sampling. In contrast, trees based exclusively on barcodes performed poorly. This approach was applied to a 1365-specimen data set of Polyommatina (including ca. 80% of described species), with nearly 8% of representative species included in the multigene backbone and the remaining 92% included only by mitochondrial COI barcodes, a phylogeny was generated that highlighted potential misplacements, unrecognized major clades, and placement for incertae sedis taxa. We use this information to make systematic rearrangements within Polyommatina, and to describe two new genera. Finally, we propose a systematic workflow to assess higher-level taxonomy in hyperdiverse groups. This research identifies an additional, enhanced value of DNA barcodes for improvements in higher-level systematics using large data sets. [Birabiro; DNA barcoding; incertae sedis; Kipepeo; Lycaenidae; missing data; phylogenomic; phylogeny; Polyommatina; supermatrix; systematics; taxonomy]

Genetic Diversity and Population Structure of Gynaephora qinghaiensis in Yushu Prefecture, Qinghai Province Based on the Mitochondrial COI Gene

Gynaephora qinghaiensis (Lepidoptera: Lymantriidae: Gynaephora), a serious economic pest in alpine meadows, is mainly distributed in Yushu prefecture, Qinghai province, China. In this study, we aimed to investigate the genetic diversity and population structure of G. qinghaiensis through analyzing the sequence of 194 mitochondrial cytochrome oxidase subunit (COI) genes (658 bp in length) identified from 10 geographic populations located in three different countries, including Zhiduo, Zaduo, and Chengduo, of Yushu prefecture. Eleven haplotypes were identified from all populations of G. qinghaiensis with high levels of haplotype diversity (0.78500) and low levels of nucleotide diversity (0.00511). High levels of genetic differentiation and low levels of gene flow were also detected among the populations of G. qinghaiensis. Analysis of molecular variance (AMOVA) showed that 90.13% of the variation was attributed to distribution among groups (Chengduo, Zhiduo, and Zaduo), and 5.22% and 4.65% were, respectively, attributed to distribution among populations, within group, and within populations. The result of mantel test showed a highly significant positive correlation (P < 0.01) between F_ST and geographical distance. A maximum likelihood tree showed that most haplotypes were grouped into three clusters corresponding to the three counties, suggesting a significant phylogeographic structure in the populations of G. qinghaiensis. The haplotype networks revealed that H2 may be the most primitive haplotype and the most adaptable in nature. Populations 7# and 8# had haplotype H2 and higher haplotype diversity; therefore, we speculated that the G. qinghaiensis in both populations were more adaptable to the environment and had greater outbreak potential and, therefore, should be focused on in terms of prevention and control. Our findings provide valuable information for further study of the population structure and phylogeny of G. qinghaiensis and provide a theoretical basis for the control of G. qinghaiensis.

Chromosomal and DNA barcode analysis of the Polyommatus (Agrodiaetus) damone (Eversmann, 1841) species complex (Lepidoptera, Lycaenidae)

The Polyommatus (Agrodiaetus) damone (Eversmann, 1841) species complex comprises from 5 to 8 species distributed in southeastern Europe and southern Siberia. Here we used chromosomal and DNA-barcode markers in order to test the taxonomic hypotheses previously suggested for this complex. We revealed that all taxa within this group demonstrate chromosomal stasis and share the same or very similar haploid chromosome number (n = 66 or n = 67). This finding is unexpected since the karyotypes are known to be very diverse and species-specific within the other taxa of the subgenus Agrodiaetus Hübner, 1822. Analysis of the mitochondrial gene COI revealed six diverged clusters of individuals within the complex. Each cluster has a specific geographic distribution and is characterized by distinct morphological features in the wing pattern. The clusters mostly (but not always) correlate with traditionally recognized species. As a result of our study, we describe a new subspecies P. (A.) iphigenides zarmitanussubsp. nov. from Uzbekistan and Tajikistan and show that the taxon originally described as Lycaena kindermanni var. melania Staudinger, 1886 represents a subspecies P. (A.) iphigenides melanius (Staudinger, 1886). Polyommatus (A.) samusi Korb, 2017 (syn. nov.) and P. (A.) melanius komarovi Korb, 2017 (syn. nov.) are considered here as junior subjective synonyms of P. (A.) iphigenides iphigenides (Staudinger, 1886).

Karyotype and DNA barcode of Polyommatus (Agrodiaetus) cyaneus (Staudinger, 1899) from its type locality: implication for taxonomic and evolutionary research in Polyommatus blue butterflies (Lepidoptera, Lycaenidae)

Chromosomal and molecular analyses of rapidly evolving organisms such as Polyommatus Latreille, 1804 blue butterflies are essential for understanding their taxonomy and evolutionary history, and the studies of populations from their type localities are crucially important for resolving problems of nomenclature and species identity. Here we present data on the topotypical population of the blue butterfly species described as Lycaena damone var. cyanea Staudinger, 1899. This taxon was described from Khankendi (Nagorno-Karabakh, Caucasus), and rediscovered at the type locality for the first time since it was collected there in 1869. The specimens were found on dry stony meadows with a predominance of Onobrychis radiata Bieberstein, 1810, on upper border of oak forests. Their haploid chromosome number (n) was established as n = 17. Chromosomal and mitochondrial DNA barcode analyses of the studied samples from type-locality provided an opportunity for the critical taxonomic re-examination of Caucasian species of the subgenus Agrodiaetus Hübner, 1822 of the genus Polyommatus Latreille, 1804. The obtained data support the interpretation of the P. (A.) cyaneus (Staudinger, 1899) and P. (A.) carmon (Herrich-Schäffer, 1851) as two different, not closely related species complexes as previously hypothesized by Hugo de Lesse. On the contrary, the treatment by Walter Forster who considered these taxa as two groups of conspecific populations was not supported by our data.

Speciation through chromosomal fusion and fission in Lepidoptera

Changes in chromosome numbers may strongly affect reproductive barriers, because individuals heterozygous for distinct karyotypes are typically expected to be at least partially sterile or to show reduced recombination. Therefore, several classic speciation models are based on chromosomal changes. One import mechanism generating variation in chromosome numbers is fusion and fission of existing chromosomes, which is particularly likely in species with holocentric chromosomes, i.e. chromosomes that lack a single centromere. Holocentric chromosomes evolved repeatedly across the tree of life, including in Lepidoptera. Although changes in chromosome numbers are hypothesized to be an important driver of the spectacular diversification of Lepidoptera, comparative studies across the order are lacking. We performed the first comprehensive literature survey of karyotypes for Lepidoptera species since the 1970s and tested if, and how, chromosomal variation might affect speciation. Even though a meta-analysis of karyological differences between closely related taxa did not reveal an effect on the degree of reproductive isolation, phylogenetic diversification rate analyses across the 16 best-covered genera indicated a strong, positive association of rates of chromosome number evolution and speciation. These findings suggest a macroevolutionary impact of varying chromosome numbers in Lepidoptera and likely apply to other taxonomic groups, especially to those with holocentric chromosomes. This article is part of the theme issue 'Towards the completion of speciation: the evolution of reproductive isolation beyond the first barriers'.

Karyotype of Polyommatus (Agrodiaetus) eriwanensis Forster, 1960 and taxonomic position of P. (A.) interjectus de Lesse, 1960 (Lepidoptera, Lycaenidae)

The karyotype of Polyommatus (Agrodiaetus) eriwanensis Forster, 1960 from the type locality ("Eriwan" [Yerevan, Armenia]) and other localities in Armenia was investigated. The number of chromosomal elements (bivalents+ multivalents) observed in male meiosis I was found to vary from 29 to 34. In individuals with n = 34, all observed elements were represented by bivalents. In other specimens, heterozygosity for different number of chromosomal fusions resulted in multivalent formation at MI stage and consequently in a lower number of recognizable chromosomal elements. We show that all karyotype peculiarities of P. (A.) interjectus de Lesse, 1960 (n = 29-32) from Turkey are similar to those in A. eriwanensis. The butterflies of these taxa have allopatric distribution and can be considered as conspecific.

Unprecedented reorganization of holocentric chromosomes provides insights into the enigma of lepidopteran chromosome evolution

Chromosome evolution presents an enigma in the mega-diverse Lepidoptera. Most species exhibit constrained chromosome evolution with nearly identical haploid chromosome counts and chromosome-level gene collinearity among species more than 140 million years divergent. However, a few species possess radically inflated chromosomal counts due to extensive fission and fusion events. To address this enigma of constraint in the face of an exceptional ability to change, we investigated an unprecedented reorganization of the standard lepidopteran chromosome structure in the green-veined white butterfly (Pieris napi). We find that gene content in P. napi has been extensively rearranged in large collinear blocks, which until now have been masked by a haploid chromosome number close to the lepidopteran average. We observe that ancient chromosome ends have been maintained and collinear blocks are enriched for functionally related genes suggesting both a mechanism and a possible role for selection in determining the boundaries of these genome-wide rearrangements.

Evolutionary Mechanisms of Varying Chromosome Numbers in the Radiation of Erebia Butterflies

The evolution of intrinsic barriers to gene flow is a crucial step in the process of speciation. Chromosomal changes caused by fusion and fission events are one such barrier and are common in several groups of Lepidoptera. However, it remains unclear if and how chromosomal changes have contributed to speciation in this group. I tested for a phylogenetic signal of varying chromosome numbers in Erebia butterflies by combining existing sequence data with karyological information. I also compared different models of trait evolution in order to infer the underlying evolutionary mechanisms. Overall, I found significant phylogenetic signals that are consistent with non-neutral trait evolution only when parts of the mitochondrial genome were included, suggesting cytonuclear discordances. The adaptive evolutionary model tested in this study consistently outperformed the neutral model of trait evolution. Taken together, these results suggest that, unlike other Lepidoptera groups, changes in chromosome numbers may have played a role in the diversification of Erebia butterflies.

A new butterfly species from south Russia revealed through chromosomal and molecular analysis of the Polyommatus (Agrodiaetus) damonides complex (Lepidoptera, Lycaenidae)

Finding a new species is a rare event in easy-to-see and well-studied organisms like butterflies, especially if they inhabit well-explored areas such as the Western Palaearctic. However, even in this region, gaps in taxonomic knowledge still exist and here we report such a discovery. Using a combined analysis of chromosomal and molecular markers we demonstrate that Polyommatus blue populations from Daghestan (South Russia), previously identified as P. aserbeidschanus, represent in fact a new species which is described here as P. australorossicussp. n. We also show that the enigmatic Polyommatus damonides described as a form of Polyommatus damone and later considered as an entity similar to P. poseidon or P. ninae is conspecific with a taxon previously known as P. elbursicus. As a result of our study, we propose several taxonomic changes within the P. damonides species complex and suggest the following new combinations: P. damonides elbursicus Forster, 1956, comb. n. and P. damonides gilanensis Eckweiler, 2002, comb. n.

Chromosomal identification of cryptic species sharing their DNA barcodes: Polyommatus (Agrodiaetus) antidolus and P. (A.) morgani in Iran (Lepidoptera, Lycaenidae)

DNA barcoding has been suggested as a universal tool for molecular species identification; however, it cannot be applied in cases when morphologically similar species share their DNA barcodes due to the common ancestry or mitochondrial introgression. Here we analyze the karyotype of Polyommatus (Agrodiaetus) morgani (Le Cerf, 1909) from the region of its type locality in the southern Zagros Mountains in Iran, provide first chromosomal evidence for P. (A.) antidolus (Rebel, 1901) in Iran and demonstrate that these two species can be easily identified through analysis of their karyotypes whereas they share their mitochondrial barcodes.

Evolutionary mechanisms of runaway chromosome number change in Agrodiaetus butterflies

Despite predictions of the classic, hybrid-sterility model of chromosomal speciation, some organisms demonstrate high rate of karyotype evolution. This rate is especially impressive in Agrodiaetus butterflies that rapidly evolved the greatest chromosome number diversity known in animal kingdom within a single subgenus. Here we analyzed karyotype evolution in Agrodiaetus using phylogenetic comparative methods. We found that chromosome numbers possess a strong phylogenetic signal. This disproves the chromosome megaevolution model that proposes multiple chromosome rearrangements to accumulate independently in each of closely related species. We found that Brownian motion gives a more adequate description of observed trait changes than Ornstein-Uhlenbeck model. This indicates that chromosome numbers evolve via random walk along branches of the phylogeny. We discovered a correlation between karyotype changes and phylogeny branch lengths. This gradual pattern is inconsistent with the hybrid-sterility model which, due to association of major chromosome changes with cladogenetic events, predicts a high degree of punctualism in karyotype evolution. Thus, low underdominace of chromosomal rearrangements and/or prevalence of the recombination-suppression model over the hybrid-sterility model of chromosome speciation are the most common engines of the runaway chromosome number change observed.

Karyosystematics and molecular taxonomy of the anomalous blue butterflies (Lepidoptera, Lycaenidae) from the Balkan Peninsula

The Balkan Peninsula represents one of the hottest biodiversity spots in Europe. However, the invertebrate fauna of this region is still insufficiently investigated, even in respect of such well-studied organisms as Lepidoptera. Here we use a combination of chromosomal, molecular and morphological markers to rearrange the group of so-called anomalous blue butterflies (also known as 'brown complex' of the subgenus Agrodiaetus Hübner, [1822] and as the Polyommatus (Agrodiaetus) admetus (Esper, 1783) species group) and to reveal its cryptic taxonomic structure. We demonstrate that Polyommatus aroaniensis (Brown, 1976) is not as widespread in the Balkans as was previously thought. In fact, it has a dot-like distribution range restricted to the Peloponnese Peninsula in South Greece. Polyommatus orphicus Kolev, 2005 is not as closely related to the Turkish species Polyommatus dantchenkoi (Lukhtanov & Wiemers, 2003) as was supposed earlier. Instead, it is a Balkan endemic represented by two subspecies: Polyommatus orphicus orphicus (Bulgaria) and Polyommatus orphicus eleniae Coutsis & De Prins, 2005 (Northern Greece). Polyommatus ripartii (Freyer, 1830) is represented in the Balkans by an endemic subspecies Polyommatus ripartii pelopi. The traditionally recognized Polyommatus admetus (Esper, 1783) is shown to be a heterogeneous complex and is divided into Polyommatus admetus sensu stricto (the Balkans and west Turkey) and Polyommatus yeranyani (Dantchenko & Lukhtanov, 2005) (east Turkey, Armenia, Azerbaijan and Iran). Polyommatus nephohiptamenos (Brown & Coutsis, 1978) is confirmed to be a species with a dot-like distribution range in Northern Greece. Finally, from Central Greece (Timfristos and Parnassos mountains) we describe Polyommatus timfristos Lukhtanov, Vishnevskaya & Shapoval, sp. n. which differs by its haploid chromosome number (n=38) from the closely related and morphologically similar Polyommatus aroaniensis (n=47-48) and Polyommatus orphicus (n=41-42). We provide chromosomal evidence for three separate south Balkan Pleistocene refugia (Peloponnesse, Central Greece and Northern Greece/South Bulgaria) and stress the biogeographic importance of Central Greece as a place of diversification. Then we argue that the data obtained have direct implications for butterfly karyology, taxonomy, biogeography and conservation.

Tsukiyamaia, a new genus of the tribe Baorini (Lepidoptera, Hesperiidae, Hesperiinae)

Skippers of the tribe Baorini are evidently a monophyletic group in the subfamily Hesperiinae. In this study, a new Baorini member Tsukiyamaia albimacula gen. n. et sp. n. is described from north Myanmar, southwest China and north Vietnam. Despite its peculiar and striking wing-pattern, this new genus has some important characters of Baorini, such as a broad and bifid uncus and a well-developed gnathos. Based on an analysis of male genitalia and the molecular phylogenies inferred from both mitochondrial and nuclear genes (28 taxa, total aligned length: 2968 bp), it is proposed that the genus Tsukiyamaia is closely related to the genus Polytremis, which has high species diversity in China. This study not only describes a new skipper but also highlights that Tsukiyamaia is important in clarifying phylogenetic relationship of Polytremis and its allies.

Phylogeny and Historical Biogeography of Asian Pterourus Butterflies (Lepidoptera: Papilionidae): A Case of Intercontinental Dispersal from North America to East Asia

The phylogenetic status of the well-known Asian butterflies often known as Agehana (a species group, often treated as a genus or a subgenus, within Papilio sensu lato) has long remained unresolved. Only two species are included, and one of them especially, Papilio maraho, is not only rare but near-threatened, being monophagous on its vulnerable hostplant, Sassafras randaiense (Lauraceae). Although the natural history and population conservation of "Agehana" has received much attention, the biogeographic origin of this group still remains enigmatic. To clarify these two questions, a total of 86 species representatives within Papilionidae were sampled, and four genes (concatenated length 3842 bp) were used to reconstruct their phylogenetic relationships and historical scenarios. Surprisingly, "Agehana" fell within the American Papilio subgenus Pterourus and not as previously suggested, phylogenetically close to the Asian Papilio subgenus Chilasa. We therefore formally synonymize Agehana with Pterourus. Dating and biogeographic analysis allow us to infer an intercontinental dispersal of an American ancestor of Asian Pterourus in the early Miocene, which was coincident with historical paleo-land bridge connections, resulting in the present "East Asia-America" disjunction distribution. We emphasize that species exchange between East Asia and America seems to be a quite frequent occurrence in butterflies during the Oligocene to Miocene climatic optima.

Intragenomic variations of multicopy ITS2 marker in Agrodiaetus blue butterflies (Lepidoptera, Lycaenidae)

The eukaryotic ribosomal DNA cluster consists of multiple copies of three genes, 18S, 5. 8S and 28S rRNAs, separated by multiple copies of two internal transcribed spacers, ITS1 and ITS2. It is an important, frequently used marker in both molecular cytogenetic and molecular phylogenetic studies. Despite this, little is known about intragenomic variations within the copies of eukaryotic ribosomal DNA genes and spacers. Here we present data on intraindividual variations of ITS2 spacer in three species of Agrodiaetus Hübner, 1822 blue butterflies revealed by cloning technique. We demonstrate that a distinctly different intragenomic ITS2 pattern exists for every individual analysed. ITS2 sequences of these species show significant intragenomic variation (up to 3.68% divergence), setting them apart from each other on inferred phylogenetic tree. This variation is enough to obscure phylogenetic relationships at the species level.

Comparative phylogeography between two generalist flea species reveal a complex interaction between parasite life history and host vicariance: parasite-host association matters

Background

In parasitic taxa, life history traits such as microhabitat preference and host specificity can result in differential evolutionary responses to similar abiotic events. The present study investigates the influence of vicariance and host association on the genetic structure of two generalist flea species, Listropsylla agrippinae, and Chiastopsylla rossi. The taxa differ in the time spent on the host (predominantly fur vs. nest) and level of host specificity.

Results

A total of 1056 small mammals were brushed to collect 315 fleas originating from 20 geographically distinct localities in South Africa. Phylogeographic genetic structure of L. agrippinae and C. rossi were determined by making use of 315 mitochondrial COII and 174 nuclear EF1-α sequences. Both parasites show significant genetic differentiation among the majority of the sampling sites confirming limited dispersal ability for fleas. The generalist fur flea with a narrower host range, L. agrippinae, displayed geographic mtDNA spatial genetic structure at the regional scale and this pattern is congruent with host vicariance. The dating of the divergence between the L. agrippinae geographic clades co-insides with paleoclimatic changes in the region approximately 5.27 Ma and this provides some evidence for a co-evolutionary scenario. In contrast, the more host opportunistic nest flea, C. rossi, showed a higher level of mtDNA and nDNA spatial genetic structure at the inter-populational scale, most likely attributed to comparatively higher restrictions to dispersal.

Conclusions

In the present study, the evolutionary history of the flea species could best be explained by the association between parasite and host (time spent on the host). The phylogeographic pattern of the fur flea with a narrower host range correspond to host spatial genetic structures, while the pattern in the host opportunistic nest flea correspond to higher genetic divergences between sampling localities that may also be associated with higher effective population sizes. These findings suggest that genetic exchange among localities are most likely explained by differences in the dispersal abilities and life histories of the flea species.

Electronic supplementary material

The online version of this article (doi:10.1186/s12862-015-0389-y) contains supplementary material, which is available to authorized users.

Chromosomal and molecular evidence for presence of Polyommatus (Agrodiaetus) poseidon (Lepidoptera, Lycaenidae) in Caucasus region

We show how combination of chromosomal and molecular markers can be applied for proper species identification in Agrodiaetus Hübner, 1822 blue butterflies. Using this approach we provide first evidence for presence of Polyommatus (Agrodiaetus) poseidon (Herrich-Schäffer, [1851]) in Georgia.

Dynamic karyotype evolution and unique sex determination systems in Leptidea wood white butterflies

Background

Chromosomal rearrangements have the potential to limit the rate and pattern of gene flow within and between species and thus play a direct role in promoting and maintaining speciation. Wood white butterflies of the genus Leptidea are excellent models to study the role of chromosome rearrangements in speciation because they show karyotype variability not only among but also within species. In this work, we investigated genome architecture of three cryptic Leptidea species (L. juvernica, L. sinapis and L. reali) by standard and molecular cytogenetic techniques in order to reveal causes of the karyotype variability.

Results

Chromosome numbers ranged from 2n = 85 to 91 in L. juvernica and 2n = 69 to 73 in L. sinapis (both from Czech populations) to 2n = 51 to 55 in L. reali (Spanish population). We observed significant differences in chromosome numbers and localization of cytogenetic markers (rDNA and H3 histone genes) within the offspring of individual females. Using FISH with the (TTAGG)_n telomeric probe we also documented the presence of multiple chromosome fusions and/or fissions and other complex rearrangements. Thus, the intraspecific karyotype variability is likely due to irregular chromosome segregation of multivalent meiotic configurations. The analysis of female meiotic chromosomes by GISH and CGH revealed multiple sex chromosomes: W₁W₂W₃Z₁Z₂Z₃Z₄ in L. juvernica, W₁W₂W₃Z₁Z₂Z₃ in L. sinapis and W₁W₂W₃W₄Z₁Z₂Z₃Z₄ in L. reali.

Conclusions

Our results suggest a dynamic karyotype evolution and point to the role of chromosomal rearrangements in the speciation of Leptidea butterflies. Moreover, our study revealed a curious sex determination system with 3–4 W and 3–4 Z chromosomes, which is unique in the Lepidoptera and which could also have played a role in the speciation process of the three Leptidea species.

Electronic supplementary material

The online version of this article (doi:10.1186/s12862-015-0375-4) contains supplementary material, which is available to authorized users.

Alpha taxonomy of the genus Kessleria Nowicki, 1864, revisited in light of DNA-barcoding (Lepidoptera, Yponomeutidae)

The taxonomy of Kessleria, a highly specialized montane genus of Yponomeutidae with larval host restriction to Saxifragaceae and Celastraceae (Saxifraga spp. - subgenus Kessleria; Saxifraga spp. and Parnassia spp. - subgenus Hofmannia), is revised based on external morphology, genitalia and DNA barcodes. An integrative taxonomic approach supports the existence of 29 species in Europe (the two known species from Asia and North America are not treated herein). A full 658 bp fragment of COI was obtained from 135 specimens representing 24 species, a further seven sequences are >560 bp. Five new species are described: Kessleriacottiensis sp. n. (Prov. Torino, Italy; Dep. Hautes Alpes, France), Kessleriadimorpha sp. n. (Dep. Alpes-de-Haute-Provence, France), Kessleriaalpmaritimae sp. n. (Dep. Alpes-Maritimes, France), Kessleriaapenninica sp. n. (Prov. Rieti, Prov. L´Aquila, Italy), and Kessleriaorobiae sp. n. (Prov. Bergamo, Italy).

Taxonomic position of several enigmatic Polyommatus (Agrodiaetus) species (Lepidoptera, Lycaenidae) from Central and Eastern Iran: insights from molecular and chromosomal data

The species-rich subgenus Polyommatus (Agrodiaetus) has become one of the best studied groups of Palearctic blue butterflies (Lepidoptera, Lycaenidae). However, the identity and phylogenetic position of some rare taxa from Iran have remained unclear. An enigmatic, recently described Central Iranian species Polyommatus (Agrodiaetus) shirkuhensis ten Hagen et Eckweiler, 2001 has been considered as a taxon closely related either to Polyommatus (Agrodiaetus) eckweileri ten Hagen, 1998 or to Polyommatus (Agrodiaetus) baltazardi (de Lesse, 1962). Polyommatus (Agrodiaetus) baltazardi, in its turn, was treated as a taxon close to Iranian-Pakistani Polyommatus (Agrodiaetus) bogra Evans, 1932. Here we used a combination of molecular and chromosomal markers to show that none of these hypotheses was true. Instead, Polyommatus (Agrodiaetus) shirkuhensis was recovered as a member of a species group close to Polyommatus (Agrodiaetus) cyaneus (Staudinger, 1899). From genetically closest species, Polyommatus (Agrodiaetus) kermansis (de Lesse, 1962), Polyommatus (Agrodiaetus) cyaneus and Polyommatus (Agrodiaetus) sennanensis (de Lesse, 1959), it differs by the wing coloration. From morphologically similar Polyommatus (Agrodiaetus) mofidii (de Lesse, 1963) and Polyommatus (Agrodiaetus) sorkhensis Eckweiler, 2003, it differs by its chromosome number, n=21. Polyommatus (Agrodiaetus) bogra and Polyommatus (Agrodiaetus) baltazardi were found to be members of two different species groups and, thus, are not closely related.

The complete mitochondrial genome of Celastrina hersilia (Lepidoptera: Lycaenidae)

The complete mitochondrial genome of Celastrina hersilia (Lepidoptera: Lycaenidae) is determined in this work. The mitochondrial genome is 15,304 bp in length, which contains typical 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), 2 ribosomal RNA genes and 1 non-coding A + T-rich region. All PCGs are initiated by ATA or ATT codons, except for COI, which uses CGA as a start codon. Four PCGs (COI, COII, ND5, and ND4) terminate with incomplete termination codons TA or T, while the others use TAA as stop codons. Most of the tRNA genes can be folded into a typical cloverleaf structure. The A + T-rich region is 370 bp in length, which contains several features common to the other lepidopteran species.

Chromosome evolution in Neotropical butterflies

We list the chromosome numbers for 65 species of Neotropical Hesperiidae and 104 species or subspecies of Pieridae. In Hesperiidae the tribe Pyrrhopygini have a modal n = 28, Eudaminae and Pyrgini a modal n = 31, while Hesperiinae have n = around 29. Among Pieridae, Coliadinae have a strong modal n = 31 and among Pierinae Anthocharidini are almost fixed for n = 15 while Pierini vary with n = 26 as the most common chromosome number. Dismorphiinae show wide variation. We discuss these results in the context of chromosome numbers of over 1400 Neotropical butterfly species and subspecies derived from about 3000 populations published here and in earlier papers of a series. The overall results show that many Neotropical groups are characterized by karyotype instability with several derived modal numbers or none at all, while almost all taxa of Lepidoptera studied from the other parts of the world have one of n = 29-31 as modal numbers. Possibly chromosome number changes become fixed in the course of speciation driven by biotic interactions. Population subdivision and structuring facilitate karyotype change. Factors that stabilize chromosome numbers include hybridization among species sharing the same number, migration, sexual selection and possibly the distribution of chromosomes within the nucleus.

Polyommatus ripartii: the biological basis for the conservation and the morphology of the developmental stages of a critically endangered, relict population in central Europe

Ripart's Anomalous Blue Polyommatus ripartii (Freyer, 1830) is one of the most seriously endangered butterfly species in central Europe, a small, relict population of which has survived in two localities in Poland. This isolated population is undoubtedly the last and northernmost remnant of a once much wider range in central Europe. P. ripartii is associated with highly xerophilous vegetation on gypsum and calcareous soils. Only active conservation measures can ensure its survival. For these to be successful, however, precise information on the butterfly's biology, behavior and also its morphology is crucial. The first to do so, this article describes the butterfly's egg-laying preferences, and specifies the numbers of eggs on a single shoot and their placement on it. A unique behavioral trait of the female--the secretion of oviposition-deterring pheromones--is reported. The preferred plant associations and nectar sources have been investigated, and information on overnight roosts is given. In addition, an exhaustive description of the morphologies of the egg, final instar and pupa, as well as new details of adult behavior are provided. The main conclusion of the this study is that the existence of a stable population in the Nida Region is determined by the presence of large patches of sainfoin, which is both the larval host plant and a source of nectar for the imago. Moreover, stress is laid on the importance of Inula ensifolia L. as the secondary nectaring plant, which may facilitate dispersion among patches of suitable habitat. Finally, the study shows that searching for the easily detected eggs may be the best method for proving the existence of the species in a given locality.

Chromosome number evolution in skippers (Lepidoptera, Hesperiidae)

Lepidoptera (butterflies and moths), as many other groups of animals and plants, simultaneously represent preservation of ancestral karyotype in the majority of families with a high degree of chromosome number instability in numerous independently evolved phylogenetic lineages. However, the pattern and trends of karyotype evolution in some Lepidoptera families are poorly studied. Here I provide a survey of chromosome numbers in skippers (family Hesperiidae) based on intensive search and analysis of published data. I demonstrate that the majority of skippers preserve the haploid chromosome number n=31 that seems to be an ancestral number for the Hesperiidae and the order Lepidoptera at whole. However, in the tribe Baorini the derived number n=16 is the most typical state which can be used as a (syn)apomorphic character in further phylogenetic investigations. Several groups of skippers display extreme chromosome number variations on within-species (e.g. the representatives of the genus Carcharodus Hübner, [1819]) and between-species (e.g. the genus Agathymus Freeman, 1959) levels. Thus, these groups can be used as model systems for future analysis of the phenomenon of chromosome instability. Interspecific chromosomal differences are also shown to be useful for discovering and describing new cryptic species of Hesperiidae representing in such a way a powerful tool in biodiversity research. Generally, the skipper butterflies promise to be an exciting group that will significantly contribute to the growing knowledge of patterns and processes of chromosome evolution.

In the shadow of phylogenetic uncertainty: the recent diversification of Lysandra butterflies through chromosomal change

The phylogeny of the butterfly genus Lysandra (Lycaenidae, Polyommatinae) has been intractable using both molecular and morphological characters, which could be a result of speciation due to karyotype instability. Here we reconstruct the phylogeny of the group using multi-locus coalescent-based methods on seven independent genetic markers. While the genus is ca. 4.9 Mya old, the diversification of the extant lineages was extremely recent (ca. 1.5 Mya) and involved multiple chromosomal rearrangements. We find that relationships are uncertain due to both incomplete lineage sorting and hybridization. Minimizing the impact of reticulation in inferring the species tree by testing for mitochondrial introgression events yields a partially resolved tree with three main supported clades: L. punctifera+L. bellargus, the corydonius taxa, and L. coridon+the Iberian taxa, plus three independent lineages without apparently close relatives (L. ossmar, L. syriaca and L. dezina). Based on these results and new karyotypic data, we propose a rearrangement recognizing ten species within the genus. Finally, we hypothesize that chromosomal instability may have played a crucial role in the Lysandra recent diversification. New chromosome rearrangements might be fixed in populations after severe bottlenecks, which at the same time might promote rapid sorting of neutral molecular markers. We argue that population bottlenecks might be a prerequisite for chromosomal speciation in this group.

Deep sympatric mtDNA divergence in the autumnal moth (Epirrita autumnata)

Deep sympatric intraspecific divergence in mtDNA may reflect cryptic species or formerly distinct lineages in the process of remerging. Preliminary results from DNA barcoding of Scandinavian butterflies and moths showed high intraspecific sequence variation in the autumnal moth, Epirrita autumnata. In this study, specimens from different localities in Norway and some samples from Finland and Scotland, with two congeneric species as outgroups, were sequenced with mitochondrial and nuclear markers to resolve the discrepancy found between mtDNA divergence and present species-level taxonomy. We found five COI sub-clades within the E. autumnata complex, most of which were sympatric and with little geographic structure. Nuclear markers (ITS2 and Wingless) showed little variation and gave no indications that E. autumnata comprises more than one species. The samples were screened with primers for Wolbachia outer surface gene (wsp) and 12% of the samples tested positive. Two Wolbachia strains were associated with different mtDNA sub-clades within E. autumnata, which may indicate indirect selection/selective sweeps on haplotypes. Our results demonstrate that deep mtDNA divergences are not synonymous with cryptic speciation and this has important implications for the use of mtDNA in species delimitation, like in DNA barcoding.

"Darwin's butterflies"? DNA barcoding and the radiation of the endemic Caribbean butterfly genus Calisto (Lepidoptera, Nymphalidae, Satyrinae)

The genus Calisto Hübner, 1823 is the only member of the diverse, global subfamily Satyrinae found in the West Indies, and by far the richest endemic Caribbean butterfly radiation. Calisto species occupy an extremely diverse array of habitats, suggestive of adaptive radiation on the scale of other classic examples such as the Galápagos or Darwin's finches. However, a reliable species classification is a key requisite before further evolutionary or ecological research. An analysis of 111 DNA 'barcodes' (655 bp of the mitochondrial gene COI) from 29 putative Calisto species represented by 31 putative taxa was therefore conducted to elucidate taxonomic relationships among these often highly cryptic and confusing taxa. The sympatric, morphologically and ecologically similar taxa Calisto confusa Lathy, 1899 and Calisto confusa debarriera Clench, 1943 proved to be extremely divergent, and we therefore recognize Calisto debarriera stat. n. as a distinct species, with Calisto neiba Schwartz & Gali, 1984 as a junior synonym syn. n. Species status of certain allopatric, morphologically similar sister species has been confirmed: Calisto hysius (Godart, 1824) (including its subspecies Calisto hysius aleucosticha Correa et Schwartz, 1986, stat. n.), and its former subspecies Calisto batesi Michener, 1943 showed a high degree of divergence (above 6%) and should be considered separate species. Calisto lyceius Bates, 1935/Calisto crypta Gali, 1985/Calisto franciscoi Gali, 1985 complex, also showed a high degree of divergence (above 6%), confirming the species status of these taxa. In contrast, our data suggest that the Calisto grannus Bates, 1939 species complex (including Calisto grannus dilemma González, 1987, Calisto grannus amazona González, 1987, stat. n., Calisto grannus micrommata Schwartz & Gali, 1984, stat. n., Calisto grannus dystacta González, 1987, stat. n., Calisto grannus phoinix González, 1987, stat. n., Calisto grannus sommeri Schwartz & Gali, 1984, stat. n., and Calisto grannus micheneri Clench, 1944, stat. n.) should be treated as a single polytypic species, as genetic divergence among sampled populations representing these taxa is low (and stable morphological apomorphies are absent). A widely-distributed pest of sugar cane, Calisto pulchella Lathy, 1899 showed higher diversification among isolated populations (3.5%) than expected, hence supporting former separation of this species into two taxa (pulchella and darlingtoni Clench, 1943), of which the latter might prove to be a separate species rather than subspecies. The taxonomic revisions presented here result in Calisto now containing 34 species and 17 subspecies. Three species endemic to islands other than Hispaniola appear to be derived lineages of various Hispaniolan clades, indicating ancient dispersal events from Hispaniola to Puerto Rico, Cuba, and Jamaica. Overall, the degree of intrageneric and intraspecific divergence within Calisto suggests a long and continuous diversification period of 4-8 Myr. The maximum divergence within the genus (ca. 13.3%) is almost equivalent to the maximum divergence of Calisto from the distant pronophiline relative Auca Hayward, 1953 from the southern Andes (14.1%) and from the presumed closest relative Eretris Thieme, 1905 (14.4%), suggesting that the genus began to diversify soon after its split from its continental sister taxon. In general, this 'barcode' divergence corresponds to the high degree of morphological and ecological variation found among major lineages within the genus.

DNA barcoding the geometrid fauna of Bavaria (Lepidoptera): successes, surprises, and questions

BACKGROUND

The State of Bavaria is involved in a research program that will lead to the construction of a DNA barcode library for all animal species within its territorial boundaries. The present study provides a comprehensive DNA barcode library for the Geometridae, one of the most diverse of insect families.

METHODOLOGY/PRINCIPAL FINDINGS

This study reports DNA barcodes for 400 Bavarian geometrid species, 98 per cent of the known fauna, and approximately one per cent of all Bavarian animal species. Although 98.5% of these species possess diagnostic barcode sequences in Bavaria, records from neighbouring countries suggest that species-level resolution may be compromised in up to 3.5% of cases. All taxa which apparently share barcodes are discussed in detail. One case of modest divergence (1.4%) revealed a species overlooked by the current taxonomic system: Eupithecia goossensiata Mabille, 1869 stat.n. is raised from synonymy with Eupithecia absinthiata (Clerck, 1759) to species rank. Deep intraspecific sequence divergences (>2%) were detected in 20 traditionally recognized species.

CONCLUSIONS/SIGNIFICANCE

The study emphasizes the effectiveness of DNA barcoding as a tool for monitoring biodiversity. Open access is provided to a data set that includes records for 1,395 geometrid specimens (331 species) from Bavaria, with 69 additional species from neighbouring regions. Taxa with deep intraspecific sequence divergences are undergoing more detailed analysis to ascertain if they represent cases of cryptic diversity.

Phylogenetic relationships of true butterflies (Lepidoptera: Papilionoidea) inferred from COI, 16S rRNA and EF-1α sequences

The molecular phylogenetic relationships among true butterfly families (superfamily Papilionoidea) have been a matter of substantial controversy; this debate has led to several competing hypotheses. Two of the most compelling of those hypotheses involve the relationships of (Nymphalidae + Lycaenidae) + (Pieridae + Papilionidae) and (((Nymphalidae + Lycaenidae) + Pieridae) + Papilionidae). In this study, approximately 3,500 nucleotide sequences from cytochrome oxidase subunit I (COI), 16S ribosomal RNA (16S rRNA), and elongation factor-1 alpha (EF-1α) were sequenced from 83 species belonging to four true butterfly families, along with those of three outgroup species belonging to three lepidopteran superfamilies. These sequences were subjected to phylogenetic reconstruction via Bayesian Inference (BI), Maximum Likelihood (ML), and Maximum Parsimony (MP) algorithms. The monophyletic Pieridae and monophyletic Papilionidae evidenced good recovery in all analyses, but in some analyses, the monophylies of the Lycaenidae and Nymphalidae were hampered by the inclusion of single species of the lycaenid subfamily Miletinae and the nymphalid subfamily Danainae. Excluding those singletons, all phylogenetic analyses among the four true butterfly families clearly identified the Nymphalidae as the sister to the Lycaenidae and identified this group as a sister to the Pieridae, with the Papilionidae identified as the most basal linage to the true butterfly, thus supporting the hypothesis: (Papilionidae + (Pieridae + (Nymphalidae + Lycaenidae))).

Assessing the value of DNA barcodes and other priority gene regions for molecular phylogenetics of Lepidoptera

BACKGROUND

Despite apparently abundant amounts of observable variation and species diversity, the order Lepidoptera exhibits a morphological homogeneity that has provided only a limited number of taxonomic characters and led to widespread use of nucleotides for inferring relationships. This study aims to characterize and develop methods to quantify the value of priority gene regions designated for Lepidoptera molecular systematics. In particular, I assess how the DNA barcode segment of the mitochondrial COI gene performs across a broad temporal range given its number one position of priority, most sequenced status, and the conflicting opinions on its phylogenetic performance.

METHODOLOGY/PRINCIPAL FINDINGS

Gene regions commonly sequenced for lepidoptera phylogenetics were scored using multiple measures across three categories: practicality, which includes universality of primers and sequence quality; phylogenetic utility; and phylogenetic signal. I found that alternative measures within a category often appeared correlated, but high scores in one category did not necessarily translate into high scores in another. The DNA barcode was easier to sequence than other genes, and had high scores for utility but low signal above the genus level.

CONCLUSIONS/SIGNIFICANCE

Given limited financial resources and time constraints, careful selection of gene regions for molecular phylogenetics is crucial to avoid wasted effort producing partially informative data. This study introduces an approach to assessing the value of gene regions prior to the initiation of new studies and presents empirical results to help guide future selections.

A pilot study on the molecular phylogeny of Drepanoidea (Insecta: Lepidoptera) inferred from the nuclear gene EF-1alpha and the mitochondrial gene COI

A molecular phylogenetic study of the Drepanoidea based on the EF-1alpha sequences and combined EF-1alpha and COI sequences was carried out in order to infer higher classification at and above the subfamily level. The sample contained 14 taxa representing 13 genera recognized in the Drepanoidea. The results revealed that the Drepaninae, Thyatirinae and Cyclidiinae respectively form monophyletic groups. The sister relationship between the Drepaninae and the Thyatirinae was validated. The monophyly of the Cyclidiinae with the Drepaninae+Thyatirinae was supported robustly. Hypsomadius insignis and Oreta vatama within the traditional definition of the Drepaninae formed an individual clade with robust support (100%) and constitutes a sister relationship to a clade containing the rest of the Drepaninae in all the topologies, which means that the subfamily Oretinae of the Drepanidae should be restored. The family Drepanidae is divided into four subfamilies: Drepaninae, Oretinae, Thyatirinae and Cyclidiinae in this work. The family Epicopeiidae formed a monophyly with high bootstrap values. The result of combined analysis of EF-1alpha and COI showed that the Epicopeiidae have a closer phylogenetic relationship with the Geometridae than with the Drepanidae and belong to neither the Drepanoidea nor the Geometroidea.

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

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

ITS2 secondary structure improves phylogeny estimation in a radiation of blue butterflies of the subgenus Agrodiaetus (Lepidoptera: Lycaenidae: Polyommatus )

BACKGROUND

Current molecular phylogenetic studies of Lepidoptera and most other arthropods are predominantly based on mitochondrial genes and a limited number of nuclear genes. The nuclear genes, however, generally do not provide sufficient information for young radiations. ITS2 , which has proven to be an excellent nuclear marker for similarly aged radiations in other organisms like fungi and plants, is only rarely used for phylogeny estimation in arthropods, although universal primers exist. This is partly due to difficulties in the alignment of ITS2 sequences in more distant taxa. The present study uses ITS2 secondary structure information to elucidate the phylogeny of a species-rich young radiation of arthropods, the butterfly subgenus Agrodiaetus. One aim is to evaluate the efficiency of ITS2 to resolve the phylogeny of the subgenus in comparison with COI , the most important mitochondrial marker in arthropods. Furthermore, we assess the use of compensatory base changes in ITS2 for the delimitation of species and discuss the prospects of ITS2 as a nuclear marker for barcoding studies.

RESULTS

In the butterfly family Lycaenidae, ITS2 secondary structure enabled us to successfully align sequences of different subtribes in Polyommatini and produce a Profile Neighbour Joining tree of this tribe, the resolution of which is comparable to phylogenetic trees obtained with COI+COII . The subgenus Agrodiaetus comprises 6 major clades which are in agreement with COI analyses. A dispersal-vicariance analysis (DIVA) traced the origin of most Agrodiaetus clades to separate biogeographical areas in the region encompassing Eastern Anatolia, Transcaucasia and Iran.

CONCLUSIONS

With the inclusion of secondary structure information, ITS2 appears to be a suitable nuclear marker to infer the phylogeny of young radiations, as well as more distantly related genera within a diverse arthropod family. Its phylogenetic signal is comparable to the mitochondrial marker COI . Compensatory base changes are very rare within Polyommatini and cannot be used for species delimitation. The implementation of secondary structure information into character-based phylogenetic methods is suggested to further improve the versatility of this marker in phylogenetic studies.