Evolution of mimicry patterns in Metriorrhynchus (Coleoptera: Lycidae): the history of dispersal and speciation in southeast Asia

Taxonomic review of the genus Ponyalis Fairmaire, 1899 (Coleoptera, Lycidae), with descriptions of six new species from China

The lycid genus Ponyalis Fairmaire, 1899 is reviewed. Six new species are described from China, including P.longicornis sp. nov., P.truncata sp. nov., P.dabieshanensis sp. nov., P.hainanensis sp. nov., P.quadricollimima sp. nov., and P.zhejiangensis sp. nov. Nine previously known species, including P.alternata (Pic, 1927), P.fukiensis (Bocak, 1999), P.gracilis (Bocak, 1999), P.himalejica (Bourgeois, 1885), P.klapperichi (Bocak, 1999), P.laticornis Fairmaire, 1899, P.nigrohumeralis (Pic, 1939), P.quadricollis (Kiesenwetter, 1874), and P.variabilis Li, Bocak & Pang, 2015 are illustrated with images of the habitus and aedeagi to make the comparisons with the new species. In addition, a distribution map and an identification key to all 24 species of Ponyalis are provided.

Eocene aposematic patterns persist in modern European Lycidae beetles despite the absence of co-mimics

Ancient aposematic signals might have evolved under different ecological circumstances. Using European Cenozoic amber and phylogenetic reconstruction, we evaluated the evolution of net-winged beetle aposematism. We describe Priabonian Hiekeolycus winkleri sp. nov. from Baltic amber, review known fossil species, and suggest earlier high diversity and morphological conservativeness of European Lycidae since the Eocene. We hypothesize the presence of red and black/red aposematic patterns in Eocene Europe. The analyses suggest the Oligocene to Miocene dispersal of additional species from East Asia and their advergence to autochthonous patterns. Recently dispersed lycids have retained similarities with their East Asian relatives. Net-winged beetles are rare in Europe after the Quaternary climatic oscillations, and we hypothesize a currently relaxed selection for shared aposematic signals. Neophobia, and eventually inborn rejection of brightly colored prey, putatively preserved ancient aposematism under changing conditions. Evidence from paleontology and phylogenetics can provide insight into the long-term persistence of old adaptations under changing conditions.

Unexpected High Species Diversity of Mesolycus Gorham (Coleoptera, Lycidae) from China, with a Preliminary Investigation on Its Phylogenetic Position Based on Multiple Genes

The lycid genus Mesolycus Gorham, 1883 is mainly distributed in East Palaearctic and Indochinese regions, but poorly studied in China; moreover, its phylogenetic placement remains controversial but has never been rigorously tested. In this study, Mesolycus was reviewed and its placement within Lycidae was tested based on a multilocus phylogeny (cox1, nad5, cox2 and Lrna) by both ML and BI analyses. The reconstructed phylogenies show that Mesolycus is a consistently recovered sister to Dilophotes Waterhouse, 1879, and they form a monophyletic clade which is well supported. This suggests that Mesolycus definitely belongs to Dilophotini rather than to Macrolycini of Lycinae. Besides, three species originally described or placed in Dilophotes are transferred to Mesolycus, including M. atricollis (Pic, 1926) comb. n., M. particularis (Pic, 1928) comb. n. and M. pacholatkoi (Bic, 2002) comb. n. Four new species are discovered in China, including M. shaanxiensis sp. n., M. dentatus sp. n., M. breviplatus sp. n. and M. varus sp. n. Two species, M. murzini Kazantsev, 2004 and M. rubromarginatus Kazantsev, 2013, are recorded from China for the first time. A key for the identification of all Mesolycus species is provided. China was revealed as the region with the highest species diversity of this genus.

Analysis of the Holarctic Dictyoptera aurora Complex (Coleoptera, Lycidae) Reveals Hidden Diversity and Geographic Structure in Müllerian Mimicry Ring

The elateroid family Lycidae is known for limited dispersal propensity and high species-level endemism. The red net-winged beetle, Dictyoptera aurora (Herbst, 1874), differs from all relatives by the range comprising almost the entire Holarctic region. Based on a five-marker phylogeny and 67 barcode entries (cox1-5' mtDNA) from the whole range, we recovered two genetically distinct species within traditionally defined D. aurora and resurrected the name D. coccinata (Say, 1835) as the oldest available synonym for Nearctic populations. Yet, no reliable morphological trait distinguishes these species except for minute differences in the male genitalia. D. coccinata is a monophylum resulting from a single Miocene dispersal event, ~15.8 million years ago, and genetic divergence implies long-term isolation by the Bering Strait. Far East Asian and west European populations are also genetically distinct, although to a lower extent. Two independent colonization events established the Fennoscandian populations after the last glacial maximum. Besides intrinsic factors, the high morphological similarity might result from stabilizing selection for shared aposematic signals. The rapidly accumulating barcode data provide valuable information on the evolutionary history and the origins of regional faunas.

Phylogenomic and mitogenomic data can accelerate inventorying of tropical beetles during the current biodiversity crisis

Conservation efforts must be evidence-based, so rapid and economically feasible methods should be used to quantify diversity and distribution patterns. We have attempted to overcome current impediments to the gathering of biodiversity data by using integrative phylogenomic and three mtDNA fragment analyses. As a model, we sequenced the Metriorrhynchini beetle fauna, sampled from ~700 localities in three continents. The species-rich dataset included ~6,500 terminals, ~1,850 putative species delimited at 5% uncorrected pairwise threshold, possibly ~1,000 of them unknown to science. Neither type of data could alone answer our questions on biodiversity and phylogeny. The phylogenomic backbone enabled the integrative delimitation of robustly defined natural genus-group units that will inform future research. Using constrained mtDNA analysis, we identified the spatial structure of species diversity, very high species-level endemism, and a biodiversity hotspot in New Guinea. We suggest that focused field research and subsequent laboratory and bioinformatic workflow steps would substantially accelerate the inventorying of any hyperdiverse tropical group with several thousand species. The outcome would be a scaffold for the incorporation of further data from environmental sequencing and ecological studies. The database of sequences could set a benchmark for the spatiotemporal evaluation of biodiversity, would support evidence-based conservation planning, and would provide a robust framework for systematic, biogeographic, and evolutionary studies.

Comparative analysis of morphospace of Neotropical Sericini (Coleoptera: Scarabaeidae): disparity in the light of species diversity and activity patterns

The striking diversity among herbivorous Scarabaeoidea is still poorly understood. Therefore, we compare in these work linear measurements of body features of Neotropical and Old World linages of Sericini chafers to uncover patterns possibly linked to foraging behavior (day or night activity) or to the success of their diversification in terms of diversity. If diversity in Sericini chafers would be linked to morphological disparity, we would expect in the much less diverse Neotropical lineage a very clear drop of morphological disparity. Comparing the two major sister clades, Old World and Neotropical Sericini, in terms of their disparity and diversity, the here elaborated distance data do not support the hypothesis that morphological disparity could be a driver for the diversity of Sericini in the Old World. The influence of the metacoxal length on morphological disparity appears to represent a possible key for a better understanding of the evolution of Sericini in the Neotropical region (including their lower diversity) and answers the question of why they are so much less diverse than their sister lineage in the Old World. The increasing length of the metacoxal plate appears to be a result of the presence of a secondary metacoxal joint in Old World Sericini, which has a crucial impact on hind leg mobility and digging behavior. General body shape and single morphological characters appear under similar general evolutionary pressure: high morphometric disparity between nocturnal and diurnal Neotropical species was also corroborated by disparity estimated from discrete morphological characters.

Conspicuousness, phylogenetic structure, and origins of Müllerian mimicry in 4000 lycid beetles from all zoogeographic regions

Biologists have reported on the chemical defences and the phenetic similarity of net-winged beetles (Coleoptera: Lycidae) and their co-mimics. Nevertheless, our knowledge has remained fragmental, and the evolution of mimetic patterns has not been studied in the phylogenetic context. We illustrate the general appearance of ~ 600 lycid species and ~ 200 co-mimics and their distribution. Further, we assemble the phylogeny using the transcriptomic backbone and ~ 570 species. Using phylogenetic information, we closely scrutinise the relationships among aposematically coloured species, the worldwide diversity, and the distribution of aposematic patterns. The emitted visual signals differ in conspicuousness. The uniform coloured dorsum is ancestral and was followed by the evolution of bicoloured forms. The mottled patterns, i.e. fasciate, striate, punctate, and reticulate, originated later in the course of evolution. The highest number of sympatrically occurring patterns was recovered in New Guinea and the Andean mountain ecosystems (the areas of the highest abundance), and in continental South East Asia (an area of moderate abundance but high in phylogenetic diversity). Consequently, a large number of co-existing aposematic patterns in a single region and/or locality is the rule, in contrast with the theoretical prediction, and predators do not face a simple model-like choice but cope with complex mimetic communities. Lycids display an ancestral aposematic signal even though they sympatrically occur with differently coloured unprofitable relatives. We show that the highly conspicuous patterns evolve within communities predominantly formed by less conspicuous Müllerian mimics and, and often only a single species displays a novel pattern. Our work is a forerunner to the detailed research into the aposematic signalling of net-winged beetles.

Biodiversity Inventory and Distribution of Metriorrhynchina Net-Winged Beetles (Coleoptera: Lycidae), with the Identification of Generic Ranges

Simple Summary

We reviewed the classification of ~900 Metriorrhynchina net-winged beetles, and modified the alpha-taxonomy to reflect recently proposed phylogenetic hypotheses. There were >200 species transferred between subtribes and genera. The resulting checklist enabled us to identify New Guinea as the hotspot of Metriorrhynchina diversification. The centers of endemism include Sulawesi and New Guinea (in total 14 genera) in contrast with a single endemic genus in continental Australia. Most genera are diverse in New Guinea and the Wallacea, and only certain species crossed zoogeographic lines and colonized South East Asia. The study should boost the biodiversity research in the group and support biogeographic and evolutionary studies.

Abstract

We reviewed the species-level classification of Metriorrhynchina net-winged beetles to make the group accessible for further studies. Altogether, 876 valid species are listed in a checklist along with known synonyms, combinations, and distribution data. The compilation of geographic distribution showed that Metriorrhynchina is distributed mainly in the Australian region with very high diversity in the islands at the northern edge of the Australian craton, i.e., in the Moluccas and New Guinea (54 and 423 spp. respectively). The neighboring northern part of the Australian continent houses a majority of known Australian species (112 spp.) and the diversity of net-winged beetles gradually decreases to the south (43 spp.). The fauna of Sulawesi is highly endemic at the generic level (4 of 10 genera, 67 of 84 spp.). Less Metriorrhynchina occur in the Solomon Islands and Oceania (in total 22 spp.). The Oriental Metriorrhynchina fauna consists of a few genera and a limited number of species, and most of these are known from the Philippines (51 of 94 Oriental spp.). We identified a high species level turn-over between all neighboring landmasses. The genus-level endemism is high in Sulawesi (4 genera) and New Guinea (11 genera), but only a single genus is endemic to Australia. During the compilation of the checklist, we identified some homonyms, and we propose the following replacement names and a new synonym: Metriorrhynchus pseudobasalis, nom. nov. for M. basalis Lea, 1921 nec M. basalis Bourgeois, 1911; Metriorrhynchus pseudofunestus, nom. nov. for M. funestus Lea, 1921 nec M. funestus (Guérin-Méneville, 1838), Trichalus pseudoternatensis, nom. nov. for T. ternatensis Kleine, 1930 nec T. ternatensis Bourgeois, 1900, Procautires subparallelus, nom. nov. for P. parallelus (Pic, 1926) nec P. parallelus (Bourgeois, 1883), and Cautires pseudocorporaali, nom. nov. for C. corporaali (Pic, 1921: 12), (formerly Odontocerus and Cladophorus) nec C. corporaali (Pic, 1921) (formerly Bulenides, later Cautires). Diatrichalus biroi Kleine, 1943, syn. nov. is proposed as a junior subjective synonym of D. subarcuatithorax (Pic, 1926). Altogether, 161 new combinations are proposed, and 47 species earlier placed in Xylobanus Waterhouse, 1879 transferred from Cautirina to Metriorrhynchina incertae sedis. The study clarifies the taxonomy of Metriorrhynchini and should serve as a restarting point for further taxonomic, evolutionary, and biogeographic studies.

Interactions in multi-pattern Müllerian communities support origins of new patterns, false structures, imperfect resemblance and mimetic sexual dimorphism

Mimicry is a hot spot of evolutionary research, but de novo origins of aposematic patterns, the persistence of multiple patterns in Müllerian communities, and the persistence of imperfect mimics still need to be investigated. Local mimetic assemblages can contain up to a hundred of species, their structure can be a result of multiple dispersal events, and the gradual build-up of the communities. Here, we investigate the structure of lowland and mountain mimetic communities of net-winged beetles by sampling the Crocker Range in north-eastern Borneo and neighbouring regions. The local endemics evolved from the Bornean lowland fauna which is highly endemic at the species level. We inferred that metriorrhynchine net-winged beetles evolved in high elevations yellow/black and reticulate aposematic high-contrast signals from a widespread low-contrast brown/black pattern. As the mountain range is ~ 6 million years old, and these patterns do not occur elsewhere, we assume their in situ origins. We demonstrate that a signal with increased internal contrast can evolve de novo in a mimetic community and can persist despite its low frequency. Additionally, a similar aposematic signal evolves from different structures and its similarity is imperfect. The community with multiple patterns sets conditions for the evolution of aposematic sexual dimorphism as demonstrated by the yellow/black male and reticulate female pattern of Micronychus pardus. These insights elucidate the complex character of the evolution of mimetic signalling in the dynamically diversifying biota of high tropical mountains.

Persistence of multiple patterns and intraspecific polymorphism in multi-species Müllerian communities of net-winged beetles

BACKGROUND

In contrast to traditional models of purifying selection and a single aposematic signal in Müllerian complexes, some communities of unprofitable prey contain members with multiple aposematic patterns. Processes responsible for diversity in aposematic signaling are poorly understood and large multi-species communities are seldom considered.

RESULTS

We analyzed the phylogeny and aposematic patterns of closely related Eniclases net-winged beetles in New Guinea using mtDNA and nextRAD data. We suggest three clades of closely related and incompletely reproductively isolated lineages, detail the extent of polymorphism among Eniclases, and categorize their low-contrast aposematic patterns. The warning signal of Eniclases consists of body shape and color, with ambiguous color perception under some circumstances, i.e., when resting on the undersides of leaves. Field observations suggest that perception of the aposematic signal is affected by beetle behavior and environmental conditions. Local communities containing Eniclases consisted of 7-85 metriorrhynchine species assigned to 3-10 colour patterns.

CONCLUSION

As a result, we suggest that under certain light conditions the aposematic colour signal is less apparent than the body shape in net-winged beetle communities. We document variable environmental factors in our study area and highly diverse multi-species communities of other net-winged beetles. Which implies dynamically changing community structure in space and time. Variable environmental conditions and diverse community composition are suggested to be favorable for the persistence of multiple aposematic patterns, imperfect mimics, and intraspecific polymorphism. Further research should identify the relative effect of these factors on purifying selection and the alleles which are responsible for phenotypic differences.

Genomic and Mitochondrial Data Identify Different Species Boundaries in Aposematically Polymorphic Eniclases Net-Winged Beetles (Coleoptera: Lycidae)

Species delineation is essential for any evolutionary and biodiversity research, and recent advances in genomic sequencing have made it possible to robustly define species boundaries and detect hidden diversity. Here, we studied 14 species of aposematically colored New Guinean Eniclases (Coleoptera: Lycidae) whose conventional morphology- and single-locus mtDNA-based taxonomy has been contentious. We analyzed mitochondrial and restriction site associated DNA fragments to obtain a phylogenetic hypothesis and compared relationships recovered by the RAD analysis with species limits based on other information. The results show the presence of cryptic diversity and common mitonuclear discordance when over 30% of individuals were incorrectly assigned to species if only mitogenomic markers were considered. Nuclear data falsified the species rank of one species and identified one earlier unrecognized lineage deserving species rank. Further, our analyses demonstrate a highly variable phenotypic differentiation, with several pairs of cryptic species standing in contrast with genetically close but phenotypically highly divergent lineages. We show that morphological and mitogenomic analyses produce reliable information for taxonomy in most cases. Nevertheless, the species boundaries among closely related species should be based on all lines of evidence, including nuclear markers.

The Malacca Strait separates distinct faunas of poorly-flying Cautires net-winged beetles

We investigated the spatial and temporal patterns of Cautires diversification on the Malay Peninsula and Sumatra to understand if the narrow and frequently dry Malacca Strait separates different faunas. Moreover, we analyzed the origin of Cautires in Malayan and Sumatran mountains. We sampled 18 localities and present the mtDNA-based phylogeny of 76 species represented by 388 individuals. The phylogenetic tree was dated using mtDNA evolution rates and the ancestral ranges were estimated using the maximum likelihood approach. The phylogeny identified multiple lineages on the Malay Peninsula since the Upper Eocene (35 million years ago, mya) and a delayed evolution of diversity in Sumatra since the Upper Oligocene (26 mya). A limited number of colonization events across the Malacca Strait was identified up to the Pliocene and more intensive faunal exchange since the Pleistocene. The early colonization events were commonly followed by in situ diversification. As a result, the Malacca Strait now separates two faunas with a high species-level turnover. The montane fauna diversified in a limited space and seldom took part in colonization events across the Strait. Besides isolation by open sea or a savannah corridor, mimetic patterns could decrease the colonization capacity of Cautires. The Malay fauna is phylogenetically more diverse and has a higher value if conservation priorities should be defined.

Molecular Phylogeny, Diversity and Zoogeography of Net-Winged Beetles (Coleoptera: Lycidae)

We synthesize the evidence from molecular phylogenetics, extant distribution, and plate tectonics to present an insight in ancestral areas, dispersal routes and the effectiveness of geographic barriers for net-winged beetle tribes (Coleoptera: Lycidae). Samples from all zoogeographical realms were assembled and phylogenetic relationships for ~550 species and 25 tribes were inferred using nuclear rRNA and mtDNA markers. The analyses revealed well-supported clades at the rank of tribes as they have been defined using morphology, but a low support for relationships among them. Most tribes started their diversification in Southeast and East Asia or are endemic to this region. Slipinskiini and Dexorini are Afrotropical endemics and Calopterini, Eurrhacini, Thonalmini, and Leptolycini remained isolated in South America and the Caribbean after their separation from northern continents. Lycini, Calochromini, and Erotini support relationships between the Nearctic and eastern Palearctic faunas; Calochromini colonized the Afrotropical realm from East Asia and Metriorrhynchini Afrotropical and Oriental realms from the drifting Indian subcontinent. Most tribes occur in the Oriental and Sino-Japanese realms, the highest alpha-taxonomic diversity was identified in Malesian tropical rainforests. The turn-over at zoogeographical boundaries is discussed when only short distance over-sea colonization events were inferred. The lycid phylogeny shows that poor dispersers can be used for reconstruction of dispersal and vicariance history over a long time-span, but the current data are insufficient for reconstruction of the early phase of their diversification.

Diversity of warning signal and social interaction influences the evolution of imperfect mimicry

Mimicry, the resemblance of one species by another, is a complex phenomenon where the mimic (Batesian mimicry) or the model and the mimic (Mullerian mimicry) gain an advantage from this phenotypic convergence. Despite the expectation that mimics should closely resemble their models, many mimetic species appear to be poor mimics. This is particularly apparent in some systems in which there are multiple available models. However, the influence of model pattern diversity on the evolution of mimetic systems remains poorly understood. We tested whether the number of model patterns a predator learns to associate with a negative consequence affects their willingness to try imperfect, novel patterns. We exposed week-old chickens to coral snake (Micrurus) color patterns representative of three South American areas that differ in model pattern richness, and then tested their response to the putative imperfect mimetic pattern of a widespread species of harmless colubrid snake (Oxyrhopus rhombifer) in different social contexts. Our results indicate that chicks have a great hesitation to attack when individually exposed to high model pattern diversity and a greater hesitation to attack when exposed as a group to low model pattern diversity. Individuals with a fast growth trajectory (measured by morphological traits) were also less reluctant to attack. We suggest that the evolution of new patterns could be favored by social learning in areas of low pattern diversity, while individual learning can reduce predation pressure on recently evolved mimics in areas of high model diversity. Our results could aid the development of ecological predictions about the evolution of imperfect mimicry and mimicry in general.

Phylogeny and evolution of Müllerian mimicry in aposematic Dilophotes: evidence for advergence and size-constraints in evolution of mimetic sexual dimorphism

Multiple patterns and intraspecific polymorphism should not persist in mutualistic Müllerian systems due to purifying and frequency-dependent selection, but they are commonly identified in nature. We analysed molecular phylogeny and reconstructed dispersal history of 58 species of Dilophotes (Coleoptera: Lycidae) in Asia. Dilophotes colonized the Great Sundas and Malay Peninsula where they joined extensive mimetic communities of net-winged beetles. We identified the brightly bi-coloured males and females which adverged on five occasions to different autochthonous models. This is the first described case of Müllerian sexual dimorphism based on sex-specific body size. We propose that the constraint, i.e. the conservative sexual size dimorphism, forced the unprofitable prey to such complex adaptation in a multi-pattern environment. Although mimetic sexual dimorphism has frequently evolved in Dilophotes, a single pattern has been maintained by both sexes in multiple closely related, sympatrically occurring species. Some patterns may be suboptimal because they are rare, crudely resemble co-mimics, or are newly evolved, but they persist in Müllerian communities for a long time. We assume that failure to closely resemble the most common model can increase the diversity of large Müllerian communities and produce mimetic dimorphism.

The comparison of molecular and morphology-based phylogenies of trichaline net-winged beetles (Coleoptera: Lycidae: Metriorrhynchini) with description of a new subgenus

Separate morphological and molecular phylogenetic analyses are presented and the classification of trichaline net-winged beetles is revised. The clade, earlier given a subfamily, tribe or subtribe rank, is a terminal lineage in Metriorrhynchina and contains DiatrichalusKleine, 1926, EniclasesWaterhouse, 1879, Flabellotrichalus Pic, 1921, Lobatang Bocak, 1998, Microtrichalus Pic, 1921, SchizotrichalusKleine, 1926, and TrichalusWaterhouse, 1877. Maibrius subgen. nov. is proposed in Flabellotrichalus with the type-species Flabellotrichalus (Maibrius) horaki sp. nov. Unlike previous studies, Lobatang is included in the trichaline clade. Further, SpinotrichalusKazantsev, 2010, stat. nov. is down-ranked to the subgenus in Lobatang Bocak, 1998 and a new combination, Lobatang (Spinotrichalus) telnovi (Kazantsev, 2010) comb. nov., is proposed. The morphology does not provide a sufficient support for robust phylogeny due to the intrageneric variability of most phenotypic traits and the limited number of characters supporting deep relationships. Most morphological generic diagnoses must be based on the shape of male genitalia. Other characters, such as the shapes of pronotum and antennae are commonly variable within genera. The fronto-lateral pronotal ridges of Eniclases + Schizotrichalus resemble the ancestral condition in Metriorrhynchini and they re-evolved in the terminal clade and do not indicate the early split of Eniclases + Schizotrichalus from other trichaline genera. The evolution of morphological traits and the conflict in the morphological and molecular phylogenetic signal are discussed in details. We suggest that the general appearance is affected by the evolution of mimetic complexes, the patterns of elytral costae by their strengthening function, and the presence of flabellate antennae by their role in sexual communication. Then, similar phenotypic traits evolve in unrelated lineages. The results demonstrate that phylogenetic classification must be based on all available information because neither morphological traits nor DNA data robustly support all recovered relationships.

Slowly dispersing neotenic beetles can speciate on a penny coin and generate space-limited diversity in the tropical mountains

We demonstrate the controversial origin of a biological species within an area of a few kilometres in the absence of physical barriers. We employed nuclear rRNA/mitochondrial and genome-wide SNP approaches to infer relationships of four species of net-winged beetles characterised by female neoteny. Three species are distributed at low elevations and a single population colonised a 40 km(2) highland plateau and established distinct biological species despite incomplete genetic isolation. The speciation process is extreme in the highly localised spatial scale, due to the low dispersal power of neotenics, and provides clear support for a microallopatric model based on ecological conditions. In contrast with neutral evolution in a homogenous environment, as demonstrated by the genetic divergence and morphological similarity of two widely distributed low-mountain species, the environmental characteristics of the high-mountain plateau led to the origin of a species adapted to the local mimetic pattern and characterised by morphologically distinct genitalia. We conclude that the low dispersal propensity promotes neutral genetic differentiation in the first stage, but environmental characteristics play an important role the final phase of the speciation process. The unexpected speciation at such an extreme geographic scale points to the in situ origin and uniqueness of the mountain fauna.

Species limits in polymorphic mimetic Eniclases net-winged beetles from New Guinean mountains (Coleoptera, Lycidae)

Species delimitation was compared in a group of closely related lineages of aposematically colored Eniclases (Coleoptera, Lycidae) using morphology, genetic distances, and Bayesian implementation of the Poisson Tree Processes model. A high diversity of net-winged beetles was found in previously unsampled regions of New Guinea and ten new species are described: Eniclasesbicolorsp. n., Eniclasesbokondinensissp. n., Eniclasesbrancucciisp. n., Eniclaseselelimensissp. n., Eniclasesinfuscatussp. n., Eniclasesnigersp. n., Eniclasespseudoapertussp. n., Eniclasespseudoluteolussp. n., Eniclasestikapurensissp. n., and Eniclasesvariabilissp. n. Different levels of genetic and morphological diversification were identified in various sister-species pairs. As a result, both morphological and molecular analyses are used to delimit species. Sister-species with uncorrected pairwise genetic divergence as low as 0.45% were morphologically distinct not only in color pattern, but also in the relative size of eyes. Conversely, differences in color pattern regardless of their magnitude did not necessarily indicate genetic distance and intraspecific mimicry polymorphism was common. Additionally, genetic divergence without morphological differentiation was detected in one sister-species pair. Low dispersal propensity, diverse mimicry patterns, and mimetic polymorphism resulted in complex diversification of Eniclases and uncertain species delimitation in recently diversified lineages.

Phylogeography of Poorly Dispersing Net-Winged Beetles: A Role of Drifting India in the Origin of Afrotropical and Oriental Fauna

Ancient dispersal history may be obscured by subsequent dispersal events. Therefore, we intend to investigate the biogeography of metriorrhynchine net-winged beetles, a group characterized by limited dispersal propensity. We used DNA data to construct phylogenies and the BayesTraits and RASP programs to identify putative ancestral areas. Further, we inferred ultrametric trees to estimate the ages of selected nodes. The time frame is inferred from tectonic calibrations and the general mutation rate of the mitochondrial genes. Metriorrhynchini consists of two lineages with Afro/Oriental and Australian distributions. The basal lineages originated in Eastern Gondwana after the split of Australia, India and Madagascar; the Afrotropical and Madagascar Metriorrhynchini separated from the Oriental clades 65 and 62 mya. Several already diversified lineages colonized continental Asia 55-35 mya. A few genera of the Australian clade dispersed to the Oriental region 5-15 mya and reached Eastern India and Southern China. Only Xylobanus crossed the Makassar Strait to Sulawesi and does not occur further to the east. The current distribution of Metriorrhynchini is a result of drifting on continental fragments and over-sea dispersal events limited to a few hundreds of kilometers. We conclude that: (1) Afrotropical and Madagascar lineages originated independently from dispersal events during India's drift to the north and the Mozambique Channel completely isolates the respective faunas since then; (2) Oriental fauna is a recently established mixture of the Indian and Australian lineages, with predominance of the older Indian clades; (3) The fauna of islands located north of Australia colonized Sulawesi after collision with the Sundaland margin and the species rich Australian lineages did not reach Western Wallacea or the Philippines. Our results suggest an impact of subtle differences in biological characteristics on biogeographic history of individual lineages, when mostly lowland and flower-visiting lineages were able to disperse across sea channels.

A revision of the Cautires obsoletus species group from Java (Coleoptera, Lycidae)

The Javanese fauna of the species group Cautires obsoletus is revised. Altogether, eight Javanese species were classified in the group; five of them are proposed to be junior subjective synonyms: Cautires fruhstorferi Dudkova & Bocak, 2010, a replacement name of Bulenides lineatus Pic, 1921, Cautires javanicus Bourgeois, 1883, Cautires inhumeralis (Pic, 1921), Cautires nigromaculatus (Pic, 1925), and Cautires pudicus (Kleine, 1931) (all synonymized to Cautires obsoletus Waterhouse, 1879). Three Javanese species are redescribed: Cautires apicalis (Pic, 1925), Cautires obsoletus (Waterhouse, 1878), and Cautires singularithorax (Pic, 1925). Cautires apicalis (Pic, 1925) is removed from the synonymy of Cautires corporaali (Pic, 1921) and reinstated as a valid name. Three new species are proposed: Cautires walterisp. n., Cautires taoisp. n., and Cautires sukosarensissp. n. All species are keyed and principal diagnostic characters are illustrated. The distribution and relationships to Cautires fauna of other Great Sundas islands are briefly discussed.

Wright's shifting balance theory and the diversification of aposematic signals

Despite accumulating evidence for selection within natural systems, the importance of random genetic drift opposing Wright's and Fisher's views of evolution continue to be a subject of controversy. The geographical diversification of aposematic signals appears to be a suitable system to assess the factors involved in the process of adaptation since both theories were independently proposed to explain this phenomenon. In the present study, the effects of drift and selection were assessed from population genetics and predation experiments on poison-dart frogs, Ranitomaya imitator, of Northern Peru. We specifically focus on the transient zone between two distinct aposematic signals. In contrast to regions where high predation maintains a monomorphic aposematic signal, the transient zones are characterized by lowered selection and a high phenotypic diversity. As a result, the diversification of phenotypes may occur via genetic drift without a significant loss of fitness. These new phenotypes may then colonize alternative habitats if successfully recognized and avoided by predators. This study highlights the interplay between drift and selection as determinant processes in the adaptive diversification of aposematic signals. Results are consistent with the expectations of the Wright's shifting balance theory and represent, to our knowledge, the first empirical demonstration of this highly contested theory in a natural system.

The role of predators in maintaining the geographic organization of aposematic signals

Selective predation of aposematic signals is expected to promote phenotypic uniformity. But while these signals may be uniform within a population, numerous species display impressive variations in warning signals among adjacent populations. Predators from different localities who learn to avoid distinct signals while performing intense selection on others are thus expected to maintain such a geographic organization. We tested this assumption by placing clay frog models, representing distinct color morphs of the Peruvian poison dart frog Ranitomeya imitator and a nonconspicuous frog, reciprocally between adjacent localities. In each locality, avian predators were able to discriminate between warning signals; the adjacent exotic morph experienced up to four times more attacks than the local one and two times more than the nonconspicuous phenotype. Moreover, predation attempts on the exotic morph quickly decreased to almost nil, suggesting rapid learning. This experiment offers direct evidence for the existence of different predator communities performing localized homogenizing selection on distinct aposematic signals.

Evidence of extreme habitat stability in a Southeast Asian biodiversity hotspot based on the evolutionary analysis of neotenic net-winged beetles

The diversification of neotenic beetle lineages has not been studied, despite the potential for defining biodiversity hotspots and elucidating the history of regional faunas. Additionally, neotenics may provide insight into the process of speciation in small populations with extremely low dispersal ability and a limited range. Here, we used two rDNA and three mtDNA markers to investigate the phylogeny of Scarelus, a neotenic lineage endemic to Southeast Asian rainforests. Most genetic differentiation was associated with Palaeogene geographical divisions, which remain distinct despite temporary connections. Dispersal events were rare, with only two inferred for Scarelus: from Borneo to the Philippines 28.3 million years ago (Ma) and from Sumatra to Java 13.9 Ma. We suggest that speciation resulted from allopatric range fragmentation, and Scarelus diversified readily when conditions were favourable; in this case, at different times in the eastern (19.3-39.1 Ma) and western (3.5-13.9 Ma) parts of Sundaland. The observed strong phenotypic similarity was preserved under speciation through complete allopatry. Neotenic Lycidae have survived for a long time in very stable habitats, and extremely low dispersal activity has not limited their persistence; however, the long-term diversification rate of neotenics is low and diversification is nonexistent under stable conditions. The modern ranges of neotenic lineages are indicative of ancient rainforest refugia and may be used in biodiversity conservation management. Most neotenics are at risk of extinction because of their small ranges and a low dispersal potential.