Integrating phylogenomics, phylogenetics, morphometrics, relative genome size and ecological niche modelling disentangles the diversification of Eurasian Euphorbia seguieriana s. l. (Euphorbiaceae)

Next generation sequencing has revolutionised biology. Restriction-associated DNA sequencing (RADseq) has primarily been used to study infraspecific relationships but has also been applied in multi-species phylogenomic analyses. In this study, we used a combination of phylogenomic (with RADseq data) and phylogenetic (with sequences of the nuclear internal transcribed spacer, ITS) methods to explore relationships within the taxonomically intricate Euphorbia seguieriana s. l., one of the most widespread Euphorbia taxa inhabiting zonal and extrazonal steppes from Iberia to Central Asia. In the inferred phylogenies the southeastern Balkan and Anatolian populations were clearly separated, supporting the distinction of E. niciciana from E. seguieriana at the species level. Within E. seguieriana, the populations from the Caucasus, Iran, and easternmost Anatolia were sister to all other populations based on RADseq, making necessary the description of a new, morphologically divergent subspecies, E. seguieriana subsp. armeniaca. Conversely, additional studies are needed to understand the status of E. seguieriana subsp. hohenackeri, which is sympatric with E. seguieriana subsp. armeniaca. Niche analyses indicated that differences in the climatic niche between E. niciciana and E. seguieriana are relatively small compared with the climatic differences between the regions over which they are distributed. Contrary to previous believes, E. niciciana and E. seguieriana are allopatric and have likely diverged during the Pleistocene in two different glacial refugia as suggested by distribution modelling. Euphorbia niciciana nowadays has a submediterranean distribution, occupying habitats that are slightly warmer, moister, and less seasonal in temperature but more seasonal in precipitation than E. seguieriana, a characteristic species of continental steppes. Using flow cytometry, we demonstrate that the relative genome sizes of E. niciciana and E. seguieriana differ significantly. Additionally, multivariate morphometric analyses of 56 morphological characters indicated clear morphological divergence of the two species. Importantly, we also provide a revised taxonomic treatment including formal nomenclatural changes, an identification key and species descriptions. Our study demonstrates that an integrative approach, combining modern phylogenomic methods with traditional phylogenetic, cytogenetic, environmental and morphological analyses can result in satisfactorily resolved relationships in intricate groups of closely related species. Finally, phylogenetic inference using ITS sequences is still a useful tool for resolving relationships among the taxa at the species level, but the phylogenomic approach based on RADseq data certainly provides better resolution both among and within species.Austrian Science Fund Tiroler Wissenschaftsfond

Eleven microsatellite loci in the sociobiologically enigmatic ant Lasius austriacus (Hymenoptera: Formicidae)

We describe the isolation and characterization of 11 microsatellite loci in the sociobiologically enigmatic ant Lasius austriacus. The polymerase chain reaction primers were tested on a population in East Austria. The number of alleles ranged from four to 19 and the observed heterozygosity from 0.200 to 0.900. Cross-species amplification tests were performed, with some loci polymorphic in all species tested, for the closely related invasive species Lasius neglectus, three further Lasius species, another formicine, Formica polyctena, and the invasive myrmicine species Tetramorium tsushimae

Stable N-isotope signatures of central European ants - assessing positions in a trophic gradient

Studies employing stable isotope technology have greatly contributed to understanding trophic relationships of tropical ants, but temperate-zone ants remain under-explored. We studied δ15N values of 43 ant species from three subfamilies sampled across central Europe. After statistically accounting for the effects of elevation and geographical location of habitats, which alter the isotopic composition of nitrogen in ecosystems, significant patterns in N-isotope signatures were detected. These signatures hint at differences across ants in the contribution of plant-derived nitrogen obtained via trophobiosis and nectarivory relative to nitrogen obtained via predation and scavenging. In general, Myrmicinae had higher δ15N values than Formicinae, in line with a greater relative importance of trophobiosis in the latter. The genus Myrmica scored especially high, indicating predominantly predacious nitrogen sources. Remarkably, also the granivore Messor cf. structor had high δ15N values. This suggests that, despite the major portion of food uptake being made up by plant seeds, this ant could derive substantial fractions of its nitrogen budget from feeding on arthropod corpses or vertebrate faeces. Moreover, this highlights that deductions from observed quantities of ingested food on its relative contribution to ants' matter balance should be accompanied by isotope analyses. At the other end of the spectrum, Camponotus and Plagiolepis had low δ15N values. In line with multiple field observations, this suggests a contribution of trophobiosis not only to their energy, but also to their nitrogen budget. Formica and Lasius had intermediate 15N values, which is in agreement with the current view that these ants have mixed diets with a balance between trophobiosis and predation. A possible influence of endosymbiotic bacteria on the isotope signatures of several genera is discussed. This study provides a first application of stable isotope technology to estimate the role of plant-derived nutrients to the nitrogen budget of a larger range of central European ants. Furthermore, it shows that N-isotope analysis is applicable across extended ecological and geographical gradients. Future studies along this line are promising to complement our current understanding of the nutritional ecology of temperate-zone ants

Colony genetic structure in the Australian jumper ant Myrmecia pilosula

Eusocial insects vary significantly in colony queen number and mating frequency, resulting in a wide range of social structures. Detailed studies of colony genetic structure are essential to elucidate how various factors affect the relatedness and the sociogenetic organization of colonies. In this study, we investigated the colony structure of the Australian jumper ant Myrmecia pilosula using polymorphic microsatellite markers. Nestmate queens within polygynous colonies, and queens and their mates, were generally unrelated. The number of queens per colony ranged from 1 to 4. Queens were estimated to mate with 1–9 inferred and 1.0–11.4 effective mates. This is the first time that the rare co-occurrence of polygyny and high polyandry has been found in the M. pilosula species group. Significant maternity and paternity skews were detected at the population level. We also found an isolation-by-distance pattern, and together with the occurrence of polygynous polydomy, this suggests the occurrence of dependent colony foundation in M. pilosula; however, independent colony foundation may co-occur since queens of this species have fully developed wings and can fly. There is no support for the predicted negative association between polygyny and polyandry in ants

No sympatric speciation here: multiple data sources show that the ant Myrmica microrubra is not a separate species but an alternate reproductive morph of Myrmica rubra

No aspect of speciation is as controversial as the view that new species can evolve sympatrically, among populations in close physical contact. Social parasitism has been suggested to yield necessary disruptive selection for sympatric speciation. Recently, mitochondrial DNA phylogeography has shown that the ant Myrmica microrubra is closely related to its host, Myrmica rubra, leading to the suggestion that sympatric speciation has occurred. We investigated the relationships between the two ant forms using mitochondrial and nuclear DNA sequences, microsatellite genotyping and morphometrics. Molecular phylogenetic and population structure analyses showed that M. microrubra does not evolve separately to its host but rather shares a gene pool with it. Probability analysis showed that mitochondrial DNA data previously adduced in favour of sympatric speciation do not in fact do so. Morphometrically, M. microrubra is most readily interpreted as a miniature queen form of M. rubra, not a separate species. Myrmica microrubra is not an example of speciation. The large (typical M. rubra) and small (M. microrubra) queen forms are alternative reproductive strategies of the same species. Myrmica microrubraSeifert 1993 is consequently synonymized here with M. rubra Linnaeus, 1758

Congruent evolutionary responses of European steppe biota to late Quaternary climate change

Quaternary climatic oscillations had a large impact on European biogeography. Alternation of cold and warm stages caused recurrent glaciations, massive vegetation shifts, and large-scale range alterations in many species. The Eurasian steppe biome and its grasslands are a noteworthy example; they underwent climate-driven, large-scale contractions during warm stages and expansions during cold stages. Here, we evaluate the impact of these range alterations on the late Quaternary demography of several phylogenetically distant plant and insect species, typical of the Eurasian steppes. We compare three explicit demographic hypotheses by applying an approach combining convolutional neural networks with approximate Bayesian computation. We identified congruent demographic responses of cold stage expansion and warm stage contraction across all species, but also species-specific effects. The demographic history of the Eurasian steppe biota reflects major paleoecological turning points in the late Quaternary and emphasizes the role of climate as a driving force underlying patterns of genetic variance on the biome level

Discovered just before extinction? The first endemic ant from the Balearic Islands (Lasius balearicus sp. nov.) is endangered by climate change

[Aim] We analyse the taxonomic status, phylogenetic relationships, distribution and age of a newly discovered ant taxon found in the mountaintops of the island of Mallorca (Spain). We also consider the potential impact of short-term climate change on the survival of this ant and make proposals on its conservation status, risks and management.[Location] Balearic Islands (Spain).[Methods] We used morphological, molecular and ecological evidence to assess the specific status of the potential new species. We gathered distribution data to conduct climate-based distribution modelling of present and future occupancy under several SRES emission scenarios.[Results] The existence of a new non-cryptic species of ant (Lasius balearicus Talavera, Espadaler & Vila, sp. nov.) is described from the island of Mallorca. Its distribution was found to be extremely restricted (Serra de Tramuntana) and elevationally constrained to island summits (between 800 and 1400 m a.s.l.). Molecular dating indicated that this species diverged about 1.51 million years ago from its nearest relatives, from which it can be distinguished based on several morphological traits. Ecological niche modelling shows a dramatic reduction of areas with suitable climatic conditions under the different scenarios studied.[Main conclusions] Lasius balearicus represents the first endemic ant to be described in the Balearic Islands, as well as the first endemic Lasius species in the Mediterranean islands. Distribution modelling predictions, the low intraspecific genetic diversity observed, and the geographical and elevational isolation of the populations indicated a low probability for the survival of the species in the short term, thus making it a potential model to study real-time climate-based biodiversity loss. As a consequence, we strongly recommend including L. balearicus in the IUCN Red List of Threatened Species under the category 'Endangered'. This case illustrates that a fraction of biodiversity remains unexplored even within Europe, arguably the best-studied region of the planet, and that the available time-window for us to study and protect it may be in some instances notably narrow. © 2014 John Wiley & Sons Ltd.Support for this research was provided by Secretaria d'Universitats i Recerca del Departament d'Economia i Coneixement de la Generalitat de Catalunya (grant 2014-SGR-1532) and the Spanish MICINN (project CGL2010-21226/BOS to G.T. and R.V., and the fellowship BES-2008-002054 to G.T.).Peer Reviewe