Patterns of genetic and reproductive traits differentiation in Mainland vs. Corsican populations of bumblebees

Very low prevalence of haemosporidian parasites in two species of marsh terns

Vector-transmitted haemosporidians are among the most common parasites in birds, but our knowledge of the inter-specific patterns of infection rates and the parasite community composition is far from complete because of the unequal distribution of the screening effort across bird families and genera. To assess infection rates and the diversity of haemosporidians from the genera Plasmodium, Haemoproteus, and Leucocytozoon in marsh terns, which represent poorly explored in this regard genus of the family gulls, terns, and skimmers (Laridae), we screened two species: the Whiskered Tern (Chlidonias hybrida) and the Black Tern (Chlidonias niger). We sampled these long-distance migratory birds on breeding grounds: the Whiskered Tern in south-central Poland and north-central Ukraine, and the Black Tern-in north-central Ukraine. We found that birds from both species were infected only sporadically, with prevalence at the population level not exceeding 3.4%. Only parasites from the genera Plasmodium and Leucocytozoon were detected. There was neither an inter-specific difference nor a difference between populations of the Whiskered Tern in infection rates. In total, we registered three lineages-one Plasmodium and two Leucocytozoon-that were previously recorded in other bird species, and two unidentified Plasmodium infections. One of the lineages (Leucocytozoon LARCAC02) represents a specialist parasite with the host range restricted to larids and geographic range restricted to Poland, and two others (Plasmodium SGS1 and Leucocytozoon CIAE02) represent generalist parasites with very broad host and geographic ranges. This study reinforces the existing evidence that terns host parasites from genera Haemoproteus, Plasmodium, and Leucocytozoon only sporadically.

New Complex of Cryptic Species Discovered in Genus Biblis (Papilionoidea: Nymphalidae: Biblidinae) in Mexico

Our research focuses on demonstrating the existence of cryptic species named under Biblis aganisa Boisduval. We used COI sequences to delimit Biblis species for Mexico using species delimitation analyses and examined phylogenetic relationships with sequences from Mexico, Costa Rica, Argentina, USA, and Guana Island using a Bayesian inference tree. We performed a discriminant analysis with quantitative traits using female and male wing and genitalia, and a tree of maximum parsimony based on 39 qualitative characters of wings, head, and male genitalia. The results were congruent in the three analyses. Three groups were formed based on DNA, ECO 01 + DHJ02, ECO 02 + DHJ01, and ECO 03. The characters that contributed over 50% separation were for wings: wing length, anal margin length, and distance from the band to the outer margin; for male genitalia, angle of the integument, uncus, and the length of the hypandrium, while for females, it was the angle of the anteapophysis and the length of the abdomen. For the analysis of qualitative characters, a tree of maximum parsimony was obtained where 20 characters were informative. We confirmed the existence of three cryptic Biblis species in Mexico, two not yet described, and one corresponding to B. aganisa (ECO 02), which is sympatric in Oaxaca and Sinaloa (ECO 03) and in the Yucatan Peninsula (ECO 01).

The life cycle of Puccinia digitariae on Digitaria eriantha and Solanum species in South Africa

Rust fungi are important plant pathogens and have been extensively studied on crops and other host plants worldwide. This study describes the heterecious life cycle of a rust fungus on Digitaria eriantha (finger grass) and the Solanum species S. lichtensteinii (large yellow bitter apple), S. campylacanthum (bitter apple), and S. melongena (eggplant) in South Africa. Following field observations, inoculation studies involving telial isolates collected from Digitaria plants produced spermogonia and aecia on S. lichtensteinii, S. campylacanthum, and S. melongena. Likewise, inoculation of finger grass with aeciospores collected from the aforementioned Solanum species produced uredinia on D. eriantha. Pennisetum glaucum (pearl millet varieties Milkstar and Okashana, as well as 17 experimental lines) and S. elaeagnifolium (silverleaf nightshade or bitter apple) were resistant to the rust isolates. Morphological descriptions and molecular phylogenetic data confirmed the identity of the rust on Digitaria as P. digitariae, herein reinstated as a species and closely related to P. penicillariae the pearl millet rust, also reinstated. Puccinia digitariae has a macrocyclic, heterecious life cycle in which teliospores overwinter on dormant D. eriantha plants. Aecia sporulate on species of Solanum during spring and early summer to provide inocula that infect new growth of Digitaria.

Five new and two known species of Heterobothrium (Monogenea: Diclidophoridae) infecting puffers of the genus Takifugu from Japanese waters

Seven species of puffers of the genus Takifugu caught in Japanese waters were examined for monogeneans on the gills. Five new species of Heterobothrium (H. gotoi n. sp. from T. porphyreus, H. tabetai n. sp. from T. vermicularis, H. aljufailiae n. sp. and H. iwatai n. sp. from T. snyderi, H. matsubarai n. sp. from T. stictonotus) and two known species (H. praeorchis Bychowsky, Mamaev & Nagibina, 1976 from T. pardalis, T. chrysops and T. flavipterus and H. bychowskyi Ogawa, 1991 from T. flavipterus) were found and described. Heterobothrium tetrodonis of Iwata (1991) was synonymized with H. bychowskyi. Currently, a total of 11 species of Heterobothrium, including the seven species in this study, were recorded from nine species of Japanese Takifugu spp. Ten species excluding H. praeorchis were found from a single host species, suggesting that they are highly host-specific and have co-evolved with the host Takifugu spp. Tagia Sproston, 1946 is synonymized with Heterobothrium. Earlier divergence of Heterobothrium of tetraodontid puffers in Diclidophoridae was suggested by the large subunit ribosomal DNA (rDNA) analyses, and interspecific relationships in this genus inferred from the internal transcribed spacer region of rDNA well corresponded to those inferred from their morphology and adhesive mode to the gills. Including the five new species and synonymization of Tagia with Heterobothrium, the genus Heterobothrium now comprises 19 species.

Environmental differences explain subtle yet detectable genetic structure in a widespread pollinator

BACKGROUND

The environment is a strong driver of genetic structure in many natural populations, yet often neglected in population genetic studies. This may be a particular problem in vagile species, where subtle structure cannot be explained by limitations to dispersal. Consequently, these species might falsely be considered quasi-panmictic and hence potentially mismanaged. A species this might apply to, is the buff-tailed bumble bee (Bombus terrestris), an economically important and widespread pollinator, which is considered to be quasi-panmictic at mainland continental scales. Here we aimed to (i) quantify genetic structure in 21+ populations of the buff-tailed bumble bee, sampled throughout two Eastern European countries, and (ii) analyse the degree to which structure is explained by environmental differences, habitat permeability and geographic distance. Using 12 microsatellite loci, we characterised populations of this species with Fst analyses, complemented by discriminant analysis of principal components and Bayesian clustering approaches. We then applied generalized dissimilarity modelling to simultaneously assess the informativeness of geographic distance, habitat permeability and environmental differences among populations in explaining divergence.

RESULTS

Genetic structure of the buff-tailed bumble bee quantified by means of Fst was subtle and not detected by Bayesian clustering. Discriminant analysis of principal components suggested insignificant but still noticeable structure that slightly exceeded estimates obtained through Fst analyses. As expected, geographic distance and habitat permeability were not informative in explaining the spatial pattern of genetic divergence. Yet, environmental variables related to temperature, vegetation and topography were highly informative, explaining between 33 and 39% of the genetic variation observed.

CONCLUSIONS

In contrast to previous studies reporting quasi-panmixia in continental populations of this species, we demonstrated the presence of subtle population structure related to environmental heterogeneity. Environmental data proved to be highly useful in unravelling the drivers of genetic structure in this vagile and opportunistic species. We highlight the potential of including these data to obtain a better understanding of population structure and the processes driving it in species considered to be quasi-panmictic.

A new rainfrog of the genus Pristimantis (Anura, Brachycephaloidea) from central and eastern Panama

Substantial molecular and morphological character differences lead us to the description of a new species of the genus Pristimantis from the cloud forest of Cerro Chucantí, Maje Mountains, Darien Province, as well as from several other mountain ranges in eastern and central Panama. Pristimantis gretathunbergaesp. nov. is a sister species to the allopatric P. erythropleura-penelopus group from northern Colombia with a mtDNA sequence divergence of > 4.4% at 16S and > 14.6% at COI. Its closest congener in sympatry is P. cruentus that differs by a large sequence divergence of > 9.6% in 16S mtDNA and 19.0% at COI, and from which it differs also by ventral and groin coloration, unusually prominent black eyes, a contrasting light upper lip, commonly a single conical to spine-like tubercle on the upper eyelid, and a larger head. While the habitat continuity at most sites in eastern Panama is moderate, habitats in central Panama are severely fragmented. Cerro Chucantí and the surrounding Maje Mountains are highly threatened by rapid deforestation and replaced by plantations and cattle pastures. Thus, investigations on the ecology of the new species and its population status, especially at the type locality, are highly recommended. As a flagship species, this new frog can help to preserve the Chucantí cloud forest including several recently described species known only from this isolated area in eastern Panama.

Emendation of the genus Neoheterobothrium and a proposal of a new genus Paraheterobothrium (Monogenea: Diclidophoridae) for five species of diclidophorids from Pleuronectiform fishes

Neoheterobothrium chilense González, Oliva & Acuña, 2002 is redescribed based on newly collected specimens from the type host, Hippoglossina macrops and type locality (Coquimbo, Northern Chile). Type specimens of Neoheterobothrium hippoglossini Piasecki, Wierzbicka & Kempter, 2000 and Choricotyle exilis Crane, 1972 are also redescribed. These three diclidophorid monogeneans infecting pleuronectiform flatfishes have pre-ovarian seminal receptacle, ootype inside the semicircle of ovary and elongated pharynx, differentiated from the most similar Orbocotyle Euzet & Suriano, 1975 in that members of the latter genus possess post-ovarian seminal receptacle, post-ovarian ootype and cylindrical or pyriform pharynx. Paraheterobothrium n. g. is proposed for P. chilense n. comb. (type), P. hippoglossini n. comb., P. exilis n. comb., P. papillosum n. comb. and P. syacii n. comb. A redescription of Neoheterobothrium affine (Linton, 1898), the type species of the genus, based on voucher specimens confirmed differences from the new genus in the presence of lamellate plate in the anterior jaw of clamps, absence of seminal receptacle and ovoid pharynx. The genus Neoheterobothrium was emended and N. cynoscioni (MacCallum, 1917) and N. mcdonaldi Payne, 1987 were removed from the genus. Neoheterobothrium now comprises N. affine (type), N. insulare Oliva & Luque, 1995, N. hirame Ogawa, 1999, and N. paralichthyi Suriano & Labriola, 1999, all of them parasites of flatfishes of the genus Paralichthys. Molecular analyses with the internal transcribed spacer 1 distinguished the clade for Paraheterobothrium spp. (P. chilense n. comb. and P. papillosum n. comb.) and Neoheterobothrium spp. (N. hirame, N. affine and N. paralichthyi), supporting this taxonomic emendation.

Patterns of intraspecific morphological variability in soil mites reflect their dispersal ability

The ability to disperse is one of the most important factors influencing the biogeography of species and speciation processes. Highly mobile species have been shown to lack geographic population structures, whereas less mobile species show genetically strongly subdivided populations which are expected to also display at least subtle phenotypic differences. Geometric morphometric methods (GMM) were now used to analyze morphological differences between European populations of a presumed non-phoretic, little mobile mite species in comparison to a highly mobile, phoretic species. The non-phoretic species Scutacarus carinthiacus showed a phenotypic population structure, whereas the phoretic species S. acarorum displayed homogeneity. These different patterns most probably can be explained by different levels of gene flow due to different dispersal abilities of the two species. GMM proved to be a sensitive tool that is especially recommendable for the analysis of (old) museum material and/or specimens in microscopic slides, which are not suitable for molecular genetic analysis.

Nanopore Sequencing of the Fungal Intergenic Spacer Sequence as a Potential Rapid Diagnostic Assay

Fungal infections are being caused by a broadening spectrum of fungi, yet in many cases, identification to the species level is required for proper antifungal selection. We investigated the fungal intergenic spacer (IGS) sequence in combination with nanopore sequencing for fungal identification. We sequenced isolates from two Cryptococcus species complexes, C. gattii and C. neoformans, which are the main pathogenic members of this genus, using the Oxford Nanopore Technologies MinION device and Sanger sequencing. There is enough variation within the two complexes to argue for further resolution into separate species, which we wanted to see if nanopore sequencing could detect. Using the R9.4.1 flow cell, IGS sequence identities averaged 99.57% compared to Sanger sequences of the same region. When the newer R10.3 flow cell was used, accuracy increased to 99.83% identity compared to the same Sanger sequences. Nanopore sequencing errors were predominantly in regions of homopolymers, with G homopolymers displaying the largest number of errors and C homopolymers displaying the least. Phylogenetic analysis of the nanopore- and Sanger-derived sequences resulted in indistinguishable trees. Comparison of average percent identities between the C. gattii and C. neoformans species complexes resulted in only a 74 to 77% identity between the two complexes. Sequencing using the nanopore platform could be completed in less than an hour, and samples could be multiplexed in groups as large as 24 sequences in a single run. These results suggest that sequencing the IGS region using nanopore sequencing could be a potential new molecular diagnostic strategy.

Spiromastigoides asexualis: Phylogenetic Analysis and Evaluation as a Cause of False-Positive Blastomyces DNA Probe Test Results

This is the first case of Spiromastigoides asexualis human infection, and it notably gave a false-positive Blastomyces DNA probe laboratory result. We further investigated other Spiromastigoides isolates as a cause of false-positive testing results, their phylogenetic relationship, and their susceptibility profiles to clinically available antifungal agents. Other S. asexualis isolates also resulted in positive Blastomyces DNA probe results, while Spiromastigoides species other than S. asexualis did not.

Stachybotriaceae on Cucurbits Demystified: Genetic Diversity and Pathogenicity of Ink Spot Pathogens

Recently, the incidence of Myrothecium leaf spot, a foliar disease of watermelon, has increased in South Carolina. However, the identity of the fungal species responsible for outbreaks of this disease has not been determined. Sequence data from four partial gene regions were used to conduct Bayesian inference in order to identify 95 isolates of Stachybotriaceae. Isolates were collected in South Carolina between July 2015 and May 2018. In total, six species of Stachybotriaceae were identified on watermelon and two other cucurbits: Albifimbria verrucaria, Gregatothecium humicola, Paramyrothecium foliicola, P. humicola, Xenomyrothecium tongaense, and Xepicula leucotricha. Two species, G. humicola and P. foliicola, were the predominant species found. Within these two species, genetic differences within small spatial scales were detected. Five species (all except Xenomyrothecium tongaense) were tested in experiments to determine their pathogenicity and relative virulence on three hosts grown in rotation in South Carolina. Southern pea plants were less susceptible than watermelon and tomato plants, which were equally susceptible. This constitutes the first reliable report of pathogenicity of any of the five tested species of Stachybotriaceae on these three vegetable crops. Another important finding was that none of the isolates were identified as P. roridum, the species considered to be the only causal agent of Myrothecium leaf spot on cucurbits. We propose the common name "ink spot" for the foliar phase of diseases caused by genera within the family Stachybotriaceae. This name is descriptive and likely to be accepted by growers. To prevent further loss incurred by ink spot, watermelon and tomato crops should be monitored for this disease.

Phylogenetic relationships between different raccoon dog (Nyctereutes procyonoides) populations based on four nuclear and Y genes

BACKGROUND

The raccoon dog (Nyctereutes procyonoides), endemic to East Asia, is classified as six subspecies according to their geographical distribution including a population introduced to Europe. Studies on phylogenetic relationship or population genetics in both native and introduced areas have been carried out recently. Lately, opinions that Japanese raccoon dogs should be classified as a different species were asserted based on several studies using karyotypes, morphometric characters, mtDNA, and microsatellites analysis. However, no data pertaining to the nuclear DNA (nDNA) or Y chromosome are available.

OBJECTIVE

To estimate the relationship among the species using different genes is necessary in understanding of the history of this species.

METHOD

Therefore, we investigated nDNA and Y chromosomes in our study to define relationships: (1) between continental raccoon dog populations, (2) between original and introduced groups, and (3) between continental and Japanese groups.

RESULTS

The analysis of four nuclear (CHRNA1, VTN, TRSP, WT1) and ZFY genes indicated that there had been no genetic differentiation among the continental populations. However, significant differences were observed between continental and Japanese raccoon dogs in VTN and ZFY genes implying genetic differentiation has been going between them.

CONCLUSION

To better understand the phylogenetic relationship among raccoon dog populations, further study will be necessary.

Sexual attraction: a review of bumblebee male pheromones

Males of many bumblebee species exhibit a conspicuous pre-mating behavior with two distinct behavioral components: scent marking and patrol flying. The marking pheromone is produced by the cephalic part of the labial gland (CLG). As far as is known, the CLG secretion is species specific, and it usually consists of two types of compounds: (i) straight-chain aliphatic alcohols, aldehydes or esters, and (ii) acyclic mono-, sesqui- and diterpenes (alcohols or acetates). Here, we summarize data from the literature reporting chemical composition of the CLG secretions of more than 80 bumblebee species. Similarities and differences within and between subgenera are discussed in the context of biosynthetic pathways and evolution.

Mitochondrial genome of Chinese grass shrimp, Palaemonetes sinensis and comparison with other Palaemoninae species

The mitogenome of Chinese grass shrimp, Palaemonetes sinensis, was determined through Illumina sequencing, and the basic characteristics and gene arrangement were analyzed. The mitogenome of P. sinensis was 15955 bp in length, consisting of 13 protein-coding genes (PCGs), 22 tRNA genes, 2 rRNA genes and one control region, with tightly packed. 33 of these genes were encoded on the heavy strand, and the remainders encoded on the light strand. The composition of P. sinensis mitogenome presented a strong A + T bias, which account for 66.7%. All PCGs were initiated by a canonical ATN codon, except nad5, which was initiated by GTG. The termination codons of the PCGs were TAA, TAG and T-. The secondary structures of 22 tRNAs of P. sinensis had the typical clover structure, except of trnS1 owing to the lack of dihydroxyuridine (DHU) arm. Gene order comparison of P. sinensis and previously-sequenced Palaemoninae revealed a unique translocation between trnT and trnP in Macrobrachium. The phylogenetic analyses showed that three Exopalaemon species formed a monophyletic group and then clustered with two Palaemon species and P. sinensis successively whereas Macrobrachium clustered with Palaemon capensis in the other clade.

Population genomics of Bombus terrestris reveals high but unstructured genetic diversity in a potential glacial refugium

Ongoing climate change is expected to cause an increase in temperature and a reduction of precipitation levels in the Mediterranean region, which might cause changes in many species distributions. These effects negatively influence species gene pools, decreasing genetic variability and adaptive potential. Here, we use mitochondrial DNA and RADseq to analyse population genetic structure and genetic diversity of the bumblebee species Bombus terrestris (subspecies Bombus terrestris lusitanicus), in the Iberian Peninsula. Although this subspecies shows a panmictic pattern of population structure across Iberia and beyond, we found differentiation between subspecies B. t. lusitanicus and B. t. africanus, probably caused by the existence of barriers to gene flow between Iberia and North Africa. Furthermore, the results revealed that the Iberian Peninsula harbours a large fraction of B. terrestris intraspecific genetic variation, with the highest number of mitochondrial haplotypes found when compared with any other region in Europe studied so far, suggesting a potential role for the Iberian Peninsula as a glacial refugium. Our findings strengthen the idea that Iberia is a very important source of diversity for the global genetic pool of this species, because rare alleles might play a role in population resilience against human- or climate-mediated changes.

Integrative taxonomy of an arctic bumblebee species complex highlights a new cryptic species (Apidae: Bombus)

Bumblebees have been the focus of much research, but the taxonomy of many species groups is still unclear, especially for circumpolar species. Delimiting species based on multisource datasets provides a solution to overcome current systematic issues of closely related populations. Here, we use an integrative taxonomic approach based on new genetic and eco-chemical datasets to resolve the taxonomic status of Bombus lapponicus and Bombus sylvicola. Our results support the conspecific status of B. lapponicus and B. sylvicola and that the low gradual divergence around the Arctic Circle between Fennoscandia and Alaska does not imply speciation in this species complex. Therefore, based on our molecular and morphological analyses, we propose to assign them subspecific status: Bombus lapponicus lapponicus from Fennoscandia and West Siberia and Bombus lapponicus sylvicola comb. nov. from Alaska and Yukon. In addition, our analyses reveal a cryptic species in the B. lapponicus complex from Alaska, which we describe here as new: Bombus (Pyrobombus) interacti sp. nov.

Signals of positive selection in mitochondrial protein-coding genes of woolly mammoth: Adaptation to extreme environments?

The mammoths originated in warm and equatorial Africa and later colonized cold and high-latitude environments. Studies on nuclear genes suggest that woolly mammoth had evolved genetic variations involved in processes relevant to cold tolerance, including lipid metabolism and thermogenesis, and adaptation to extremely varied light and darkness cycles. The mitochondria is a major regulator of cellular energy metabolism, thus the mitogenome of mammoths may also exhibit adaptive evolution. However, little is yet known in this regard. In this study, we analyzed mitochondrial protein-coding genes (MPCGs) sequences of 75 broadly distributed woolly mammoths (Mammuthus primigenius) to test for signatures of positive selection. Results showed that a total of eleven amino acid sites in six genes, namely ND1, ND4, ND5, ND6, CYTB, and ATP6, displayed strong evidence of positive selection. Two sites were located in close proximity to proton-translocation channels in mitochondrial complex I. Biochemical and homology protein structure modeling analyses demonstrated that five amino acid substitutions in ND1, ND5, and ND6 might have influenced the performance of protein-protein interaction among subunits of complex I, and three substitutions in CYTB and ATP6 might have influenced the performance of metabolic regulatory chain. These findings suggest metabolic adaptations in the mitogenome of woolly mammoths in relation to extreme environments and provide a basis for further tests on the significance of the variations on other systems.

Strong, but incomplete, mate choice discrimination between two closely related species of paper wasp

Paper wasps (genus Polistes) are one of the most species-rich genera of social insect. Prior studies have found that male coloration, male colour pattern, territory choice and female caste are potential drivers of intraspecific mate choice in paper wasps. However, there has been no formal assessment of interspecific mate choice in this group; therefore, the mechanism driving diversification in paper wasps remains an open question. In this study, we measured interspecific and intraspecific mating behaviour between two closely related species of paper wasps, Polistes fuscatus and Polistes metricus. These two species have ample opportunity to interbreed because P. fuscatus and P. metricus forage, nest and mate in the same habitats. We tested the strength of reproductive isolation between these species using no-choice and choice mating trials. Our results show strong, symmetric, prezygotic isolation between P. fuscatus and P. metricus. Males discriminated between conspecifics and heterospecifics but attempted to mate with females of the other species in ~10% of heterospecific mating trials. Female wasps were more discriminating than males and probably evaluated species identity and male quality through visual or olfactory cues. We additionally report sexual dimorphism in P. metricus body size.

Gene expression is implicated in the ability of pikas to occupy Himalayan elevational gradient

Species are shifting their ranges due to climate change, many moving to cooler and higher locations. However, with elevation increase comes oxygen decline, potentially limiting a species’ ability to track its environment depending on what mechanisms it has available to compensate for hypoxic stress. Pikas (Family Ochotonidae), cold-specialist small mammal species, are already undergoing elevational range shifts. We collected RNA samples from one population of Ochotona roylei in the western Himalaya at three sites– 3,600, 4,000, and 5,000 meters–and found no evidence of significant population genetic structure nor positive selection among sites. However, out of over 10,000 expressed transcripts, 26 were significantly upregulated at the 5,000 m site and were significantly enriched for pathways consistent with physiological compensation for limited oxygen. These results suggest that differences in gene expression may play a key role in enabling hypoxia tolerance on this local scale, indicating elevational flexibility that may facilitate successful range shifts in response to climate change.

BumbleKey: an interactive key for the identification of bumblebees of Italy and Corsica (Hymenoptera, Apidae)

BumbleKey is a matrix-based, interactive key to all 45 species of bumblebees of Italy and Corsica. The key allows to identify adult males and females (queens and workers) using morphological characters. The key is published online, open-access, at http://www.interactive-keys.eu/bumblekey/default.aspx.

Diversification in continental island archipelagos: new evidence on the roles of fragmentation, colonization and gene flow on the genetic divergence of Aegean Nigella (Ranunculaceae)

Background and Aims

Disentangling the relative roles of past fragmentation (vicariance), colonization (dispersal) and post-divergence gene flow in the genetic divergence of continental island organisms remains a formidable challenge. Amplified fragment length polymorphisms (AFLPs) were used to (1) gain further insights into the biogeographical processes underlying the Pleistocene diversification of the Aegean Nigella arvensis complex; (2) evaluate the role of potential key factors driving patterns of population genetic variability (mating system, geographical isolation and historical contingencies); and (3) test the robustness of conclusions previously drawn from chloroplast (cp) DNA.

Methods

Genetic diversity was analysed for 235 AFLP markers from 48 populations (497 individuals) representing 11 taxa of the complex using population genetic methods and Bayesian assignment tests.

Key Results

Most designated taxa are identifiable as genetically distinct units. Both fragmentation and dispersal-driven diversification processes occurred at different geological time scales, from Early to Late Pleistocene, specifically (1) sea barrier-induced vicariant speciation in the Cyclades, the Western Cretan Strait and Ikaria; and (2) bi-regional colonizations of the 'Southern Aegean Island Arc' from the Western vs. Eastern Aegean mainland, followed by allopatric divergences in Crete vs. Rhodos and Karpathos/Kasos. Outcrossing island taxa experienced drift-related demographic processes that are magnified in the two insular selfing species. Population genetic differentiation on the mainland seems largely driven by dispersal limitation, while in the Central Aegean it may still be influenced by historical events (island fragmentation and sporadic long-distance colonization).

Conclusions

The biogeographical history of Aegean Nigella is more complex than expected for a strictly allopatric vicariant model of divergence. Nonetheless, the major phylogeographical boundaries of this radiation are largely congruent with the geography and history of islands, with little evidence for ongoing gene exchange between divergent taxa. The present results emphasize the need to investigate further biological and landscape features and contemporary vs. historical processes in driving population divergence and taxon diversification in Aegean plant radiations.

The cephalic labial gland secretions of two socially parasitic bumblebees Bombus hyperboreus (Alpinobombus) and Bombus inexspectatus (Thoracobombus) question their inquiline strategy

Social parasitic Hymenopterans have evolved morphological, chemical, and behavioral adaptations to overcome the sophisticated recognition and defense systems of their social host to invade host nests and exploit their worker force. In bumblebees, social parasitism appeared in at least 3 subgenera independently: in the subgenus Psithyrus consisting entirely of parasitic species, in the subgenus Alpinobombus with Bombus hyperboreus, and in the subgenus Thoracobombus with B. inexspectatus. Cuckoo bumblebee males utilize species-specific cephalic labial gland secretions for mating purposes that can impact their inquiline strategy. We performed cephalic labial gland secretions in B. hyperboreus, B. inexspectatus and their hosts. Males of both parasitic species exhibited high species specific levels of cephalic gland secretions, including different main compounds. Our results showed no chemical mimicry in the cephalic gland secretions between inquilines and their host and we did not identify the repellent compounds already known in other cuckoo bumblebees.

Variability in Sexual Pheromones Questions their Role in Bumblebee Pre-Mating Recognition System

Sex-specific chemical secretions have been widely used as diagnostic characters in chemotaxonomy. The taxonomically confused group of bumblebees has reaped the benefit of this approach through the analyses of cephalic labial gland secretions (CLGS). Most of currently available CLGS descriptions concern species from the West-Palearctic region but few from the New World. Here, the CLGS of four East-Palearctic species Bombus deuteronymus, B. filchnerae, B. humilis, and B. exil (subgenus Thoracobombus) are analysed. Our results show high levels of variability in the major compounds in B. exil. In contrast, we describe a low differentiation in CLGS compounds between B. filchnerae and its phylogenetically closely related taxon B. muscorum. Moreover, the chemical profiles of B. filchnerae and B. muscorum are characterized by low concentrations of the C16 component, which is found in higher concentrations in the other Thoracobombus species. This raises the possibility that courtship behavior as well as environmental constraints could affect the role of the bumblebee males' CLGS.

Scent of a break-up: phylogeography and reproductive trait divergences in the red-tailed bumblebee (Bombus lapidarius)

Background

The Pleistocene climatic oscillations are considered as a major driving force of intraspecific divergence and speciation. During Ice Ages, populations isolated in allopatric glacial refugia can experience differentiation in reproductive traits through divergence in selection regimes. This phenomenon may lead to reproductive isolation and dramatically accentuates the consequences of the climatic oscillations on species. Alternatively, when reproductive isolation is incomplete and populations are expanding again, further mating between the formerly isolated populations can result in the formation of a hybrid zone, genetic introgression or reinforcement speciation through reproductive trait displacements. Therefore changes in reproductive traits driven by population movements during climatic oscillations can act as an important force in promoting pre-zygotic isolation. Notwithstanding, divergence of reproductive traits has not been approached in the context of climatic oscillations. Here we investigate the impact of population movements driven by climatic oscillations on a reproductive trait of a bumblebee species (Bombus lapidarius). We characterise the pattern of variation and differentiation across the species distribution (i) with five genes (nuclear and mitochondrial), and (ii) in the chemical composition of male marking secretions (MMS), a key trait for mate attraction in bumblebees.

Results

Our results provide evidence that populations have experienced a genetic allopatric differentiation, in at least three main refugia (the Balkans, Centre-Eastern Europe, and Southern Italy) during Quaternary glaciations. The comparative chemical analyses show that populations from the Southern Italian refugium have experienced MMS differentiation and an incipient speciation process from another refugium. The meeting of Southern Italian populations with other populations as a result of range expansion at a secondary contact zone seems to have led to a reinforcement process on local MMS patterns.

Conclusions

This study suggests that population movement during Quaternary climatic oscillations can lead to divergence in reproductive traits by allopatric differentiation during Ice Ages and by reinforcement during post-glacial recolonization.