Isolation mechanisms in closely related grasshopper species <Emphasis Type="Italic">Chorthippus albomarginatus</Emphasis> and <Emphasis Type="Italic">Ch. oschei</Emphasis> (Orthoptera: Acrididae)

Two closely related grasshopper species Chorthippus albomarginatus and Ch. oschei are known to hybridize in the narrow contact zone at the territory of Ukraine and Moldova. Different isolaton mechanisms providing reproductive isolation between the two species were studied. In choice mating experiments, females of the both species demonstrated a strong assortative mating (80–90% preference for the conspecific males). Comparison of the parental and hybrid viability revealed a reduced hatching and increased larval mortality in F₁ and F₂ hybrids. In choice mating experiments, the hybrid females mated less assortatively than the parental females. An assymmetry was found in mating preferences and in viability of hybrids. The results demonstrate the existence of pre-and post-mating isolation between Ch. albomarginatus and Ch. oschei. A possible fate of the hybrid zone is discussed.     

Composition and distribution of sibling species of <Emphasis Type="Italic">Chironomus</Emphasis> Meigen, 1803 (Diptera,Chironomidae) in Curonian Lagoon of the Baltic Sea

The species composition of Chironomus in the Curonian Lagoon has been investigated. It was shown that three sibling species of the plumosus group, namely, Ch. plumosus, Ch. balatonicus, and Ch. muratensis, and a first-generation interspecific hybrid Ch. muratensis × Ch. plumosus lived here. The occurrence frequency in the lagoon was 87, 19, 6, and 3% for Ch. plumosus, Ch. balatonicus, Ch. muratensis × Ch. plumosus, and Ch. muratensis, respectively. The species Ch. plumosus was recorded in all the areas (southern, central, and northern), while Ch. balatonicus was found only in the northern area in the village of Juodkrante near the city of Klaipeda. Presumably, the distribution of these sibling species is due to the presence of a salinity gradient in the lagoon.     

Little known leaf beetles of the genus <Emphasis Type="Italic">Chrysolina</Emphasis> (Coleoptera,Chrysomelidae) from China

Chrysolina (Semenowia) chalcea (Weise, 1889), Ch. (Pezocrosita) cyanopurpurea (Ballion, 1878), and Ch. (Chrysocrosita) fuyunica Chen, 1961 are redescribed. A male (topotype) of Ch. cyanopurpurea was examined for the first time. Ch. belousovi Lopatin, 2000 is a new junior synonym of Ch. cyanopurpurea; Ch. bienkowskii Lopatin, 2000 is a new junior synonym of Ch. chalcea. The taxonomic position of all the taxa mentioned is discussed.     

Findings of the leaf beetles <Emphasis Type="Italic">Chrysolina tundralis</Emphasis> and <Emphasis Type="Italic">Chrysolina roddi</Emphasis> (Coleoptera,Chrysomelidae) in the middle part of European Russia

Two species of leaf beetles, Chrysolina tundralis and Ch. roddi, were found in the “Galich’ya Gora” Nature Reserve (the middle part of European Russia), 1200 and 700 km, respectively, from the main part of the ranges of these species. Adults and larvae of Ch. tundralis feed on Lamium purpureum, those of Ch. roddi feed on Seseli intermedia there. Diagnostic characters of the adults of both species are reported.     

On Two Little Known Species of Leaf Beetles (Coleoptera,Chrysomelidae) from the South Urals

120 years ago G.G. Jacobson described two species of leaf beetles from the South Urals that have remained poorly studied until recently. Chrysolina roddi, previously known only from the foothills and low mountains of the South Urals, the low Zhiguli Mountains, and the limestone cliffs on the Don River, is recorded here for the first time from the alpine tundra of the Iremel massif; its host plant in the alpine zone is the small alpine lovage Pachypleurum simplex (= Ligusticum mutellinoides), family Apiaceae. Two species of the subgenus Crositops, Ch. roddi and Ch. kabaki, are presently treated as foothill-alpine disjunct taxa. The distribution of Ch. poretzkyi, described from the low-montane part of Bashkortostan, also shows a foothill-alpine disjunction. Alpine populations of Ch. poretzkyi are described here as a new subspecies Ch. (Arctolina) poretzkyi olschwangi Mikhailov subsp. n. Revision of the type of Ch. poretzkyi that has long been considered lost confirms that this species belongs to the subgenus Arctolina, in disagreement with its previous placement in the subgenus Pleurosticha. Within Arctolina, the identity of Ch. tundralis and its differences from Ch. poretzkyi are discussed.     

The Larvae of Three Species of Jewel Beetles of the Subgenus <Emphasis Type="Italic">Chrysoblemma</Emphasis> Jakovlev, 1889, Genus <Emphasis Type="Italic">Sphenoptera</Emphasis> Dejean, 1833 (Coleoptera,Buprestidae), from Turkmenistan

The larvae of three species of jewel beetles of the subgenus Chrysoblemma Jakovlev of the genus Sphenoptera Dejean are described: Sphenoptera (Ch.) tamarisci beckeri Dohrn reared from Horaninovia ulicina Fisch. et Mey., Atriplex tatarica L. and Salsola arbuscula Pall.; Sphenoptera (Ch.) tomentosa Jakovlev from Salsola arbuscula; Sphenoptera (Ch.) amplicollis Jakovlev from Salsola orientalis S.G. Gmel. and Halothamnus glaucus (Bieb.) Botsch. Differential diagnoses to distinguish them from the previously described sphenopterine larvae are given.     

Composition of the subgenus <Emphasis Type="Italic">Zeugotaenia</Emphasis>, genus <Emphasis Type="Italic">Chrysolina</Emphasis> (Coleoptera,Chrysomelidae), and examination of the nomenclatural types

Zeugotaenia Motschulsky, 1860 is resurrected as a valid name for the subgenus of Chrysolina with the type species Chrysomela limbata Fabricius, 1775. Diagnosis of the subgenus is compiled. Neotypes of Chrysomela limbata and Ch. limbifera Küster, 1846, and lectotypes of Chrysomela findelii Suffrian, 1851, Ch. hochhuthii Suffrian, 1851, and Ch. discipennis Faldermann, 1835 are designated. The types of Chrysomela limbata jenisseiensis Breit, 1920 and Chrysolina limbata kavani Bechyné, 1950 and the topotypes of Chrysomela limbata luigionii Depoli, 1936 are examined. Chrysolina furva Peyerimhoff, 1926 and Ch. dohrnii Fairmaire, 1865 do not belong to the subgenus Zeugotaenia.     

A first report on coexistence and hybridization of <Emphasis Type="Italic">Mytilus trossulus</Emphasis> and <Emphasis Type="Italic">M. edulis</Emphasis> mussels in Greenland

Semi-sessile Mytilus mussels are used as indicators of climate changes, but their geographic distribution is not sufficiently known in the Arctic. The aim of this study was to investigate the taxonomic status and genetic differentiation of Mytilus populations in a Northwest Greenlandic fjord at Maarmorilik, impacted by contaminations from a former mine. In this study, mussels were collected at three sites differing in exposure to environmental factors. A total of 54 polymorphic SNPs found in the Mytilus EST and DNA sequences analyzed were successfully applied to 256 individuals. The results provided the first evidence for the existence of M. trossulus in Greenland. The mussel from M. trossulus and M. edulis taxa are shown to coexist and hybridize in the fjord. The three studied sites were found to differ significantly in the distribution of taxa with a higher prevalence of M. trossulus in the inner fjord. The identified M. edulis × M. trossulus hybrids mostly had a hybrid index score of about 0.5, indicating a similar number of alleles characteristic for M. trossulus and M. edulis. There was a low number of backcrosses between ‘pure’ taxa and hybrids. This newly discovered hybrid zone between the two taxa is unique in comparison with the Canadian populations. As Mytilus mussels in Greenland hitherto have been regarded as the one taxon M. edulis, the results have importance for biogeography and future monitoring and environmental studies.     

Morphological and molecular investigations of <Emphasis Type="Italic">Gagea</Emphasis> (Liliaceae) in southeastern Kazakhstan with special reference to putative altitudinal hybrid zones

The most important center of speciation in the genus Gagea is thought to be in Central Asia. Here, we focus on species diversity in southeastern Kazakhstan (around Almaty, Ili-Alatau range of the Western Tian-Shan mountains). We studied an elevational transect, reaching from lowland steppes to the alpine zone (500–2750 m a. s. l.), and carried out detailed morphological and molecular investigations for populations of Gagea spp. Nine species were identified in different altitudinal zones; one of these (Gagea almaatensis) is described as new to science. We could detect two altitudinal contact zones between closely related species: G. filiformis and G. granulosa (sect. Minimae), and G. almaatensis and G. kuraminica (sect. Gagea). Morphological and molecular investigations (ITS data and cpDNA networks) indicate ongoing hybridization of co-occurring G. filiformis into G. granulosa and putative bidirectional hybridization events between G. almaatensis and G. kuraminica.     

A review of the <Emphasis Type="Italic">Chrysolina lineella</Emphasis> species-group of the subgenus <Emphasis Type="Italic">Anopachys</Emphasis> Motschulsky, 1860, genus <Emphasis Type="Italic">Chrysolina</Emphasis> Motschulsky, 1860 (Coleoptera,Chrysomelidae, Chrysomelinae)

The Chrysolina lineella species-group of the subgenus Anopachys Motschulsky, 1860 is revised. Chrysolina watanabei Takizawa, 1970 is revalidated from the synonymy with Ch. lineigera (Jacobson, 1901). Ch. sundukovi Mikhailov, 2006 is a new junior synonym of Ch. watanabei. Special attention is paid to the infraspecific variability of the male and female genitalia. The structure of the aedeagal flagellum and the spermatheca are used as diagnostic characters. A key to species is included. Ch. watanabei is for the first time recorded from the Asian continent (Primorskii Territory of Russia and Northeastern China).     

Pattern of natural introgression in a <Emphasis Type="Italic">Nothofagus</Emphasis> hybrid zone from South American temperate forests

Interspecific gene flow is a common phenomenon in Nothofagaceae species; however, the dynamics of introgression in hybrid zones remains largely unknown. We focused on two ecologically and morphologically different Nothofagus species from Patagonia, Nothofagus nervosa and Nothofagus obliqua. In a natural hybrid zone, we established two plots 280 m apart in altitude (ca. 1.9 °C difference in mean temperature), and two subplots which captured microsite variation (abundance and spatial distribution of species and predominance of wind direction). We used intensive sampling of individuals (2055, including adults and regeneration) and molecular genotyping of 6 highly species-specific nuclear microsatellites for the identification and classification of hybrids, based on estimates of ancestry and interclass heterozygosity. We evaluated the relative contribution of our sampling effects to variation in hybrid incidence and direction of introgression using generalized linear mixed effects models. We determined that introgressive hybridization occurs at a global rate of 7.8% and that variation was mostly explained by plots (frequency at low altitude was approximately twice that found at high altitude), while it was less influenced by subplots. The high altitude plot was dominated by late-generation backcrosses to N. obliqua (asymmetric bimodality), whereas the low altitude plot consisted of intermediate hybrids (unimodality) and showed asymmetry for introgression between subplots. Differences were not detected between adults and regeneration, suggesting early-acting reproductive isolating barriers. F1 hybrids occur at a global frequency of 3.8%, and are fertile, as the detection of first- and late-generation hybrids indicates.     

The hybrid nature of <Emphasis Type="Italic">Danaea plicata</Emphasis> (Marattiaceae), a Costa Rican endemic

We present evidence that Danaea plicata, endemic to Costa Rica, is a hybrid between D. carillensis and D. crispa. The laminae of D. plicata are intermediate in several morphological characters between the two putative parents, and the spores of D. plicata are misshapen and collapsed. The stomatal density of D. plicata is intermediate between that of D. crispa, which has no stomata, and D. carillensis. Circumstantial evidence also supports hybrid origin: D. plicata occurs only within the elevational range of its putative parents, and it is often found growing with them. This is the second report of a hybrid in Danaea. A lectotype is designated for D. plicata .     

A new species,a new synonym,and new records of the hover-fly genus <Emphasis Type="Italic">Cheilosia</Emphasis> Meigen (Diptera,Syrphidae)

A new species, Cheilosia richterae sp. n., is described in the nominotypical subgenus, being most closely related there to Ch. annulifemur Stackelberg, 1930. Two species, Ch. sootryeni Nielsen, 1970 and Ch. rufimana (Becker, 1984), are recorded from Russia for the first time. Ch. kuznetzovae Skufjin, 1977 is recorded for the first time from the Urals and western Siberia. The subgenus Nephocheila Barkalov, 2002 is synonymized with Nephomyia Matsumura, 1916. Figures of the male and female heads and the male genitalia are given for all the species.     

Molecular evidence for hybridization between invasive <Emphasis Type="Italic">Solidago canadensis</Emphasis> and native <Emphasis Type="Italic">S</Emphasis>. <Emphasis Type="Italic">virgaurea</Emphasis>

Hybridization between alien and native species is biologically very important and could lead to genetic erosion of native taxa. Solidago × niederederi was discovered over a century ago in Austria and described by Khek as a natural hybrid between the alien (nowadays regarded also as invasive) S. canadensis and native S. virgaurea. Although interspecific hybridization in the genus Solidago is considered to be relatively common, hybrid nature of S. × niederederi has not been independently proven using molecular tools, to date. Because proper identification of the parentage for the hybrid Solidago individuals solely based on morphological features can be misleading, in this paper we report an additive polymorphism pattern expressed in the ITS sequences obtained from individuals representing S. × niederederi, and confirm the previous hypothesis that the parental species of this hybrid are S. canadensis and S. virgaurea. Additionally, based on variability at the cpDNA rpl32-trnL locus, we showed that in natural populations hybridization occurs in both directions.     

Host specificity of Asian <Emphasis Type="Italic">Chrysochus</Emphasis> Chevr. in Dej. (Coleoptera,Chrysomelidae: Eumolpinae) and their potential use for biological control of invasive <Emphasis Type="Italic">Vincetoxicum</Emphasis> species

Three Asian leaf beetles of the genus Chrysochus were investigated as potential biological control agents of Vincetoxicum rossicum and V. nigrum, invasive weeds in northeastern North America. Chrysochus chinensis and Ch. globicollis were collected from a field host in a different genus and subtribe. Preliminary no-choice laboratory tests with Ch. goniostoma showed that its physiological host range is too broad. Based on these data, we are not considering these three species as potential biological control agents of invasive Vincetoxicum species.     

Concordant morphological and molecular clines in a contact zone of the Common and Spined toad (<Emphasis Type="Italic">Bufo bufo</Emphasis> and <Emphasis Type="Italic">B. spinosus</Emphasis>) in the northwest of France

Background

Hybrid zones are regions where individuals of two species meet and produce hybrid progeny, and are often regarded as natural laboratories to understand the process of species formation. Two microevolutionary processes can take place in hybrid zones, with opposing effects on population differentiation. Hybridization tends to produce genetic homogenization, reducing species differences, whereas the presence of mechanisms of reproductive isolation result in barriers to gene flow, maintaining or increasing differences between taxa.

Results

Here we study a contact zone between two hybridizing toad species, Bufo bufo and B. spinosus, through a combination of molecular (12 polymorphic microsatellites, four nuclear and two mitochondrial SNP markers) and morphological data in a transect in the northwest of France. The results show largely concordant clines across markers, defining a narrow hybrid zone of ca. 30 km wide. Most hybrids in the centre of the contact zone are classified as F₂ or backcrossed individuals, with no individuals assigned to the F₁ hybrid class.

Conclusions

We discuss the implications of these results for our understanding of the evolutionary history of these species. We anticipate that the toad contact zone here described will become an important asset in the study of hybrid zone dynamics and evolutionary biology because of its easy access and the abundance of the species involved.

     

Features of Interspecific Contacts and Hybridization of Ground Squirrels (Marmotinae,Sciuridae, Rodentia) in Mongolia

Using molecular genetic methods, we investigated the secondary contact zones of two pairs of species of ground squirrels of Mongolia. In common colonies of marmots M. sibirica and M. baibacina, we revealed a high frequency of occurrence of hybrid individuals that were viable and fertile. A hybridization between S. alaschanicus and S. pallidicauda was sporadic in nature. The hypothesis about an extensive hybrid zone in these species of ground squirrels was not confirmed. An occupation of suboptimal biotopes by individuals of different species was the main factor contributing to hybridization in both case. The complex social behavior in marmots affected on the localization and diffusion of the hybridization process.