Selfing facilitates reproductive isolation among three sympatric species of Pitcairnia (Bromeliaceae)

 The reproductive biology of three sympatric species Pitcairnia flammea, P. corcovadensis and P. albiflos (Bromeliaceae) was studied on Corcovado Mountain in the city of Rio de Janeiro, Brazil. Controlled pollination experiments were also conducted using plants transplanted to a greenhouse. The three species are self-compatible and interspecifically cross compatible. Pitcairnia corcovadensis was principally an autonomous self-pollinator, having scarce pollinator activity, anthers and stigmas at the same level, and absence of nectar. In P. flammea, many flowers opened per day, the stigma and anther were close to each other, and its nectar was regularly consumed by hummingbirds; all factors that promote geitonogamy in this species. Although fully self-compatible, P. albiflos always opened a few flowers per days showing an adaptation to cross-pollination. Observations during two flowering seasons showed that despite different times for peak flowering, blooming of these three species overlapped in April. They grow in mixed clumps that may facilitate promiscuous pollination between them but no intermediate forms were observed under natural conditions. The absence of temporal isolation, geographic isolation and isolation via post-pollination reproduction suggests that evolution toward selfing was important to avoid hybridization between these sympatric species. Received May 10, 2001 Accepted February 25, 2002     

Agonistic relationships among sympatric mediterranean ant species (Hymenoptera: Formicidae)

The potential aggressiveness of nine ant species belonging to the same community was estimated by means of two laboratory approaches: individual confrontations and group confrontations. Interspecific aggressiveness was not directly related to size of species in individual tests, although in group tests mortality of smaller ants increased with increasing size difference between the opponents. Tempo was related to the defense strategy of species (low-tempo species used immobility as a mechanism to avoid attacks, while high-tempo species tended to escape when coming into contact with more aggressive ones), but not with their potential aggressiveness: the most aggressive ants in individual and group tests were both low-tempo and high-tempo species when only these two categories were considered. No specific level of aggression was related to the subfamily to which the species belong (both myrmicines and formicines dominated in individual and group tests) or to the degree of taxonomic similarity between species.     

Description of intracerebral ocelli in two species of North American crayfish: Orconectes limosus (Cambaridae) and Pacifastacus leniusculus (Astacidae)

Abstract. Among malacostracan crustaceans, intracerebral ocelli were first discovered in Isopoda, but they have been more recently reported from a crayfish ( Cherax destructor ) and a sandhopper ( Talitrus saltator ). This electron microscopic study increases the number of crayfish taxa in which intracerebral ocelli are now known to occur by two: Astacidae and Cambaridae. These photoreceptors are always integrated into the anteromedio-dorsal part of the brain and are not visible externally. Each ocellus is made up of 4–5 photoreceptor cells and is characterized by the presence of a fused rhabdom. The occurrence of different kinds of lysosomes in the cytoplasm is indicative of metabolic activity and perhaps membrane turnover. One typical feature of crayfish ocelli is their extraordinary variability in number. This trait is exemplified by individuals of Pacifastacus leniusculus , where as many as 14 ocelli were identified in a single brain. The arrangement of the ocelli is often not symmetrical with regard to the brain's midline and the ocelli always lack dioptric structures. Thus, it is difficult to see how they are involved in image formation. However, further research is needed to determine the precise role of these "hidden" receptors.     

Consequences of the last glacial maximum on Nyctelia confusa (Coleoptera: Tenebrionidae) in Patagonia

The Last Glacial Maximum (LGM) has affected the population size and spatial distribution of a number of organisms in southern Patagonia. It has been hypothesized that species were able to persist in isolated refuges, which has generated processes of population expansion and genetic structure of populations after the LGM. In the present study, we evaluate these hypotheses and their association with local morphotypes in the endemic species Nyctelia confusa, a coleopteran that has low vagility and restricted distribution in the region. Accordingly, sixty‐nine specimens were sequenced for the gene for mitochondrial cytochrome c oxidase I. Effective population size was estimated through time, along with population structure and the phylogenetic signal of the morphs. The results suggest the existence of recent population expansion (10 Kyr BP), although there was no evidence of population structure or the phylogenetic signal for the described morphs. We propose that, during the LGM, N. confusa survived in multiple refuges, probably in the oriental slopes of the Andes range. The surviving populations would have expanded once the steppe was re‐established after the glaciers receded. This may have produced various secondary contact zones, homogenizing the genetic diversity, which would explain the observed pattern of panmixia. The morphological differentiation reported previously may be a result of local ecological adaptation not associated with the historical events of the LGM.     

Taxonomic review of the genus Pseudostegania Butler, 1881, with description of four new species and comments on its tribal placement in the Larentiinae (Lepidoptera: Geometridae)

The genus Pseudostegania Butler is revised. In addition to the two species known, four species are described as new: P. lijiangensis sp. nov. from Yunnan Province, P. qinlingensis sp. nov. from Gansu and Shaanxi Provinces, P. zhoui sp. nov. from Sichuan Province (China) and P. burmaensis sp. nov. from Burma (Myanmar); two species are newly combined with Pseudostegania: P. distinctaria (Leech, 1897), comb. nov. and P. yargongaria (Oberthür, 1916), comb. nov. All the known species are redescribed and lectotypes are designated for P. defectata (Christoph, 1881), P. distinctaria and P. yargongaria. The generic characters, based on all species, are summarized. The tribal placement of Pseudostegania is discussed. Illustrations of moths and genitalia are presented.     

Taxonomic notes on the genus Holepyris (Hymenoptera: Bethylidae) from Korea with descriptions of six new species

Six new species of the genus Holepyris (Hymenoptera: Bethylidae: Epyrinae) from Korea are described: H. brevicarinatus sp. nov., H. crinitus sp. nov., H. dimidiatus sp. nov., H. longicephalus sp. nov., H. mucro sp. nov. and H. multo sp. nov. They are described with illustrations of male genitalia and the biometric measurement data. A key to the Korean species of Holepyris based on males is provided.     

Revision of the lygaeid genus Nysius (Heteroptera: Lygaeidae: Orsillinae) of Japan,with description of a new species

Japanese species of the lygaeid–orsilline genus Nysius were revised, and five species including a new species, N. hidakai, were recognized. Male and female genitalia of all the species were illustrated, and a key to species of Japanese Nysius was provided. The DNA barcoding information of each species except N. expressus were recorded.     

Genetic diversity of genus Vespa including an invaded species of V. velutina (Hymenoptera: Vespidae) in Korea inferred from DNA barcoding data

With about 5000 known species, the Vespidae is a large family belongs to order Hymenoptera. The genus Vespa with 22 species is one of the four genera of the subfamily Vespinae. In Korea, 10 species and subspecies are recognized. Because of their social behavior, their treat to human health and their impact in apiculture, the reliable and sometimes automated identification of these insects to species level are important. To test the efficacy of DNA barcoding method for identification of species of the genus Vespa in Korea, 30 samples of eight Korean species of genus Vespa were collected and mitochondrial DNAs of 658 bp fragment cytochrome oxidase subunit 1 (CO1) region were sequenced. A Bayesian Inference based on COI gene of the Korean Vespa species was constructed. The phylogenetic tree shoed that identification of all specimens is possible based on COI gene and we found strong relation between the sequences of the collected species from different localities in South Korea which clustered together with 100% support with sequences of the same species in GenBank. The results demonstrate that DNA barcoding is a useful technique for rapid and accurate species recognition in Korean Vespa species. The DNA barcode part of COI for V. binghami is provided for the first time that can help for identification of this species through DNA barcoding. Also, the genetic diversity among Korean Vespa velutina was zero suggests that the invasion might have occurred in a single event with small number of founders.     

Intra-specific variation in the morphology and the benefit of large genital sclerites of males in the adzuki bean beetle (Callosobruchus chinensis)

Rapid evolution has led to a large diversity in the sizes and morphology of male genitals across taxa, but the mechanisms driving this evolution remain controversial. In this study, we investigated the function of male genital sclerites in the adzuki bean beetle (Callosobruchus chinensis) and compared the length and morphology of genital sclerites between two populations that vary in their degree of polyandry. We found that the length of male genital sclerites was negatively correlated with copulation duration but positively correlated with the speed of matings with multiple females. Additionally, we found that the average length and number of genital sclerite spines of males from the more polyandrous population were larger than those from the less polyandrous population. We suggest that the genital sclerite of male adzuki bean beetles evolved by sexual selection, and a larger genital sclerite has a selective advantage because it allows for rapid copulations with multiple females.     

Flies in the ointment: a morphological and molecular comparison of Lucilia cuprina and Lucilia sericata (Diptera: Calliphoridae) in South Africa

Abstract.  Complementary nuclear (28S rRNA) and mitochondrial (COI) genes were sequenced from blowflies that phenotypically resembled Lucilia cuprina (W.), Lucilia sericata (Meigen) or exhibited characters of both species. The aim was to test a long-held hypothesis that these species hybridize under natural conditions in South Africa ( Ullyett, 1945 ). Blowflies were obtained predominantly from the Cape Town metropolitan area, but reference samples were acquired for L. sericata from Pretoria. Several L. cuprina -like flies were shown to possess a conflicting combination of nuclear and mitochondrial genes that has also been seen in Hawaiian specimens. Homoplasy, sampling of pseudogenes, hybridization and incomplete lineage sorting are discussed as possible hypotheses for the pattern and the latter is concluded to represent the most likely explanation.     

Barcoding of biting midges in the genus Culicoides: a tool for species determination

Biting midges of the genus Culicoides (Diptera: Ceratopogonidae) are insect vectors of economically important veterinary diseases such as African horse sickness virus and bluetongue virus. However, the identification of Culicoides based on morphological features is difficult. The sequencing of mitochondrial cytochrome oxidase subunit I (COI), referred to as DNA barcoding, has been proposed as a tool for rapid identification to species. Hence, a study was undertaken to establish DNA barcodes for all morphologically determined Culicoides species in Swedish collections. In total, 237 specimens of Culicoides representing 37 morphologically distinct species were used. The barcoding generated 37 supported clusters, 31 of which were in agreement with the morphological determination. However, two pairs of closely related species could not be separated using the DNA barcode approach. Moreover, Culicoides obsoletus Meigen and Culicoides newsteadi Austen showed relatively deep intraspecific divergence (more than 10 times the average), which led to the creation of two cryptic species within each of C. obsoletus and C. newsteadi. The use of COI barcodes as a tool for the species identification of biting midges can differentiate 95% of species studied. Identification of some closely related species should employ a less conserved region, such as a ribosomal internal transcribed spacer.     

Phylogeny and divergence time of island tiger beetles of the genus Cylindera (Coleoptera: Cicindelidae) in East Asia

To examine the diverse colonization histories in eight tiger beetle species of the genus Cylindera (Coleoptera: Cicindelidae) on the East Asian islands, we conducted phylogenetic analyses and divergence time estimation using mitochondrial cytochome oxidase subunit I (COI) and nuclear 28S rDNA sequences. The island fauna consisted of four subgenera: Apterodela, Cicindina, Ifasina, and Cylindera. Apterodela is a flightless group with large bodies, whereas the others are fliers with small bodies. In Apterodela, the divergence among endemic species in Taiwan, Japan, and the mainland was ancient (2.1–4.7 Mya), as expected from their flightlessness. Their dispersal might have occurred across the extended landmass in East Asia during the Pliocene. In the subgenus Cicindina, Cylindera elisae has spread throughout East Asia, from which an endemic species, Cylindera bonina, was derived on the oceanic Bonin Islands during the early Pleistocene (0.9 Mya). This indicates the significance of Cylindera bonina, which is currently confined to a single island, for conservation. In the subgenus Ifasina, Cylindera kaleea is widely distributed in East Asia, and its sister species Cylindera humerula, endemic to Okinawa Island, diverged 1.0 Mya, whereas Cylindera psilica on Taiwan and the Yaeyama Islands diverged approximately 0.8 Mya. In the subgenus Cylindera, the colonization of Cylindera gracilis in Japan from the mainland occurred during the last glacial period. With the exception of C. bonina, which likely colonized new territories by flight or drifting, other dispersal events might have used land connections that occurred repeatedly during the Pliocene and Pleistocene. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 715–727.     

Systematic and morphological studies of the genus Chaetopleurophora Schmitz (Diptera: Phoridae) occurring in Japan

Japanese species of the genus Chaetopleurophora are reviewed. All belong to the C. erythronota group. The following three species from Japan are described: C. rhomboidea sp. nov., C. pygidialis Schmitz and C. dividua sp. nov. The male and female genitalia are studied and further examples of unique characters of the genus including asymmetric features are added. The male aedeagus of the genus is illustrated for the first time. The aedeagus of the species treated in this study consists of only two components, the inner core plate and the outer jacket plate. The jacket plate wraps sinistrally around the core plate. The combination of the core plate and the jacket plate forms complex, asymmetric features of the aedeagus in the Phoridae. The structure around the genital opening in the female genitalia protrudes posteriorly under the segment IX + X, and shows asymmetric features in C. rhomboidea sp. nov. with a bilaterally different degree of sclerotization, shifted genital opening to the right side and a membranous ribbon just on the left side. In addition, C. dividua sp. nov. is different from most of the species in the C. erythronota group, and very closely related to C. multiseriata (known in North America) in the male and female genitalia, wing venation and bristle formation on the scutellum. It is suggested that C. dividua sp. nov. forms a monophyletic group with C. multiseriata and the related species.     

Incongruence of morphology and genetic markers in Hyles tithymali (Lepidoptera: Sphingidae) from the Canary Islands

Hyles t. tithymali on the Canary Islands has been observed to occur in two larval morphotypes, connected by intermediate forms along a geographical cline from east to west. In this study, it was tested whether this distribution of phenotypes reflects a genealogical division of the population. mtDNA sequence data (COI + II, tRNA-leu) and genomic fingerprints from intersimple sequence repeat (ISSR)-PCR data were used. The sequence data had low variation (max. 0.4%), and phylogenetic analyses did not reveal groups that correlated with the morphotype. The samples did not group according to their island of origin and the most common haplotype was shared among all islands. Although nine haplotypes occurred only on the westernmost islands, the data showed little phylogeographical structure. The population of H. t. tithymali appears to reflect a comparatively rapid and recent colonization event of the Canary Islands. The ISSR-PCR data were very variable and did not reveal patterns corresponding to morphological variation or geographical distribution. Although the two morphs observed may represent the first stage of differentiation between two lineages, the recent origin of H. t. tithymali provided insufficient time for complete lineage sorting of ancestral polymorphism. Hence, the population of Hyles t. tithymali on the Canary Islands appears genetically more homogeneous than that was expected from the phenotypic distribution of the two morphotypes in the population.     

Molecular phylogeny of the genus Apatrobus (Coleoptera: Carabidae: Patrobinae) in western Japan

We performed a molecular phylogenetic analysis of the ground beetles Apatrobus (Carabidae), endemic to Japan, using the mitochondrial cytochrome c oxidase subunit I (COI) and the nuclear 28S rRNA (28S) genes. We focused on the species divergence in Kyushu, Shikoku and western Honshu and used 15 of 19 species and three populations with undetermined species in the DNA analysis. The gene trees showed that, of the Apatrobus species studied, A. hayachinensis Nakane from northern Honshu was not included in the monophyletic group of the other Apatrobus species and likely to be of a different genus. Divergence time estimation suggested that Apatrobus species excluding A. hayachinensis diverged 5.2 million years ago and the subsequent divergence of species occurred during the Pliocene and Pleistocene. In each of the main islands, Kyushu, Shikoku and Honshu, two or more distinct lineages occurred and all species had restricted distribution areas, suggesting that ancient dispersal and vicariance among the three main islands resulted in the nested biogeographical pattern of species distribution.     

The evolution of intrinsic reproductive isolation in the genus Cakile (Brassicaceae)

In theory, adaptive divergence can increase intrinsic post‐zygotic reproductive isolation (RI), either directly via selection on loci associated with RI, or indirectly via linkage of incompatibility loci with loci under selection. To test this hypothesis, we measured RI at five intrinsic post‐zygotic reproductive barriers between 18 taxa from the genera Cakile and Erucaria (Brassicaceae). Using a comparative framework, we tested whether the magnitude of RI was associated with genetic distance, geographic distance, ecological divergence and parental mating system. Early stages of post‐zygotic RI related to F₁ viability (i.e. initial seed set) tended to be stronger than later stages related to F₁ fecundity (i.e. flower number, fruit number). Mating system significantly influenced early stages of RI, such that RI was lowest when the mother was selfing and father was outcrossing, consistent with an imbalance between sink strength and resistance to provisioning. We found little evidence that adaptive divergence accelerates the evolution of intrinsic post‐zygotic RI, consistent with a nonecological model of evolution that predicts the nonlinear accumulation of RI and RI asymmetry with time (i.e. genetic distance), irrespective of adaptive divergence. Thus, although certain aspects of ecological divergence do not appear to have contributed strongly to the evolution of RI in this system, divergence in mating system actually reduced RI, suggesting that mating system evolution may play a significant role in speciation dynamics.