A molecular analysis of the Gelechiidae (Lepidoptera,Gelechioidea) with an interpretative grouping of its taxa

We re‐examine the higher level phylogeny and evolutionary affinities of the family Gelechiidae (Lepidoptera: Gelechioidea) based on DNA sequence data for one mitochondrial gene (cytochrome c oxidase subunit I) and seven nuclear genes (Elongation Factor‐1α, wingless, Ribosomal protein S5, Isocitrate dehydrogenase, Cytosolic malate dehydrogenase, Glyceraldehyde‐3‐phosphate dehydrogenase and Carbamoylphosphate synthase domain protein). Fifty‐two taxa representing nearly all established subfamilies and tribes of Gelechiidae, and about 10% of described gelechiid genera, in addition to five outgroup taxa were sequenced. Data matrices (6157 bp total) were analysed under model‐based evolutionary methods (Maximum Likelihood and Bayesian Inference), resulting in novel high‐level phylogenetic interrelationships. The best supported cladogram divided the Gelechiidae into six distinct clades corresponding to the subfamilies Anacampsinae, Dichomeridinae, Apatetrinae, Thiotrichinae, Anomologinae and Gelechiinae (+ Physoptilinae, which were not available for study). The results suggest the following adjustments in gelechiid interrelationships: Brachmini is nested within Dichomeridinae; Anarsiini is the sister group of Chelariini; Pexicopiinae is the sister group of Apatetrinae, here suggested to be treated as a tribe Pexicopiini of Apatetrinae. A new subfamily Thiotrichinae ( subfam.n. ) is proposed on the basis of the resurrected genus Thiotricha Meyrick ( gen.rev. ), which includes Macrenches Meyrick, Palumbina Rondani and Polyhymno Chambers. Gelechiidae display a wide array of life‐history strategies, but the diversity in patterns of larval mode of life has direct phylogenetic correlation only below subfamily level, suggesting multiple origins and/or frequent reversals for traits such as external or internal feeding and leaf mining within the family.     

Basement Membrane Formation in Transfilter Tooth Culture and Its Relation to Odontoblast Differentiation

The mesenchymal cells of the developing tooth differentiate into odontoblasts as a result of an epithelio-mesenchymal interaction. Odontoblast differentiation was studied in vitro by cultivating dental mesenchyme and epithelium with interposed filters. Separation of the two components by enzyme treatment resulted in removal of the basement membrane. When the epithelium was grown alone, or transfilter from killed lens capsule, the basement membrane was not restored. Transfilter cultivation with dental mesenchyme resulted in basement membrane formation, but only if the filter pores allowed penetration of cytoplasmic processes. Hence, a close association between the epithelial and the mesenchymal cells seems to be a prerequisite for the restoration of the basement membrane. Differentiation of odontoblasts took place only in explants in which a basement membrane was formed. Differentiation did not occur when contact of the mesenchymal cells with the basement membrane was prevented by small pore size filters. Further experiments demonstrating an intact basement membrane suggested that membrane contacts between the epithelial and the mesenchymal cells are not needed for odontoblast differentiation. Hence, we suggest that differentiation of odontoblasts is triggered via contact of the mesenchymal cells with the basement membrane.     

Herbivores inhibit climate-driven shrub expansion on the tundra

Recent Pan-Arctic shrub expansion has been interpreted as a response to a warmer climate. However, herbivores can also influence the abundance of shrubs in arctic ecosystems. We addressed these alternative explanations by following the changes in plant community composition during the last 10 years in permanent plots inside and outside exclosures with different mesh sizes that exclude either only reindeer or all mammalian herbivores including voles and lemmings. The exclosures were replicated at three forest and tundra sites at four different locations along a climatic gradient (oceanic to continental) in northern Fennoscandia. Since the last 10 years have been exceptionally warm, we could study how warming has influenced the vegetation in different grazing treatments. Our results show that the abundance of the dominant shrub, Betula nana , has increased during the last decade, but that the increase was more pronounced when herbivores were excluded. Reindeer have the largest effect on shrubs in tundra, while voles and lemmings have a larger effect in the forest. The positive relationship between annual mean temperature and shrub growth in the absence of herbivores and the lack of relationships in grazed controls is another indication that shrub abundance is controlled by an interaction between herbivores and climate. In addition to their effects on taller shrubs (>0.3 m), reindeer reduced the abundance of lichens, whereas microtine rodents reduced the abundance of dwarf shrubs (<0.3 m) and mosses. In contrast to short-term responses, competitive interactions between dwarf shrubs and lichens were evident in the long term. These results show that herbivores have to be considered in order to understand how a changing climate will influence tundra ecosystems.     

Unravelling the determinants of stream midge biodiversity in a boreal drainage basin

1. Few extensive lotic studies have examined patterns in the biodiversity of non‐biting midges (Diptera: Chironomidae) along major environmental gradients. Our aim was to fill this gap by describing patterns in species diversity, assemblage composition and distributions of midges across a boreal drainage basin. 2. We found that the diversity of midges, as measured by rarefied species richness, Fisher’s α and Pielou’s evenness, responded positively to stream size in regression analysis. By contrast, species density was most strongly correlated to a gradient in suspended solids and phosphorus in stream water, as well as macrophyte cover. Spatial variables were not significantly correlated with species diversity. 3. Midge assemblage composition was best explained by a model incorporating five composite environmental gradients in canonical correspondence analysis. The environmental gradients were stream size, macrophyte cover, alkalinity, nitrogen and suspended solids. Spatial variables did not overcome the effects of environmental gradients on assemblage composition. 4. Cluster analysis divided the 27 study sites into four groups with relatively similar midge assemblages. These groups were statistically significant in multi‐response permutation procedure, and 15 of the 49 midge taxa recorded varied significantly among the groups in indicator value analysis. Discriminant function analysis showed that stream size, macrophyte cover and habitat structure predicted 66.7% of sites into correct groups. 5. The information provided by the present analyses may be of considerable importance in conservation planning at the drainage basin level. The fact that species diversity and assemblage composition varied primarily along the stream size gradient suggests that sites belonging to the different size classes (first to fifth order) are needed to conserve the biodiversity of midges. The other environmental gradients should also be considered in conservation planning, because they explained significant amounts of variability in midge assemblage composition.     

Variation in larval chaetotaxy in Orthosia gothica (Lepidoptera: Noctuidae): effects of mother,sex and side,and implications for systematics

Insect larval characteristics, including chaetotaxy, are used widely in systematics, including for classification and phylogenetic reconstruction. Despite their common use, basic aspects of larval morphology, including intraspecific variation, effects of relatedness between individuals, sex and asymmetry, are little investigated. In the larvae of the noctuid moth Orthosia gothica, properties of shape and size were separated to examine their effects separately. Siblings were found not to cover the entire variation of a population, and therefore specimens originating from a single female do not represent independent samples. This methodological bias may potentially lead to wrong conclusions regarding species characteristics. We observed slight differences between the left and right sides of the specimens studied, implying that one side should be examined consistently in studying larval chaetotaxy. We found no differences between sexes, but this may apply only to the species examined here; in general, sex should be determined and accounted for. We discovered considerable variation in seta numbers, which further emphasizes the importance of sufficient material, particularly in cladistic analyses in which setal counts are often used as characters.     

Rapid northwards expansion of a forest insect pest attributed to spring phenology matching with sub‐Arctic birch

Species range displacements owing to shifts in temporal associations between trophic levels are expected consequences of climate warming. Climate‐induced range expansions have been shown for two irruptive forest defoliators, the geometrids Operophtera brumata and Epirrita autumnata, causing more extensive forest damage in sub‐Arctic Fennoscandia. Here, we document a rapid northwards expansion of a novel irruptive geometrid, Agriopis aurantiaria, into the same region, with the aim of providing insights into mechanisms underlying the recent geometrid range expansions and subsequent forest damage. Based on regional scale data on occurrences and a quantitative monitoring of population densities along the invasion front, we show that, since the first records of larval specimens in the region in 1997–1998, the species has spread northwards to approximately 70°N, and caused severe defoliation locally during 2004–2006. Through targeted studies of larval phenology of A. aurantiaria and O. brumata, as well as spring phenology of birch, along meso‐scale climatic gradients, we show that A. aurantiaria displays a similar dynamics and development as O. brumata, albeit with a consistent phenological lag of 0.75–1 instar. Experiments of the temperature requirements for egg hatching and for budburst in birch showed that this phenological lag is caused by delayed egg hatching in A. aurantiaria relative to O. brumata. A. aurantiaria had a higher development threshold (LDT_A.a.=4.71 °C, LDT_O.b.=1.41 °C), and hatched later and in less synchrony with budburst than O. brumata at the lower end of the studied temperature range. We can conclude that recent warmer springs have provided phenological match between A. aurantiaria and sub‐Arctic birch which may intensify the cumulative impact of geometrid outbreaks on this forest ecosystem. Higher spring temperatures will increase spring phenological synchrony between A. aurantiaria and its host, which suggests that a further expansion of the outbreak range of A. aurantiaria can be expected.     

Community concordance between bryophyte and insect assemblages in boreal springs: a broad-scale study in isolated habitats

1. We examined species–environment relationships and community concordance between aquatic bryophytes and insects in boreal springs. We sampled bryophytes (Marchantiophyta and Bryophyta), benthic macroinvertebrates and environmental variables in 138 springs in Finland, spanning a latitudinal gradient of 1000 km. Macroinvertebrates were subdivided into two groups: Ephemeroptera, Plecoptera, Trichoptera and Coleoptera (EPTC taxa) and chironomid midges (Diptera; Chironomidae). Our aim was to test whether EPTC taxa could be used as surrogates in biodiversity surveys and bioassessment for the two less-well known organism groups, chironomids and bryophytes.
2. Bryophyte assemblages were clearly differentiated along gradients in thermal conditions and water chemistry (pH, conductivity). Chironomids and EPTC were also differentiated in relation to thermal conditions and, to a lesser extent, physical habitat variables, but were only weakly associated to spring water chemistry. Chironomid and EPTC assemblages were more concordant with each other than with bryophytes, but all concordances were relatively weak.
3. Our results suggest that even if the overall compositional patterns of the three taxonomic groups were significantly concordant, the relative importance of environmental drivers underlying their community compositions differed strongly. The results thus imply that spring bryophytes and insects are relatively poor surrogates for each other. The proportion of spring specialists was highest in bryophytes, promoting their primacy for spring bioassessment and biodiversity conservation. We suggest that adequate variation in water chemistry be assured to protect spring bryophyte biodiversity, whereas preserving the physical variation of springs is more important for macroinvertebrates.