Phylogeography of a Holarctic nematode, Soboliphyme baturini, among mustelids: climate change, episodic colonization, and diversification in a complex host–parasite system

Phylogeography of Soboliphyme baturini , a nematode parasite in mustelids, is explored across Beringia. Sequences of the mitochondrial cytochrome c oxidase subunit I and nicotinamide adenine dinucleotide dehydrogenase subunit 4 genes were evaluated from 37 S. baturini , representing 19 localities throughout Alaska, Canada, and Siberia. A total of 30 haplotypes was recovered and maximum parsimony and Bayesian phylogenetic analyses support the recognition of a single species with a distribution extending from the Palearctic to the Nearctic. Within S. baturini , a host-specific partition in North America between Martes caurina and Martes americana was not identified. Instead, substantial geographic structure within S. baturini relates to the dynamic geological history of this northern region and especially the North Pacific Coast. Beringia and other coastal refugia along the western margin of North America played a large role during stadial maxima in the persistence and divergence of the parasite. Repeated events for biotic expansion and geographic colonization across the Bering Land Bridge and the Holarctic during glacial maxima in the Pleistocene appear to have facilitated at least two episodes of host-switching of this nematode among mustelids in populations now distributed in eastern Beringia.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 651–663.     

Hammering homoplasy: multiple gains and losses of vibrational sounding in cryptine wasps (Insecta: Hymenoptera: Ichneumonidae)

Many hosts of parasitic wasps are, when attacked, either at an immobile stage, living in a concealed environment, or both, thus making their detection especially difficult. Cryptine ichneumonid wasps often parasitize beetle or moth larvae, prepupae or even pupae in tunnels in wood, and many others attack cocooned hosts in various states of concealment. The structure of the antennal tips shows a range of adaptations at least the most extreme of which appear to be involved in locating deeply concealed hosts through vibrational sounding (= echolocation through solid media). We show that, within the Cryptinae, the tips of the antenna are modified into a hammer-like structure that is suitable for knocking a substrate; this form of echo-location is typical to the tribe Cryptini, although it is also found in a few phygadeuontines and in the hemigastrine genus Echthrus . Electron micrographs are presented to illustrate the different degrees of antennal modifications found in the subfamily. Comparative analysis using independent contrasts was then used to demonstrate a statistically significant association between degree of antennal hammer development and attacking, typically wood-boring, beetle hosts of the families Cerambycidae and Buprestidae.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 82–102.     

The Deschampsia cespitosa complex (Poaceae: Aveneae) with special reference to Russia

The Deschampsia cespitosa complex in Russia is revised. Related taxa common to Russia and adjacent regions (i.e. northern Europe, Arctic America and Japan) are also considered. Deschampsia cespitosa s.l. is characterized by open to less commonly rather contracted panicles, spikelets (1) 2 (3)-flowered, 4-toothed lemmas with the lateral teeth larger, and awns straight or bent, inserted from the base to the top of the lemmas. Due to extensive overlapping in diagnostic characters, it is not possible to accept the specific status for D. borealis (Traut.) Roshev., D. brevifolia R.Br., D. macrothyrsa Tatew. et Ohwi and D. obensis Roshev; instead, they are treated as subspecies of D. cespitosa (L.) Beauv. Morphological differences are insufficient for a clear differentiation among subspecies, and geographical distributions also need to be considered. A total of 14 subspecies is accepted. Observations on ecology, problems of specific and subspecific delimitation, a distribution map, and considerations of evolution of the complex are provided. One new combination is made, Deschampsia cespitosa ssp. sukatschewii (Popl.) Chiapella & Prob.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 142 , 213–228.     

Pronemouridae fam. nov. (Insecta: Plecoptera), the stem group of nemouridae and notonemouridae,from the Middle Jurassic of Inner Mongolia,China

Abstract: A new family, Pronemouridae fam. nov., with a new genus, Pronemoura gen. nov., and five new species of fossil stoneflies are described from Daohugou village (Middle Jurassic), Inner Mongolia, China: P. shii sp. nov., P. angustithorax sp. nov., P. longialata sp. nov., P. minuta sp. nov. and P. peculiaris sp. nov. Wing venation of pronemourinids presents some or considerable variety in the fore and hind wings of the same or different individuals. Pronemourinidae, retaining plesiomorphic characters (short, multisegmented cerci and CuA with forks), should be treated as the stem group of Nemouridae and Notonemouridae. Based on fossil data, we propose a model in which the extant plecopterid distribution began in the Early Cretaceous. Nemouridae and Notonemouridae must have occurred in Asia and begun to migrate from here by at least the Early Cretaceous.     

The role of mammals in maintaining plant species richness in a floating Typha marsh in southern Ontario

Animals are known to influence and sometimes help maintain plant species richness in terrestrial systems. This study investigated the effects of mammals in influencing plant species richness of a floating Typha marsh at Point Pelee National Park. The extent of use of the marsh by terrestrial mammals was documented by mapping mammal trails from air photographs. Trail densities ranging from 70 to 1550 m ha–1 in various areas of the marsh, provided evidence for widespread, and in some places frequent, mammal activity. Plant surveys indicated a pattern of increased species richness and frequency associated with these trails, particularly in late summer when Typha biomass increased off trails. Three mechanisms by which mammals might influence species richness: disturbance of the dominant Typha, nutrient enrichment, and seed dispersal, were investigated using field and lab experiments. Two types of disturbance, trampling and herbivory, at two levels of intensity were simulated within 2×2m plots with and without fertilizer added. Disturbance significantly affected species richness; high levels of trampling decreased while high levels of clipping increased species richness. Nutrients had no effect; there were no significant disturbance×nutrients interactions. The importance of seed dispersal by raccoon was studied by collecting raccoon scat from within the marsh, incubating scat in a growth chamber and comparing the species that emerged to those growing in the marsh. Although substantial numbers of viable seeds of terrestrial species were found in scat, only one of these species was actually part of the Typha mat community. We concluded that mammals do influence plant species richness in this marsh primarily through disturbance of the dominant Typha.     

Habitat association and coexistence of endemic and introduced ant species in the Galápagos Islands

1. We investigated ant communities in all main vegetation zones of the model island of Santa Cruz in the Galápagos archipelago (155 collection points, spread over 21 sites; 28 ant species collected), and evaluated the distribution, coexistence, and effect of environmental factors in a community composed of endemic, probably endemic, and introduced ants of the New World and exotic origin. 2. Introduced species were the most frequent, occurring in 98% of the samples, yet endemic and probably endemic species still occurred in 54% of the samples, and constituted one of three most common species. The present study revealed that the habitat type along with altitude and the tree cover are the primary factors shaping ant community composition. Little evidence was found for a competitively structured assemblage of ant species. 3. The present study confirmed the predominance of two dominant invasive species, Solenopsis geminata Fabricius and Wasmannia auropunctata Roger, whose abundances are negatively correlated. The abundance of S. geminata is positively correlated with the overall species richness, and with the proportion of other introduced species. The presence of both invasive ants is associated with a low evenness of ant communities. 4. The present study (i) stresses the dominance of introduced species and the relative resistance of endemic species, (ii) highlights the on‐going processes of species introductions and (iii) points out the need for adequate monitoring and conservation of the pristine and threatened environments that constitute the Galápagos Islands.     

Plant‐mediated effects of butterfly egg deposition on subsequent caterpillar and pupal development,across different species of wild Brassicaceae

1. Herbivory can change plant quality, which may have consequences for interactions between the inducing herbivore and other insect community members. 2. Studies investigating the effects of plant quality on herbivore performance often have neglected the egg stage, and instead introduced larvae onto the plant. Recently, we reported that herbivore oviposition by Pieris brassicae (Linnaeus) (Large Cabbage White Butterfly) reduced the plant quality of Brassica nigra L. (black mustard) for subsequent herbivores. 3. It remains unclear how persistent and common these plant‐mediated effects of oviposition are. Here, five species of wild Brassicaceae were used (B. nigra L., Brassica oleracea L., Sinapis arvensis L., Moricandia arvensis L., and Moricandia moricandioides Boiss). The response to oviposition by the specialist P. brassicae was determined by following the natural sequence of events: oviposition, egg, larval, and pupal development. All tested plant species are known to interact with P. brassicae in nature. Caterpillar, pupal mass, and development time on plants exposed to butterfly eggs were assessed compared with egg‐free plants. 4. It was shown that the plant‐mediated effects of oviposition are not specific for B. nigra but occur in most of the tested plant species except for M. arvensis. However, the strength of the plant‐mediated effect on caterpillar growth depended on plant species. Thus, across different members of the Brassicaceae family, oviposition can influence plant quality and has negative consequences on P. brassicae growth. Further studies are needed to assess to what extent this trait might be phylogenetically conserved.     

Persistence of flower visitors and pollination services of a generalist tree in modified forests

Flower‐visiting insects provide essential pollination services to many plant species. It is thus of critical importance to understand the effects of anthropogenic landscape modification on these animals. Particularly at the landscape scale, we still lack information on how flower visitors are affected by different intensities of human disturbance. In this study, we chose six representative types of forest modification across a heterogeneous South African landscape. At 36 study sites we observed insect visitation to Celtis africana flowers in two consecutive years. This generalist tree species has small unspecialized flowers which we found to be pollinated by a diverse array of insects as well as by wind. Visitation rates to flowers of C. africana differed significantly among the six forest types and between two study years. Visitation rates were enhanced in modified forests, facilitated by a high abundance of feral honeybees (Apis mellifera). Fruit set in C. africana showed significant positive associations with insect visitation and with the diversity of flower visitors, but was only weakly predicted by forest type. Our findings imply that even though forest modification can strongly alter flower visitors, pollination services for trees with unspecialized flowers may persist at a landscape scale. We advise conservation managers to maintain modified forest fragments in addition to natural forests as these may contribute to sustain pollination services in human‐modified landscapes.