Phylogenetic reconstruction of the wolf spiders (Araneae: Lycosidae) using sequences from the 12S rRNA, 28S rRNA, and NADH1 genes: implications for classification, biogeography, and the evolution of web building behavior

Current knowledge of the evolutionary relationships amongst the wolf spiders (Araneae: Lycosidae) is based on assessment of morphological similarity or phylogenetic analysis of a small number of taxa. In order to enhance the current understanding of lycosid relationships, phylogenies of 70 lycosid species were reconstructed by parsimony and Bayesian methods using three molecular markers; the mitochondrial genes 12S rRNA, NADH1, and the nuclear gene 28S rRNA. The resultant trees from the mitochondrial markers were used to assess the current taxonomic status of the Lycosidae and to assess the evolutionary history of sheet-web construction in the group. The results suggest that a number of genera are not monophyletic, including Lycosa, Arctosa, Alopecosa, and Artoria. At the subfamilial level, the status of Pardosinae needs to be re-assessed, and the position of a number of genera within their respective subfamilies is in doubt (e.g., Hippasa and Arctosa in Lycosinae and Xerolycosa, Aulonia and Hygrolycosa in Venoniinae). In addition, a major clade of strictly Australasian taxa may require the creation of a new subfamily. The analysis of sheet-web building in Lycosidae revealed that the interpretation of this trait as an ancestral state relies on two factors: (1) an asymmetrical model favoring the loss of sheet-webs and (2) that the suspended silken tube of Pirata is directly descended from sheet-web building. Paralogous copies of the nuclear 28S rRNA gene were sequenced, confounding the interpretation of the phylogenetic analysis and suggesting that a cautionary approach should be taken to the further use of this gene for lycosid phylogenetic analysis.     

Mitochondrial permeability transition pore induces mitochondria injury in Huntington disease

Background

Mitochondrial impairment has been implicated in the pathogenesis of Huntington’s disease (HD). However, how mutant huntingtin impairs mitochondrial function and thus contributes to HD has not been fully elucidated. In this study, we used striatal cells expressing wild type (STHdh^Q7/Q7) or mutant (STHdh^Q111/Q111) huntingtin protein, and cortical neurons expressing the exon 1 of the huntingtin protein with physiological or pathological polyglutamine domains, to examine the interrelationship among specific mitochondrial functions.

Results

Depolarization induced by KCl resulted in similar changes in calcium levels without compromising mitochondrial function, both in wild type and mutant cells. However, treatment of mutant cells with thapsigargin (a SERCA antagonist that raises cytosolic calcium levels), resulted in a pronounced decrease in mitochondrial calcium uptake, increased production of reactive oxygen species (ROS), mitochondrial depolarization and fragmentation, and cell viability loss. The mitochondrial dysfunction in mutant cells was also observed in cortical neurons expressing exon 1 of the huntingtin protein with 104 Gln residues (Q104-GFP) when they were exposed to calcium stress. In addition, calcium overload induced opening of the mitochondrial permeability transition pore (mPTP) in mutant striatal cells. The mitochondrial impairment observed in mutant cells and cortical neurons expressing Q104-GFP was prevented by pre-treatment with cyclosporine A (CsA) but not by FK506 (an inhibitor of calcineurin), indicating a potential role for mPTP opening in the mitochondrial dysfunction induced by calcium stress in mutant huntingtin cells.

Conclusions

Expression of mutant huntingtin alters mitochondrial and cell viability through mPTP opening in striatal cells and cortical neurons.

     

Phylogeny of the orb-weaving spider family Araneidae (Araneae: Araneoidea)

We present a new phylogeny of the spider family Araneidae based on five genes (28S, 18S, COI, H3 and 16S) for 158 taxa, identified and mainly sequenced by us. This includes 25 outgroups and 133 araneid ingroups representing the subfamilies Zygiellinae Simon, 1929, Nephilinae Simon, 1894, and the typical araneids, here informally named the “ARA Clade”. The araneid genera analysed here include roughly 90% of all currently named araneid species. The ARA Clade is the primary focus of this analysis. In taxonomic terms, outgroups comprise 22 genera and 11 families, and the ingroup comprises three Zygiellinae and four Nephilinae genera, and 85 ARA Clade genera (ten new). Within the ARA Clade, we recognize ten informal groups that contain at least three genera each and are supported under Bayesian posterior probabilities (≥ 0.95): “Caerostrines” (Caerostris, Gnolus and Testudinaria), “Micrathenines” (Acacesia, Micrathena, Ocrepeira, Scoloderus and Verrucosa), “Eriophorines” (Acanthepeira, Alpaida, Eriophora, Parawixia and Wagneriana), “Backobourkiines” (Acroaspis, Backobourkia, Carepalxis, Novakiella, Parawixia, Plebs, Singa and three new genera), “Argiopines” (Arachnura, Acusilas, Argiope, Cyrtophora, Gea, Lariniaria and Mecynogea), “Cyrtarachnines” (Aranoethra, Cyrtarachne, Paraplectana, Pasilobus and Poecilopachys), “Mastophorines” (Celaenia, Exechocentrus and Mastophora,), “Nuctenines” (Larinia, Larinioides and Nuctenea), “Zealaraneines” (Colaranea, Cryptaranea, Paralarinia, Zealaranea and two new genera) and “Gasteracanthines” (Augusta, Acrosomoides, Austracantha, Gasteracantha, Isoxya, Macracantha, Madacantha, Parmatergus and Thelacantha). Few of these groups are currently corroborated by morphology, behaviour, natural history or biogeography. We also include the large genus Araneus, along with Aculepeira, Agalenatea, Anepsion, Araniella, Cercidia, Chorizopes, Cyclosa, Dolophones, Eriovixia, Eustala, Gibbaranea, Hingstepeira, Hypognatha, Kaira, Larinia, Mangora, Metazygia, Metepeira, Neoscona, Paraplectanoides, Perilla, Poltys, Pycnacantha, Spilasma and Telaprocera, but the placement of these genera was generally ambiguous, except for Paraplectanoides, which is strongly supported as sister to traditional Nephilinae. Araneus, Argiope, Eriophora and Larinia are polyphyletic, Araneus implying nine new taxa of genus rank, and Eriophora and Larinia two each. In Araneus and Eriophora, polyphyly was usually due to north temperate generic concepts being used as dumping grounds for species from southern hemisphere regions, e.g. South-East Asia, Australia or New Zealand. Although Araneidae is one of the better studied spider families, too little natural history and/or morphological data are available across these terminals to draw any strong evolutionary conclusions. However, the classical orb web is reconstructed as plesiomorphic for Araneidae, with a single loss in “cyrtarachnines”–“mastophorines”. Web decorations (collectively known as stabilimenta) evolved perhaps five times. Sexual dimorphism generally results from female body size increase with few exceptions; dimorphic taxa are not monophyletic and revert to monomorphism in a few cases.     

Four new Mouse Spider species (Araneae,Mygalomorphae, Actinopodidae,Missulena) from Western Australia

Four new species of the Mouse Spider genus Missulena Walckenaer, 1805 (family Actinopodidae) are described from Western Australia based on morphological features of adult males. Missulena leniae sp. n.(from the Carnarvon and Yalgoo biogeographic regions), Missulena mainae sp. n. (Carnarvon), Missulena melissae sp. n. (Pilbara) and Missulena pinguipes sp. n. (Mallee) represent a broad spectrum of morphological diversity found in this genus and differ from other congeners by details of the male copulatory bulb, colour patterns, eye sizes, leg morphology and leg spination. Two of the species, M. pinguipes sp. n. and M. mainae sp. n., are characterised by swollen metatarsi of the fourth legs in males, a feature not previously recorded in the family. A key to males of all named Missulena species from Australia is presented and allows their identification based on external morphology.     

Predicting the post-fire responses of animal assemblages: testing a trait-based approach using spiders

1. Developing a predictive understanding of how species assemblages respond to fire is a key conservation goal. In moving from solely describing patterns following fire to predicting changes, plant ecologists have successfully elucidated generalizations based on functional traits. Using species traits might also allow better predictions for fauna, but there are few empirical tests of this approach. 2. We examined whether species traits changed with post-fire age for spiders in 27 sites, representing a chronosequence of 0-20 years post-fire. We predicted a priori whether spiders with ten traits associated with survival, dispersal, reproduction, resource-utilization and microhabitat occupation would increase or decrease with post-fire age. We then tested these predictions using a direct (fourth-corner on individual traits and composite traits) and an indirect (emergent groups) approach, comparing the benefits of each and also examining the degree to which traits were intercorrelated. 3. For the seven individual traits that were significant, three followed predictions (body size, abundance of burrow ambushers and burrowers was greater in recently burnt sites); two were opposite (species with heavy sclerotisation of the cephalothorax and longer time to maturity were in greater abundance in long unburnt and recently burnt sites respectively); and two displayed response patterns more complex than predicted (abdominal scutes displayed a U-shaped response and dispersal ability a hump shaped curve). However, within a given trait, there were few significant differences among post-fire ages. 4. Several traits were intercorrelated and scores based on composite traits used in a fourth-corner analysis found significant patterns, but slightly different to those using individual traits. Changes in abundance with post-fire age were significant for three of the five emergent groups. The fourth-corner analysis yielded more detailed results, but overall we consider the two approaches complementary. 5. While we found significant differences in traits with post-fire age, our results suggest that a trait-based approach may not increase predictive power, at least for the assemblages of spiders we studied. That said, there are many refinements to faunal traits that could increase predictive power.     

Construction and Characterization of a Magnaporthe grisea Bacterial Artificial Chromosome Library

Diaz-Perez, S. V., Crouch, V. W., and Orbach, M. J. 1996. Construction and characterization of a Magnaporthe grisea bacterial artificial chromosome library. Fungal Genet. Biol. 20, 280-288. A bacterial artificial chromosome (BAC) library of Magnaporthe grisea containing 4128 clones with an average insert size of 66-kb has been constructed. This library represents seven genome equivalents of M. grisea and has been demonstrated to be representative of the genome by screening for the presence of several single-copy genes and DNA markers. The utility of the library for use in map-based cloning projects was shown by the spanning of a nine-cosmid, 207-kb DNA contig with only 3 BAC clones. In addition, using a lys1-3 auxotroph, we have shown that BAC clones at least 113 kb can be transformed into M. grisea to screen for complementation of mutations. Thus, BACs isolated in chromosome walks can be rapidly screened for the presence of the sought after gene. The ease of construction of BAC libraries and of isolation and manipulation of BAC clones makes the BAC system an ideal one for physical analyses of fungal genomes.     

Foraging decisions of individual workers vary with colony size in the greenhead ant Rhytidoponera metallica (Formicidae, Ectatomminae)

Summary. The ability of worker ants to adapt their behaviour depending on the social environment of the colony is imperative for colony growth and survival. In this study we use the greenhead ant Rhytidoponera metallica to test for a relationship between colony size and foraging behaviour. We controlled for possible confounding ontogenetic and age effects by splitting large colonies into small and large colony fragments. Large and small colonies differed in worker number but not worker relatedness or worker/brood ratios. Differences in foraging activity were tested in the context of single foraging cycles with and without the opportunity to retrieve food. We found that workers from large colonies foraged for longer distances and spent more time outside the nest than foragers from small colonies. However, foragers from large and small colonies retrieved the first prey item they contacted, irrespective of prey size. Our results show that in R. metallica, foraging decisions made outside the nest by individual workers are related to the size of their colony.Received 23 March 2004; revised 3 June 2004; accepted 4 June 2004.