Regional Synthesis of Habitat Relationships in Shrubland Birds

Abstract: Shrubland birds are declining throughout the eastern United States. To manage scrub-shrub habitats for birds, managers need information on avian habitat relationships. Past studies have produced contradictory results in some cases and may be of limited generality because of site- and habitat-specific factors. We studied shrubland birds across 6 habitats in 3 New England states to provide more general information on habitat relationships than has been possible in past studies. Our study sites included all major scrub-shrub habitats in New England: wildlife openings, regenerating clear-cuts, beaver ponds, utility rights-of-way, pitch pine (Pinus rigida) woodlands, and scrub oak (Quercus ilicifolia) barrens and ranged from Connecticut to northern New Hampshire, with research conducted from 2002 to 2007. Using N-mixture models of repeated point counts, we found that 6 of 12 shrubland birds preferred areas with greater shrub cover. An additional 4 species appeared to prefer areas with lower-stature vegetation and greater forb cover. Eight of 10 bird species showed relationships with cover of individual plant species, with Spiraea spp., willows (Salix spp.), alders (Alnus spp.), and invasive exotics being the most important. We recommend that shrubland management for birds focus on providing 2 distinct habitats: 1) areas of tall (>1.5 m) vegetation with abundant shrub cover and 2) areas of lower (<1.5 m) vegetation with abundant forb cover but fewer shrubs.     

Evolution in Apiales: nuclear and chloroplast markers together in (almost) perfect harmony

Relationships within the angiosperm order Apiales have long been difficult to interpret. Traditionally, the order comprised two families, Apiaceae and Araliaceae. Recent studies, however, suggest three additional lineages should also be recognized in the order (Pittosporaceae plus two tribes segregated from Araliaceae, Mackinlayeae and Myodocarpeae), and that one taxon (Apiaceae subfamily Hydrocotyloideae) is polyphyletic. Nuclear data also support the placement of five enigmatic genera ( Aralidium , Griselinia , Melanophylla , Pennantia and Torricellia ) within an expanded Apiales. To date, detailed molecular studies of Apiales have relied largely on data derived from plastid sequences, especially mat K and rbc L. To test and complement the results of these studies, the 26S (large subunit) of nuclear ribosomal DNA was sequenced and analysed phylogenetically. Results from this study confirm that Apiales comprise five major lineages: core Apiaceae, core Araliaceae, Pittosporaceae, the Mackinlaya group and the Myodocarpus group. Moreover, using an expanded sampling of members of subfamily Hydrocotyloideae, the nature and extent of the polyphyly is confirmed, with members of this taxon found among four distinct clades within Apiales. © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 144 , 123–147.     

Modelling the growth response of Staphylococcus xylosus to changes in temperature and glycerol concentration/water activity

The growth response of Staphylococcus xylosus strain CM21/3 to changes in temperature and water activity (glycerol concentration) was similar to that observed when water activity was adjusted by added NaCl. At each water activity level the effect of temperature on bacterial growth rate was described well by the square root model. T _MIN (the notional minimum temperature for growth) was found to be constant and was similar to the value obtained for the same organism grown in media containing NaCl. Growth rate was proportional to glycerol concentration/water activity allowing the combined effect of this factor and temperature to be modelled by substitution of the constant b in the basic square root model by a term for water activity. The observed minimum water activity for growth at the optimum temperature was close to that predicted by the model.     

Estimating the frequency of Asian cytochrome B haplotypes in standard European and local Spanish pig breeds

Mitochondrial DNA has been widely used to perform phylogenetic studies in different animal species. In pigs, genetic variability at the cytochrome B gene and the D-loop region has been used as a tool to dissect the genetic relationships between different breeds and populations. In this work, we analysed four SNP at the cytochrome B gene to infer the Asian (A1 and A2 haplotypes) or European (E1 and E2 haplotypes) origins of several European standard and local pig breeds. We found a mixture of Asian and European haplotypes in the Canarian Black pig (E1, A1 and A2), German Piétrain (E1, A1 and A2), Belgian Piétrain (E1, A1), Large White (E1 and A1) and Landrace (E1 and A1) breeds. In contrast, the Iberian (Guadyerbas, Ervideira, Caldeira, Campanario, Puebla and Torbiscal strains) and the Majorcan Black pig breeds only displayed the E1 haplotype. Our results show that the introgression of Chinese pig breeds affected most of the major European standard breeds, which harbour Asian haplotypes at diverse frequencies (15–56%). In contrast, isolated local Spanish breeds, such as the Iberian and Majorcan Black pig, only display European cytochrome B haplotypes, a feature that evidences that they were not crossed with other Chinese or European commercial populations. These findings illustrate how geographical confinement spared several local Spanish breeds from the extensive introgression event that took place during the 18th and 19th centuries in Europe.     

Infection and Root-Nodule Development in Stylosanthes Species by Rhizobium

Root nodules of the tropical forage legume Stylosanthes occurredonly at lateral root junctions and resulted from direct invasionby rhizobia through spaces between epidermal cells. No infectionthreads were present in either the root hairs or nodules. Invasionof the host cortical cells was through structurally alteredcell walls. The bacteria reached the site of nodule initiationin the lateral root cortex by progressive collapse of the initiallyinvaded cells which were compressed by neighbouring cells toform intercellular thread-like infection zones. The bacteriamultiplied in the invaded cells of the nodule initial whichdivided repeatedly to form the nodule. Bacteroids formed onlywhen the host cells ceased to divide. Some abnormal associations occurred in S. capltata and S. hamata40264A. Division of invaded cells was restricted in S. capitataand the bacteria became enlarged and grossly deformed. In S.hamata restricted cell division was immediastely followed bythe brcakdown of the host cells and, although the bacteria multiplied,no bacteroids were formed. Bacteria isolated from these nodulesformed both effective and abnormal nodules when inoculated ontothe same host.