On the 13C/12C isotopic signal of day and night respiration at the mesocosm level

While there is currently intense effort to examine the ¹³C signal of CO₂ evolved in the dark, less is known on the isotope composition of day‐respired CO₂. This lack of knowledge stems from technical difficulties to measure the pure respiratory isotopic signal: day respiration is mixed up with photorespiration, and there is no obvious way to separate photosynthetic fractionation (pure c_i/c_a effect) from respiratory effect (production of CO₂ with a different δ¹³C value from that of net‐fixed CO₂) at the ecosystem level. Here, we took advantage of new simple equations, and applied them to sunflower canopies grown under low and high [CO₂]. We show that whole mesocosm‐respired CO₂ is slightly ¹³C depleted in the light at the mesocosm level (by 0.2–0.8‰), while it is slightly ¹³C enriched in darkness (by 1.5–3.2‰). The turnover of the respiratory carbon pool after labelling appears similar in the light and in the dark, and accordingly, a hierarchical clustering analysis shows a close correlation between the ¹³C abundance in day‐ and night‐evolved CO₂. We conclude that the carbon source for respiration is similar in the dark and in the light, but the metabolic pathways associated with CO₂ production may change, thereby explaining the different ¹²C/¹³C respiratory fractionations in the light and in the dark.     

Characterization of EST derived SSRs from the bay scallop,Argopecten irradians

Interest in bay scallop conservation has resulted in organized stock enhancement efforts and increased attention to fisheries management issues. Genetic markers can facilitate the monitoring of enhancement efforts, characterization of wild populations, and optimize hatchery practices. We have identified eight polymorphic simple sequence repeat markers including one dinucleotide, six trinucleotide and one compound dinucleotide repeats, in expressed sequence tags generated from multiple bay scallop cDNA libraries. The numbers of alleles range from two to five. The expected and observed heterozygosities range from 0.093 to 0.720 and 0.095 to 0.600, respectively.     

BARK-SPLIT–A VIRUS DISEASE OF PLUMS

The bark-split disease of plums commences with necrotic lesions in the outer bark, causing depressions on the surface; these lesions extend in area and depth, resulting in split and roughened bark, and crippling or killing trees of sensitive varieties like Cambridge Gage.
The causal virus was transmitted by grafting in the dormant season, but, probably because it is localized in older tissues, it was rarely transmitted or scion-perpetuated by summer budding.
About 90% of Common Plum clonal rootstocks from East Malling Research Station's layer-beds were found to be infected. Apparently virus-free Common Plum was propagated by cuttings from the roots of Common Plum under normal Cambridge Gage trees.
A different type of bark-split disease developed on Shiro Plum inoculated with virus from a tree of Quetsche Précoce de Zimmer. Leaf symptoms accompanying infection with this and with the virus from Common Plum were similar.
Bark-split disease is compared and contrasted with diamond canker of French Prune in California, and features that distinguish bark-split from bacterial canker are described.     

The Influence of Tiwanaku on Life in the Chilean Atacama: Mortuary and Bodily Perspectives

ABSTRACT  Using a contextualized bioarchaeological framework, in this article, I examine the complex relationship between the Tiwanaku polity of the Bolivian altiplano (C.E. 550–1000) and the inhabitants of the San Pedro de Atacama oases of northern Chile, in Tiwanaku's far periphery. I focus on how influences from Tiwanaku might have affected the presentation of Atacameño group identity in the mortuary context. I compare skeletal and mortuary data from 300 individuals buried during the peak of Tiwanaku influence in the Atacama to assess mortuary context, trauma, and body modifications. Results suggest a complex response to Tiwanaku influence. Data from the grave and mortuary assemblage reveal traditional Atacameño tombs with occasional foreign objects. Evidence of increased traumatic injury suggests that this relationship was not without some conflict. Finally, the maintenance of bodily expressions of local identity indicates a society that used their bodies to mark Atacameño identity.     

Orchestrating the score: complex multimodal courtship in the Habronattus coecatus group of Habronattus jumping spiders (Araneae: Salticidae)

Jumping spiders in the genus Habronattus use complex multimodal signals during courtship displays. In the present study, we describe multimodal displays from the Habronattus coecatus clade, comprising a diverse group of 23 described species. Habronattus coecatus group displays are made up of sex‐specific ornamentation and temporally coordinated combinations of motion displays and vibratory songs. Vibratory songs are complex, consisting of up to 20 elements organized in functional groupings (motifs) that change as courtship progresses. This temporal structuring of displays is analogous to a musical composition. Vibratory elements are associated with movement displays involving coloured and patterned ornaments on the male body. We describe general patterns of multimodal displays for 11 species including one, Habronattus borealis, which appears to have lost complex display behaviour. Habronattus coecatus group courtship is one of the most complex communication systems yet described in arthropods and this group may reveal important factors driving the evolution of complex signals. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 522–547.     

Acoustic differentiation reflects mitochondrial lineages in Blyth's leaf warbler and white-tailed leaf warbler complexes (Aves: Phylloscopus reguloides, Phylloscopus davisoni)

The present study evaluated the degree of differentiation between closely-related species of Blyth's leaf warbler complex ( Phylloscopus reguloides s.l. ) and white-tailed leaf warbler complex ( Phylloscopus davisoni s.l. ) by molecular (cytochrome b and 16S rRNA) and bioacoustic markers (sonagraphic analysis of songs). Molecular phylogenetic results corroborate the recently suggested splittings of the two former taxa into three and two species, respectively. By contrast to previous opinion, differentiation of territorial songs parallels the genetic diversification in both groups. In the P. reguloides group, all recently established species can be distinguished by a characteristic song pattern. Regularly structured songs composed of repeated two- or three-note syllables were found in all species of the group, whereas trill songs with single notes repeated are unique to Phylloscopus claudiae . The phylogenetic relationships of Phylloscopus occipitalis are ambiguous among different molecular trees, but song pattern clearly corroborates a close relationship to the P. reguloides group. In the white-tailed leaf warbler group, songs are irregularly structured and often descending in frequency with exception of P. davisoni and Phylloscopus ogilviegranti disturbans . Song pattern corroborates the genetic affiliation of Phylloscopus hainanus and Phylloscopus xanthoschistos to the molecular white-tailed leaf warbler clade. All target species correspond to distinct acoustic clusters resulting from discriminant analysis of several spectral and structural song parameters. Linear correlation between genetic and acoustic differentiation (pairwise p -distances versus difference of discriminant functions) is significant within both groups, except for one case, in which discriminant function 1 was correlated with a spectral parameter (minimum frequency) only.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 584–600.     

The Pathway of Assimilate Flow from Source to Sink in Urtica dioica L., Studied with14C under Ambient Atmospheric Conditions

The contribution of individual vascular bundles of the stemto the flow of assimilates from a selected source leaf to thesink regions was investigated inUrtica dioica L., a plant witha decussate leaf arrangement. Two homologous sets of eight vascularstrands were recognized, arranged in mirror symmetry in thestem internodes. In each set, three of the bundles were identifiedas traces of one leaf merging into the vascular system of thestem one node below the origin of the leaf. The main bundleof a stem-half bifurcates at each end of the internode intotwo subdominant bundles, which combine in the next but one nodeto form the dominant bundle again. Each set of vascular strandsalso contains two minor bundles which pass more or less withoutinterruption through the whole stem. The uppermost mature source leaf (leaf number 5 as counted fromthe tip) was exposed to¹⁴CO₂in a closed gas circuit. The concentrationof the carbon-labelled CO₂was maintained at the ambient CO₂levelto maintain the natural source strength of the leaf. By theend of the usual nocturnal dark phase, carbon from the sourceleaf had been imported predominantly by sink leaves of the sameorthostichy. Lesser, but significant amounts of radiocarbonwere also incorporated into the sink leaves of the adjacenttwo orthostichies via the marginal leaf traces. In spite ofthe junction of the vascular strands in the nodes and an interfascicularconnection of the stem bundles, randomization of the photosynthatesfrom individual leaves was minimal in the vascular system ofthe stem in the upward direction, and also low in the flux tothe roots. Substantial amounts of radioactivity were also foundin the lately-formed xylem elements of the vascular strandsand their interfascicular connections, indicating active secondarygrowth. Assimilate distribution; source–sink connections; Urtica dioica ; vascular architecture     

Novel,panzootic and hybrid genotypes of amphibian chytridiomycosis associated with the bullfrog trade

Global amphibian declines are linked with the presence of specific, highly virulent genotypes of the emerging fungal disease chytridiomycosis caused by Batrachochytrium dendrobatidis (Bd) known as the global panzootic lineage (Bd‐GPL). The global trade in amphibians for human consumption is suspected to have facilitated emergence of the disease, but evidence to support this is largely lacking. Here, we investigated the role the Lithobates catesbeianus (North American bullfrog) trade in spreading Bd genotypes by comparing strains associated with L. catesbeianus to a global panel using 36 sequenced loci from multiple chromosomal regions. Most bullfrogs were infected with Bd‐GPL genotypes, but we also detected novel, highly divergent Bd genotypes (Bd‐Brazil) from a live bullfrog in a US market and from native Brazilian anurans in the Atlantic Forest where bullfrogs are widely farmed. Sexual reproduction was also detected for the first time in Bd in the form of a hybrid genotype between the Bd‐GPL and Bd‐Brazil lineages in the Atlantic Forest. Despite the demonstration that ribosomal RNA types in Bd fail to undergo concerted evolution (over 20 sequence types may be found in a single strain), the Bd‐GPL and Bd‐Brazil lineages form largely separate clusters of related internal transcribed spacer (ITS) RNA sequences. Using ITS sequences, we then demonstrate the presence of Bd‐Brazil in Japan, primarily on invasive L. catesbeianus. The finding that Bd is capable of sexual reproduction between panzootic and endemic genotypes emphasizes the risk of international wildlife trade as a source of additional Bd epizootics owing to hybridization.