Egg cluster size variation in relation to the larval food abundance inLuehdorfia puziloi (Lepidoptera: Papilionidae)

Mean egg cluster size of Luehdorfia puziloi yessoensis varied among habitats. The mean egg cluster size tended to be large when abundance of the larval food leaves expressed as the fresh weight of leaves per unit area at a given habitat was high. Since this variation was observed among closely located study plots (butterflies can easily move between study plots), the egg cluster size variation among habitats is likely to be a result of flexible response by females to varying food abundance for larvae.     

Population and size-specific distribution of Atlantic salmon Salmo salar in the Baltic Sea over five decades

Population-specific assessment and management of anadromous fish at sea requires detailed information about the distribution at sea over ontogeny for each population. However, despite a long history of mixed-stock sea fisheries on Atlantic salmon, Salmo salar, migration studies showing that some salmon populations feed in different regions of the Baltic Sea and variation in dynamics occurs among populations feeding in the Baltic Sea, such information is often lacking. Also, current assessment of Baltic salmon assumes equal distribution at sea and therefore equal responses to changes in off-shore sea fisheries. Here, we test for differences in distribution at sea among and within ten Atlantic salmon Salmo salar populations originating from ten river-specific hatcheries along the Swedish Baltic Sea coast, using individual data from >125,000 tagged salmon, recaptured over five decades. We show strong population and size-specific differences in distribution at sea, varying between year classes and between individuals within year classes. This suggests that Atlantic salmon in the Baltic Sea experience great variation in environmental conditions and exploitation rates over ontogeny depending on origin and that current assessment assumptions about equal exploitation rates in the offshore fisheries and a shared environment at sea are not valid. Thus, our results provide additional arguments and necessary information for implementing population-specific management of salmon, also when targeting life stages at sea.     

Substrate docking and molecular dynamic simulation for prediction of fungal enzymes from Trichoderma species-assisted extraction of nanocellulose from oil palm leaves

Abstract

Fungi of the Trichoderma species are valued industrial enzymes in support of the ‘zero-waste’ technology to convert agro-industrial biomass into valuable products, i.e. nanocellulose (NC). In this study, an in silico approach using substrate docking and molecular dynamic (MD) simulation was used to predict the order of which the multilayers of cellulosic polymers, i.e. lignin, hemicellulose and cellulose in oil palm leaves (OPL) are degraded by fungal enzymes, endocellulase and exocellulase. The study aimed to establish the catalytic tendencies of the enzymes to optimally degrade the cellulosic components of OPL for high yield production of NC. Energy minimized endocellulase and exocellulase models revealed satisfactory scores of PROCHECK (90.0% and 91.2%), Verify3D (97.23% and 98.85%) and ERRAT (95.24% and 91.00%) assessments. Active site prediction by blind docking, COACH meta-server and multiple sequence alignment indicated the catalytic triads for endocellulase and exocellulase were Ser116–His205–Glu249 and Ser382–Arg124–Asp385, respectively. Binding energy of endocellulase docked with hemicellulose (?6.0 ? kcal mol^?1) was the most favourable followed by lignin (?5.6 ? kcal mol^?1) and cellulose (?4.4 ? kcal mol^?1). Exocellulase, contrarily, bonded favorably with lignin (?8.7 ? kcal mol^?1), closely followed by cellulose (?8.5 ? kcal mol^?1) and hemicellulose (?8.4 ? kcal mol^?1). MDs simulations showed that interactions of complexes, endocellulase–hemicellulose and the exocellulase–cellulose being the most stable. Thus, the findings of the study successfully identified the specific actions of sugar-acting enzymes for NC production.

Communicated by Ramaswamy H. Sarma     

Isolation of microsatellite markers from the drepanosiphid aphid Tuberculatus quercicola (Homoptera,Aphididae)

We isolated five polymorphic microsatellite loci from the drepanosiphid aphid Tuberculatus quercicola (Matsumura) that is associated with the Daimyo oak, Quercus dentata Thunberg, using the magnetic particles method. The isolated loci were polymorphic, with four to 16 alleles in 40 aphids. Expected heterozygosities ranged from 0.4 to 0.82. These loci can be used to quantify seasonal changes in clonal diversity in the metapopulation and the extent of clonal mixing in the colonies.     

Dispersal ability rather than ecological tolerance drives differences in range size between lentic and lotic water beetles (Coleoptera: Hydrophilidae)

Aim In aquatic ecosystems, standing (lentic) and running (lotic) waters differ fundamentally in their stability and persistence, shaping the comparative population genetic structure, geographical range size and speciation rates of lentic versus lotic lineages. While the drivers of this pattern remain incompletely understood, the suite of traits making up the ability of a species to establish new populations is instrumental in determining such differences. Here we explore the degree to which the association between habitat type and geographical range size results from differences in dispersal ability or fundamental niche breadth in the members of the Enochrus bicolor complex, an aquatic beetle clade with species across the lentic–lotic divide. Location Western Mediterranean, with a special focus on North Africa, the Iberian Peninsula and Sicily. Methods DNA sequences for four loci were obtained from species of the E. bicolor complex and analysed using phylogenetic inference. Dispersal and establishment abilities were assessed in lentic–lotic species pairs of the complex, using flight wing morphometrics and thermal tolerance ranges as surrogates, respectively. Results There were clear differences in range size between the lotic and lentic taxa of the complex, which appears to have had a lotic origin with two transitions to standing waters. Only small differences were observed in temperature tolerance and acclimation ability between the two lotic–lentic sister species studied. By contrast, wing morphometrics revealed clear, consistent differences between lotic and lentic Enochrus species pairs, the latter having a higher dispersal capacity. Main conclusions We hypothesize that there have been two habitat shifts from lotic to lentic waters, which have allowed marked expansions in geographical range size in western Mediterranean species of the E. bicolor complex. Differences in dispersal rather than in establishment ability appear to underlie differences in geographical range extent, as transitions to lentic waters were associated with changes in wing morphology, but not in thermal tolerance range. In this lineage of water beetles, selection for dispersal in geologically short‐lived lentic systems has driven the evolution of larger range sizes in lentic taxa compared with those of their lotic relatives.