Effects of neonatal nutrition on adult reproduction in a passerine bird

Effects of neonatal nutrition on adult reproductive performance have been little studied. In Zebra Finches Taeniopygia guttata , poor neonatal nutrition is known to be associated with reduced blood antioxidant levels in adulthood, which could impair reproductive performance. Here, we compare the effects of standard-quality (SQ) or lower-quality (LQ) neonatal nutrition on components of fecundity. Compared with controls, LQ birds took longer to initiate egg-laying, and then laid eggs at a slower rate. LQ birds did not, however, show reduced clutch mass or size, or yolk antioxidant levels (retinol; α- or γ-tocopherol; carotenoids). Zebra Finches breed opportunistically, often only once in their short lifetime. Therefore, the timing but also the number and quality of eggs are critical fitness-related traits. Our results indicate that LQ birds had impaired reproductive capacity, suggesting resource accumulation constraints. Maximizing egg number and quality appears to have been more important than rapid egg production.     

Influence of genotype and geography on shell shape and morphometric trait variation among North Atlantic blue mussel (Mytilus spp.) populations

The influence of geography and genotype on shell shape (outline) and trait (morphometric) variation among North Atlantic blue mussels and their hybrids has been examined. Shape differences among reference taxa (Mytilus trossulus, Mytilus edulis and Mytilus galloprovincialis) were consistent with an association between taxon‐specific genes and shape genes. Newfoundland M. edulis × M. trossulus populations and northern Quebec M. trossulus populations exhibited an uncoupling of taxon‐specific genes from shape genes, whereas Nova Scotia M. trossulus populations and SW England M. edulis × M. galloprovincialis populations exhibited an association between taxon‐specific genes and shape genes. We found no evidence of a geographic effect (NE versus NW Atlantic) for shape variation, indicating that the genotype effect is stronger than any geographic effect at macrogeographic scales. Pronounced differences were observed in trait variability consistent with an association between taxon‐specific genes and trait genes in European populations, and trait divergence of New York M. edulis from all European mussels. Trait variability in mussels from Newfoundland, Nova Scotia and northern Quebec indicated an uncoupling of taxon genes from trait genes, whereas trait variability in SW England M. edulis × M. galloprovincialis populations was consistent with background genotype, indicating a strong association between taxon genes and trait genes. A pronounced macrogeographic split (NE versus NW Atlantic) regardless of taxonomy was observed, indicating that geography exerts a greater influence than genotype on trait variation at the macrogeographic scale. This is consistent with pronounced within‐taxon genetic divergence, indicative of different selection regimes or more likely of different evolutionary histories of mussels on either side of the North Atlantic. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96 , 875–897.     

Neural networks and cluster analysis for unsupervised classification of cultivated species of Tilia (Malvaceae)

A case study of the classification of 19 species of the genus Tilia (Malvaceae) using morphological data is presented. The value of a self‐organizing map (SOM) neural network when applied to this problem is compared with that of a standard cluster analysis method. An interpretation of the results and a discussion of traditional classification systems are provided in order to evaluate the practical usefulness of the SOM methodology. The SOM technique is shown to provide an easily understandable two‐dimensional topological map which enables simple linear separation of taxonomic groups. Good separation of traditional infrageneric groups in Tilia is achieved and suggestions about changes to the existing classification are provided. It is concluded that the SOM and cluster analysis methods, whilst both producing results similar to existing classifications, are most effective at different hierarchical levels. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 159 , 300–314.     

Soil carbon fluxes and stocks in a Great Lakes forest chronosequence

We measured soil respiration and soil carbon stocks, as well as micrometeorological variables in a chronosequence of deciduous forests in Wisconsin and Michigan. The chronosequence consisted of (1) four recently disturbed stands, including a clearcut and repeatedly burned stand (burn), a blowdown and partial salvage stand (blowdown), a clearcut with sparse residual overstory (residual), and a regenerated stand from a complete clearcut (regenerated); (2) four young aspen ( Populus tremuloides ) stands in average age of 10 years; (3) four intermediate aspen stands in average age of 26 years; (4) four mature northern hardwood stands in average age of 73 years; and (5) an old-growth stand approximately 350-years old. We fitted site-based models and used continuous measurements of soil temperature to estimate cumulative soil respiration for the growing season of 2005 (days 133–295). Cumulative soil respiration in the growing season was estimated to be 513, 680, 747, 747, 794, 802, 690, and 571 g C m⁻² in the burn, blowdown, residual, regenerated, young, intermediate, mature, and old-growth stands, respectively. The measured apparent temperature sensitivity of soil respiration was the highest in the regenerated stand, and declined from the young stands to the old-growth. Both, cumulative soil respiration and basal soil respiration at 10 °C, increased during stand establishment, peaked at intermediate age, and then decreased with age. Total soil carbon at 0–60 cm initially decreased after harvest, and increased after stands established. The old-growth stand accumulated carbon in deep layers of soils, but not in the surface soils. Our study suggests a complexity of long-term soil carbon dynamics, both in vertical depth and temporal scale.     

Detectability of American Mink Using Rafts to Solicit Field Signs in a Population Control Context

Abstract: American mink (Neovison vison) are an ecologically damaging invasive species where they have been introduced in Europe. Effectiveness of mink population control by trapping has been difficult to assess, without knowing how efficiently mink are caught by traps or detected by other methods. Use of track-recording rafts to detect mink and guide trapping effort has proved efficient and leads to a supposition that no detection indicates absence of mink. To draw this conclusion with any confidence requires a measure of detectability. We applied occupancy models to data from an earlier study to estimate detectability of individual American mink on track-recording rafts. Estimated detectability of individual mink, per raft, and 2-week check period varied between 0.4 in late summer and 0.6 in late autumn. By inference, risk of failing to detect a mink that was present would be <5% given 4–6 independent opportunities to detect it. These opportunities could be created either by using a raft spacing that ensured multiple detections of each mink or by monitoring rafts through a succession of check intervals. Within certain simple constraints, raft location did not contribute substantially to detection probability. These findings will allow field operators, strategists, and funders to assess with confidence the success of efforts to control mink density. We expect the estimation of individual detectability to be similarly valuable in population control or eradication of other species.     

Do insects lose flight before they lose their wings? Population genetic structure in subalpine stoneflies

Wing reduction and flightlessness are common features of alpine and subalpine insects, and are typically interpreted as evolutionary adaptations to increase fecundity and promote local recruitment. Here, we assess the impact of wing reduction on dispersal in stoneflies (Plecoptera: Gripopterygidae: Zelandoperla ) in southern New Zealand. Specifically, we present comparative phylogeographic analyses (COI; H3) of strong-flying Zelandoperla decorata (144 individuals, 63 localities) vs. the co-distributed but weak-flying Zelandoperla fenestrata species group (186 individuals, 81 localities). The latter group exhibits a variety of morphotypes, ranging from fully winged to completely wingless. Consistent with its capacity for strong flight-mediated dispersal, Z .  decorata exhibited no substantial phylogeographic differentiation across its broad South Island range. Conversely the weak-flying fenestrata species group exhibited substantial genetic structure across both fine and broad geographic scales. Intriguingly, the variable degrees of wing development observed within the fenestrata species group had no apparent impact on levels of phylogeographic structure, which were high regardless of morphotype, suggesting that even fully winged specimens of this group do not fly. This finding implies that Zelandoperla flight loss occurs independently of wing loss, and might reflect underlying flight muscle reduction.     

Characterization of the Galactose-Specific Binding Activity of a Purified Soluble Entamoeba histolytica Adherence Lectin

ABSTRACT. We studied galactose (Gal)-specific binding of the soluble purified 260-kDa Entamoeba histolytica adherence protein to glycosylation deficient Chinese hamster ovary (CHO) cell mutants. Our goal was to further define the lectin's functional activity and carbohydrate receptor specificity. The adherence protein was purified by acid elution from an immunoaffnity column; however, exposure of the surface membrane lectin on viable trophozoites to identical acid pH conditions had no effect on carbohydrate binding activity. Saturable Gal-specific binding of soluble lectin to parental CHO cells was demonstrated at 4°C by radioimmunoassay; the dissociation coefficient (Kd was 2.39 × 10^?8 M^?1 with 5.97 × 10⁴ lectin receptors present per CHO cell. Gal-specific binding of lectin to Lec2 CHO cell mutants, which have increased N- and O-linked terminal Gal residues on cell surface carbohydrates, was increased due to an enhanced number of receptors (2.41 × 10⁵/cell) rather than a significantly reduced dissociation constant (4.93 × 10^?8 M^?1). At 4°C, there was no measurable Gal-specific binding of the adherence protein to the Lec and IdlD.Lecl CHO mutants, which contain surface carbohydrates deficient in terminal Gal residues. Binding of lectin (20 μg/ml) to CHO cells was equivalent at 4°C and 37°C and unaltered by adding the microfilament inhibitor, Cytochalasin D (10 μg/ml). Gal-specific binding of the lectin at 4°C was calcium independent and reduced by 81% following adsorption of only 0.2% of the lectin to CHO cells. In summary, these findings indicate that the purified E. histolytica adherence lectin demonstrates saturable Gal-specific binding to 1–6 branched-N-linked and not O-linked galactose terminal cell surface carbohydrates; however, apparently only a small percentage of purified amebic lectin molecules actually possess galactose binding activity.     

Evolution of the scarab hindwing articulation and wing base: a contribution toward the phylogeny of the Scarabaeidae (Scarabaeoidea: Coleoptera)

A study is made of the articulation and base of hindwings of Scarabaeidae. The survey is based on an examination of over 150 genera from sixteen scarabaeid subfamilies and taxa of uncertain phylogenetic status. Relationships among all subfamilies of Scarabaeidae are examined here for the first time. The constructed phylogeny shows that the scarabaeid lineage (Scarabaeidae) is comprised of two major lines: an aphodiine line (containing Aphodiinae, including Aegialiini, Aulonocnemis and Scarabaeinae), and an orphnine line (containing Orphninae, Melolonthinae, Acoma , Chnaunanthus , Hopliini, Oncerus , Rutelinae, Dynastinae, Trichiinae, Cetoniinae, Osmoderma and Valginae).     

Evolutionary Modifications of the Spiralian Developmental Program

SYNOPSIS. The Spiralia, an assemblage of phyla united by theirstereotypic pattern of early embryonic cell divisions (spiralcleavage), is an interesting group in which to investigate theevolution of development. This paper examines modificationsof developmental mechanisms within the Spiralia with emphasison the basallybranching forms. Although demonstrating a notabledegree of evolutionary conservation, the equal quartet cleavagepattern, which appears to be the ancestral condition, nonethelessexhibits modifications within the various spiralian groups,such as unequal cleavage, changes in cell size and rate of division,formation of two rather than four quadrants (duet spiral cleavage),and in extreme cases the loss of any trace of the spiral pattern.While the cell lineages of spiralians are remarkably conserved,one can discern evolutionary changes, for example in the cellsthat give rise to mesodenn. Studies of blastomere specificationin many spiralian groups and analyses of axis determinationindicate that embryos with equal versus unequal cleavage typicallyuse different determinative mechanisms to establish cell fatesand the dorsoventral axis. These properties are establishedearly in species exhibiting unequal cleavage. While previousexperiments suggested that equal cleavage was associated withlate specification, there is now evidence of precocious specificationof quadrant fates in some equal-cleaving species, such as thenemerteans and the polyclad turbellarians