2‐(Undecyloxy)‐ethanol is a major component of the male‐produced aggregation pheromone of Monochamus sutor

The small white‐marmorated longicorn beetle, Monochamus sutor (L.) (Coleoptera: Cerambycidae), is widely distributed throughout Europe and Asia. It is a potential vector of the pine wood nematode, Bursaphelenchus xylophilus (Steiner et Buhrer) Nickle, the causal agent of the devastating pine wilt disease. Volatiles were collected from both male and female beetles after maturation feeding. In analyses of these collections using gas chromatography (GC) coupled to mass spectrometry, a single male‐specific compound was detected and identified as 2‐(undecyloxy)‐ethanol. In analyses by GC coupled to electroantennography the only consistent responses from both female and male antennae were to this compound. Trapping tests were carried out in Spain, Sweden, and China. 2‐(Undecyloxy)‐ethanol was attractive to both male and female M. sutor beetles. A blend of the bark beetle pheromones ipsenol, ipsdienol, and 2‐methyl‐3‐buten‐2‐ol was also attractive to both sexes in Spain and Sweden, and further increased the attractiveness of the 2‐(undecyloxy)‐ethanol. The host plant volatiles α‐pinene, 3‐carene, and ethanol were weakly attractive, if at all, in all three countries and did not significantly increase the attractiveness of the blend of 2‐(undecyloxy)‐ethanol and bark beetle pheromones. 2‐(Undecyloxy)‐ethanol is thus proposed to be the major, if not only, component of the male‐produced aggregation pheromone of M. sutor, and its role is discussed. This compound has been reported as a pheromone of several other Monochamus species and is another example of the parsimony that seems to exist among the pheromones of many of the Cerambycidae. Traps baited with 2‐(undecyloxy)‐ethanol and bark beetle pheromones should be useful for monitoring and control of pine wilt disease, should M. sutor be proven to be a vector of the nematode.     

THE EVOLUTION OF LOCOMOTOR RHYTHMICITY IN TETRAPODS

Differences in rhythmicity (relative variance in cycle period) among mammal, fish, and lizard feeding systems have been hypothesized to be associated with differences in their sensorimotor control systems. We tested this hypothesis by examining whether the locomotion of tachymetabolic tetrapods (birds and mammals) is more rhythmic than that of bradymetabolic tetrapods (lizards, alligators, turtles, salamanders). Species averages of intraindividual coefficients of variation in cycle period were compared while controlling for gait and substrate. Variance in locomotor cycle periods is significantly lower in tachymetabolic than in bradymetabolic animals for datasets that include treadmill locomotion, non‐treadmill locomotion, or both. When phylogenetic relationships are taken into account the pooled analyses remain significant, whereas the non‐treadmill and the treadmill analyses become nonsignificant. The co‐occurrence of relatively high rhythmicity in both feeding and locomotor systems of tachymetabolic tetrapods suggests that the anatomical substrate of rhythmicity is in the motor control system, not in the musculoskeletal components.     

VACCINATION AND REDUCED COHORT DURATION CAN DRIVE VIRULENCE EVOLUTION: MAREK’S DISEASE VIRUS AND INDUSTRIALIZED AGRICULTURE

Marek’s disease virus (MDV), a commercially important disease of poultry, has become substantially more virulent over the last 60 years. This evolution was presumably a consequence of changes in virus ecology associated with the intensification of the poultry industry. Here, we assess whether vaccination or reduced host life span could have generated natural selection, which favored more virulent strains. Using previously published experimental data, we estimated viral fitness under a range of cohort durations and vaccine treatments on broiler farms. We found that viral fitness maximized at intermediate virulence, as a result of a trade‐off between virulence and transmission previously reported. Our results suggest that vaccination, acting on this trade‐off, could have led to the evolution of increased virulence. By keeping the host alive, vaccination prolongs infectious periods of virulent strains. Improvements in host genetics and nutrition, which reduced broiler life spans below 50 days, could have also increased the virulence of the circulating MDV strains because shortened cohort duration reduces the impact of host death on viral fitness. These results illustrate the dramatic impact anthropogenic change can potentially have on pathogen virulence.     

Natural history and behaviour of Dunatothrips aneurae Mound (Thysanoptera: Phlaeothripidae), a phyllode‐gluing thrips with facultative pleometrosis

Thrips of the genus Dunatothrips (Thysanoptera: Phlaeothripidae) construct domiciles by tying phyllodes of Australian Acacia trees together with silk‐like glue. Females often co‐found domiciles (pleometrosis), an apparently cooperative behaviour that potentially provides insights into social evolution. However, little is known about their basic natural history, limiting the scope for testable predictions. Here, we address this crucial prerequisite step by investigating some key outstanding questions in the most common species, D. aneurae, on its host, Acacia aneura. We detail distribution in space and time, mating, dispersal, domicile building and defence. Dunatothrips aneurae was distributed in loosely reproductively synchronized patches, and tended to prefer east‐facing, terminal phyllodes on thin‐phyllode A. aneura varieties. Mature domiciles contained middens, concentrated areas of waste, suggesting active maintenance of domiciles and the potential for the division of labour. We observed inbreeding and outbreeding. Dunatothrips aneurae males engaged in short, truncated matings with sisters before dispersing locally, mating with females in nearby immature domiciles; longer distance dispersal, although it must happen, is still undocumented. Males and females mated multiply. Lone females required male presence to initiate domiciles, constructed them without male help and lost wings on nesting by abscission. Silk production occurred well before egg laying. Aggression or defence appeared to be entirely absent. Taken together, these observations suggest that research into co‐founding behaviour should focus on: (1) local crowding; (2) lack of aggression; and (3) potential division of labour with respect to egg production, silk production and domicile maintenance. These results should provide a springboard for questions on the potential evolution of cooperation in this species. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109 , 802‐816.     

Relatedness and resource diversity interact to influence the intensity of competition

When resource competition occurs between close relatives, the negative effects of competition are potentially amplified. However, kin selection theory predicts that natural selection should promote the evolution of mechanisms that minimize the intensity of competition between kin. Experimental tests of these hypotheses are mixed, however. Moreover, there is little consensus regarding the generality of either outcome, suggesting that the conditions important in determining the effects of competition between kin are likely complex and not fully understood. We performed two experiments using spadefoot toad tadpoles (Spea multiplicata) to evaluate the hypothesis that individuals can minimize the negative effects of exploitative competition by using alternative resources when competing with close relatives. Supporting our hypothesis, we found that only when individuals had access to alternative resources were the negative effects of competition between siblings less than between unrelated competitors. We suggest that mechanisms to lessen kin competition may be more likely to evolve in environments where alternative resources are available, and that selection to minimize exploitative competition between kin may promote the evolution of resource polyphenism. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 110 , 689–695.     

Geographical patterns of nucleotide diversity and population differentiation in three closely related European pine species in the Pinus mugo complex

Nucleotide polymorphism at 12 nuclear loci and two mitochondrial gene fragments was studied in three closely related pine species from the Pinus mugo complex in populations across the species distributional range in Europe. Despite large differences in the census sizes of the populations, high and similar levels of nucleotide diversity (θ_sil = ～0.013–0.017) were found at nuclear loci in the three pine species. More rapid decay of overall linkage disequilibrium (LD) and recombination to diversity ratio (ρ/θ) was observed across the species distributional range in P. mugo (ρ = 0.0369 ± 0.0028; ρ/θ = ～2.2) than in P. uncinata (ρ = 0.0054 ± 0.0011; ρ/θ = ～0.4) and P. uliginosa (ρ = 0.0051 ± 0.0010, ρ/θ = ～0.4). However, regional groups of P. mugo showed similar levels of LD and ρ/θ ratio to the other species. An excess of rare nucleotide variants was found in P. mugo at four loci, but, overall, the allelic frequency spectrum in the three species did not deviate significantly from neutrality (multilocus Tajima's D = ?0.681, D = ?0.118 and D = ?0.266, P > 0.05, respectively). Bayesian clustering methods showed no clear correspondence of clusters to species or geographical regions. Some differences between populations and species were found in a hierarchical analysis of molecular variance (AMOVA) and in the distribution of the mitochondrial DNA haplotypes, suggesting rather limited gene flow between the taxa and ongoing divergence. As all three pine taxa have similar genetic backgrounds, they form an excellent system for searching for loci involved in adaptive variation and speciation. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 172 , 225–238.     

Universal scaling of species‐abundance distributions across multiple scales

The scale‐dependent species abundance distribution (SAD) is fundamental in ecology, but few spatially explicit models of this pattern have thus far been studied. Here we show spatially explicit neutral model predictions for SADs over a wide range of spatial scales, which appear to match empirical patterns qualitatively. We find that the assumption of a log‐series SAD in the metacommunity made by spatially implicit neutral models can be justified with a spatially explicit model in the large area limit. Furthermore, our model predicts that SADs on multiple scales are characterized by a single, compound parameter that represents the ratio of the survey area to the species’ average biogeographic range (which is in turn set by the speciation rate and the dispersal distance). This intriguing prediction is in line with recent empirical evidence for a universal scaling of the species‐area curve. Hence we hypothesize that empirical SAD patterns will show a similar universal scaling for many different taxa and across multiple spatial scales.     

Zinc-induced Self-association of Complement C3b and Factor H: IMPLICATIONS FOR INFLAMMATION AND AGE-RELATED MACULAR DEGENERATION*

The sub-retinal pigment epithelial deposits that are a hallmark of age-related macular degeneration contain both C3b and millimolar levels of zinc. C3 is the central protein of complement, whereas C3u is formed by the spontaneous hydrolysis of the thioester bridge in C3. During activation, C3 is cleaved to form active C3b, then C3b is inactivated by Factor I and Factor H to form the C3c and C3d fragments. The interaction of zinc with C3 was quantified using analytical ultracentrifugation and x-ray scattering. C3, C3u, and C3b associated strongly in >100 μm zinc, whereas C3c and C3d showed weak association. With zinc, C3 forms soluble oligomers, whereas C3u and C3b precipitate. We conclude that the C3, C3u, and C3b association with zinc depended on the relative positions of C3d and C3c in each protein. Computational predictions showed that putative weak zinc binding sites with different capacities exist in all five proteins, in agreement with experiments. Factor H forms large oligomers in >10 μm zinc. In contrast to C3b or Factor H alone, the solubility of the central C3b-Factor H complex was much reduced at 60 μm zinc and even more so at >100 μm zinc. The removal of the C3b-Factor H complex by zinc explains the reduced C3u/C3b inactivation rates by zinc. Zinc-induced precipitation may contribute to the initial development of sub-retinal pigment epithelial deposits in the retina as well as reducing the progression to advanced age-related macular degeneration in higher risk patients.     

Ca2+ Signals Generated by CatSper and Ca2+ Stores Regulate Different Behaviors in Human Sperm

[Ca²⁺]_i signaling regulates sperm motility, enabling switching between functionally different behaviors that the sperm must employ as it ascends the female tract and fertilizes the oocyte. We report that different behaviors in human sperm are recruited according to the Ca²⁺ signaling pathway used. Activation of CatSper (by raising pH_i or stimulating with progesterone) caused sustained [Ca²⁺]_i elevation but did not induce hyperactivation, the whiplash-like behavior required for progression along the oviduct and penetration of the zona pellucida. In contrast, penetration into methylcellulose (mimicking penetration into cervical mucus or cumulus matrix) was enhanced by activation of CatSper. NNC55-0396, which abolishes CatSper currents in human sperm, inhibited this effect. Treatment with 5 μm thimerosal to mobilize stored Ca²⁺ caused sustained [Ca²⁺]_i elevation and induced strong, sustained hyperactivation that was completely insensitive to NNC55-0396. Thimerosal had no effect on penetration into methylcellulose. 4-Aminopyridine, a powerful modulator of sperm motility, both raised pH_i and mobilized Ca²⁺ stored in sperm (and from microsomal membrane preparations). 4-Aminopyridine-induced hyperactivation even in cells suspended in Ca²⁺-depleted medium and also potentiated penetration into methylcellulose. The latter effect was sensitive to NNC55-039, but induction of hyperactivation was not. We conclude that these two components of the [Ca²⁺]_i signaling apparatus have strikingly different effects on sperm motility. Furthermore, since stored Ca²⁺ at the sperm neck can be mobilized by Ca²⁺-induced Ca²⁺ release, we propose that CatSper activation can elicit functionally different behaviors according to the sensitivity of the Ca²⁺ store, which may be regulated by capacitation and NO from the cumulus.