Laboratory investigation of <Emphasis Type="Italic">Fallopia</Emphasis> × <Emphasis Type="Italic">bohemica</Emphasis> fruits dispersal by watercourses

Seed and fruit dispersal along watercourses favours the long-distance migration of invasive species, not only for aquatic or wetland species, but also for terrestrial wind-dispersed plants, like the Japanese knotweed. The present paper aims at investigating the role of watercourses in the dispersal of the knotweed due to its frequent occurrence on riverbanks and production of fertile achenes (type of fruit of the Japanese knotweed). This dispersal occurs along two steps after the fruits deposit on the water surface: floatation first and then sinking towards the bottom of the watercourse. Regarding the first step, the effects of agitation of the water, temperature, surface tension and luminosity on the achenes floatability are experimentally studied. While no influence of luminosity is observed, an increase of temperature greatly decreases the floating time. Floating time also decreases as the contact between water and the fruit is enhanced (through submersion of achenes, agitation of the water or lower surface tension). Regarding the second step, the fall velocity of the fruits in water at rest is measured and appears to be independent of the seed history (floating time). 3D helical motions are systematically observed with constant tangential velocity with respect to the falling velocity. The trajectory of the fruits in a shear flow is then measured and the evolution of their velocity components along the sinking process is discussed. Finally, the contribution of both steps to the long-distance migration of the seeds is estimated.     

Covering behaviour in <Emphasis Type="Italic">Paracentrotus</Emphasis><Emphasis Type="Italic">lividus</Emphasis>: is light important?

"Covering" or "heaping" behaviour is common to a number of regular echinoids living in a variety of different habitats. Many theories have been proposed to explain this behaviour, among which are several that link covering to light, including ultraviolet (UV) light. However, previous investigations of this light theory have been largely qualitative. In the present study, we used a systematic laboratory protocol to examine quantitatively the covering behaviour of the shallow water echinoid, Paracentrotus lividus, under four different light regimes: white light (400-700 nm), UV-A+B (315-400 nm), UV-A (320-400 nm), and darkness. These experiments demonstrated that light, in particular UV light, influences the covering behaviour of P. lividus. Under the UV regimes, significantly more individuals were found to display covering behaviour, and individuals spent more time at the base of aquaria, farthest from the light source. Moreover, covering items were retained for the longest period of time under the UV-A+B regime. We propose that protection against the harmful effects of UV radiation may be one of the functions of covering behaviour in P. lividus.     

Life cycle of <Emphasis Type="Italic">Oithona</Emphasis> <Emphasis Type="Italic">similis</Emphasis> (Copepoda: Cyclopoida) in Kola Bay (Barents Sea)

The annual population dynamics (nauplii, old copepodites CIV–CV and adults) and seasonal variations in reproductive parameters of the cyclopoid copepod Oithona similis were investigated on the basis of the data 1999–2006 in Kola Bay, a large subarctic fjord in the Barents Sea. Population density of O. similis ranged from 110 to 9,630 ind m⁻³ and averaged 1,020 ± 336 ind m⁻³. The relative abundance of adults was high during winter (~60%). At the end of winter (mid-March), the population included a large percentage of later-stage copepodites (stage CIV 23% and stage CV 57%). There were two periods of mass spawning, in late June and September. Autumn and summer generations strongly differed in abundance, average prosome length (PL), clutch size (CS), egg diameter (D), egg production rates (EPR and SEPR) and female secondary production. Average PL decreased with increasing water temperature, while D and CS were strongly correlated with PL but unaffected by temperature. Annual average EPR and SEPR were 0.55 ± 0.18 eggs female⁻¹ day⁻¹ and 0.0011 ± 0.003 day⁻¹, respectively. Female secondary production averaged 0.8 ± 0.3 μg C m⁻³ day⁻¹ (range 0.001–3.58). There were positive relationships between abundance, EPR, SEPR, production and water temperatures. Reproductive parameters appeared to be controlled by hydrological factors and food conditions.     

Sex pheromone of <Emphasis Type="Italic">Ectinus aterrimus</Emphasis> (L<Emphasis Type="SmallCaps">inné</Emphasis>, 1761) (Coleoptera: Elateridae)

Summary.   Ectinus aterrimus (L.) is a fairly common European click beetle species which develops mainly in forests. In pheromone gland extracts of female E. aterrimus, examined using gas chromatography – mass spectrometry (GC-MS), one single compound was present. This was identified as 7-methyloctyl 9-methyldecanoate by comparison with a synthetic sample. Field trapping trials revealed a highly significant attraction of male E. aterrimus towards this ester. The structure of the compound differs remarkably from the pheromones of the closely related Agriotes spp., which exclusively use terpene esters.     

Sibling competition in guinea pigs (<Emphasis Type="Italic">Cavia aperea</Emphasis> f. <Emphasis Type="Italic">porcellus</Emphasis>): scrambling for mother’s teats is stressful

Lactation is the most energy-intense period in the life of a female mammal. This can cause severe conflict between mother and offspring over the duration of lactation but also between siblings over the amount of milk each pup gets from its mother. Thus, competitive interactions between siblings are expected, and competition is likely to increase with litter size, particularly in species where the number of offspring exceeds the number of teats. We studied sibling competition in the domestic guinea pig (Cavia aperea f. porcellus), which has two teats, but frequently bears litters of up to five pups. By cross-fostering we created non-competition (control) litters with two pups and competition litters with four pups and observed nursing behaviour on days 5, 10, 15 and 20 postpartum. Pups of larger litters had lower growth rates, indicating increased competition among siblings in these litters. Pups of larger litters had to wait longer for access to a teat and spent less time suckling than pups of smaller litters but ate more solid food instead. Additionally, we manipulated the individual short-term need of pups by separating half of the pups of each litter for 2 h from their mothers before observation. Within a litter, hungry pups achieved access to milk faster and spent more time suckling than non-hungry pups. Pups competed mostly by scramble competition. Aggressive interactions occurred only in large litters. Pups of large litters had higher cortisol levels than pups in small litters. These effects decreased with age as pups became increasingly independent of maternal milk. Pup behaviour appears to fit better with models of scramble competition than with those of honest signalling. This contribution is part of the special issue “Sibling competition and cooperation in mammals” (guest editors: Robyn Hudson and Fritz Trillmich).     

Influence of male harassment and female competition on female feeding behaviour in a sexual–asexual mating complex of mollies (<Emphasis Type="Italic">Poecilia mexicana</Emphasis>, <Emphasis Type="Italic">P. formosa</Emphasis>)

Differential interests between the sexes regarding the number of copulations can result in sexual harassment. Hence, females may have less time available for foraging. Male sexual harassment often leads to fitness reduction in females. We used the mating complex of the bisexual fish Poecilia mexicana and the co-occurring all-female Poecilia formosa to study sexual harassment and its incurred cost on female feeding efficiency. P. formosa is a sperm-dependent parthenogen that requires mating with host males to induce embryogenesis, but the male genes are not used. We therefore predicted P. mexicana males to prefer conspecific females. Hence, costs of male sexual harassment should not occur in unisexuals. While P. formosa are at a disadvantage compared to P. mexicana females due to male mate choice (leading to sperm limitation), this could be traded-off by suffering less from sexual harassment. In our experiment, we found males to direct significantly more pre-copulatory mating behaviour towards conspecific females, whereas actual mating attempts did not differ between species. Contrary to our prediction, both types of females started feeding later and spent less time feeding in the presence of a male partner compared to the time spent feeding with another female, suggesting that females of both species suffer from male harassment. The focal females' feeding time declined with increasing body size of the female competitor, and the same pattern was found when a male was present. We discuss that—besides sexual harassment—other factors such as food competition and female mate choice may affect female feeding efficiency.     

(<Emphasis Type="Italic">Z</Emphasis>)-9-Pentacosene − contact sex pheromone of the locust borer, <Emphasis Type="Italic">Megacyllene robiniae</Emphasis>

Summary. Male locust borers, Megacyllene robiniae (Förster), responded to females only after contacting them with their antennae, indicating that mate recognition was mediated by a contact sex pheromone. GC-MS analyses of whole-body extracts of males and females determined that the profiles of compounds in the extracts were qualitatively similar, but differed considerably in the ratios of compounds between sexes. Biological activities of reconstructed blends of the most abundant straight-chain (nC₂₃, nC₂₄, nC₂₅, nC₂₆), methyl-branched (3me-C₂₃, 3me-C₂₅), and unsaturated (Z9:C₂₃, Z9:C₂₅, Z9:C₂₇ compounds in extracts from females were assessed in arena bioassays, assessing four distinct steps in the mating behavior sequence of males (orientation, arrestment, body alignment, mounting and attempting to couple the genitalia). Males were unresponsive to freeze-killed, solventwashed females treated with blends of straight-chain and methyl-branched alkanes, but responded strongly to females treated with the blend of alkenes. Further trials determined that the complete sequence of mating behaviors, up to and including coupling the genitalia, was elicited by Z9:C₂₅ alone. Z9:C₂₅ comprised 16.4 ± 1.3% of the total hydrocarbons in whole-body hexane extracts of females and was co-dominant with two other hydrocarbons that were not active. In contrast, in solid phase microextraction (SPME) wipe samples from several areas of the cuticle, Z9:C₂₅ appeared as the single dominant peak, comprising 34.6 – 37.8% of the sampled hydrocarbons. Our data indicate that Z9:C₂₅ is a contact sex pheromone of M. robiniae, being the most abundant hydrocarbon on the surface of the cuticular wax layer of females where it is readily accessible to the antennae of males.     

Multiple color signals may reveal multiple messages in male Schreiber’s green lizards, <Emphasis Type="Italic">Lacerta schreiberi</Emphasis>

Multiple traits may either signal different characteristics of a male or be redundant. These multiple signals may convey different messages if they are intended for different receivers (e.g., male or females) that have different interests. We examined the functions of multiple colorful visual traits of male Schreiber’s green lizard (Lacerta schreiberi). Results showed that interindividual variation in the characteristics of coloration of males can be related to variation in morphology, health state, dominance status, and pairing status, but that different relationships were found for each color signal. For example, dominant males had brighter “blue” throat and with higher values of ultraviolet (UV) and bluish coloration and darker and greenish dorsal coloration than subordinate males. Health state was also reflected in coloration; males with a higher immune response had “blue” throats with lower amounts of UV coloration, but had “yellow” chests with higher amounts of UV coloration. Males found guarding females also differed in coloration from males found alone. These data suggest that characteristics of coloration of the different multiple signals may reveal different messages for different receivers, either male or female conspecifics. The development of the different signals, based on different morphological and physiological mechanisms and trade-offs, may allow signal reliability of multiple colorful traits in different social contexts.     

Short-term effects of data-loggers on Cory’s shearwater (<Emphasis Type="Italic">Calonectris diomedea</Emphasis>)

We investigated the possible effects of a 12-g data-logger attached to a darvic ring on the performance of Corys shearwater (Calonectris diomedea, 600–850 g) from two different colonies in the western Mediterranean Sea. We compared return rates, current breeding success and body condition between equipped and unequipped birds. Effects on feeding ecology during winter and breeding period was also evaluated through the measurement of stable isotopes of carbon (¹³C) and nitrogen (¹⁵N) in one of the colonies. We found no evidence of negative effects of loggers on demographic parameters analysed or in feeding ecology. Power analyses suggested a high power to detect medium effect size, but a low power to detect small changes. Despite the non-significant results we could only exclude medium to strong effects of the devices on one of these parameters. We detected some short-term negative effects on body condition for the equipped birds, but these were unlikely to have had important consequences. Results suggest that the use of loggers is an adequate methodology to obtain information from seabirds at sea, but data should be carefully interpreted with regard to potential biases during severe environmental conditions.Communicated by S.A. Poulet, Roscoff     

The life cycles of two coexisting copepods, <Emphasis Type="Italic">Calanus chilensis</Emphasis> and <Emphasis Type="Italic">Centropages brachiatu</Emphasis>s,in the upwelling zone off northern Chile (23°S)

A time series study of the copepods Calanus chilensis and Centropages brachiatus was carried out at the coastal upwelling zone of Mejillones (23°S, northern Chile), to analyze their annual life cycles in association with upwelling variation. These species co-exist in the upwelling zone. Weekly sampling of zooplankton and oceanographic variables including Chlorophyll-a and phytoplankton composition were obtained during January–December 2002 at a fixed station (ca. 90 m depth). Stages of abundances, their proportions, changes in body length of adult females, sex ratio and egg production rate (EPR), were used as proxies to examine copepods’ demography. Upwelling, assessed by weekly Ekman transport and oceanographic conditions, was intermittent throughout the year with lack of periodicity components. Populations of both copepod species did not correlate with these non-predictable upwelling events. C. chilensis reproduced year-round and the population showed ca. 15 peaks of adults with an average time interval between peaks of 20 days. C. brachiatus showed a similar life cycle, also having 15 peaks of adults at about 22 days of time intervals. Cross-correlation functions and spectral analysis showed that both populations correlated positively through time, but not in phase, evidencing a time lag for their reproductive cycles. The lag was also evident in their population abundances. Both species differ in their development rates and this may result in non-in phase life cycles. Our findings suggest that species-dependent attributes, such as development rates, modulated by adaptations to temperature, might impose constraints in the species life cycles determining the population cycles. Such attributes must be considered when modeling and understanding population dynamics and secondary production of copepods.     

Simulation of exchange flow between open water and floating vegetation using a modified RNG <Emphasis Type="Italic">k</Emphasis>-<Emphasis Type="Italic">ε</Emphasis> turbulence model

The paper focuses on the numerical simulation of the exchange flow between open water and floating vegetation, which plays an important role in maintaining the ecological balance by transporting nutrient matter. The simulation was conducted using a new solver developed upon OpenFOAM. A modified RNG k-ε turbulence model, which is expected to model both the high- and low-Reynolds number flows correctly, was used to determine the eddy viscosity. Several particular terms were added into the momentum equations and turbulence model equations to model the effects of vegetation and buoyancy. Among these terms, the term for the effect of vegetation in the ε-equation was re-modelled. The model was validated by properly predicting the profiles of mean velocity and turbulent kinetic energy for flows through suspended canopies. The density flow between open and vegetated water was simulated with the same conditions as those of the experiment conducted by Zhang and Nepf. The predicted results agreed well with the experimental data and provided more detailed information of such exchange flow. The convection between the root layer and the layer beneath the roots, which was not observed in the experiment, was observed in the numerical simulation.     

Variation in colony geometry modulates internal light levels in branching corals, <Emphasis Type="Italic">Acropora humilis</Emphasis> and <Emphasis Type="Italic">Stylophora pistillata</Emphasis>

Colonial photosynthetic marine organisms often exhibit morphological phenotypic plasticity. Where such plasticity leads to an improved balance between rates of photosynthesis and maintenance costs, it is likely to have adaptive significance. To explore whether such phenotypic plasticity leads to more favourable within-colony irradiance for reef-building branching corals, this relationship was investigated for two coral species Acropora humilis and Stylophora pistillata, along a depth gradient representing light habitats ranging from 500 to 25 μmol photons m⁻² s⁻¹, during 2006 at Heron Island, Great Barrier Reef (23.44°S, 151.91°E). In the present study changes in flow-modulated mass transfer co-varied with light as a function of depth. In low-light (deep) habitats, branch spacing (colony openness) in A. humilis and S. pistillata was 40–50% greater than for conspecifics in high-light environments. Also, branches of A. humilis in deep water were 40–60% shorter than in shallow water. Phenotypic changes in these two variables lead to steeper within-colony light attenuation resulting in 38% higher mean internal irradiance (at the tissue surface) in deep colonies compared to shallow colonies. The pattern of branch spacing was similar for S. pistillata, but this species displayed an alternate strategy with respect to branch length: shade adapted deep and cave colonies developed longer and thinner branches, allowing access to higher mass transfer and irradiance. Corals in cave habitats allowed 20% more irradiance compared to colonies found in the deep, and had a 47% greater proportion of irradiance compared to colonies in the shallow high-light environment. Such phenotypic regulation of internal light levels on branch surfaces partly explains the broad light niches of many branching coral species. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Is <Emphasis Type="Italic">Hippolyte williamsi</Emphasis> gonochoric or hermaphroditic? A multi-approach study and a review of sexual systems in <Emphasis Type="Italic">Hippolyte</Emphasis> shrimps

Sexual systems vary considerably among caridean shrimps and while most species are gonochoric, others are described as sequential protandric hermaphrodites or simultaneous hermaphrodites with an early male phase. At present, there is confusion about the sexual system exhibited by several species mostly because those studies attempting to reveal their sexual system draw inferences solely from the distribution of the sexes across size classes. Here we investigated the sexual system of the shrimp Hippolyte williamsi from Chile to determine if the species is protandric or gonochoric with sexual dimorphism (males smaller than females). Morphological identification and size frequency distributions indicated that the population comprised small males, small immature females, and large mature females, which was confirmed by dissections. No transitional individuals were found. Males maintained in the laboratory molted 1–8 times, and many grew up to reach sizes observed in only a small fraction of males in the field. No indication of sex change was recorded. Our results indicate that H. williamsi is a sexually dimorphic gonochoric species and emphasizes the importance of using several kinds of evidence (size measurements, growth experiments, morphological dissections, and histological studies) to reveal the sexual system of Hippolyte species. Whether the observed size dimorphism between males and females in many species of Hippolyte is expression of contrasting sexual and natural selection, and whether divergent sexual fitness functions can contribute to the evolution of hermaphroditism remains to be revealed in future studies.     

Genetic variation among life-history stages of mussels in a<Emphasis Type="Italic"> Mytilus edulis–M</Emphasis>.<Emphasis Type="Italic"> trossulus</Emphasis> hybrid zone

The mussel species Mytilus edulis L. and M. trossulus Gould coexist and hybridize throughout a large area that includes the north coast of Maine and Atlantic Canada. Previous studies provided genetic evidence for limited hybridization between the two species for mussels >15 mm. The present study used two genetic markers (ITS, Glu-5) to examine the genetic composition of early life-history stages by sampling veliger and pediveliger larvae, juveniles (<2.0 to 15.0 mm shell length) and adults (>15 mm shell length) in Trinity Bay, Newfoundland, during three consecutive years (1995–1997) to determine if differential mortality limits the relative abundance of hybrids. The relative frequency of the two species and the different hybrid genotypes was similar among the larvae, juveniles and small adult mussels. The double hybrid genotype (F₁-like) was the rarest genotype observed. There was no evidence for differential mortality during the early life-history stages, and factors limiting production of hybrids appear to operate before the late larval stage. The observed frequency of hybrids is probably due to a combination of pre- and postzygotic reproductive isolating mechanisms operating early in the mussels life history. M. trossulus dominated the early life-history stages, possibly due to a higher population density and a greater reproductive output than M. edulis. Differential mortality may explain the observed decrease in frequency of M. trossulus and increase in frequency of M. edulis with increasing shell length. A similar frequency of hybrid mussels from larvae to the size class of 55 mm shell length may indicate a rate of mortality intermediate between the two parental species. The M. edulis–M. trossulus hybrid zone appears to be maintained by reproductive isolating mechanisms limiting the production of hybrids and life-history differences that allow the two species to coexist.Communicated by J.P. Grassle, New Brunswick     

Strategies of a parasite of the ant–<Emphasis Type="Italic">Acacia</Emphasis> mutualism

Mutualisms can be exploited by parasites—species that obtain resources from a partner but provide no services. Though the stability of mutualisms in the presence of such parasites is under intensive investigation, we have little information on life history traits that allow a species to be a successful mutualist or rather a parasite, particularly in cases where both are closely related. We studied the exploitation of Acacia myrmecophytes by the ant, Pseudomyrmex gracilis, contrasting with the mutualistic ant Pseudomyrmex ferrugineus. P. gracilis showed no host-defending behavior and had a negative effect on plant growth. By preventing the mutualist from colonization, P. gracilis imposes opportunity costs on the host plant. P. gracilis produced smaller colonies with a higher proportion of alates than did the mutualist and thus showed an “r-like” strategy. This appears to be possible because P. gracilis relies less on host-derived food resources than does the mutualist, as shown by behavioral and stable isotope studies. We discuss how this system allows the identification of strategies that characterize parasites of mutualisms.     

Infant handling and mortality in yellow baboons (<Emphasis Type="Italic">Papio cynocephalus</Emphasis>): evidence for female reproductive competition?

This study examines negative and positive infant handling behavior in 24 free-ranging yellow baboon infants (Papio cynocephalus) studied over a 5-year period in Mikumi National Park, Tanzania. We test predictions of the female reproductive competition hypothesis to explain patterns of infant handling behavior by adult females (excluding the infants mother) in relation to observed cases of infant mortality by age 3 months (25% of infants in this study). Results show that: (1) low-ranking infants received more negative infant handling than high-ranking infants; conversely high-ranking infants received more positive infant handling; (2) female kin engaged in higher levels of positive infant handling than did non-kin, whereas non-kin showed higher levels of negative infant handling; (3) rates of negative infant handling varied by season, with high levels at the onset of the rainy season; and (4) high level of negative infant handling was a significant predictor of infant mortality by age 3 months (infant rank and sex did not predict survival). We discuss how the occurrence and interpretation of infant handling behavior in the literature has likely been confused by different definitions of this behavior, as well as differences in the socio-ecological context in which this behavior occurs.Communicated by C. Nunn     

Does the antidiabetic drug metformin affect embryo development and the health of brown trout (<Emphasis Type="Italic">Salmo trutta</Emphasis> f. <Emphasis Type="Italic">fario</Emphasis>)?

Background

Due to the rising number of type 2 diabetes patients, the antidiabetic drug, metformin is currently among those pharmaceuticals with the highest consumption rates worldwide. Via sewage-treatment plants, metformin enters surface waters where it is frequently detected in low concentrations (µg/L). Since possible adverse effects of this substance in aquatic organisms have been insufficiently explored to date, the aim of this study was to investigate the impact of metformin on health and development in brown trout (Salmo trutta f. fario) and its microbiome.

Results

Brown trout embryos were exposed to 0, 1, 10, 100 and 1000 µg/L metformin over a period from 48 days post fertilisation (dpf) until 8 weeks post-yolk sac consumption at 7 °C (156 dpf) and 11 °C (143 dpf). Chemical analyses in tissues of exposed fish showed the concentration-dependent presence of metformin in the larvae. Mortality, embryonic development, body length, liver tissue integrity, stress protein levels and swimming behaviour were not influenced. However, compared to the controls, the amount of hepatic glycogen was higher in larvae exposed to metformin, especially in fish exposed to the lowest metformin concentration of 1 µg/L, which is environmentally relevant. At higher metformin concentrations, the glycogen content in the liver showed a high variability, especially for larvae exposed to 1000 µg/L metformin. Furthermore, the body weight of fish exposed to 10 and 100 µg/L metformin at 7 °C and to 1 µg/L metformin at 11 °C was decreased compared with the respective controls. The results of the microbiome analyses indicated a shift in the bacteria distribution in fish exposed to 1 and 10 µg/L metformin at 7 °C and to 100 µg/L metformin at 11 °C, leading to an increase of Proteobacteria and a reduction of Firmicutes and Actinobacteria.

Conclusions

Overall, weight reduction and the increased glycogen content belong to the described pharmaceutical effects of the drug in humans, but this study showed that they also occur in brown trout larvae. The impact of a shift in the intestinal microbiome caused by metformin on the immune system and vitality of the host organism should be the subject of further research before assessing the environmental relevance of the pharmaceutical.

     

Mutual tolerance or reproductive competition? Patterns of reproductive skew among male redfronted lemurs (<Emphasis Type="Italic">Eulemur fulvus rufus</Emphasis>)

The social organization of gregarious lemurs significantly deviates from predictions of the socioecological model, as they form small groups in which the number of males approximately equals the number of females. This study uses models of reproductive skew theory as a new approach to explain this unusual group composition, in particular the high number of males, in a representative of these lemurs, the redfronted lemur (Eulemur fulvus rufus). We tested two central predictions of “concession” models of reproductive skew theory, which assume that subordinates may be allowed limited reproduction by dominant group members as an incentive to remain in the group, thereby increasing the group’s overall productivity. Accordingly, relatives are predicted to receive less reproduction than non-relatives, and the overall amount of reproductive concessions given to subordinates is predicted to increase as the number of subordinates increases. In addition, we tested whether the number of females in a group, a variable not previously incorporated in reproductive skew theory, affected reproductive skew among males. Using microsatellite analyses of tissue DNA, we determined paternities of 49 offspring born into our study population in Kirindy forest (western Madagascar) since 1996 to determine patterns of male reproductive skew to test these predictions. Our analyses revealed remarkable reproductive skew, with 71% of all infants being sired by dominant males, but both predictions of reproductive skew models could not be supported. Instead, the number of females best predicted the apportionment of reproduction among the males in this species, suggesting that current reproductive skew models need to incorporate this factor to predict reproductive partitioning among male primates and perhaps other group-living mammals. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Both Peter M. Kappeler and Markus Port contributed equally to this paper.     

Why do Horsfield’s bronze-cuckoo <Emphasis Type="Italic">Chalcites basalis</Emphasis> eggs mimic those of their hosts?

The Horsfield’s bronze-cuckoo (Chalcites basalis) egg closely matches the appearance of its host fairy-wren (Malurus spp.) eggs. Mimicry of host eggs by cuckoos is usually attributed to coevolution between cuckoos and hosts, with host discrimination against odd-looking eggs selecting for ever better mimicry by cuckoos. However, this process cannot explain Horsfield’s bronze-cuckoo egg mimicry because fairy-wren hosts rarely reject odd-looking eggs from their nest. An alternative hypothesis is that cuckoos have evolved egg mimicry to disguise their eggs from other cuckoos. Female cuckoos remove one egg from the nest during parasitism and would potentially benefit by selectively removing any cuckoo egg that has already been laid in the nest because otherwise, their egg will be evicted by the first nestling cuckoo along with the host clutch. We used painted, non-mimetic eggs to test whether cuckoos selectively remove odd-looking eggs during parasitism. We found that they were no more likely to remove a non-mimetic egg from a superb fairy-wren Malurus cyaneus clutch than would be expected by chance. Thus, our study does not support the cuckoo egg replacement hypothesis to explain mimicry of host eggs by cuckoos.     

Heterologous expression of <Emphasis Type="Italic">LamA</Emphasis> gene encoded endo-β-1,3-glucanase and CO<Subscript>2</Subscript> fixation by bioengineered <Emphasis Type="Italic">Synechococcus</Emphasis> sp. PCC 7002

The gene for the catalytic domain of thermostable endo-β-1,3-glucanase (laminarinase) LamA was cloned from Thermotoga maritima MSB8 and heterologously expressed in a bioengineered Synechococcus sp. PCC 7002. The mutant strain was cultured in a photobioreactor to assess biomass yield, recombinant laminarinase activity, and CO₂ uptake. The maximum enzyme activity was observed at a pH of 8.0 and a temperature of 70°C. At a CO₂ concentration of 5%, we obtained a maximum specific growth rate of 0.083 h^–1, a biomass productivity of 0.42 g?L^–1?d^–1, a biomass concentration of 3.697 g?L^–1, and a specific enzyme activity of the mutant strain of 4.325 U?mg^–1 dry mass. All parameters decreased as CO₂ concentration increased from 5% to 10% and further to 15% CO₂, except enzyme activity, which increased from 5% to 10% CO₂. However, the mutant culture still grew at 15% CO₂ concentration, as reflected by the biomass productivity (0.26 g?L^–1?d^–1), biomass concentration (2.416 g?L^–1), and specific enzyme activity (3.247 U?mg^–1 dry mass).

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