The ontogeny of courtship, colour and sperm production in male guppies

The onset of sexual behaviour in three age classes of male guppy Poecilia reticulata occurred in synchrony with the appearance of body colouration and anal fin differentiation but not with sperm production. There was also a positive correlation between sperm production and sexual behaviour in the two older age classes.     

Alternative life cycles controlled by temperature and photoperiod in the oligophagous bug, Dybowskyia reticulata

Abstract. Effects of temperature and photoperiod on the induction and re-induction of adult diapause were examined in Dybowskyia reticulata (Dallas) (Heteroptera: Pentatomidae). Adults collected from the field after overwintering in early summer continued oviposition under long-day conditions of LD 16:8 h at 20 or 25°C, while they re-entered diapause under short-day conditions of LD 12:12 h at 25, 27.5 or 30°C. By contrast, adults reared in the laboratory from eggs at 20 or 25°C entered diapause under both long-day and short-day conditions, whereas those reared at 27.5 and 30°C entered diapause only under short-day conditions. Under quasi-natural conditions in 1993, when summer temperature was low, most adults of the first generation entered diapause in late July. However, in the warmer summer of 1996, oviposition was recorded in many females that ecdysed into adults from July to early August. Even though the seeds of the host plants occur in a restricted period from early summer to early autumn, in warmer years D. reticulata may produce a second generation. The response to temperature with a threshold between 25 and 27.5°C in D. reticulata brings about a switch between the univoltine and bivoltine life cycles.     

Male mating strategies under predation risk: do females call the shots?

Many authors have reported that, under elevated risk of predation,male guppies (Poecilia reticulata) alter their behavior fromcourtship to forced copulation (gonopodial thrusts not precededby sigmoid displays). This shift is presumed to benefit thebrightly colored male, whose intense courting activity mightotherwise increase his risk of detection and attack by predators.However, there is some evidence that females engaged in reproductiveactivity with males may be even more vulnerable to predatorsthan the males themselves, which suggests an alternative hypothesis:females in high-risk situations are less receptive to male courtship,and this leads males to change their behavior. We tested thishypothesis by providing either males and females separately,or both sexes concurrently, with information about elevatedpredation risk from a cichlid (Crenicichla sp.). We found thatwhen only females were provided with information about increased risk,males performed fewer courtship displays and fewer thrusts.They did not perform more forced copulations in any treatmentgroup. Nonetheless, our results suggest that the female's perceptionof predation risk can be at least as important as the male'sin changing male mating behavior.     

Isolation and characterization of 43 microsatellite DNA markers for guppy (Poecilia reticulata)

Thirty‐nine polymorphic microsatellite DNA markers were isolated from the guppy (Poecilia reticulata) genomic library. All of the loci showed moderate allelic variation ranging from two to seven alleles, with observed heterozygosities from 0.000 to 0.938. The microsatellite DNA markers isolated will be available for use in analysis of quantitative trait loci in breeding programmes and for population genetic studies on experimental fish.     

Predator preference for brightly colored males in the guppy: a viability cost for a sexually selected trait

Although conspicuous visual sexual signals, such as bright colors,in males serve to attract females in numerous species, theymay also attract the attention of potential predators and thusmay be costly in terms of increasing individual risk of mortalityto predation. Most models of the evolution of extravagant malesexual traits and female preferences for them assume that thesexually preferred male trait is costly to produce and maintain.However, there is surprisingly little empirical evidence fordirect fitness costs associated with sexually selected visualtraits that enhance male mating success. In the present study,we report a direct fitness cost for sexually selected, brightbody-color patterns in males in the form of an associated greaterrisk of mortality to predation. By using the guppy (Poeciliareticulata) and the blue acara cichlid fish (Aequidens pulcher)as a model prey–predator system, we demonstrate experimentallythat individual cichlids preferentially and consistently approached,attacked, and captured the more brightly colored of two size-matchedmale guppies presented simultaneously in staged encounters.This resulted in the brightly colored male incurring, on average,a significantly higher risk of mortality given an encounterwith the predator than with the drabber male in matched pairs.Our results constitute strong behavioral evidence for a directviability cost associated with bright coloration in male guppies,and they corroborate the generally accepted paradigm that directionalpredation by visual fish predators against brightly colored,adult male guppies underlies the evolution of the known divergentcolor patterns in natural guppy populations that experiencedifferent intensities of predation. The viability cost associatedwith bright conspicuous coloration in male guppies potentiallyreinforces for females the reliability of this sexually selectedtrait as an indicator trait of male quality.     

Which Extent is Plasticity to Light Involved in the Ecotypic Differentiation of a Tree Species from Savanna and Forest?

Light intensity and heterogeneity are some of the main environmental factors that differ between forest and savanna habitats, and plant species from these habitats form distinct functional types. In this study, we tested the hypothesis that not only differences in morphological and physiological traits but also phenotypic plasticity in response to light are involved in adaptation to forest and savanna habitats by investigating ecotypic differentiation between populations of Plathymenia reticulata (Leguminosae: Mimosoideae), a tree from the Brazilian Atlantic Forest and the Brazilian Cerrado (savanna). Seeds from four natural populations (one from each biome core area and two from ecotonal regions) were grown in a common garden with four light treatments. Fifteen morphological and physiological characteristics were evaluated until individuals reached 6 mo old. Comparisons among populations showed differences for seven traits in at least one light treatment. These differences pointed to local adaptation to different biomes. Populations showed different levels of phenotypic plasticity in response to light in seven traits. Higher plasticity was found either in the forest core population or ecotonal populations; lower values were found in the cerrado core population. Lower plasticity in the cerrado population emphasizes the stress resistant syndrome, as lower plasticity is probably advantageous in a habitat where a conservative resource use is crucial. Higher plasticity in forest individuals suggests higher ability in exploiting the light heterogeneity in this habitat. Also, higher plasticity in ecotonal populations can be important to ensure the maintenance of P. reticulata in these temporally and spatially dynamic areas. Abstract in Portugese is available at http://www.blackwell‐synergy.com/loi/btp .     

人工授精平角涡虫早期胚胎和幼虫的扫描电镜观察

为探明平角涡虫(Planocera reticulata)胚胎发育规律,采用人工授精方法,获得不同发育阶段的无卵外胶膜胚胎,并运用扫描电镜技术,观察了受精卵早期胚胎发育和幼虫发育.结果表明,从第3次卵裂开始表现出螺旋式卵裂的特征.在囊胚时期和原肠时期在动物极顶端有几个卵裂球向内下陷形成一凹陷.浮游幼虫期的幼虫利用体表纤...     

Characteristic Odor Components of Citrus reticulata Blanco (Ponkan) Cold-pressed Oil

Citrus reticulata Blanco (ponkan) cold-pressed oil and its oxygenated fraction were studied by analytical (GC and GC/MS) and sensory analyses. The monoterpene group was predominant, accounting for more than 89.6% (w/w), of which limonene was the most abundant (80.3%). Among the oxygenated compounds, octanal and decanal were the major ones among 12 aldehydes accounting for >1.5%; six alcohols were identified with a total concentration of >0.7%, while oxides, ketones and esters did not quantitatively or qualitatively contribute to the oil. Sniffing the ponkan cold-pressed oil and its oxygenated fraction demonstrated that octanal and decanal were the characteristic odor components of ponkan. Reconstruction of the ponkan aroma model and its sensory evaluation by a hedonic test were performed, showing that, in addition to octanal and decanal which played important roles, (R)-(+)-limonene contributed to the aroma model as a background component, making the aroma model very similar to that of the original.     

中国及越南樟科植物新评注

<正> 作者近年来在编写《广西植物志》工作中,对本所收藏的樟科植物标本作了清理,同时也把编写《中国植物志》时搁下的一些疑难标本作了进一步研究,现将结果在本文中报道。所引用的标本,均存本所标本室。     

木耳属二新种*

本文报道了在西沙群岛采集的木耳属二新种,命名为西沙木耳和网脉木耳,并附汉文和拉丁文描述。此外,还讨论了新种与近似种之间的区别。