Photosynthetic Characteristic of Three Varieties of Lilium (Liliaceae)“Oriental Hybrids”in the Middle of Yunnan Province

To understand the ecophysiological adaptation of Lilium“Oriental Hybrids”which was grown for the commercial bulb, the gas exchange, leaf N and chlorophyll content of three varieties were investigated in the middle of Yunnan province. Among three varieties, light saturated photosynthetic rate at ambient CO₂ (A_max ) of“Siberia”was the highest, while“Siberia” (was the lowest. The difference in A_max was related to the carboxylation efficiency (CE), leaf mass per unit area and leaf N content per mass, which indicated that their photosynthetic capacity was influenced by the activity and/or the number of Rubisco. Three varieties had lower photosynthetic saturation point and photosynthetic compensation point, but their photosynthetic rate not decreased up to 2 000μmol m^{- 2} s ^{- 1}. This indicated that three varieties had broad adaptability to light intensity. There were significant differences in photosynthetic optimum temperature among three varieties. However, the variety“Siberia”had the highest photosynthetic optimum temperature ( 25.5℃- 34.9℃ ), and it was suitable to grow in the warm area. “Sorbonne”had the lowest photosynthetic optimum temperature ( 19.3℃- 25.6℃ ), and it can be grown in the cool area.“Tiber”could maintain high photosynthetic rate at a wide range of temperature, so it was more suitable for the climate in the middle of Yunnan province.     

How does Merendera montana (L.) Lange (Liliaceae) benefit from being consumed by mole-voles?

The relationships between a geophyte (Merendera montana (L.) Lange – Liliaceae) and a mole-vole (Microtus duodecimcostatus de Sélys-Longchamps) in the Spanish Pyrenees were investigated by analysing plant density, asexual reproductive strategies, and chemical composition of M. montana, and by observing the feeding behavior of M. duodecimcostatus in captivity. We found that M. montana contains toxic alkaloids, the concentration of which varies throughout the year; being minimal at the end of the vegetative period. Alkaloids are stored in the whole plant, particularly in the leaves which are scarcely consumed by herbivores. Nevertheless, mole-voles eat this plant profusely both in the field and in captivity, where they showed preference for the corm. The corm has lower alkaloid concentration and higher levels of energetic substances than the other plant parts, particularly leaves. Although corm consumption causes plant death, M. montana grows more abundantly in areas colonized by mole-voles than in undisturbed grasslands with high plant cover and absence of mole-vole populations. Both asexual reproduction and seedlings of this species are more frequent in highly disturbed areas. Results strongly suggest a protocooperative relationship between mole-voles and this geophyte: the burrowing behavior of mole-voles favours dispersal and reproductive success of the plant, enhancing its habitat availability; the plant in turn supplies abundant and nutritious food at a low and "acceptable" toxicity cost.     

Reactive oxygen species and melanoma: an explanation for gender differences in survival?

Epidemiological research consistently shows a female advantage in melanoma survival. So far, no definite candidate for the explanation of this phenomenon has emerged. We propose that gender differences in oxidative stress caused by radical oxygen species (ROS) underlie these survival differences. It is known that males express lower amounts of anti-oxidant enzymes, resulting in more oxidative stress than females. The primary melanoma environment is characterized by high ROS levels, from exogenous sources as well as ROS production within melanoma cells themselves. ROS are known to be able to promote metastasis through a wide variety of mechanisms. We hypothesize that the higher levels of ROS in men enhance selection of ROS-resistance in melanoma cells. Subsequently, ROS can stimulate the metastatic potential of melanoma cells. In addition, due to the lower anti-oxidant defenses in men, ROS produced by melanoma cells cause more damage to healthy tissues surrounding the tumor, further stimulating metastasis. Therefore, ROS may explain the observed differences between males and females in melanoma survival.     

Hepatic vasopressin receptors (VPRs) exhibit species heterogeneity—absence of VPRs in sheep liver

1. We have studied the binding characteristics of the hepatic VPRs expressed by rat, cow, pig, sheep and human and have demonstrated species heterogeneity.2. These species differences are manifested as variation in the VPR capacity (rat > cow > pig > human > sheep), and in the affinity of these receptors for their natural ligand AVP (rat = human > pig = cow).3. A single class of VPRs, with high affinity for AVP, is present in rat, cow, human and pig liver. In contrast, ovine hepatocytes do not express a VPR.4. The affinity of the V_1a-selective antagonist d(CH₂)₅Tyr(Me)²AVP is highly dependent on the species utilised, such that rat > human > cow.     

Sound production in four damselfish (Dascyllus) species: phyletic relationships?

Most studies of fish sounds show that the sounds are species-specific, with unique spectral and timing characteristics. This raises the question as to whether these sounds can be used to understand phyletic relationships between species and which acoustic parameters are subject to variation between species. In the present study, 597 sounds (and 2540 pulses) related to signal jumps of four Dascyllus species ( Dascyllus aruanus , Dascyllus trimaculatus , Dascyllus albisella , and Dascyllus flavicaudus ) from different geographic regions (Madagascar, Moorea, Rangiroa, and Hawaii) were analysed. It was possible to discern species-specific sounds, but also variation in sounds between populations. Large variations in sound length were found between Dascyllus species, whereas differences in interpulse duration were found to be variable between populations. In the regions where species live in sympatry, it appears that they restrict the variability in their sounds. This could comprise evidence of adaptation with character displacement of sonic characteristics where different species co-occur. However, sonic characteristics still overlapped substantially between species, suggesting that females would need to sample more than one sound and potentially use other cues to discriminate between species.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 928–940.     

Endoplasmic reticulum marker enzymes in Golgi fractions--what does this mean?

NADPH cytochrome c (cyt c) reductase and glucose-6-phosphatase, two enzymes thought to be restricted to the endoplasmic reticulum (ER) and widely used as ER markers, are present in isolated Golgi fractions assayed immediately after their isolation. Both enzymes are rapidly inactivated in fractions stored at 0 degrees C in 0.25 M sucrose, conditions which do not affect the activity of other enzymes in the same preparation. The inactivation process was shown to be dependent on time and protein concentration and could be prevented by EDTA and catalase. Morphological evidence shows that extensive membrane damage occurs parallel with the inactivation. Taken together with the immunological data in the companion paper, the findings indicate that the enzymes NADPH cyt c reductase and probably glucose-6-phosphate are indigenous components of Golgi membranes.     

Leaf litter breakdown rates in boreal streams: does shredder species richness matter?

1. Leaf litter breakdown rates were assessed in 23 boreal streams of varying size (first–seventh order) in central and northern Sweden. 2. Shredders were most abundant in small streams, while shredder species richness showed a hump-shaped relationship with stream order, with most species in fourth order streams. 3. In a partial least-squares regression analysis, year, water temperature, shredder species richness and shredder abundance were those factors correlating most strongly with leaf breakdown rates. Shredder species richness was more strongly correlated with leaf litter breakdown rates than shredder abundance, and shredder biomass showed no such correlation. 4. These data suggest that shredder species richness is an important variable in terms of leaf litter dynamics in streams.     

Contact in context: does intergroup contact function (better) in high-threat contexts?

Are interpersonal contacts effective in reducing group threat and prejudice in all contexts? Studies have found that the contact effect is stronger in regions and countries where large immigrant populations contribute to high levels of contextual group threat This paper tests the robustness of the observed positive association between contextual-level group threat and contact effects by identifying three methodological reasons for why the association might be spurious: (1) a potential omitted variable bias; (2) a potential self-selection effect; and (3) a potential ceiling effect. Using the 2002 European Social Survey, we find that the positive association is indeed robust. We interpret this as evidence that contact effects are strongest in those European contexts where the need for improved intergroup relations between immigrants and natives is most dire.     

Paracorethrura Melichar, 1915 (Hemiptera: Lophopidae): two distinct species or sexual dimorphism in a species?

A taxonomic update is provided for Paracorethrura Melichar, 1915. P. arrhen n. sp. is described from Vietnam and brings up the number of species to two for the genus: P. iocnemis (Jacobi, 1905) being known only by female specimens and P. arrhen only by males, CO1 sequences are provided in order to check if they are truly two different species or if we are witnessing some sexual dimorphism.     

Microhabitat segregation in three rocky intertidal fish species in Portugal: does it reflect interspecific competition?

Recruits of Lipophrys pholis , Coryphoblennius galerita and Gobius cobitis spend the low tide under water in pools, and in the case of G. cobitis also in channels. The pools used by the two blenniids show greater similarity than those used by G. cobitis. Larger juveniles and adults of C. galerita continue to use the same type of pools, which are temporarily abandoned by the males during the breeding season when they use emersed holes and crevices as nests. The much faster growing L. pholis and G. cobitis leave the pools in their first autumn, when they are c. 7 cm long. Whereas G. cobitis >7 cm move to channels and large upper pools, with a smooth substratum, sand and boulders, L. pholis begin to use emersed crevices where they spend low tide often in large groups. When L. pholis or C. galerita were added or removed selectively from pools, their numbers returned to pre-experimental levels after 2 weeks, suggesting that, although intraspecific competition may be strong, interspecific competition was unlikely to explain these results fully.     

Extreme phenotypic variation in Cetraria aculeata (lichenized Ascomycota): adaptation or incidental modification?

Background and Aims

Phenotypic variability is a successful strategy in lichens for colonizing different habitats. Vagrancy has been reported as a specific adaptation for lichens living in steppe habitats around the world. Among the facultatively vagrant species, the cosmopolitan Cetraria aculeata apparently forms extremely modified vagrant thalli in steppe habitats of Central Spain. The aim of this study was to investigate whether these changes are phenotypic plasticity (a single genotype producing different phenotypes), by characterizing the anatomical and ultrastructural changes observed in vagrant morphs, and measuring differences in ecophysiological performance.

Methods

Specimens of vagrant and attached populations of C. aculeata were collected on the steppes of Central Spain. The fungal internal transcribed spacer (ITS), glyceraldehyde-3-phosphate dehydrogenase (GPD) and the large sub-unit of the mitochondrial ribosomal DNA (mtLSUm), and the algal ITS and actin were studied within a population genetics framework. Semi-thin and ultrathin sections were analysed by means of optical, scanning electron and transmission electron microscopy. Gas exchange and chlorophyll fluorescence were used to compare the physiological performance of both morphs.

Key Results and Conclusions

Vagrant and attached morphs share multilocus haplotypes which may indicate that they belong to the same species in spite of their completely different anatomy. However, differentiation tests suggested that vagrant specimens do not represent a random sub-set of the surrounding population. The morphological differences were related to anatomical and ultrastructural differences. Large intercalary growth rates of thalli after the loss of the basal–apical thallus polarity may be the cause of the increased growth shown by vagrant specimens. The anatomical and morphological changes lead to greater duration of ecophysiological activity in vagrant specimens. Although the anatomical and physiological changes could be chance effects, the genetic differentiation between vagrant and attached sub-populations and the higher biomass of the former show fitness effects and adaptation to dry environmental conditions in steppe habitats.     

Asian (Taiwan) Taenia: species or strain?

Recent studies on the epidemoiological pattern of taenisis in Southeast Asia have indicated the existence of a third form of human Taenia which is distinguishable from Taenia saginata and T. solium. Don McManus and Josephine Bowles here review how new genetic evidence supports earlier conclusions that the Asian Taenia is a distinct entity but is closely related T. saginata, and suggests its taxonomic classification as a subspecies or strain of T. saginata is more appropriate than formal designation as a new species.     

Sand pits as habitats for beetles (Coleoptera): does area affect species number and composition?

Species living in open sandy habitats are declining in northern Europe because of habitat loss and degradation. However, mining of sand creates potential new habitats for these species in the form of sand pits. In this study we investigated the beetle fauna in sand pits in order to determine what kind of sand pits are the most valuable for conservation, in terms of sand pit area (primarily) and the proportion of sand material, vegetation cover, tree cover and edge habitats. Thirteen sand pits in Uppsala County, Sweden, ranging in size from 0.02 to 18 ha, were included in this study. A total of 2,500 individuals of beetles, belonging to 256 species, were sampled by pitfall traps. Thirty-nine of the species were classified as specialized sand-dwelling species and two were Swedish Red List species. We found that the area of sand pits affects both species number and species composition of beetles. A positive species-area relationship was found, best explained by a quadratic power function, for the habitat-specific species (i.e., sand species). Our recommendation is to prioritize sand pits with areas between 0.3 and 5 ha, with preference towards the lower end of this range, for conserving sand-dwelling beetles.     

Parentage analysis in Chamaelirium luteum (L.) Gray (Liliaceae): why do some males have higher reproductive contributions?

Much of the contemporary study of adaptation in natural populations involves the regression of some component of fitness, usually survivorship or viability, on one or more characters of interest. It is difficult to apply this approach to measures of paternal reproduction, however, because paternity is typically estimated indirectly from genetic markers, rather than being measured directly from progeny counts. Here, we present maximum likelihood methods for modelling relative male reproductive success as a log-linear function of one or more potentially predictive features, as well as providing a framework for the assessment of pairwise (male:female) effects, as they affect male reproductive performance. We also provide nonparametric statistical tests for alternative models. Using this formulation, we examine the impact of inflorescence morphology on male reproductive success in Chamaelirium luteum L., and we also assess the importance of intermate distances between males and particular females. While male reproductive success and male inflorescence morphology are both quite variable, reproductive morphology does not appear to predict male reproductive success in this study. Intermate distance is an extremely effective predictor of pairwise success, however; but averaged over females, there is almost no net effect for different males.     

Prioritizing species conservation: does the Cape Verde kite exist?

The Cape Verde kite (Milvus milvus fasciicauda) is considered to be one of the rarest birds of prey in the world and at significant risk of extinction. For this reason there is great interest in both the taxonomic and the population status of this group. To help resolve its taxonomic status, we provide phylogenetic analyses based on three mitochondrial genes for a sampling of kites in the genus Milvus, including a broad geographical sampling of black kites (Milvus migrans), red kites (Milvus milvus), Cape Verde kite museum specimens collected between 1897 and 1924, and five kites trapped on the Cape Verde Islands during August 2002. We found that the historical Cape Verde kites, including the type specimen, were non-monophyletic and scattered within a larger red kite clade. The recently trapped kites from the Cape Verde Islands were all phylogenetically diagnosed as black kites. Our findings suggest that the traditional Cape Verde kite is not a distinctive evolutionary unit, and the case for species status, as recently suggested by others, is not supported. We do find support for recognition of at least one clade of yellow-billed kites, traditionally considered as a black kite subspecies, as a distinctive phylogenetic species.     

Photoconvertible protochlorophyll(ide) in vivo: A single species or two species in dynamic equilibrium?

The decreasing absorbances in vivo of protochlorophyll(ide) at 635 and 650 nm bear the same relationships to one another during photoconversion to chlorophyll(ide) a in the leaves of dark-grown barley seedlings, regardless of whether the actinic light is absorbed primarily at 630, 640 or 671 nm. Accordingly, the absorption bands at 635–637 and 650 nm of photoconvertible protochlorophyll(ide) are attributed to a single species of membrane-bound protochlorophyll(ide) molecule or, alternatively, to two species which are in dynamic equilibrium.     

Does sex make a difference? Genetic diversity and spatial genetic structure in two co-occurring species of Gagea (Liliaceae) with contrasting reproductive strategies

Gagea lutea and G. spathacea are spring geophytes naturally co-occurring in woodlands, characterised by contrasting reproductive strategies probably caused by divergent ploidy levels. The hexaploid G. lutea relies on vegetative reproduction by subterranean bulbils in young stages but completely switches to sexual reproduction once a certain bulb size is attained. The nonaploid G. spathacea seems to be sterile and reproduces only vegetatively; the plants continue to form bulbils even in the rare event of flowering. This study used AFLP genotyping to investigate the consequences of these reproductive strategies for genetic diversity. For 150 and 100 samples from three Western Pomeranian populations of G. lutea and G. spathacea, respectively, AFLP fingerprints were analysed for three different spatial scales, the patch, the transect, and the region. Applying a threshold for genotypic identity of <0.05 simple matching distance, 22?C30 genets were detected in the three G. lutea populations, with all genets confined to single populations. Clonal genets consisted of 2?C9 samples and extended over up to 28?m, but never occupied the whole length of a transect; 67?C75% of all patches had different genets. Genetic distances between genets within populations were similar to those recorded between populations. Genotyping of G. spathacea revealed a single clonal genet for all three populations sampled within a distance of 30?km. The absent genetic diversity confirms the suspected sexual sterility. Gagea spathacea seems to be one of the few non-apomictic, fully clonal vascular plants able to occupy a significant range solely by dispersal of vegetative diaspores.