Audience effect is context dependent in Siamese fighting fish, Betta splendens

Investigations of communication networks in animals have focusedprimarily on determining whether animals extract informationfrom peripheral contests (eavesdropping) or respond to the presenceof bystanders (audience effect). The possibility that an animal'sresponse to being watched might be context dependent, however,has been explored in far less detail. This study investigatedthe influence of two contexts, exposure to audiences of differentsexes and presence or absence of a nest, on the aggressive behaviorof interacting male Siamese fighting fish, Betta splendens.Males interacted in the presence (male, female) or absence ofan audience in three different nest conditions (0, 1, or 2 nests).Audience sex and territorial status influenced aggressive behaviorin the interacting males, but a strong audience x nest interactionalso was uncovered. Males were more aggressive when neithermale had a nest and a male audience was present than when afemale or no audience was present. Males also were more aggressivewhen only one male had a nest and a male audience was presentthan when a female or no audience was present. When both maleshad nests and a male audience was present, however, males wereless aggressive than when only one male or neither male hada nest. In sum, aggressive behavior was influenced by the interactionbetween audience and nest; neither nest nor audience alone wassufficient to explain the results. Male Siamese fighting fishalter their behavior based on both external cues, the sex ofthe audience, and internal cues, reproductive state and resourcepossession. Our results emphasize the importance of consideringaspects of an animal's environment when examining audience effectsand communication networks in general.     

Effects of leaf litter on the growth of boreal feather mosses: Implication for forest floor development

Question: What is the effect of leaf litter on growth and mortality of feather mosses. Three experiments were conducted to isolate the shading effect from the effect of leaching of soluble compounds from the leaf litter effect on feather moss mortality and growth. Location: Edmonton, Alberta and the northern boreal coniferous forest, west‐central Alberta, Canada. Methods: In a field experiment Populus tremuloides (aspen) leaf litter was applied to beds of feather mosses dominated by Hylocomium splendens. Treatments were one layer of leaves held in place with netting; one layer of leaves coarsely ground, sprinkled over the moss layer; a shade cloth equivalent to one layer of leaves; and a control. In two growth chamber experiments, the application of aqueous extracts of P. tremuloides and Pinus contorta leaf litter and the effect of shade and soluble carbohydrates were tested on the growth and mortality of Ptilium crista‐castrensis. Results: Mortality of Hylocomium was greatest under the intact leaves, followed by the treatments using shade cloth and ground leaves and finally the control. The application of aqueous extracts of aspen leaf litter resulted in senescence or death of nearly all Ptilium shoots compared to no effects for the control or for similar extracts of pine needle litter. Extracts from aspen litter had greater concentrations of phenolic compounds and soluble sugars than pine extracts. Addition of sugars to Ptilium allowed it to grow and accumulate carbohydrates, even in low light conditions. Conclusions: Results suggest that broad‐leaved deciduous overstory species can limit the growth of feather mosses through their leaf litter and by implication affect the humus form, nutrient cycling, and understory composition of these forests.     

Seasonal and spatial patterns of population density in the marine macroalga Mazzaella splendens (Gigartinales, Rhodophyta)

Insight into demographic processes that operate at larger spatial scales can be achieved through studying local populations when a particular species of interest is examined over time, by many investigators, in a variety of locations. On the west coast of North America, Mazzaella splendens (Setchell et Gardner) Fredericq is such a species of interest. A synthesis of local demographic studies of M. splendens from the late 1960s to the present reveals a pattern that is potentially common to the larger natural populations. This is the pattern: population density is high in summer and low in winter for both alternate free‐living life history phases of M. splendens. The magnitude of this seasonal change decreases in increasingly wave‐exposed habitats. In wave‐sheltered habitats there is a seasonal alternation from summer haploid to winter diploid dominance. This alternation gradually changes to constant diploid dominance as wave exposure in the habitat increases. Changes in population density are primarily a function of appearances and disappearances of perennating basal crusts (genets), as modules are produced or lost, rather than differential module production by genets of one phase over those of the other. To test the generality of this pattern, we examined seasonal changes in density, in local populations of M. splendens, in both a wave‐sheltered and a wave‐exposed habitat at Second Beach, Barkley Sound. Greater seasonal fluctuation in population density at wave‐sheltered, compared to wave‐exposed habitats is supported as a pattern potentially common to the natural populations of M. splendens. A change from summer haploid dominance in wave‐sheltered areas to summer diploid dominance in wave‐exposed areas is similarly supported. All changes in population density were the result of appearances and disappearances of genets rather than differential module production by haploid versus diploid basal crusts, also consistent with previous observations. A seasonal alternation in phase dominance, however, was absent from the wave‐sheltered site at Second Beach, Barkley Sound for 3 consecutive years. Seasonal alternation in phase dominance of M. splendens appears dependent on local conditions and is not common to all natural populations.     

土壤理化性质与海州香薷(Elsholtzia splendens Nakai)铜锌积累的关系

土壤理化性质是决定重金属矿山废弃地植被恢复效率和成败的重要因素之一。选取芜湖市南陵县境内大工山-凤凰山古铜矿区的3处弃土场和两处对照点,调查了其植被覆盖度、物种组成,并分析了土壤性质与海州香薷铜、锌积累的相关性。结果显示,矿区土壤污染程度随废弃时间的增加和植物多样性的提高而降低,但仍未达到安全水平。海州香薷对铜、锌的积累主要发生在地下部分,地上部分的最高铜浓度为179.83mg/kg,远未达到铜超积累植物的标准,只是一种规避植物。海州香薷的铜、锌积累量主要取决于土壤铜、锌浓度水平,同时与土壤全磷、有效磷和pH值等因素显著相关,而与土壤有机质无相关性;并且海州香薷对铜、锌两种主要污染元素的积累可能存在某种协同作用。     

Trade-off between leaf size and vein density of Achnatherum splendens in Zhangye wetland

Aims Trade-offs between leaf size and vein density are the basis of the theory of leaf economics spectrum, and are to understand the relationship between the physical build and physiological metabolism of plant leaves under different degrees of competition for resources. Our objective was to study the changes in the relationship between leaf size and vein density (leaf dry biomass and leaf area) in Achnatherum splendens populations with four plant bundle densities located in the flood plain wetland of Zhangye. Methods The study site was located at floodplain wetlands of Zhangye, Gansu Province, China. Survey and sampling were carried out in the communities that A. splendens dominated. According to the plant bundle density, the A. splendens communities were divided into four density gradients with “bundle” for the sampling units, high density (I, > 12 bundle·m^-2), medium density (II, 8-12 bundle·m^-2), medium density (III, 4-8 bundle·m^-2) and Low density (IV, <4 bundle·m^-2). According to the density of each combination, we chose seven (5 m × 5 m) A. splendens samples, resulting in a total of 28 samples (4 × 7). The soil physical and chemical properties of four density gradients were investigated and six samples of A. splendens were used to measure the leaf area, leaf dry biomass and vein density in laboratory, and biomass of different organs was measured after being dried at 85 °C in an oven. 28 plots were categorized into three groups: high, medium and low density, and the standardized major axis (SMA) estimation method was used to examine the allometric relationships between leaf area, leaf dry biomass and vein density. Important findings The results showed that with the population density changed from high, medium, to low, the soil moisture decreased, and soil electric conductivityincreased. The leaf area, leaf biomass and height of A. splendens decreased, and the vein density, specific leaf area and photosynthetically active radiation (PAR) increased gradually. In addition, leaf net photosynthetic rate (P_n), transpiration rate (T_r) and twig number firstly increased then decreased. There was a highly significantly negative correlation (p < 0.01) between the leaf size and vein density on the high- and low-level densities (I, IV), whereas less significant (p < 0.05) on the level of medium density (II, III). The SMA slope of regression equation in the scaling relationships between leaf size and vein density was significantly smaller than -1 (p < 0.05).     

Can we consider the stocks of alfonsinos Beryx splendens and Beryx decadactylus from the Azores a discrete fishery management unit?

This paper summarises the detailed information on catch, fork length, weight, sex and maturity of alfonsinos Beryx splendens and Beryx decadactylus collected from targeted surveys in Azores waters, complemented by fishery data, over the past c. 20 years. To date, it was not possible to define if the Azorean component of the population can be considered as a discrete local management unit. The reason for this is the lack of available information for these resources covering the entire spatial distribution of the species in the North Atlantic Ocean. Additionally, there are some conflicts between the different genetic results available, poor understanding about the species movements and data from the Azores show some discrepancies in aspects of reproduction. Consequently, there is no analytical assessment for this resource and the stock of Beryx spp. is currently managed based on the precautionary approach. Outputs of recent analyses are presented in this study and possible assumptions and strategies for the assessment are discussed.     

Rediscovery of Leptopanchax splendens (Cyprinodontiformes: Aplocheilidae): a seasonal killifish from the Atlantic Forest of south-eastern Brazil that was recently considered extinct

A recent collection of the seasonal killifish found Leptopanchax splendens c. 5 km from the type locality, 74 years after its last record. The species was historically common in its type locality, the Estrela River basin in south-eastern Brazil, until 1950, after which it was not encountered and thought to have become extinct due to widespread deforestation and urbanization in the region. Despite the rediscovery, this study finds that other recently published reports of L. splendens are misidentifications.     

Can infection by eugregarine parasites mediate species coexistence in Calopteryx damselflies?

1. Parasitism may be an important factor determining the coexistence of closely related species. Although host–parasite interactions can affect the ecology and distribution of the host species, virtually nothing is known about how other interspecific interactions affecting the host, such as competition or predation, relate to the parasite burden of the host. 2. We studied parasite‐mediated competition between two closely related Calopteryx damselflies, C. virgo L. and C. splendens Harris. We investigated a total of 31 populations, including 18 allopatric and 13 sympatric populations. We measured the occurrence of gut parasites, eugregarines. 3. We found that the prevalence of gregarines was higher in C. virgo than in C. splendens. On average, more than half of the C. virgo individuals were infected by eugregarines both in allopatric and sympatric populations. However, hardly any allopatric C. splendens populations had gregarines, but most of sympatric populations had infected individuals. 4. According to our results, co‐existence of the host species affects the likelihood of the subordinate species showing higher levels of parasitism. Interspecific aggression, lower species genetic heterozygosity, and the difference in host species immunity are proposed as possible explanations for greater parasite burdens in the inferior species at sympatric sites.     

Taxonomic revision of the Koeleria splendens C. Presl group (Poaceae) in Italy based on morphological characters

Abstract

The Italian populations of Koeleria splendens C. Presl, critical group of the Mediterranean flora, are examined from the taxonomic and nomenclatural viewpoints. On the basis of literature data, herbarium investigations and field surveys, many morphologically well-differentiated taxa have been recognized. This group is widespread in the Italian peninsula and Sicily, where it is represented by the following units: K. splendens C. Presl, with four subspecies [subsp. splendens, subsp. grandiflora (Bertol. ex Schultes) Domin, subsp. brutia Brullo, Gangale & Uzunov, and subsp. ophiolitica subsp. nova], K. lucana sp. nova, K. subcaudata (Ascherson & Graebner) Ujhelyi, K. australis Kerner, K. callieri (Domin) Ujhelyi, and K. insubrica sp. nova. As concerns their distribution, both K. splendens and K. lucana are endemic to the Italian territory, while the other species occur also in some eastern Mediterranean countries. The taxonomic position of K. lobata, recently treated by some authors as a synonym of K. splendens, is also examined. A phylogenetic analysis was performed using morphological characters. Finally, a detailed iconography of the main morphological features and an analytical key of the Italian taxa (K. lobata included) are given.     

Long‐term warming and litter addition affects nitrogen fixation in a subarctic heath

Nitrogen (N) availability is the main constraint on primary production in most Arctic ecosystems, with microbial fixation of atmospheric N as the primary source of N input. However, there are only few reports on N fixation rates in relation to climate change in the Arctic. In order to investigate the effects of anticipated global climate change on N fixation rates in a subarctic moist heath, a field experiment was carried out in Northern Sweden. Warming was induced by plastic tents, and in order to simulate the effects of future increased tree cover, birch litter was added each fall for 9 years before the measurements. We analyzed N fixation rates on both whole‐ecosystem level and specifically on two moss species: Sphagnum warnstorfii and Hylocomium splendens. The whole‐ecosystem N fixation of the warmed plots almost tripled compared with the control plots. However, in the Sphagnum and Hylocomium mosses we observed either no change or occasionally even a decrease in N fixation after warming. Both measured on whole‐ecosystem level and on the two moss species separately, litter addition increased N fixation rates. The results suggest that warming will lead to a general increased ecosystem N input, but also that the N fixation associated to some moss species is likely to decrease. Hence, this study shows that the scale of measurements is crucial when investigating on ecosystem responses to manipulations.