THE WHISTLED SONGS OF THE EUROPEAN STARLING STURNUS VULGARIS AND THE SPOTLESS STARLING STURNUS UNICOLOR IN NORTH-EAST SPAIN

ABSTRACT

This paper describes the whistled songs of two allopatric populations of the European starling and spotless starling in NE Spain. The results show that European starlings in NE Spain sing the same whistled themes found earlier in other European populations and confirm the universal character of these themes. There are some differences between European starlings from NE Spain and other populations: rising phases appear for Inflection theme high-form, Inflection theme and Simple theme, and also differences of rate of emission appear for others (Rhythmic theme). Harmonic theme has not been found. Likewise, the first analysis of the spotless starling's whistled song shows that it shares the same general whistled song structure with the European starling; whistles have similar structural parameters (modulation, duration, frequency) and can be classified in the same categories or themes; a new theme appears, the Trilled theme, which has not been found to date in the European starling. Dialectal areas have been found in both species for the same themes (Inflection theme, Simple theme). The males of both studied populations have larger repertoires in comparison to other studied populations of the European starling.     

Melanins in Physiological Conditions Protect Against Lipoperoxidation. A Study on Albino and Pigmented Xenopus

The susceptibility to lipoperoxidation in liver of albino and pigmented Xenopus laevis Daudin, has been studied. Albino Xenopus liver was richer in polyunsaturated fatty acids (PUFAs) than the pigmented one; moreover, it was also richer in mitochondrial superoxide dismutase (MnSOD) and in reduced glutathione (GSH). The thiobarbituric acid-reactive substances (TBARS) values were more abundant in the albino tissue compared to the pigmented tissue both during spontaneous and Fe⁺⁺ induced lipoperoxidation. Therefore, when isolated and purified melanin, in physiological quantities, was added to albino tissue, the TBARS values drastically decreased. Thus, melanin, in our experimental conditions, protects the albino tissue even more than SOD and GSH do. Melanin, in our opinion, acts as an antioxidant, because it is able to scavenge O₂^?.     

Nutrient stoichiometry of linked catchment‐lake systems along a gradient of land use

1. Catchments export nutrients to aquatic ecosystems at rates and ratios that are strongly influenced by land use practices, and within aquatic ecosystems nutrients can be processed, retained, lost to the atmosphere, or exported downstream. The stoichiometry of carbon and nutrients can influence ecosystem services such as water quality, nutrient limitation, biodiversity, eutrophication and the sequestration of nutrients and carbon in sediments. However, we know little about how nutrient stoichiometry varies along the pathway from terrestrial landscapes through aquatic systems. 2. We studied the stoichiometry of nitrogen and phosphorus exported by three catchments of contrasting land use (forest versus agriculture) and in the water column and sediments of downstream reservoirs. We also related stoichiometry to phytoplankton nutrient limitation and the abundance of heterocystous cyanobacteria. 3. The total N : P of stream exports varied greatly among catchments and was 18, 54 and 140 (molar) in the forested, mixed‐use and agricultural catchment, respectively. Total N : P in the mixed layers of the lakes was less variable but ordered similarly: 35, 52 132 in the forested, mixed‐use and agricultural lake, respectively. In contrast, there was little variation among systems in the C : N and C : P ratios of catchment exports or in reservoir seston. 4. Phytoplankton in the forested lake were consistently N limited, those in the agricultural lake were consistently P limited, and those in the mixed‐use lake shifted seasonally from P‐ to N limitation, reflecting N : P supply ratios. Total phytoplankton and cyanobacteria biomass were highest in the agricultural lake, but heterocystous (potentially N fixing) cyanobacteria were most abundant in the forested lake, corresponding to low N : P ratios. 5. Despite large differences in catchment export and water column N : P ratios, the N : P of sediment burial (integrated over several decades) was very low and remarkably similar (4.3–7.3) across reservoirs. N and P budgets constructed for the agricultural reservoir suggested that denitrification could be a major loss of N, and may help explain the relatively low N : P of buried sediment. 6. Our results show congruence between the catchment export N : P, reservoir N : P, phytoplankton N versus P limitation and the dominance of heterocystous cyanobacteria. However, the N : P stoichiometry of sediments retained in the lakes was relatively insensitive to catchment stoichiometry, suggesting that a common set of biogeochemical processes constrains sediment N : P across lakes of contrasting catchment land use.     

Persistent Controversy in Statistical Approaches in Wildlife Sciences: A Perspective of Students

ABSTRACT The controversy over the use of null hypothesis statistical testing (NHST) has persisted for decades, yet NHST remains the most widely used statistical approach in wildlife sciences and ecology. A disconnect exists between those opposing NHST and many wildlife scientists and ecologists who conduct and publish research. This disconnect causes confusion and frustration on the part of students. We, as students, offer our perspective on how this issue may be addressed. Our objective is to encourage academic institutions and advisors of undergraduate and graduate students to introduce students to various statistical approaches so we can make well-informed decisions on the appropriate use of statistical tools in wildlife and ecological research projects. We propose an academic course that introduces students to various statistical approaches (e.g., Bayesian, frequentist, Fisherian, information theory) to build a foundation for critical thinking in applying statistics. We encourage academic advisors to become familiar with the statistical approaches available to wildlife scientists and ecologists and thus decrease bias towards one approach. Null hypothesis statistical testing is likely to persist as the most common statistical analysis tool in wildlife science until academic institutions and student advisors change their approach and emphasize a wider range of statistical methods.     

Numerical taxonomy of Juniperus thurifera, J. excelsa and J. foetidissima (Cupressaceae) based on morphological characters

Juniperus excelsa and J. thurifera are considered to originate from the same ancestor. As a result of occurring in geographically isolated refuges – J. excelsa in SE Europe and SW Asia and J. thurifera in SW Europe and NW Africa – their divergence could have taken place at the end of the Tertiary, with the climate cooling. Juniperus foetidissima occurs in SE Europe and SW Asia in territories shared with J. excelsa and is similar to and sometimes misidentified with it. The occurrence of the latter two species over the same area suggests they should be more similar to each other than to the geographically distant J. thurifera . Four populations of J. excelsa ssp. excelsa , four of J. thurifera and two of Juniperus foetidissima were examined on the basis of features of 10 cones and 10 shoots of 18–36 specimens each. Results of discrimination analysis, Mahalanobis distances and cluster analysis showed great similarity to J. excelsa and J. thurifera , while J. foetidissima was more distant. The results support the hypothesis of a common ancestor of J. excelsa and J. thurifera , but suggest another origin of J. foetidissima .  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 155 , 483–495.     

In comparison with nitrate nutrition,ammonium nutrition increases growth of the frostbite1 Arabidopsis mutant

Ammonium nutrition inhibits the growth of many plant species, including Arabidopsis thaliana. The toxicity of ammonium is associated with changes in the cellular redox state. The cellular oxidant/antioxidant balance is controlled by mitochondrial electron transport chain. In this study, we analysed the redox metabolism of frostbite1 (fro1) plants, which lack mitochondrial respiratory chain complex I. Surprisingly, the growth of fro1 plants increased under ammonium nutrition. Ammonium nutrition increased the reduction level of pyridine nucleotides in the leaves of wild‐type plants, but not in the leaves of fro1 mutant plants. The observed higher activities of type II NADH dehydrogenases and cytochrome c oxidase in the mitochondrial electron transport chain may improve the energy metabolism of fro1 plants grown on ammonium. Additionally, the observed changes in reactive oxygen species (ROS) metabolism in the apoplast may be important for determining the growth of fro1 under ammonium nutrition. Moreover, bioinformatic analyses showed that the gene expression changes in fro1 plants significantly overlap with the changes previously observed in plants with a modified apoplastic pH. Overall, the results suggest a pronounced connection between the mitochondrial redox system and the apoplastic pH and ROS levels, which may modify cell wall plasticity and influence growth.     

Variation in ephippial buoyancy in Daphnia pulicaria

1. Freshwater zooplankton often produce diapausing eggs to survive environmental stress. The diapausing eggs of Daphnia (Crustacea, Cladocera) are encased in an ephippium that either floats at the surface or sinks to the sediment. These two types of ephippia may represent different strategies between spatial (floaters) and temporal (sinkers) dispersal of offspring. 2. We observed floating and sinking characteristics of ephippia obtained from eight lakes. We then conducted an experiment with 26 Daphnia pulicaria clones obtained from six of these lakes and observed the production of buoyant and non‐buoyant ephippia under high and low food conditions. 3. Ephippia were more often non‐buoyant than buoyant both from females caught in nature and those reared in the laboratory. The experiment revealed that each clone was able to produce both types of ephippia, but that there was considerable among‐clone variation in the percentage of non‐buoyant ephippia produced. 4. We conclude that production of non‐buoyant versus buoyant ephippia may be driven by both genetic and environmental factors.     

Ontogeny of worker body size distribution in bumble bee (Bombus impatiens) colonies

1. Bumble bees exhibit worker size polymorphisms; highly related workers within a colony may vary up to 10‐fold in body mass. As size variation is an important life history feature in bumble bees, the distribution of body sizes within the colony and how it fluctuates over the colony cycle were analysed. 2. Ten commercially purchased colonies of Bombus impatiens (Cresson) were reared in ad libitum conditions. The size of all workers present and newly emerging workers (callows) was recorded each week. 3. The average size of bumble bee workers did not change with colony age, but variation in body size tended to decrease over time. The average size of callows did not change with population size, but did tend to decrease with colony age. In all measures, there was considerable variation among colonies. 4. Colonies of B. impatiens usually produced workers with normally distributed body sizes throughout the colony life cycle. Unlike most polymorphic ants, there was no increase in worker body size with colony age or colony size. This provides the first, quantitative data on the ontogeny of bumble bee worker size distribution. The potential adaptive significance of this size variation is discussed.     

Spatio-temporal impact of climate change on the activity and voltinism of the spruce bark beetle, Ips typographus

The spruce bark beetle Ips typographus is one of the major insect pests of mature Norway spruce forests. In this study, a model describing the temperature-dependent thresholds for swarming activity and temperature requirement for development from egg to adult was driven by transient regional climate scenario data for Sweden, covering the period of 1961–2100 for three future climate change scenarios (SRES A2, A1B and B2). During the 20th century, the weather supported the production of one bark beetle generation per year, except in the north-western mountainous parts of Sweden where the climate conditions were too harsh. A warmer climate may sustain a viable population also in the mountainous part; however, the distributional range of I. typographus may be restricted by the migration speed of Norway spruce. Modelling suggests that an earlier timing of spring swarming and fulfilled development of the first generation will significantly increase the frequency of summer swarming. Model calculations suggest that the spruce bark beetle will be able to initiate a second generation in South Sweden during 50% of the years around the mid century. By the end of the century, when temperatures during the bark beetle activity period are projected to have increased by 2.4–3.8 °C, a second generation will be initiated in South Sweden in 63–81% of the years. The corresponding figures are 16–33% for Mid Sweden, and 1–6% for North Sweden. During the next decades, one to two generations per year are predicted in response to temperature, and the northern distribution limit for the second generation will vary. Our study addresses questions applicable to sustainable forest management, suggesting that adequate countermeasures require monitoring of regional differences in timing of swarming and development of I. typographus , and planning of control operations during summer periods with large populations of bark beetles.