Daily and seasonal variations ofAlternaria andCladosporium airborne spores in León (North-West, Spain)

The spores ofAlternaria andCladosporium are present throughout the year in the atmosphere of León (NW Spain), although they show an important seasonal variation. To understand the relationship between the number of spores and climatic factors,Alternaria andCladosporium spores counts for January 1994 to December 1995 were examined by means of correlation analyses. The results of weekly samples of both years showed that the spores concentration of two taxa are significantly and positively correlated with maximum and minimum temperature and sunshine hours and negatively with relative humidity. The statistical analysis of daily samples generally showed the same results. In the hourly distribution of spore concentrations we can see a similar behaviour ofAlternaria andCladosporium, with most spores collected in the 12–14 h period.     

SDF-1 alpha regulates mesendodermal cell migration during frog gastrulation

During frog gastrulation, mesendodermal cells become apposed to the blastocoel roof (BCR) by endoderm rotation, and migrate towards the animal pole. The leading edge of the mesendodermal cells (LEM) contributes to the directional migration of involuting marginal zone (IMZ) cells, but the molecular mechanism of this process is not well understood. Here we show that CXCR4/SDF-1 signaling mediates the directional movement of the LEM in Xenopus embryos. Expression of xCXCR4 was detected in the IMZ, and was complemented by xSDF-1alpha expression in the inner surface of the BCR. Over-expression of xCXCR4 and xSDF-1alpha caused gastrulation defects. An xCXCR4 N-terminus deletion construct and xSDF-1alpha-MO also inhibited gastrulation. Furthermore, explants of LEM migrate towards the dorsal BCR in the presence of xSDF-1alpha, and altered xCXCR4 expression in the LEM inhibited LEM migration. These results suggest that CXCR4/SDF-1 signaling is necessary for the migrations of massive numbers of cells during gastrulation.     

Nonideal nest box selection by tree swallows breeding in farmlands: Evidence for an ecological trap?

Animals are expected to select a breeding habitat using cues that should reflect, directly or not, the fitness outcome of the different habitat options. However, human‐induced environmental changes can alter the relationships between habitat characteristics and their fitness consequences, leading to maladaptive habitat choices. The most severe case of such nonideal habitat selection is the ecological trap, which occurs when individuals prefer to settle in poor‐quality habitats while better ones are available. Here, we studied the adaptiveness of nest box selection in a tree swallow (Tachycineta bicolor) population breeding over a 10‐year period in a network of 400 nest boxes distributed along a gradient of agricultural intensification in southern Québec, Canada. We first examined the effects of multiple environmental and social habitat characteristics on nest box preference to identify potential settlement cues. We then assessed the links between those cues and habitat quality as defined by the reproductive performance of individuals that settled early or late in nest boxes. We found that tree swallows preferred nesting in open habitats with high cover of perennial forage crops, high spring insect biomass, and high density of house sparrows (Passer domesticus), their main competitors for nest sites. They also preferred nesting where the density of breeders and their mean number of fledglings during the previous year were high. However, we detected mismatches between preference and habitat quality for several environmental variables. The density of competitors and conspecific social information showed severe mismatches, as their relationships to preference and breeding success went in opposite direction under certain circumstances. Spring food availability and agricultural landscape context, while related to preferences, were not related to breeding success. Overall, our study emphasizes the complexity of habitat selection behavior and provides evidence that multiple mechanisms may potentially lead to an ecological trap in farmlands.     

Describing and understanding behavioral responses to multiple stressors and multiple stimuli

Understanding the effects of environmental change on natural ecosystems is a major challenge, particularly when multiple stressors interact to produce unexpected “ecological surprises” in the form of complex, nonadditive effects that can amplify or reduce their individual effects. Animals often respond behaviorally to environmental change, and multiple stressors can have both population‐level and community‐level effects. However, the individual, not combined, effects of stressors on animal behavior are commonly studied. There is a need to understand how animals respond to the more complex combinations of stressors that occur in nature, which requires a systematic and rigorous approach to quantify the various potential behavioral responses to the independent and interactive effects of stressors. We illustrate a robust, systematic approach for understanding behavioral responses to multiple stressors based on integrating schemes used to quantitatively classify interactions in multiple‐stressor research and to qualitatively view interactions between multiple stimuli in behavioral experiments. We introduce and unify the two frameworks, highlighting their conceptual and methodological similarities, and use four case studies to demonstrate how this unification could improve our interpretation of interactions in behavioral experiments and guide efforts to manage the effects of multiple stressors. Our unified approach: (1) provides behavioral ecologists with a more rigorous and systematic way to quantify how animals respond to interactions between multiple stimuli, an important theoretical advance, (2) helps us better understand how animals behave when they encounter multiple, potentially interacting stressors, and (3) contributes more generally to the understanding of “ecological surprises” in multiple stressors research.     

Erratum to: Weather-induced ischemia and arrhythmia in patients undergoing cardiac rehabilitation: another difference between men and women

Given the accumulating evidence that people with underlying heart disease are a particularly vulnerable group for triggers like changing meteorological parameters, the objective of this longitudinal study was to analyze the influence of weather parameters on blood pressure, arrhythmia and ischemia in cardiovascular patients. A panel study with repeated measurements was conducted in a rehabilitation clinic in Timmendorfer Strand (Baltic Sea, Germany) with 872 cardiovascular patients. Heart rate, blood pressure and electrocardiography changes were measured during repeated bicycle ergometries. Generalized Estimating Equations were used for regression analyses of immediate, delayed and cumulative influences of the daily measured meteorological data. For men, a decrease in air temperature and in water vapor pressure doubled the risk of ST-segment depression during ergometry [odds ratio (OR) for 1 day delay: 1.88 (1.24; 2.83) for air temperature] with a delay of 1-2 days. For women, an increase of their heart rate before the start of the ergometry [same day: 4.36 beats/min (0.99; 7.74) for air temperature] and a 2- to 3-fold higher risk for ventricular ectopic beats [1 day delay: OR 2.43 (1.17; 5.05) for air temperature] was observed with an increase in temperature and water vapor pressure in almost all analyzed time-windows. The study indicates that meteorological parameters can induce changes in heart function which may lead to adverse cardiovascular events especially in susceptible, diseased individuals. The observed effect on ST-segment depression could be a link between the association of weather changes and cardiovascular morbidity and mortality.     

Influence of weather on reproductive success of northern fulmars in the Canadian high Arctic

The northern fulmar (Fulmarus glacialis) is a common seabird of the North Atlantic Ocean, with breeding colonies broadly dispersed between 45°N and 80°N. At higher latitudes, breeding fulmars experience extensive sea-ice and presumably snow and low temperatures which do not affect fulmars in the southern part of the breeding range. We studied the relationship between weather and reproductive success of northern fulmars breeding at two colonies in the Canadian high Arctic. Collectively, hatching success, fledging success, and productivity (chicks fledged per egg laid) were similar between our study and results from colonies located south of the Arctic. However, a larger proportion of fulmars at apparently occupied sites (AOS) in high Arctic colonies appeared to forego egg-laying, resulting in lower proportions of chicks fledged per AOS. Extreme inclement weather was the major factor influencing nesting success, resulting in pulses of egg or chick loss during or immediately following major storms, although the mechanism of effects appeared to differ between the two colonies. For Arctic fulmars, the risks of nest failure due to stochastic, deleterious weather events may be offset by the predictable abundance of food supplies during chick-rearing in Arctic waters.     

Maximum vehicle cabin temperatures under different meteorological conditions

A variety of studies have documented the dangerously high temperatures that may occur within the passenger compartment (cabin) of cars under clear sky conditions, even at relatively low ambient air temperatures. Our study, however, is the first to examine cabin temperatures under variable weather conditions. It uses a unique maximum vehicle cabin temperature dataset in conjunction with directly comparable ambient air temperature, solar radiation, and cloud cover data collected from April through August 2007 in Athens, GA. Maximum cabin temperatures, ranging from 41–76°C, varied considerably depending on the weather conditions and the time of year. Clear days had the highest cabin temperatures, with average values of 68°C in the summer and 61°C in the spring. Cloudy days in both the spring and summer were on average approximately 10°C cooler. Our findings indicate that even on cloudy days with lower ambient air temperatures, vehicle cabin temperatures may reach deadly levels. Additionally, two predictive models of maximum daily vehicle cabin temperatures were developed using commonly available meteorological data. One model uses maximum ambient air temperature and average daily solar radiation while the other uses cloud cover percentage as a surrogate for solar radiation. From these models, two maximum vehicle cabin temperature indices were developed to assess the level of danger. The models and indices may be useful for forecasting hazardous conditions, promoting public awareness, and to estimate past cabin temperatures for use in forensic analyses.     

Altitudinal distribution of territorial Pallas’s Leaf Warblers (Phylloscopus proregulus) in Korea and its disruption by fir (Abies)-planting

Pallas’s Leaf Warbler (Phylloscopus proregulus) is a common breeding bird above 700 m in the forests of the Myohyang range, Korea. Within the largely natural forest are several temple gardens, four of which at 140–520 m held territorial Pallas’s Leaf Warblers. All had mature planted firs (Abies), which occur naturally in the area only over 1,000 m. The planted firs evidently stimulated the warblers to settle below their natural altitudinal range, but cannot be the only stimulus because the natural lower distribution of the warbler is 300 m below that of the tree.     

Incubation behaviour of the Meadow Pipit (Anthus pratensis) in an alpine ecosystem of Central Europe

Incubation behaviour of the Meadow Pipit (Anthus pratensis) was investigated in mountainous conditions in Central Europe (the Krkonoše Mountains of the Czech Republic), in relation to the time of day and weather. Twenty-four-hour recordings of incubation behaviour were made with a time-lapse video recorder and mini-camera. The influences of year, nest, time of day, temperature, precipitation and previous bouts on session and recess duration were then analysed. The incubation behaviour of Meadow Pipits in general did not differ from the behaviour of other small female-only incubating passerines. Despite relatively cold climatic conditions in the study area, the mean length of sessions and recesses (19.69 and 5.53 min), as well as nest-attentiveness (77.19%), agreed with values which are most often found in other species. However, the Meadow Pipit incubation in the study area was, in terms of nest-attentiveness, more intensive than in other surveyed populations of this species. Incubation behaviour was strongly influenced by the time of day—incubating females increased nest-attentiveness during the morning and evening hours. After the time of day was filtered out, the influence of temperature was found only on sessions (not recesses). Sessions were the longest when the air temperature was approximately 12–16°C and shortened when the temperature was lower or higher. Precipitation forced female Meadow Pipits to take longer sessions and shorter recesses, which corresponds to their general tendency to give priority to the needs of the clutch ahead of their own temporary feeding needs.