Javier A. Alonso

Prevalence and Factors Associated With Circadian Blood Pressure Patterns in Hypertensive Patients

Ambulatory blood pressure (BP) monitoring has become useful in the diagnosis and management of hypertensive individuals. In addition to 24-hour values, the circadian variation of BP adds prognostic significance in predicting cardiovascular outcome. However, the magnitude of circadian BP patterns in large studies has hardly been noticed. Our aims were to determine the prevalence of circadian BP patterns and to assess clinical conditions associated with the nondipping status in groups of both treated and untreated hypertensive subjects, studied separately. Clinical data and 24-hour ambulatory BP monitoring were obtained from 42 947 hypertensive patients included in the Spanish Society of Hypertension Ambulatory Blood Pressure Monitoring Registry. They were 8384 previously untreated and 34 563 treated hypertensives. Twenty-four-hour ambulatory BP monitoring was performed with an oscillometric device (SpaceLabs 90207). A nondipping pattern was defined when nocturnal systolic BP dip was <10% of daytime systolic BP. The prevalence of nondipping was 41% in the untreated group and 53% in treated patients. In both groups, advanced age, obesity, diabetes mellitus, and overt cardiovascular or renal disease were associated with a blunted nocturnal BP decline (P<0.001). In treated patients, nondipping was associated with the use of a higher number of antihypertensive drugs but not with the time of the day at which antihypertensive drugs were administered. In conclusion, a blunted nocturnal BP dip (the nondipping pattern) is common in hypertensive patients. A clinical pattern of high cardiovascular risk is associated with nondipping, suggesting that the blunted nocturnal BP dip may be merely a marker of high cardiovascular risk.

A field test of ideal free distribution in flock-feeding common cranes

This is a contribution to Project PB91-0081 of the Direccion General de Investigacion Cientifica y Tecnica.

Patch use in cranes: a field test of optimal foraging predictions

Abstract The marginal value theorem states that foragers should leave patches when the instantaneous capture rate has fallen to the average capture rate for the habitat. This predicts that patch residence time should increase with increasing patch quality and decrease with increasing habitat quality. These and other predictions from prescient, Bayesian and fixed-time models were tested using observations on 14 radio-tagged free-living common cranes,Grus grus, foraging in cereal farmland. Cranes behaved as Bayesian foragers. Their intake rates on leaving patches changed with patch and habitat quality. The behaviour of cranes was consistent with marginal value theorem predictions only in patches where energy return was lower than required to meet daily food requirements. In contrast, birds left richer patches earlier than expected and at higher intake rates than poor patches. In addition, cranes stayed longer in larger flocks. These results suggest that cranes changed their foraging rules according to their expected energy balance.

Mitigation of bird collisions with transmission lines through groundwire marking

Abstract A study was conducted to evaluate the effectiveness of groundwire marking in reducing bird mortality through collision at a power transmission line in southwestern Spain. Monthly flight intensity observations and weekly searches for dead birds were carried out at four sectors of the line comprising 28·2 km, during two consecutive winters, 1989–1990 and 1990–1991, respectively before and after groundwire marking with coloured PVC spirals. Flight intensity and collision frequency decreased respectively by 61% and 60% at marked spans compared to the same spans prior to marking, while there was no significant change in collision frequency at spans left unmarked. After marking, the percentage of birds flying between the cables decreased and that flying above them increased. Our results suggest that many birds avoided flying across the marked spans of the line or climbed while approaching them, and therefore collided less frequently. The percentage decrease in mortality observed in our study falls within the range of results of other groundwire marking or removal studies.

PARTIAL MIGRATION, AND LEK AND NESTING AREA FIDELITY IN FEMALE GREAT BUSTARDS

Abstract We examined the seasonal movements of wing-tagged and radio-marked adult female Great Bustards Otis tarda in a population in northwestern Spain. Four different movement patterns were found: females that migrated between breeding and wintering areas (20%), females that only left their year-round home range area to mate (32%), females that migrated from a wintering-mating area to a nesting-summering area (16%), and females that stayed all year round within a relatively small home range area (32%). All females displayed fidelity to their nesting and wintering areas, and most also showed fidelity to their leks. Migration patterns were not affected either in timing or distance by breeding success. The maximum distance between natal and dispersal locations during their first year of life was significantly higher in migratory females than in sedentary ones. These patterns explained the seasonal variations in population numbers observed in the study area. Surveys showed that the number of females increased from 600–700 breeding birds, with 1,000–1,100 birds present from October to March.

Carrying capacity of staging areas and facultative migration extension in common cranes

This is a contribution to projects PB87-0389 and PB91-0081 of the Direccion General de Investigacion Cientifica y Tecnica.

Natal dispersal in great bustards: the effect of sex, local population size and spatial isolation

1. We investigated the causes of natal dispersal in four Spanish areas where 35 breeding groups of the polygynous great bustard Otis tarda were monitored intensively. A total of 392 juveniles were radio-tracked between 1991 and 2006 by ground and via aeroplane to avoid potential biases derived from the non-detection of long-distance dispersers. 2. We explored 10 explanatory variables that were related to individual phenotypic features, habitat and conspecific traits in terms of group size and breeding performance, and spatial distribution of available breeding groups. Probability of group change and natal dispersal distances were investigated separately through multifactorial analyses. 3. Natal dispersal occurred in 47.8% of the birds and median natal dispersal distance of dispersers was 18.1 km (range 4.97-178.42 km). Sex largely determined the dispersal probability, with 75.6% of males being dispersers and 80.0% of females being philopatric, in contrast to the general pattern of female-biased dispersal found in most avian species. 4. Both the frequency of natal dispersal and dispersal distances were affected by the spatial distribution of breeding groups. More isolated groups showed a higher proportion of philopatric individuals, the effect being more evident in males than in females. This implies a reduction in gene flow in fragmented populations, as most genetic exchange is achieved through male dispersal. Additionally, dispersers hatched in more isolated groups tended to exhibit longer dispersal distances, which increases the associated energetic costs and mortality risks. 5. The dispersal decision was influenced by the number of conspecifics in the natal group. The individual probability of natal dispersal was related inversely to the size of the natal group, which supports the balanced dispersal model and the conspecific attraction hypothesis. 6. Overall, our results provide a good example of phenotypic plasticity and reinforce the current view that dispersal is an evolutionary complex trait conditioned by the interaction of individual, social and environmental causes that vary between individuals and populations.

Migration Patterns in Male Great Bustards (Otis tarda)

The Great Bustard (Otis tarda) is distributed from Iberia and Morocco in the west to China in the east and has been considered sedentary in all but the northern and eastern parts of its range (Gewalt 1959, Glutz et al. 1973, Cramp and Simmons 1980). However, some studies have reported seasonal changes in population numbers in different areas in the Iberian Peninsula (Hidalgo and Carranza 1990, Alonso et al. 1995), suggesting that the species is a partial migrant (sensu Terrill and Able 1988) in this region. We describe seasonal movements of marked adult male Great Bustards and discuss observed patterns in relation to the following questions: (1) Do migratory males display interannual fidelity to breeding and postbreeding areas? (2) Do males travel significantly farther than females in their seasonal movements? We also suggest several hypotheses that could explain patterns of partial and differential migration in male Great Bustards. Methods.—Our study was carried out in the Wildlife Reserve of Villafafila (41 50 N, 5 35 W; ca. 700 m elevation), which extends over 32,682 ha of dry, treeless and gently undulating farmland in the Province of Zamora, northwestern Spain. The land is almost entirely cultivated with wheat and barley. The remaining surface (ca. 9%) is occupied by natural grassland used for sheep grazing. The Reserve holds the world’s densest population of Great Bustards (Alonso et al. 1995), which are ground-dwelling lekking birds that inhabit natural and cultivated grasslands. The Great Bustard is endangered in most of its range except for the Iberian Peninsula, which is the main stronghold for the species (Alonso and Alonso 1996). It exhibits one of the highest amounts of sexual size dimorphism of all vertebrates, and males and females generally occur in separate flocks. Between late winter and early spring, males concentrate at traditional arenas where they fight to establish rank and display in an exploded-lek mating system (see Hoglund and Alatalo 1995). Juvenile males usually disperse after independence. From their third year on, they begin to establish territories at

Endothelin-1 Upregulation in the Kidney of Uninephrectomized Spontaneously Hypertensive Rats and Its Modification by the Angiotensin-Converting Enzyme Inhibitor Quinapril

Endothelin (ET-1) is a potent vasoconstrictor that plays an important role in the control of renal circulation and tubular function. The contribution of this peptide to the pathogenesis of systemic hypertension and renal failure remains largely undefined. In spontaneously hypertensive rats (SHR) uninephrectomized at 20 weeks of age (UNX-SHR) and followed until 45 weeks of age, we determined ET-1 gene expression in renal tissue by reverse transcription-polymerase chain reaction and its localization by in situ hybridization in paraffin-embedded kidney sections. Age-matched SHR and normotensive Wistar-Kyoto (WKY) rats were chosen as controls. At the end of the follow-up, UNX-SHR had high systolic blood pressure, intense proteinuria, mesangial expansion, focal and segmental glomerular sclerosis, and tubulointerstitial lesions. In relation to WKY and SHR, UNX-SHR exhibited an increase in ET-1 gene expression in renal cortex and medulla. By in situ hybridization and immunoperoxidase staining, an overexpression of ET-1 gene and protein were seen in mesangial and glomerular epithelial cells and in some proximal tubules and vessels. Angiotensin-converting enzyme (ACE) activity was significantly increased in the renal brush border. Since in mesangial cells, angiotensin II induces ET-1 synthesis, a group of UNX-SHR received the ACE inhibitor quinapril from the time of UNX. These animals had a decrease in blood pressure, proteinuria, and serum and brush border ACE activity and in the expression and synthesis of ET-1 in all renal areas. On the whole, these data show that UNX-SHR have an upregulation of ET-1 gene and protein in several structures of the kidney compared with SHR and WKY rats. Quinapril diminished ACE activity and ET-1 expression and synthesis coincidentally with an improvement in proteinuria and morphological lesions. The beneficial effects of ACE inhibitors may be due to the diminution of both angiotensin II and ET-1 generation.

Great bustard population structure in central Spain: concordant results from genetic analysis and dispersal study

We found significant sex differences in the mtDNA genetic structure and dispersal patterns of great bustards in a population of 11 breeding groups, ‘leks’, in central Spain. The analysis of genetic distances showed that the female population was divided into three groups of leks separated by ca. 50 km, whereas male haplotypes were randomly distributed among leks. Genetic distances among pairs of leks were positively correlated with geographical distances in females but not in males. While female haplotype distributions were homogeneous among leks at close distances, differences in male genetic structure were highly variable even between two close leks. These results from genetic analyses were concordant with those from a radiotracking study on natal dispersal. Natal dispersal distances were higher in males than in females. Also, the frequency of movement of a female between two leks was positively correlated with their genetic affinity and geographical proximity. In males, the frequency of movement was correlated with geographical proximity but not with genetic affinity. Males dispersed among genetically unrelated leks, contributing to keep nuclear genetic diversity in the population, whereas females tended to be philopatric. These results suggest that isolation–by–distance influences the distribution of maternal lineages at a regional level.