Carlos Lara-Romero

Assessing Intraspecific Variation in Effective Dispersal Along an Altitudinal Gradient: A Test in Two Mediterranean High-Mountain Plants

Background Plant recruitment depends among other factors on environmental conditions and their variation at different spatial scales. Characterizing dispersal in contrasting environments may thus be necessary to understand natural intraspecific variation in the processes underlying recruitment. Silene ciliata and Armeria caespitosa are two representative species of cryophilic pastures above the tree line in Mediterranean high mountains. No explicit estimations of dispersal kernels have been made so far for these or other high-mountain plants. Such data could help to predict their dispersal and recruitment patterns in a context of changing environments under ongoing global warming. Methods We used an inverse modelling approach to analyse effective seed dispersal patterns in five populations of both Silene ciliata and Armeria caespitosa along an altitudinal gradient in Sierra de Guadarrama (Madrid, Spain). We considered four commonly employed two-dimensional seedling dispersal kernels exponential-power, 2Dt, WALD and log-normal. Key Results No single kernel function provided the best fit across all populations, although estimated mean dispersal distances were short (<1 m) in all cases. S. ciliata did not exhibit significant among-population variation in mean dispersal distance, whereas significant differences in mean dispersal distance were found in A. caespitosa. Both S. ciliata and A. caespitosa exhibited among-population variation in the fecundity parameter and lacked significant variation in kernel shape. Conclusions This study illustrates the complexity of intraspecific variation in the processes underlying recruitment, showing that effective dispersal kernels can remain relatively invariant across populations within particular species, even if there are strong variations in demographic structure and/or physical environment among populations, while the invariant dispersal assumption may not hold for other species in the same environment. Our results call for a case-by-case analysis in a wider range of plant taxa and environments to assess the prevalence and magnitude of intraspecific dispersal variation.

Non-invasive monitoring of adrenocortical activity in European badgers (Meles meles) and effects of sample collection and storage on faecal cortisol metabolite concentrations

Due to the increasing demand for methods to quantify adrenal activity in response to stressors in wild animals, we evaluated whether stimulation with adrenocorticopic hormone (ACTH) increases faecal cortisol metabolite levels in European badgers. We also conducted several experiments to evaluate the effect of storage time and collection methods on cortisol metabolite levels of faecal samples. Faecal samples were collected from five captive European badgers (Meles meles) and cortisol metabolites were quantified by an enzyme immunoassay. Faecal cortisol metabolite levels increased 1-2 days after ACTH injection and dropped to pre-treatment levels 3 days after ACTH stimulation. We found that cortisol metabolite levels were not affected by the 8-hour time lapse from collection in the field until freezing of faecal samples, environmental exposure (temperature 25.66 ± 2.55°C; range 21.2032.20) or mean relative humidity 62.77 ± 9.90% (range 42.00-79.00). Cortisol metabolites were not homogenously distributed in the scats. Cortisol metabolite levels were significantly lower when faecal extracts and samples were frozen for long periods of time (14 weeks or more). Thus, the measurement of faecal cortisol metabolites is a suitable method for the non-invasive evaluation of adrenocortical activity in European badgers. However, some aspects related to the collection and storage of faecal samples should be considered in future studies conducted with this species.

Direct and indirect effects of shrub encroachment on alpine grasslands mediated by plant–flower visitor interactions

Summary Mutualistic interactions structure ecological communities and they are strongly influenced by the combined effect of different drivers of global change. Land-use changes and global warming have elicited rapid shrub encroachment in alpine grasslands in recent decades, which may have detrimental outcomes for native alpine forbs. In spite of the importance of this process, we lack knowledge about how shrub encroachment modifies community-wide patterns of plant–pollinator mutualistic interactions. Based on the functional biodiversity hypothesis (FBH), which predicts higher pollinator biodiversity in species-rich plant communities, we asked whether the increase in nutritional resources available for pollinators due to shrub expansion modifies pollinator niche breadth and species richness, and whether these changes affect plant–plant interactions. For this purpose, we compared quantitative plant–flower visitor interaction network assemblages at replicated plots in two habitat types in dry cryophilic grasslands of Sierra de Guadarrama (Spain): (i) encroached pastures (EP) and (ii) pastures dominated by forb species where shrub species are absent (PA). As predicted by FBH, flower visitor richness increased in EP, but their niche breadth did not vary. Furthermore, shrubs had more interactions with flower visitors and received more visits per plant than forbs in EP in agreement with their significantly higher linkage and strength. Overall, results revealed that moderate levels of shrub encroachment affected the flower visitation patterns of forb species in alpine grasslands as flower visitor diversity increased and plant–plant competition for shared flower visitors became greater. These findings highlight the need to use an integrative approach to study the cascading effects of global change drivers on species interactions and their impact on the structure and functioning of threatened ecological communities.

Characterization of microsatellites in the mountain plant Armeria caespitosa (Plumbaginaceae) and transferability to congeners

PREMISE OF THE STUDY The focus of this study is to develop microsatellite markers in Armeria caespitosa, a narrow endemic of central Spain. Microsatellite loci are sought to clarify population structure and estimate gene flux among populations. METHODS AND RESULTS Enriched microsatellite genomic libraries were used for microsatellite isolation. Sixteen microsatellite loci were characterized, eight of which can be used for successful genotyping. Allele number ranged from two to seven per locus. Observed and expected heterozygosity ranged from 0.300 to 0.800 and from 0.296 to 0.733, respectively. Cross-amplification of seven and six loci was successful for A. maritima and A. cantabrica, respectively. CONCLUSIONS These microsatellites are suitable in the study of population genetics and gene flow among A. caespitosa populations. The information provided by these markers may be useful in the study of this plants response to global warming.

A new large-scale index (AcED) for assessing traffic noise disturbance on wildlife: stress response in a roe deer (Capreolus capreolus) population

Anthropogenic noise is a growing ubiquitous and pervasive pollutant as well as a recognised stressor that spreads throughout natural ecosystems. However, there is still an urgent need for the assessment of noise impact on natural ecosystems. This article presents a multidisciplinary study which made it possible to isolate noise due to road traffic to evaluate it as a major driver of detrimental effects on wildlife populations. A new indicator has been defined: AcED (the acoustic escape distance) and faecal cortisol metabolites (FCM) were extracted from roe deer faecal samples as a validated indicator of physiological stress in animals moving around in two low-traffic roads that cross a National Park in Spain. Two key findings turned out to be relevant in this study: (i) road identity (i.e. road type defined by traffic volume and average speed) and AcED were the variables that best explained the FCM values observed in roe deer, and (ii) FCM concentration was positively related to increasing traffic volume (road type) and AcED values. Our results suggest that FCM analysis and noise mapping have shown themselves to be useful tools in multidisciplinary approaches and environmental monitoring. Furthermore, our findings aroused the suspicion that low-traffic roads (< 1000 vehicles per day) could be capable of causing higher habitat degradation than has been deemed until now.