Publicaciones Científicas

de la Peña, E., Barja, I. & Carranza, J. (2021)

de la Peña, E., Barja, I. & Carranza, J. (2021). Social environment with high intrasexual competition enhances the positive relationship between faecal testosterone and cortisol metabolite levels in red deer. Mammalian Biology

The relationship between reproductive and physiological stress hormones in vertebrates is poorly understood. In many species of mammals and especially in humans, the most widespread idea is that there is a negative relationship between them, i.e. higher stress levels are associated with lower testosterone levels. Likewise, the subordination stress paradigm supports that subordinates suffer greater stress in a competitive situation, while the dominant ones have higher levels of testosterone. However, this predominant idea of a negative relationship between testosterone and cortisol concentrations may be influenced by unnatural circumstances, such as chronic stress in humans or forced interactions between subordinates and dominants in laboratory or captivity. Some studies have reported that dominant males under natural conditions may show higher physiological stress and also higher testosterone levels than subordinates. But for this positive relationship, the question is whether there is a causal link or whether both hormones only coincide due to other factors. We hypothesized that testosterone should be related to physiological stress only as a result of individual males being subjected to stressful situations, such as intrasexual competition. We studied this topic in Iberian red deer (Cervus elaphus hispanicus) males in two types of populations with high and low levels of intrasexual competition. We found a positive relationship between faecal testosterone and cortisol metabolite levels, but also a significant interaction showing that this relationship occurs more intensely in populations with high competition level for mating. These results reinforce the positive relationship between both hormones under natural conditions and support the hypothesis that it is mediated by male-male competition for mates.

F. Millán, M. et al. (2021)

F. Millán, M., Carranza, J., Pérez-González, J., Valencia, J., Torres-Porras, J., Seoane, J.M., de la Peña, E., Alarcos, S., Sánche-Prieto, C., Castillo, L., Flores, A, Membrillo; A. (2021) Rainfall decrease and red deer rutting behaviour: Weaker and delayed rutting activity though higher opportunity for sexual selection. PLoS ONE 16(1): e0244802.

In the last decades, climate change has caused an increase in mean temperatures and a reduction in average rainfall in southern Europe, which is expected to reduce resource availability for herbivores. Resource availability can influence animals’ physical condition and population growth. However, much less is known on its effects on reproductive performance and sexual selection. In this study, we assessed the impact of three environmental factors related to climate change (rainfall, temperature and vegetation index) on Iberian red deer Cervus elaphus hispanicus reproductive timing and sexual behaviour, and their effects on the opportunity for sexual selection in the population. We measured rutting phenology as rut peak date, the intensity of male rutting activity as roaring rate, and the opportunity for sexual selection from the distribution of females among harem holding males in Doñana Biological Reserve (Southwest Spain), from data of daily observations collected during the rut over a period of 25 years. For this study period, we found a trend for less raining and hence poorer environmental conditions, which associated with delayed rutting season and decreased rutting intensity, but that appeared to favour a higher degree of polygyny and opportunity for sexual selection, all these relationships being modulated by population density and sex ratio. This study highlights how climate change (mainly rainfall reduction in this area) can alter the conditions for mating and the opportunity for sexual selection in a large terrestrial mammal.

Barros, T. et al. (2020)

Barros, T., Ferreira, E., Rocha, R.G., Brotas, G., Carranza, J., Fonseca, C. y Torres, R.T. (2020)  The Multiple Origins of Roe Deer Populations in Western Iberia and Their Relevance for Conservation. Animals 2020, 10, 2419.

The roe deer (Capreolus capreolus) is native and widespread in Europe and its phylogeography has been clarified in the last decades. Southern peninsulas are considered as reservoirs of genetic diversity and the source for the recolonization of Europe after the last glacial maximum. Even though roe deer populations have been genetically characterized, there is a major knowledge gap about the populations at the western edge of its distribution. To fill this caveat, and based on mitochondrial and nuclear DNA data, we aim to: (i) characterize the genetic diversity and structure of roe deer in western Iberia; (ii) clarify the origins and phylogeographical affinities of these populations, namely the relict population from Peneda Gerês National Park (PNPG, Portugal) and the likely allochthonous populations from central and south (CS) Portugal; (iii) discuss the implications of our findings for the management and conservation of the roe deer. Three major genetic clusters were inferred based on nuclear genotypes and were structured in a similar way as the three major mtDNA clades present in Iberia. Patterns inferred with nuclear markers confirmed PNPG as a relict population. Roe deer from CS Portugal share haplotypes with Central Europe rather than with other western Iberian populations, confirming its mainly allochthonous origin. Our results highlight western Iberia as a diversity hotspot for roe deer. We highlight the role of intraspecific genetic diversity as a source of resilience against ongoing global changes; the need for transboundary management and the importance of genetic data to inform management and conservation. When considered, repopulation or translocation measures should follow the IUCN Law of Reintroductions and meticulously conducted in order to preserve the genetic heritage of the species.

Broggini, C. et al. (2020)

Broggini, C., Membrillo, A. y Carranza, J. (2020) An open platform system based on SNP type genetic markers for discrimination between Alectoris rufa and Alectoris chukar Molecular and Cellular Probes, Volume 54 (2020) 101673. ISSN 0890-8508.

The red-legged partridge (Alectoris rufa) is one of the most emblematic game species in Southern Europe. For the conservation of its natural populations against hybridization with chukar partridges (Alectoris chukar) a public and agreed control system able to detect genetic introgression between the two species should be established. As the already available method has not been implemented yet, this paper presents an improvement of the genetic analysis technique by using an open platform system to optimize the diagnostic procedure. Here we present the results obtained from the design of an Open Array™ platform with the available SNPs with proved diagnosis capacity between the two species of interest. By this procedure we genotyped 380 partridge samples, both from farms and field populations, which resulted in an overall percentage of genotyping performed with success of 99.64%. The Open Array genotyping plates showed high performance, specificity and an easy reproducibility compared to conventional techniques of genotyping.

Carranza, J. et al. (2020)

Carranza, J., de la Peña, E., Mateos, C., Pérez-González, J., Alarcos, S., Torres-Porras, J., Valencia, J., Sánchez-Prieto, C., Castillo, L. (2020) The dark ventral patch: A bimodal flexible trait related to male competition in red deer. PLoS ONE 15(11): e0241374.

Sexual signals play a central role in male-male competition in polygynous species. In red deer (Cervus elaphus), male’s ventral area become dark during the rutting season due to urine spraying behaviour and retains many chemical compounds potentially revealing individual features. Here we investigate the variation in size of this trait, exploring its relationship with age and male competitive features such as antlers or body size, as well as populational level of intrasexual competition for mates. We found that the size of the dark ventral patch followed a clearly bimodal distribution, i.e. males mostly expressed the full-size trait or just developed a very small one. For these two groups of males according to trait expression, the relationships of trait size with age and antler size differed. Populational level of intrasexual competition appeared to affect the relationship between antler size and the probability of a fully developed ventral patch. These results indicate that the trait encodes information on body size, antler size, age and populational level of mate competition, thus suggesting a role in signalling male’s competitive features and willingness to allocate reproductive effort within a particular season.

Guzmán, J.L. et al. (2020)

Guzmán, J.L., Viñuela, J., Carranza, J., Torres Porras, J. y Arroyo, B. (2020) Red-legged partridge Alectoris rufa productivity in relation to weather, land use, and releases of farm-reared birds. European Journal of Wildlife Research 66:87 (2020).

Productivity (offspring production) is a key demographic parameter influencing population dynamics, particularly in r-strategy species, and thus critical for implementing well-based management of populations. Accordingly, the study of factors influencing productivity is useful to develop management strategies in species of conservation concern or subject to exploitation. We studied productivity (covey size and young/adult ratio) of red-legged partridges (Alectoris rufa) in Spain through a large-scale sampling in Andalucia and Castilla-La Mancha, two large areas in central-southern Spain, the core of the distribution of the species. We evaluated potential environmental factors related with productivity that have been considered important in previous local studies (weather, land use, and intensity of releases of farm-reared partridges), using a dataset of 15,357 observations of partridges over three breeding seasons (2010, 2011, and 2012). Average productivity at the end of July was 3 young/adult, indicating 50% chick mortality between hatching and fledging and high breeding failure. We found marked effects of weather, year, and land use on partridge productivity, confirming some previous results at local scale and supporting widespread and simultaneous effects of these factors. We also detected a large-scale negative relationship with farm-bred partridge release intensities, with lower young/ adult ratios in areas with high release intensity. This suggests that partridge releases may be contributing to the decline of wild populations. Our results support that correcting the effects of agricultural intensification is the main key to the long-term conservation of the species and suggest that, in dry spring years (leading to low average productivity), many populations could be exposed to overhunting. These results stress the importance of both small- and large-scale adjustments of hunting pressure to partridge productivity, in order to preserve wild populations. Poor hunting bags in “bad” years, along with the increasing demand in the hunting market, may have stimulated the widespread use of releases, further reducing productivity and leading to the current compromised conservation status of wild populations. We discuss some potential solutions to this conflicting situation from the socioeconomic and environmental points of view

de la Peña, E. et al. (2020)

de la Peña, E., Martín, J., Carranza, J. (2020) Ultrastructural morphological features of the hair in a sexual signal: the dark ventral patch of male red deer. Journal of Zoology ISSN 0952-8369

Chemical signals play a decisive role in communication in many mammal species.In red deer (Cervus elaphus), the dark ventral patch has recently been described asa male chemical signal involved in intrasexual competition. Morphological special-izations of the hair of this area might contribute to retaining the volatile com-pounds found here. In this study, we examined differences in the ultrastructurebetween hair associated with the dark ventral patch and hairs from the dorsolateralregion of the body as a control. We obtained a gallery of images from a scanningelectron microscope to study the possible variation in the detailed anatomy as wellas the surface and pattern of cuticular scales of hairs of the two body regionsexamined. In addition, we used a 2D-3D microscope to measure hair diameter(thickness) and the shape and size of the cuticular scales. We found that the hairsof the dark ventral patch were narrower than those from the dorsolateral region.We also found a different cuticular scale pattern of the dark ventral patch hairs,suggesting a possible specialization for the retention of compounds associated withthis chemical signal. Moreover, some intersexual differences in hair morphologyalso support this idea. This study shows, for the rst time, the differentiation ofhairs related to the dark ventral patch, which contributes to our better understand-ing of this chemical communication in red deer

Carranza, J. et al. (2020)

Carranza, J., Pérez-Barbería, J., Mateos, C., Alarcos, S., Torres-Porras, J., Pérez-González, J., Sánchez-Prieto, C.B., Valencia, J., Castillo, L., de la Peña, E., Barja, I., Seoane, J.M., Reglero, M.M., Flores, A., Membrillo, A. (2020) Social environment modulates investment in sex trait versus lifespan: red deer produce bigger antlers when facing more rivalry. Scientific Reports 10:9234

Theory predicts that the plastic expression of sex-traits should be modulated not only by their production costs but also by the benefits derived from the presence of rivals and mates, yet there is a paucity of evidence for an adaptive response of sex-trait expression to social environment. We studied antler size, a costly and plastic sex trait, and tooth wear, a trait related to food intake and longevity, in over 4,000 male Iberian red deer (Cervus elaphus hispanicus) from 56 wild populations characterized by two contrasting management practices that affect male age structure and adult sex-ratio. As a consequence, these populations exhibit high and low levels of male-male competition for mating opportunities. We hypothesized that males under conditions of low intra-sexual competition would develop smaller antlers, after controlling for body size and age, than males under conditions of high intra-sexual competition, thus reducing energy demands (i.e. reducing intake and food comminution), and as a consequence, leading to less tooth wear and a concomitant longer potential lifespan. Our results supported these predictions. To reject possible uncontrolled factors that may have occurred in the wild populations, we carried out an experimental design on red deer in captivity, placing males in separate plots with females or with rival males during the period of antler growth. Males living with rivals grew larger antlers than males living in a female environment, which corroborates the results found in the wild populations. As far as we know, these results show, for the first time, the modulation of a sexual trait and its costs on longevity conditional upon the level of intra-sexual competition.

Castillo, L. et al. (2020)

Castillo, L., Del Río, L.m., Carranza, J., Mateos, C., Tejado, J.J., López, F. (2020) Ultrasound speed in red deer antlers: a non-invasive correlate of density and a potential index of relative quality.Animal Biodiversity and Conservation 43.2: 255-269.

Deer antlers can be used as an index of individual performance both in ecological and productive contexts. Their quality is often measured only by their biometrical features, such as size, asymmetry or weight. Mechanic characteristics cannot normally be measured without destroying the antler and hence losing the commercial value of the trophies. Here, we studied ultrasonic velocities, density, and tensile strength across various sections of cast antlers of Iberian red deer (Cervus elaphus hispanicus). We found that the speed value depended on the section of the antler and the propagation direction. For antler sections, velocities were lowest for mid–beam and highest for brow tine. Results were similar for density and indirect tensile strength, probably related to differences in functionality among antler sections. Density explained most of the variability of ultrasound–speed. The time elapsed from antler shed affected density more than ultrasound speed. The indirect tensile strength showed a non–linear, decelerating relationship with ultrasound speed. We discuss the applications of ultrasound speed as a non–invasive tool to measure density and physical properties of antlers and antler sections, and their potential use as an index of quality.

Linares, O. et al. (2020)

Linares, O., Carranza, J., Soliño, M., Delibes-Mateos, M., Ferreras, P., Descalzo, E., & Martínez-Jauregui, M. (2020). Citizen science to monitor the distribution of the Egyptian mongoose in southern Spain: who provide the most reliable information?. European Journal of Wildlife Research, 66(4), 1-5.

The Egyptian mongoose (Herpestes ichneumon L.) is a medium-size carnivore widely distributed in Africa and in a small part of southern Europe, the Iberian Peninsula, where mongoose populations have recently expanded. The mongoose is relatively easily detectable because of its diurnal habits and because it is the only species of Herpestidae occurring in the Iberian Peninsula. Therefore, its distribution could be monitored through citizen science. In this sense, information provided by stakeholders that make frequent use of natural environments, including hunters, landowners, or wildlife rangers, would be potentially very valuable. Nevertheless, the accuracy of the information provided by these stakeholders as regards mongoose occurrence has never been tested. To do so, we compared mongoose occurrences gathered through field transects (i.e., 2-km walking surveys in which direct observations and indirect signs were recorded) carried out in 218 Andalusian municipalities during 2010–2015 with those obtained through questionnaires conducted in 2016 to hunters (n = 251), landowners (n = 116), and wildlife rangers (n = 133). We did not find any significant difference between mongoose distribution estimated by the reference method (i.e., field surveys) and by questionnaire to wildlife rangers. In contrast, mongoose occurrences reported by hunters and landowners were significantly correlated among them, but not with those collected in field transects (nor with those provided by the rangers). This suggests that a participatory network for monitoring mongoose distribution could rely on the information provided by wildlife rangers. Previous studies showed that hunters can provide useful information from less accessible areas like private estates where official data are not collected. In this sense, our results suggest that further effort is needed to incorporate hunters and landowners in a participatory network to monitor mongoose distribution, and this could include collaborative actions to promote their involvement in addition to increasing their skills in mongoose detection.