Pérez-González, J. & Carranza, J. (2023) Genetic Diversity of Wild Boar and Deer. Animals 2023, 13, 11. https://doi.org/10.3390/ ani13010011

Genetic diversity provides the long-term capacity of species, communities, and the biosphere to persist under change. It is a fundamental element of biodiversity that is globally declining, mainly in habitats that are more affected by humans [1]. The monitoring and maintenance of genetic diversity is crucial for the conservation of threatened populations and species [2,3]. Furthermore, genetic diversity can have consequences beyond population conservation. Low levels of genetic diversity may favor pathogen success and the spread of infectious diseases in communities [4,5]. Therefore, the maintenance of genetic diversity can also be considered a public health concern.

https://doi.org/10.3390/ani13010011

F. Millán M., Carranza J., Seoane J.M. et Pérez-González J. (2022) Forage quality of consecutive years interact to affect body condition, reproductive rate and rut phenology in Iberian red deer. PLoS ONE 17(12): e0278367. https://doi.org/10.1371/journal.pone.0278367

Body condition for reproduction in capital breeders such as the red deer (Cervus elaphus) is mostly determined by their stored energy reserves. Thus, environmental conditions and resource availability may affect reproductive performance and breeding success. In warm Mediterranean regions, current climate change is driving to a hotter and drier scenario that is expected to affect the biology and dynamics of many populations. We examined the impact of these local climate variations on red deer body condition and the relationship with female reproductive phenology and breeding success. We used satellite information of landscape vegetation along with a 22-year data series of direct field behavioural observations during the rutting season in Doñana National Park (SW Spain). We analyzed faecal nitrogen content (FN) from faeces collected during the rut. We found that poor vegetation availability in drier years was related to worse body condition of deer (measured by FN) and a delay in the rutting season, which associated with lower reproductive rates (measured by the proportion of females with calves observed the next year). We also evidenced an interesting interaction between environmental conditions in consecutive years on the timing of breeding season, with timing of breeding being more delayed when previous year resource availability was high and many females bred, and the consecutive one was poor, so females hardly recovered condition and the rut occurred later. These findings highlight the carry-over effect of reproduction in capital breeders and the potential impact of climate-change conditions on red deer breeding.

https://doi.org/10.1371/journal.pone.0278367

Broggini, C., Abril, N, Carranza, J & Membrillo, A. (2022) Evaluation of candidate reference genes for quantitative real‑time PCR normalization in blood from red deer developing antlers. scientific reports. https://doi.org/10.1038/s41598-022-20676-9

Sexual selection favors male traits that increase their ability to monopolize the breeding access to several females. Deer antlers are cranial appendages that regenerate annually in males. Throughout life, the phenology of antler growth advances and antler mass increases until the stag reaches, between 8 and 10 years old, maximum body mass and highest reproductive success. The molecular mechanisms of antler development are of great interest in both evolutionary and regenerative medicine studies. To minimize errors in the assessment of gene expression levels by qRT‑PCR, we analyzed the stability of a panel of eight candidate reference genes and concluded that qRT‑PCR normalization to three stable genes is strongly convenient in experiments performed in red deer antler blood. To validate our proposal, we compared the expression level of three genes linked to red deer antler growth (ANXA2, APOD and TPM1) in fifteen male red deer classified as young (up to 4 years old) and adults (4–6 years old). Our data confirms that B2M, ACTB and RPLP0 are valuable reference genes for future gene expression studies in red deer antler blood, which would provide increased insight into the effects of intrinsic factors that determine antler development in red deer

https://rdcu.be/cWw3c

Vedel, G., de la Peña, E., Moreno Rojas, J.M., Montenegro Gómez, J.C. & Carranza, J. (2022) Stable carbon and nitrogen isotope values in hair reveal management differences and hidden practices in wild boar populations. Science of The Total Environment, 823. 154071, ISSN 0048-9697,
https://doi.org/10.1016/j.scitotenv.2022.154071.

The analysis of stable isotopes in different tissues has been widely used to obtain information on the ecology and nutritional patterns of wildlife. The isotope ratios of the stable isotopes of carbon and nitrogen (δ¹³C and δ¹⁵N) analysed in different tissues are directly related to the animal’s diet and, to some extent, to the environment where the individual has growth. Specifically, this type of analysis in hair samples has become relevant as it provides information on the quality and long-term composition of the diet that produced the isotope accumulation during the tissue growth. We took samples of wild boar (Sus scrofa) hair from 7 different populations in the south-west of Spain (Mediterranean habitats), in the 2018/2019 hunting season. The main objectives of this study were (i) to investigate the use of hair stable isotopes to reveal differences in composition and quality of the diet of wild boar within the same population or between populations, and (ii) to use hair isotopes as a tool to uncover hidden management practices that may occur in hunting areas associated with the use of supplementary feeding or even captive breeding and release. Each animal had a hair (long 10 cm) analysed in duplicate, previously cut into parts of equal size (from the oldest part of the hair to the most recent part), that were analysed separately. We found differences in δ¹³C and δ ¹⁵N between hair parts and populations, which can be related to management actions at different times during the hair growth. Moreover, the use of corn, a type of plant not occurring naturally in the study area, can be documented with the isotope analysis to prove unauthorized supplementary feeding or captive origin of wild boar in hunting areas.

https://www.sciencedirect.com/science/article/pii/S0048969722011639?via%3Dihub

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 https://doi.org/10.1007/s42991-021-00100-x

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.

https://link.springer.com/article/10.1007/s42991-021-00100-x

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.

https://doi.org/10.1371/journal.pone.0244802

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.

https://doi.org/10.3390/ani10122419

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.

https://doi.org/10.1016/j.mcp.2020.101673

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. https://doi.org/10.1371/journal.pone.0241374

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.

https://doi.org/10.1371/journal.pone.0241374

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). https://doi.org/10.1007/s10344-020-01394-x

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

https://doi.org/10.1007/s10344-020-01394-x