Ecological interactions and species coexistence in iberian mesocarnivore communities

Programa Doutoral em Biodiversidade, Genética e Evolução Departamento de Biologia-Universidade do Porto.[EN]: In predator communities, mesopredator biomass typically exceeds that of apex predators. Consequently, the energetic requirements of mesocarnivores (as a community) suggest that their impact on lower trophic levels should be significant. Several cases of ecosystem disruptions have been described as a result of changes in predator communities (e.g. irruptions of prey species released from top-down regulation, or over-suppression of prey via a predator-pit effect). However, the structure of mesocarnivore communities is complex, and results from a multidimensional web of interactions with several trophic levels, upheld through top-down and bottom-up effects, intraguild interactions and habitat quality. Therefore, understanding the factors that act together in structuring such systems is crucial for adequate planning and management of conservation policies. The ecological and behavioral traits of carnivores deem them particularly difficult to study. Additionally, community-wide or multiple species research studies are particularly difficult to implement. Yet, non-invasive techniques have become commoner and technological advances, namely in the field of molecular genetics, have made for such studies more accessible. In this research we aimed to address two fundamental questions: to assess the reliability and improve current sampling methods for ecological studies of mesocarnivores in Southwestern Europe; and to evaluate the strategies used by mesocarnivores that facilitate their coexistence in SW European communities../..[PO]: Em comunidades de predadores, a biomassa dos mesopredadores excede a dos predadores de topo. Consequentemente, os requisitos energéticos dos mesocarnívoros (como comunidade) sugerem que o seu impacto sobre os níveis tróficos inferiores são significativos. Vários casos de desregulação nos ecossistemas têm sido descritos como resultado de alterações nas comunidades de mesocarnívoros (e.g. a explosão demográfica de espécies presa após a supressão da predação, ou imposição de um efeito de poço de predação imposto por predadores em espécies presa). No entanto, a estrutura das comunidades de mesocarnívoros é complexa e resulta de uma teia multidimensional de interações entre os diferentes níveis tróficos existentes, através de efeitos de regulação superior e inferior, interações com espécies do mesmo nível trófico ou qualidade do habitat. Assim, a compreensão dos factores que atuam para estruturar estes sistemas revela-se fundamental para uma adequada gestão e planeamento de ações de conservação. As características ecológicas e comportamentais dos mesocarnívoros fazem com que estas espécies sejam particularmente difíceis de estudar. Por outro lado, estudos sobre comunidades ou sobre múltiplas espécies em simultâneo revelam-se especialmente difíceis de implementar. No entanto, os progressos recentes em técnicas não-invasivas têm promovido a sua implementação, tornando-as mais comuns no estudo de mamíferos carnívoros terrestres. Adicionalmente, desenvolvimentos nas tecnologias associadas a estas amostragens, nomeadamente ao nível dos métodos moleculares, têm permitido uma maior acessibilidade a este tipo de aproximações. Na presente dissertação são focadas duas questões fundamentais: a avaliação da adequabilidade e desenvolvimento de metodologias não-invasivas para o estudo de mesocarnívoros e a investigação das estratégias utilizadas pelos mesocarnívoros presentes nas comunidades terrestres que permitem a sua coexistência no Sudoeste (SW) da Europa../..Agradeço à fundação para a Ciência e Tecnologia pela atribuição da bolsa de doutoramento (ref: SFRH/BD/37795/2007). Agradeço ao Ministerio de Ciencia e Innovación de Espanha, pelo projeto que financiou grande parte dos trabalhos (de campo e laboratoriais) para esta tese (projeto ref: CGL2009-10741). Ao Organismo Autónomo Parques Nacionales de Espanha, pelo projeto que financiou grande parte dos trabalhos (de campo e laboratoriais) para esta tese (projeto ref: project ref: OAPN 352/2011).Peer Reviewe

Plasticity in circadian activity patterns of mesocarnivores in Southwestern Europe: implications for species coexistence

Limiting similarity theory predicts that competing species must segregate along one or more dimensions of their ecological niche in order to coexist. In predator communities, interspecific interactions are influenced by a diversity of factors; therefore, the behavioural patterns of composing species will differ due to locally adapted interactions. We deployed 32-41 camera-traps in five study areas across the Iberian Peninsula to investigate the temporal relations between mesocarnivores in SW Europe. The selection for a period of the diel cycle and plasticity in activity patterns was evaluated using the Jacobs Selection Index (JSI) and the coefficient of activity overlap ({increment}1). Furthermore, we investigated whether temporal shifts can facilitate coexistence by reducing activity overlap. Seven species of mesocarnivores were detected and were assigned into one of three behaviourally distinct groups: Diurnal (JSIday ≥ 0.8), strictly nocturnal (JSInight ≥ 0.8) or facultative nocturnal species (0.4 ≥ JSInight > 0.8). Most species exhibited substantial flexibility, which allowed them to locally adapt their foraging strategies (intraspecific {increment}1 = 0.70-0.77). Mean Δ1 from all interspecific pairwise comparisons was negatively correlated with the number of carnivore species with ≥10 detections (r -0.76, p = 0.02). Our results suggest that temporal segregation is likely to play an important role in facilitating mesocarnivore coexistence, especially with increasing community complexity, where most species' activity peaks were asynchronous. These results contribute to understanding the dynamics and behavioural strategies of coexisting mesocarnivores, crucial for forecasting the possible outcomes of conservation or management actions.This work was partially supported by a PhD grant from the Fundação para a Ciência e a Tecnologia (FCT) to PM (SFRH/BD/37795/2007) and two research projects, one from the Spanish National Plan (project ref: CGL2009-10741) funded by the Spanish Ministry of Science and Innovation and EU-FEDER funds, and another one from the Spanish Organismo Autónomo Parques Nacionales (project ref: OAPN 352/2011).Peer Reviewe

Catch me if you can: diel activity patterns of mammalian prey and predators

The activity patterns exhibited by animals are shaped by evolution, but additionally fine-tuned by flexible responses to the environment. Predation risk and resource availability are environmental cues which influence the behavioural decisions that make both predators and prey engage in activity bursts, and depending on their local importance, can be strong enough to override the endogenous regulation of an animals' circadian clock. In Southern Europe, wherever the European rabbit (Oryctolagus cuniculus) is abundant, it is the main prey of most mammalian mesopredators, and rodents are generally the alternative prey. We evaluated the bidirectional relation between the diel activity strategies of these mammalian mesopredators and prey coexisting in south-western Europe. Results revealed that even though predation risk enforced by mammalian mesocarnivores during night-time was approximately twice and five times higher than during twilight and daytime, respectively, murids consistently displayed unimodal nocturnal behaviour. Conversely, the European rabbits exhibited a bimodal pattern that peaked around sunrise and sunset. Despite the existence of some overlap between the diel rhythms of mesocarnivores and rabbits, their patterns were not synchronized. We suggest that the environmental stressors in our study areas are not severe enough to override the endogenous regulation of the circadian cycle in murids. European rabbits, however, are able to suppress their biological tendency for nocturnality by selecting a predominantly crepuscular pattern. In spite of the higher energetic input, mesocarnivores do not completely track rabbits' activity pattern. They rather track rodents' activity. We propose that these systems have probably evolved towards a situation where some degree of activity during high-risk periods benefits the overall prey population survival, while the accessibility to sufficient prey prevents predators to completely track them.This work was partially supported by a PhD grantfrom the Fundaçao para a Ciência e a Tecnologia (FCT) to PM (SFRH/BD/37795/2007) and two research projects, one from the Spanish National Plan (project ref: CGL2009-10741) funded by the Spanish Ministry of Science and Innovation and EU-FEDER funds and one from the Spanish Organismo Autónomo Parques Nacionales (project ref: OAPN352/2011).Peer Reviewe

Sampling variables and their thresholds for the precise estimation of wild felid population density with camera traps and spatial capture–recapture methods

1. Robust monitoring, providing information on population status, is fundamental for successful conservation planning. However, this can be hard to achieve for species that are elusive and occur at low densities, such as felids. These are often keystones of functioning ecosystems and are threatened by habitat loss and human persecution. 2. When elusive species can be individually identified by visible characteristics, for example via camera-trapping, observations of individuals can be used in combination with capture–recapture methods to calculate demographic parameters such as population density. In this context, spatial capture–recapture (SCR) outperforms conventional non-spatial methods, but the precision of results is inherently related to the sampling design, which should therefore be optimised. 3. We focussed on territorial felids in different habitats and investigated how the sampling designs implemented in the field affected the precision of population density estimates. We examined 137 studies that combined camera trapping and SCR methods for density estimation. From these, we collectedspatiotemporal parameters of their sampling designs, monitoring results, such as the number of individuals captured and the number of recaptures, as well as SCR detection parameters. We applied generalised linear mixed-effects models and tree-based regression methods to investigate the influence of variables on the precision of population density estimates and provide numerical thresholds. 4. Our analysis shows that the number of individuals, recapture frequency, and capture probability play the most crucial roles. Surveys yielding over 20 captured individuals that were recaptured on average at least once obtain the most precise population density estimates. 5. Based on our findings, we provide practical guidelines for future SCR studies that apply to all territorial felids. Furthermore, we present a standardised reporting protocol for study transparency and comparability. Our results will improve reporting and reproducibility of SCR studies and aid in setting up optimised sampling designs.publishedVersio

Estimating home-range size: when to include a third dimension?

Most studies dealing with home ranges consider the study areas as if they were totally flat, working only in two dimensions, when in reality they are irregular surfaces displayed in three dimensions. By disregarding the third dimension (i.e., topography), the size of home ranges underestimates the surface actually occupied by the animal, potentially leading to misinterpretations of the animals' ecological needs. We explored the influence of considering the third dimension in the estimation of home-range size by modeling the variation between the planimetric and topographic estimates at several spatial scales. Our results revealed that planimetric approaches underestimate home-range size estimations, which range from nearly zero up to 22%. The difference between planimetric and topographic estimates of home-ranges sizes produced highly robust models using the average slope as the sole independent factor. Moreover, our models suggest that planimetric estimates in areas with an average slope of 16.3° (±0.4) or more will incur in errors ≥5%. Alternatively, the altitudinal range can be used as an indicator of the need to include topography in home-range estimates. Our results confirmed that home-range estimates could be significantly biased when topography is disregarded. We suggest that study areas where home-range studies will be performed should firstly be scoped for its altitudinal range, which can serve as an indicator for the need for posterior use of average slope values to model the surface area used and/or available for the studied animals.This work was partially supported by a research project from the Spanish National Plan (project ref: CGL2009-10741) funded by the Spanish Ministry of Science and Innovation and EU-FEDER funds. P. M. was supported by a Ph.D. grant from the Fundaçao para a Ciència e a Tecnologia (FCT) (SFRH/BD/37795/2007). N. S. was partially supported by a postdoctoral grant from FCT (SFRH/BPD/26666/2006). L. M. R. was funded by a Postdoctoral fellowship from the FCT and Fundo Social Europeu (III Quadro Comunitario de Apoio) (SFRH/BPD/35842/2007) and FAPESP (Proc. Ref.: 2011/00408-4).Peer Reviewe

Efficiency of hair snares and camera traps to survey mesocarnivore populations

Mammalian carnivore communities affect entire ecosystem functioning and structure. However, their large spatial requirements, preferred habitats, low densities, and elusive behavior deem them difficult to study. In recent years, noninvasive techniques have become much more common as they can be used to monitor multiple carnivore species across large areas at a relatively modest cost. Hair snares have the potential to fulfill such requirements, but have rarely been tested in Europe. Our objective was to quantitatively assess the effectiveness of hair snares for surveying mesocarnivores in the Iberian Peninsula (Southwestern Europe), by comparison with camera-trapping. We used an occupancy modeling framework to assess method-specific detectability and occupancy estimates and hypothesized that detection probabilities would be influenced by season, sampling method, and habitat-related variables. A total of 163 hair samples were collected, of which 136 potentially belonged to mesocarnivores. Genetic identification success varied with diagnostic method: 25.2 % using mitochondrial CR, and 9.9 % using the IRBP nuclear gene. Naïve occupancy estimates were, in average, 5.3 ± 1.2 times higher with camera-trapping than with hair-snaring, and method-specific detection probabilities revealed that camera traps were, in average, 6.7 ± 1.1 times more effective in detecting target species. Overall, few site-specific covariates revealed significant effects on mesocarnivore detectability. Camera traps were a more efficient method for detecting mesocarnivores and estimating their occurrence when compared to hair snares. To improve hair snares' low detection probabilities, we suggest increasing the number of sampling occasions and the frequency at which hair snares are checked. With some refinements to increase detection rates and the success of genetic identification, hair-snaring methods may be valuable for providing deeper insights into population parameters, attained through adequate analysis of genetic information, that is not possible with camera traps.This work was partially supported by a PhD grant from the Fundação para a Ciência e a Tecnologia (FCT) to PM (SFRH/BD/37795/2007) and two research projects, one from the Spanish National Plan (project ref: CGL2009-10741) funded by the Spanish Ministry of Science and Innovation and EU-FEDER funds, and one from the Spanish Organismo Autónomo Parques Nacionales (project ref: OAPN 352/2011). PCA was supported by the Luso-American Development Foundation (FLAD) and FCT sabbatical grant SFRH/BSAB/1278/2012.Peer Reviewe

Conservation status and Action Plan for the recovery of Iberian lynx populations in Portugal

From the first half of the 20th century onwards, the Portuguese Iberian lynx population was distributed in three major nuclei: Sado Valley, Malcata and Contenda-Barrancos. In the following decades these areas were subjected to a process that culminated in the specie’s considerable regression, probably as consequence of a major allocation of potential habitat to forestry and of prey scarcity as a result of viral diseases. The most recent survey, conducted from 2002 till 2004, revealed that the species is presently on the verge of extinction. Aware of the critical situation of the Iberian lynx in Portugal, the Institute of Nature Conservation and Biodiversity developed a Conservation Action Plan for the Iberian lynx in order to provide a consistent and effective approach to conserve the species in Portuguese territory. The on-going Action Plan is being applied in all Natura 2000 Sites, located in the lynx historical distribution that present suitable characteristics for the species potential presence or landscape features that can be optimised for lynx survival and that can be relevant for the species life-cycle. The goal of this Plan is to apply pre-release strategic reintroduction activities in order to make it possible, in the long-term, the reintroduction of Iberian lynx. Integrated in the plan, there are several ongoing conservation projects, which include habitat and prey restoration and the construction of a breeding centre that will be integrated within the overall Iberian Lynx Ex situ Conservation Programm

Analysis of Connectome Graphs Based on Boundary Scale

The purpose of this work is to advance in the computational study of connectome graphs from a topological point of view. Specifically, starting from a sequence of hypergraphs associated to a brain graph (obtained using the Boundary Scale model, BS² ), we analyze the resulting scalespace representation using classical topological features, such as Betti numbers and average node and edge degrees. In this way, the topological information that can be extracted from the original graph is substantially enriched, thus providing an insightful description of the graph from a clinical perspective. To assess the qualitative and quantitative topological information gain of the BS² model, we carried out an empirical analysis of neuroimaging data using a dataset that contains the connectomes of 96 healthy subjects, 52 women and 44 men, generated from MRI scans in the Human Connectome Project. The results obtained shed light on the differences between these two classes of subjects in terms of neural connectivity

Protein metabolism and physical fitness are physiological determinants of body condition in Southern European carnivores

The physiological significance of biometric body condition indices (bBCI) is poorly understood. We hypothesized that bBCI are composite metrics of nutritional physiology, physical fitness and health. To test this hypothesis, we first compared the performance of eight bBCI, using 434 Southern European carnivores from six species as a model system; and then identified, by non-destructive methods, the hematology and serum biochemistry correlates of three selected bBCI. Fulton’s K Index, Major Axis Regression Residuals and Scaled Mass Index were the only bBCI insensitive to the effect of sex and age. The most informative physiological parameters in explaining the variation of these bBCI were the albumin (Effect Size (ES) = − 1.66 to − 1.76), urea (ES = 1.61 to 1.85) and total bilirubin (ES = − 1.62 to − 1.79). Hemoglobin and globulins (positive) and cholesterol (negative) were moderately informative (0.9 <|ES|< 1.5). This study shows that most bBCI do not control for the effect of age and sex in Southern European carnivores. Our results support that bBCI are composite measures of physiologic processes, reflecting a positive gradient from protein-poor to protein-rich diets, accompanied by increased physical fitness. Biometric body condition indices allow the integration of ecologically relevant physiological aspects in an easily obtained metric.Spanish Ministry of Economy, Industry and Competitiveness [FJCI-2015-24949]; Junta de Comunidades de Castilla-La Mancha [Project PREG-05-23]; Organismo Autónomo Parques Nacionales [Project OAPN352/2011]; Juan de la Cierva research contracts from Ministerio de Ciencia e Innovación, Funder Id: 10.13039/501100004837 from the Spanish Ministry of Economyinfo:eu-repo/semantics/publishedVersio