Analysing animal social network dynamics: the potential of stochastic actor-oriented models

This is the final version of the article. Available from the publisher via the DOI in this record.Animals are embedded in dynamically changing networks of relationships with conspecifics. These dynamic networks are fundamental aspects of their environment, creating selection on behaviours and other traits. However, most social network-based approaches in ecology are constrained to considering networks as static, despite several calls for such analyses to become more dynamic. There are a number of statistical analyses developed in the social sciences that are increasingly being applied to animal networks, of which stochastic actor-oriented models (SAOMs) are a principal example. SAOMs are a class of individual-based models designed to model transitions in networks between discrete time points, as influenced by network structure and covariates. It is not clear, however, how useful such techniques are to ecologists, and whether they are suited to animal social networks. We review the recent applications of SAOMs to animal networks, outlining findings and assessing the strengths and weaknesses of SAOMs when applied to animal rather than human networks. We go on to highlight the types of ecological and evolutionary processes that SAOMs can be used to study. SAOMs can include effects and covariates for individuals, dyads and populations, which can be constant or variable. This allows for the examination of a wide range of questions of interest to ecologists. However, high-resolution data are required, meaning SAOMs will not be useable in all study systems. It remains unclear how robust SAOMs are to missing data and uncertainty around social relationships. Ultimately, we encourage the careful application of SAOMs in appropriate systems, with dynamic network analyses likely to prove highly informative. Researchers can then extend the basic method to tackle a range of existing questions in ecology and explore novel lines of questioning

Reviving the Arabian leopard: harnessing historical data to map habitat and pave the way for reintroduction

The Arabian leopard (Panthera pardus nimr) has experienced dramatic range and population contractions over the last century. Conservation efforts for this felid focused on captive breeding and identification of suitable conditions for reintroductions. With this study, we unravelled historical collaring and direct observations data to understand the spatial use of the last leopards recorded in the region of Israel and the West Bank (IWB). Through datasets of leopard occurrence, we characterised suitable habitats, assessed niche overlap with the Arabian leopard's main prey, the Nubian ibex (Capra nubiana), and evaluated their distributions with respect to currently protected habitats. We estimated home-ranges employing area-corrected density kernel methods and investigated suitable conditions through multiple scales habitat modelling. Average home ranges for the population were 73.24 ± 47.91 km2 and 77.46 ± 54.94 km2, depending on the time lag adopted. Ecological response to predictors highlighted reliance by both predator and prey on the same habitat characteristics, suggesting they occupied essentially identical niches. These characteristics were intermediately rugged topographic conditions and high indices of vegetation in scarcely populated desert environments, mostly encompassed within protected areas. The distribution of leopard and ibex overlapped substantially according to several metrics. Notably, more than half of potential habitat for both species is encompassed by protected areas and military zones. Given the coincidence in their ecological requirements, and highly congruent distributions, an important step towards future reintroduction of Arabian leopards will include gaining a better understanding of ibex populations, alongside attention to the practicality of enforcing habitat protection

The prospective kindergarten and elementary school teachers’ understanding of the ratio concept

Este artigo centra-se na compreensão que futuros educadores e professores dos primeiros anos de escolaridade evidenciam do conceito de razão. No estudo participaram 81 estudantes do 2º ano da Licenciatura em Educação Básica, de uma universidade portuguesa, aos quais foi aplicado um questionário, incidindo em quatro dimensões: significado de razão; usos do conceito de razão; representação simbólica de razão; e representações para explicação do conceito de razão. Em termos de resultados, as maiores frequências foram obtidas para a: ideia de razão como comparação/relação entre grandezas; crença em que o conceito de razão pode ser usado em contextos diversificados; crença em que pode ser representado através de operações envolvendo letras, números ou apenas os sinais das operações, quando é pedida a sua representação simbólica, e através de diagramas e representações gráficas, quando é solicitada a descrição da sua explicação. Estes resultados revelam fragilidades no conhecimento matemático dos estudantes, sobretudo no que se refere à definição do conceito de razão e às suas representações.This paper focuses on the prospective kindergarten and elementary school teachers’ understanding of the ratio concept. Eighty-one undergraduates preparing to become kindergarten and primary school teachers, in a Portuguese university, participated in the study. They answered to a questionnaire aiming at evaluating their understanding of the ratio concept based on four dimensions: meaning of ratio; use of the ratio concept; symbolic representations of ratio; and representations for explaining the ratio concept. As far as results are concerned, the highest frequencies were obtained for: the idea of ratio as a comparison/relationship between two magnitudes; the belief that this concept is used in several contexts; the belief that it can be represented through operations with letters, figures or operation signals, as in symbolic representations; and through diagrams and graphical representations, as in representations for explaining the ratio concept. The results show weaknesses in prospective teachers’ mathematical knowledge of ratio, namely with regard to its definition and representations.Este trabalho contou com o apoio de Fundos Nacionais através da FCT – Fundação para a Ciência e a Tecnologia no âmbito do projecto PEst-OE/CED/UI1661/2014 do CIEd-UM.info:eu-repo/semantics/publishedVersio

Acoustic sequences in non-human animals: a tutorial review and prospectus.

Animal acoustic communication often takes the form of complex sequences, made up of multiple distinct acoustic units. Apart from the well-known example of birdsong, other animals such as insects, amphibians, and mammals (including bats, rodents, primates, and cetaceans) also generate complex acoustic sequences. Occasionally, such as with birdsong, the adaptive role of these sequences seems clear (e.g. mate attraction and territorial defence). More often however, researchers have only begun to characterise - let alone understand - the significance and meaning of acoustic sequences. Hypotheses abound, but there is little agreement as to how sequences should be defined and analysed. Our review aims to outline suitable methods for testing these hypotheses, and to describe the major limitations to our current and near-future knowledge on questions of acoustic sequences. This review and prospectus is the result of a collaborative effort between 43 scientists from the fields of animal behaviour, ecology and evolution, signal processing, machine learning, quantitative linguistics, and information theory, who gathered for a 2013 workshop entitled, 'Analysing vocal sequences in animals'. Our goal is to present not just a review of the state of the art, but to propose a methodological framework that summarises what we suggest are the best practices for research in this field, across taxa and across disciplines. We also provide a tutorial-style introduction to some of the most promising algorithmic approaches for analysing sequences. We divide our review into three sections: identifying the distinct units of an acoustic sequence, describing the different ways that information can be contained within a sequence, and analysing the structure of that sequence. Each of these sections is further subdivided to address the key questions and approaches in that area. We propose a uniform, systematic, and comprehensive approach to studying sequences, with the goal of clarifying research terms used in different fields, and facilitating collaboration and comparative studies. Allowing greater interdisciplinary collaboration will facilitate the investigation of many important questions in the evolution of communication and sociality.This review was developed at an investigative workshop, “Analyzing Animal Vocal Communication Sequences” that took place on October 21–23 2013 in Knoxville, Tennessee, sponsored by the National Institute for Mathematical and Biological Synthesis (NIMBioS). NIMBioS is an Institute sponsored by the National Science Foundation, the U.S. Department of Homeland Security, and the U.S. Department of Agriculture through NSF Awards #EF-0832858 and #DBI-1300426, with additional support from The University of Tennessee, Knoxville. In addition to the authors, Vincent Janik participated in the workshop. D.T.B.’s research is currently supported by NSF DEB-1119660. M.A.B.’s research is currently supported by NSF IOS-0842759 and NIH R01DC009582. M.A.R.’s research is supported by ONR N0001411IP20086 and NOPP (ONR/BOEM) N00014-11-1-0697. S.L.DeR.’s research is supported by the U.S. Office of Naval Research. R.F.-i-C.’s research was supported by the grant BASMATI (TIN2011-27479-C04-03) from the Spanish Ministry of Science and Innovation. E.C.G.’s research is currently supported by a National Research Council postdoctoral fellowship. E.E.V.’s research is supported by CONACYT, Mexico, award number I010/214/2012.This is the accepted manuscript. The final version is available at http://dx.doi.org/10.1111/brv.1216

Hawk Eyes II: Diurnal Raptors Differ in Head Movement Strategies When Scanning from Perches

Background Relatively little is known about the degree of inter-specific variability in visual scanning strategies in species with laterally placed eyes (e.g., birds). This is relevant because many species detect prey while perching; therefore, head movement behavior may be an indicator of prey detection rate, a central parameter in foraging models. We studied head movement strategies in three diurnal raptors belonging to the Accipitridae and Falconidae families. Methodology/Principal Findings We used behavioral recording of individuals under field and captive conditions to calculate the rate of two types of head movements and the interval between consecutive head movements. Cooper\u27s Hawks had the highest rate of regular head movements, which can facilitate tracking prey items in the visually cluttered environment they inhabit (e.g., forested habitats). On the other hand, Red-tailed Hawks showed long intervals between consecutive head movements, which is consistent with prey searching in less visually obstructed environments (e.g., open habitats) and with detecting prey movement from a distance with their central foveae. Finally, American Kestrels have the highest rates of translational head movements (vertical or frontal displacements of the head keeping the bill in the same direction), which have been associated with depth perception through motion parallax. Higher translational head movement rates may be a strategy to compensate for the reduced degree of eye movement of this species. Conclusions Cooper\u27s Hawks, Red-tailed Hawks, and American Kestrels use both regular and translational head movements, but to different extents. We conclude that these diurnal raptors have species-specific strategies to gather visual information while perching. These strategies may optimize prey search and detection with different visual systems in habitat types with different degrees of visual obstruction

Variance in Centrality within Rock Hyrax Social Networks Predicts Adult Longevity

BACKGROUND: In communal mammals the levels of social interaction among group members vary considerably. In recent years, biologists have realized that within-group interactions may affect survival of the group members. Several recent studies have demonstrated that the social integration of adult females is positively associated with infant survival, and female longevity is affected by the strength and stability of the individual social bonds. Our aim was to determine the social factors that influence adult longevity in social mammals. METHODOLOGY/PRINCIPAL FINDINGS: As a model system, we studied the social rock hyrax (Procavia capensis), a plural breeder with low reproductive skew, whose groups are mainly composed of females. We applied network theory using 11 years of behavioral data to quantify the centrality of individuals within groups, and found adult longevity to be inversely correlated to the variance in centrality. In other words, animals in groups with more equal associations lived longer. Individual centrality was not correlated with longevity, implying that social tension may affect all group members and not only the weakest or less connected ones. CONCLUSIONS/SIGNIFICANCE: Our novel findings support previous studies emphasizing the adaptive value of social associations and the consequences of inequality among adults within social groups. However, contrary to previous studies, we suggest that it is not the number or strength of associations that an adult individual has (i.e. centrality) that is important, but the overall configuration of social relationships within the group (i.e. centrality SD) that is a key factor in influencing longevity

Genetic Biomarkers for ALS Disease in Transgenic SOD1G93A Mice

The pathophysiological mechanisms of both familial and sporadic Amyotrophic Lateral Sclerosis (ALS) are unknown, although growing evidence suggests that skeletal muscle tissue is a primary target of ALS toxicity. Skeletal muscle biopsies were performed on transgenic SOD1G93A mice, a mouse model of ALS, to determine genetic biomarkers of disease longevity. Mice were anesthetized with isoflurane, and three biopsy samples were obtained per animal at the three main stages of the disease. Transcriptional expression levels of seventeen genes, Ankrd1, Calm1, Col19a1, Fbxo32, Gsr, Impa1, Mef2c, Mt2, Myf5, Myod1, Myog, Nnt, Nogo A, Pax7, Rrad, Sln and Snx10, were tested in each muscle biopsy sample. Total RNA was extracted using TRIzol Reagent according to the manufacturer's protocol, and variations in gene expression were assayed by real-time PCR for all of the samples. The Pearson correlation coefficient was used to determine the linear correlation between transcriptional expression levels throughout disease progression and longevity. Consistent with the results obtained from total skeletal muscle of transgenic SOD1G93A mice and 74-day-old denervated mice, five genes (Mef2c, Gsr, Col19a1, Calm1 and Snx10) could be considered potential genetic biomarkers of longevity in transgenic SOD1G93A mice. These results are important because they may lead to the exploration of previously unexamined tissues in the search for new disease biomarkers and even to the application of these findings in human studies

A Formação na Maturidade como Apropriação da Própria História de Vida

No presente artigo, a disposição e a competência para a apropriação da própria história de vida são consideradas como modos de formação1 na maturidade. Estas se relacionam com fatores históricos e sócio-políticos e estão inscritas em contextos multigeracionais de formação e processos de desenvolvimento ao longo da vida. Nesta perspectiva, conceitos como geração, geracionalidade, geratividade e transmissão transgeracional ganham destaque e serão aprofundados no texto. A linha argumentativa que sustenta este ponto de vista baseia-se em estudos de países de língua alemã sobre crianças da Segunda Guerra Mundial que envelheceram. Apesar de se tratar de uma situação específica, nos parece possível a extensão das reflexões também para o contexto brasileiro

Male hyraxes increase song complexity and duration in the presence of alert individuals

The goal of vocal communication is the efficient delivery of signals to a target audience. Long and complex vocalizations are especially challenging because they are subject to environmental interference and may incur significant costs for the signaler. One of the various ways of increasing the efficiency of signal delivery is enhancement of communicational efforts only when potential audience is perceived nearby in an attempt to maximize the benefit over the cost of signaling (audience effect). Another way is signaling subsequently to events that intensify individual alertness in order to ensure audience attentiveness and sensitivity to the transmitted information. Rock hyraxes (Procavia capensis) are social mammals that use complex acoustic signals to communicate. Adult male hyraxes produce elaborate vocalizations (known as songs) that serve as honest advertisements of their quality. By combining analysis of male hyrax songs recorded in the field over a period of 11 years and playback experiments, we found that songs performed during and following attention-grabbing events (agonistic interactions, alarm calls, predator presence, and songs performed as a reply to conspecific singing) have an increased structural and syntactic complexity in comparison to spontaneous singing. Male hyraxes demonstrate a cognitive ability to optimize their advertising efforts in response to multiple types of events. This signaling strategy exploits the effective communication window created by attention-grabbing events and by the presence of an alert audience to delivers structurally and syntactically enhanced signal. To our knowledge, this is the first report of syntactic complexity of vocal signaling being altered following various triggers that change conspecifics mental state in terrestrial mammals.Male rock hyraxes (small, short-tailed, herbivorous social mammals) produce enhanced songs when an attentive audience is present. These long and complex songs advertise male quality and rank but can potentially expose the caller to predation. To optimize advertising efforts, males enhance their songs following external attention-grabbing events, which increase the probability of being noted by potential listeners. Similar vocal modifications are observed in humans when a speaker is aware of audience attention