Formation Of Territories Research Articles

A mathematical model for the territorial competition of the subterranean termites Coptotermes formosanus and Reticulitermes flavipes (Isoptera: Rhinotermitidae)

The foraging territories of two subterranean termites, Coptotermes formosanus Shiraki and Reticulitermes flavipes (Kollar), were simulated using a two-dimensional model to explore how territorial competition changes according to two variables characterizing territory formation: the total number of territories, and the blocking probability. Meanwhile, the blocking probability quantitatively describes the likelihood that a tunnel will be terminated when another tunnel is encountered. In our previous study, we introduced an interference coefficient γ to characterize territorial competition, and obtained γ as a function of the total number of territories and the blocking probability for a single termite species by model simulation. In the field, the territorial competition of more than two termite species is frequently observed. Here, we extended the γ function to be able to explain the competition between the two species by applying statistical regression to the simulation data. Further, we statistically checked the extended γ function by comparing the γ function for a single species. We also discuss another approach to mathematically derive the extended γ function, which can be easily generalized for use in cases of territorial competition involving more than two termite species.

How do animal territories form and change? Lessons from 20 years of mechanistic modelling.

Territory formation is ubiquitous throughout the animal kingdom. At the individual level, various behaviours attempt to exclude conspecifics from regions of space. At the population level, animals often segregate into distinct territorial areas. Consequently, it should be possible to derive territorial patterns from the underlying behavioural processes of animal movements and interactions. Such derivations are an important element in the development of an ecological theory that can predict the effects of changing conditions on territorial populations. Here, we review the approaches developed over the past 20 years or so, which go under the umbrella of ‘mechanistic territorial models’. We detail the two main strands to this research: partial differential equations and individual-based approaches, showing what each has offered to our understanding of territoriality and how they can be unified. We explain how they are related to other approaches to studying territories and home ranges, and point towards possible future directions.

Desterritorialização/reterritorialização: processos vivenciados por professoras de uma escola de Educação Especial no contexto da educação inclusiva

Este trabalho analisa os processos de desterritorialização/reterritorialização vivenciados por professoras de uma escola de Educação Especial da rede pública estadual do município de Governador Valadares (MG) no contexto das transformações da Educação Especial no sentido da educação inclusiva. A pesquisa foi construída em uma perspectiva interdisciplinar, pela articulação de concepções advindas dos campos da Educação e dos estudos territoriais, por meio das categorias território, territorialidade e desterritorialização/reterritorialização. Os dados, de caráter qualitativo, foram coletados com entrevistas semiestruturadas realizadas com seis professoras da escola. Os processos de desterritorialização/reterritorialização são compreendidos em três planos: histórico-temporal, espacial e simbólico. Aparecem marcados por modificações de práticas, concepções, códigos, saberes, por meio das quais as professoras abandonam alguns territórios e constituem outros. Por meio desses processos, fazem parte do devir da escola e da Educação Especial.

Stable territory formation in ecology and its potential generality in pattern formations

Stable territory formation is frequently observed in ecology. Until now, only the reaction–diffusion scheme has successfully produced stable patterns in the predator–prey system. However, it is a density-based scheme and in principle it cannot be used to derive a comprehensive understanding from a mean-field scheme. The application of our new stochastic individual-based scheme to predator–prey systems successfully produced stable patterns such as net, stripe, and lattice patterns for the first time. This study clearly shows that non-interacting time is an important factor in stable pattern formation. Specifically, of high importance is the existence of finite time to build the appetites of predators. In some cases, extreme increases of the appetites of predators lead to chaotic changes of the population, which are similar to the locust outbreak in Africa.

Cytological changes in meristematic cells of Allium cepa L. root tip treated with extracts from callus of Catharanthus roseus (L.) G. Don

The effect of an ethanolic extract from callus of <em>Catharanthus roseus</em> on <em>Allium cepa</em> root cells divisions was investigated. Two lines: white and green callus, were established on solid B5 medium with IAA 1 mg/l and kinetin 0.1 mg/l. The HPLC analysis of callus extracts showed the presence of indole alkaloids, however not known pharmacologically active alkaloids or derivatives used in semisynthesis (vinblastine, ajmalicine, serpentine, yohimbine, vindoline and catharanthine) have been found. The ethanolic extract of <em>C. roseus</em> callus inhibited the number of mitoses in <em>Allium cepa</em> root tip cells. Short (1-3 hours) treatment resulted in an increase in the index of late prophases, with characteristic light spaces, and the index of metaphases with twisted chromosomes forming an equatorial plate or irregular structures of c-metaphases. At the same time, the percentage of anaphases and telophases decreased significantly. Longer treatment of the root tip inhibited mitotic activity, stopping it completely already after 12 hours. Interphase nuclei became at first denser and homogeneous, eventually their structure became , partitioned into zones and formation of chromatin territories, with distinct large nucleoli has been observed. Electron microscope observations revealed well developed rough endoplasmic reticulum and thick, invaginating cell membrane.

Centromere Tethering Confines Chromosome Domains

The organization of chromosomes into territories plays an important role in a wide range of cellular processes, including gene expression, transcription, and DNA repair. Current understanding has largely excluded the spatiotemporal dynamic fluctuations of the chromatin polymer. We combine in vivo chromatin motion analysis with mathematical modeling to elucidate the physical properties that underlie the formation and fluctuations of territories. Chromosome motion varies in predicted ways along the length of the chromosome, dependent on tethering at the centromere. Detachment of a tether upon inactivation of the centromere results in increased spatial mobility. A confined bead-spring chain tethered at both ends provides a mechanism to generate observed variations in local mobility as a function of distance from the tether. These predictions are realized in experimentally determined higher effective spring constants closer to the centromere. The dynamic fluctuations and territorial organization of chromosomes are, in part, dictated by tethering at the centromere.

Thiessen polygons as a model for animal territory estimation

Thiessen polygons are often used to model territory characteristics. However, information about the quality of Thiessen polygon‐based estimates is currently lacking. We used published data to investigate the match between Thiessen polygons and mapped bird territories regarding territory size, shape and neighbourhood. Although territory sizes and the number of neighbours were strongly correlated between these two methods, both parameters were overestimated by the Thiessen polygons. Therefore, caution is required when Thiessen polygons are used as a model for absolute values and when the assumptions of Thiessen polygons, such as formation of discrete territories and a contiguous study area, are not met.

1615 クロマチンテリトリー形成の数理モデル

1615 クロマチンテリトリー形成の数理モデル

Using Chimaeric Expression Sequence Tag as the Reference to Identify Three-Dimensional Chromosome Contacts

Transcription-induced chimaeric transcripts, the potential post-transcriptional processing products, might reflect the spatial proximity of actively transcribed genes co-localized in transcription factories. A growing number of expression data deposited in databases provide us with the raw material for screening such chimaeric transcripts and using them as the probes to identify interactions between genes in cis or in trans. Based on the high-quality chimaeric transcripts gleaned from human expression sequence tag data with selection criteria, we identified the patterns of inter- and intrachromosomal gene–gene interactions. On top the contact pattern from interchromosomal interactions, we also observed an exponential behaviour of the intrachromosomal interactions within a certain length scale, which is consistent with the independent experimental results from Hi-C screening and with the Random Loop Model. A compatible result is found for mouse. Transcription-induced chimaeric transcripts, most of which might be accidental products with trivial functions, shed light on the spatial organization of chromosomes. These inter- and intrachromosomal interactions might contribute to the compaction of chromosomes, their segregation and formation of the chromosome territories, and their spatial distribution within the nucleus.

El arte rupestre como geosigno del paisaje (valle de Yocavil, Catamarca, Argentina)

En el presente trabajo se aborda la apropiación del espacio habitado implicada en la conformación de los territorios y los paisajes y el arte rupestre, entendido como sistema de comunicación y elemento activo en la construcción de dichos paisajes. A partir del análisis de la Gruta Grabada de Chiquimí (GCh), un alero con grabados rupestres, se exploran dos aspectos íntimamente relacionados con la vida de las poblaciones prehispánicas que ocuparon el valle de Yocavil (provincia de Catamarca, Argentina). Por un lado se aborda la GCh como representación estética relacionada a la cosmovisión de la gente que participó en su producción. Por otro lado, se la analiza como elemento activo en la construcción de los paisajes locales, para lo cual se desarrolla un análisis visual y espacial a escala de paisaje. Se propone así la consideración de la GCh como geosigno, lugar sacralizado donde se plasman la cosmovisión, creencias y normas culturales de las p

Capacity and Service (CapServ) Adaptive Trust Computation by Territory Formation in Ubiquitous Environment

Ubiquitous computing has been studied extensively as a post desktop model. Secure communication among various heterogeneous networks is been a challenge in service environment with location dynamism of the nodes. In this paper the authors proposed model for trust worthy communications among devices of various networks in a ubiquitous environment with varied service needs, security needs and computational-storage capacities. The model uses a novel approach for computing trust - adaptive to capacity and services.

Chromosome Territories Meet a Condensin

Chromosome Territories Meet a Condensin

Condensin II Promotes the Formation of Chromosome Territories by Inducing Axial Compaction of Polyploid Interphase Chromosomes

The eukaryotic nucleus is both spatially and functionally partitioned. This organization contributes to the maintenance, expression, and transmission of genetic information. Though our ability to probe the physical structure of the genome within the nucleus has improved substantially in recent years, relatively little is known about the factors that regulate its organization or the mechanisms through which specific organizational states are achieved. Here, we show that Drosophila melanogaster Condensin II induces axial compaction of interphase chromosomes, globally disrupts interchromosomal interactions, and promotes the dispersal of peri-centric heterochromatin. These Condensin II activities compartmentalize the nucleus into discrete chromosome territories and indicate commonalities in the mechanisms that regulate the spatial structure of the genome during mitosis and interphase.

Territorial developments based on graffiti: A statistical mechanics approach

We study the well-known sociological phenomenon of gang aggregation and territory formation through an interacting agent system defined on a lattice. We introduce a two-gang Hamiltonian model where agents have red or blue affiliation but are otherwise indistinguishable. In this model, all interactions are indirect and occur only via graffiti markings, on-site as well as on nearest neighbor locations. We also allow for gang proliferation and graffiti suppression. Within the context of this model, we show that gang clustering and territory formation may arise under specific parameter choices and that a phase transition may occur between well-mixed, possibly dilute configurations and well separated, clustered ones. Using methods from statistical mechanics, we study the phase transition between these two qualitatively different scenarios. In the mean-fields rendition of this model, we identify parameter regimes where the transition is first or second order. In all cases, we have found that the transitions are a consequence solely of the gang to graffiti couplings, implying that direct gang to gang interactions are not strictly necessary for gang territory formation; in particular, graffiti may be the sole driving force behind gang clustering. We further discuss possible sociological—as well as ecological—ramifications of our results.

흰개미 테리토리행동 연구를 위한 시뮬레이션 모델

흰개미는 땅 아래 서식하면서 네트워크형태의 터널 구조물을 만들어 먹이자원을 획득한다. 종에 따라서는 지하 150m 깊이까지 터널을 형성하기도 하고, 목재의 섬유질을 찾기 위해 종종 지표면까지 이동하기도 하는데, 이로 인해 목재로 지어진 건축물 특히 가옥에 엄청난 피해를 끼친다. 지구 온난화에 의한 온도상승으로 흰개미가 활동하기에 적합한 고온 지역이 넓어지며 이와 같은 피해는 꾸준히 증가하고 있다. 이 피해규모는 흰개미 테리토리영역의 크기 및 그 분포와 밀접한 관련을 가지고 있다. 흰개미 본 연구에서는 흰개미 두 종(Coptotermes formosanus (Shiraki) 와 Reticulitermesflavipes (Kollar))에 대한 테리토리행동을 시뮬레이션 할 수 있는 실험치 기반의 모델을 제안하였다. 모델은 콜로니별로 형성하는 터널네트워크의 성장부분과, 서로 다른 콜로니 사이의 터널교차를 고려한 영역성 부분, 이렇게 두 부분으로 구성된다. 본 모델을 이용하여 터널 성장확률에 따라 테리토리간 경쟁이 어떻게 변하는지에 대한 간단한 결과를 보여 주었다. Subterranean termites forage by constructing tunnel networks in soil and encounter food resources during tunnel excavation. Some species of termites can travel up to 150 m underground. They often travel to the surface to find wood cellulose to feed their colony, which in turn causes extensive damage to wooden architecture, such as timber-frame houses. This type of damage has been constantly increasing along with global warming because higher temperatures provide an ecological niche for termites. The damage is closely related to termite territory size and distribution. Recently, as a way to research termite control, the necessity of a mathematical model to simulate termite territory formation in relation to damage has increased. So far, however, few studies have been conducted on the development of a model because it is difficult to quantify or characterize the relationship between territorial behavior and field conditions including complicated environmental factors. In the present study, we suggest a simulation model of the territoriality of the Formosan subterranean termites, Coptotermes formosanus (Shiraki), and Reticulitermes flavipes (Kollar), based on empirical data. The model consists of 2 procedures. One describes tunnel network growth for each colony, and the other represents territoriality based on tunnel-tunnel interactions between different colonies. Using the model, we show changes in territorial competition according to the termination probability of tunnel growth.

THE ECOLOGY OF GANG TERRITORIAL BOUNDARIES*

Within any type of system, the actors in the system inevitably compete over resources. With competition comes the possibility of conflict. To minimize such effects, actors often will partition the system into geographic territories. It is against the larger ecological backdrop of competition and conflict that we examine territory formation among urban street gangs. Although previous studies have examined the social and built environment where gangs form, and how the presence of a gang influences local levels of violence, we know little about how competitive interactions are tied to the formation and maintenance of gang territories. We use formal spatial Lotka–Volterra competition models to derive hypotheses about competition‐driven territory formation. By using data on 563 between‐gang shootings, involving 13 rival street gangs in the Hollenbeck Policing Division of Los Angeles, we show that violence strongly clusters along the boundaries between gangs in a way that is quantitatively predicted by the theory. The results suggest that even weak competitive interactions between gangs are sufficient to drive gang territory formation without recourse to other processes or assumptions.

Territorial Dynamics and Stable Home Range Formation for Central Place Foragers

Uncovering the mechanisms behind territory formation is a fundamental problem in behavioural ecology. The broad nature of the underlying conspecific avoidance processes are well documented across a wide range of taxa. Scent marking in particular is common to a large range of terrestrial mammals and is known to be fundamental for communication. However, despite its importance, exact quantification of the time-scales over which scent cues and messages persist remains elusive. Recent work by the present authors has begun to shed light on this problem by modelling animals as random walkers with scent-mediated interaction processes. Territories emerge as dynamic objects that continually change shape and slowly move without settling to a fixed location. As a consequence, the utilisation distribution of such an animal results in a slowly increasing home range, as shown for urban foxes (Vulpes vulpes). For certain other species, however, home ranges reach a stable state. The present work shows that stable home ranges arise when, in addition to scent-mediated conspecific avoidance, each animal moves as a central place forager. That is, the animal's movement has a random aspect but is also biased towards a fixed location, such as a den or nest site. Dynamic territories emerge but the probability distribution of the territory border locations reaches a steady state, causing stable home ranges to emerge from the territorial dynamics. Approximate analytic expressions for the animal's probability density function are derived. A programme is given for using these expressions to quantify both the strength of the animal's movement bias towards the central place and the time-scale over which scent messages persist. Comparisons are made with previous theoretical work modelling central place foragers with conspecific avoidance. Some insights into the mechanisms behind allometric scaling laws of animal space use are also given.

Adaptation of an ecological territorial model to street gang spatial patterns in Los Angeles

Territorial behavior is often found in nature. Coyotes and wolves organize themselves around a den site and mark their territory to distinguish their claimed region. Moorcroft et al. model the formation of territories and spatial distributions of coyote packs and their markings in [31]. We modify this ecological approach to simulate spatial gang dynamics in the Hollenbeck policing division of eastern Los Angeles. We incorporate important geographical features from the region that would inhibit movement, such as rivers and freeways. From the gang and marking densities created by this method, we create a rivalry network from overlapping territories and compare the graph to both the observed network and those constructed through other methods. Data on the locations of where gang members have been observed is then used to analyze the densities created by the model.

The natural history of mudskippers in northern Australia, with field identification characters

We provide field identification characters and report on the natural history of mudskippers (Gobiidae: Oxudercinae) in Cairns, Darwin, Derby and Broome, northern Australia. Nine species in four genera are recorded (Boleophthalmus birdsongi, B. caeruleomaculatus, Periophthalmodon freycineti, Periophthalmus argentilineatus, P. darwini, P. minutus, P. novaeguineaensis, P. takita and Scartelaos histophorus). The intertidal zonation of mudskippers conforms to previously reported patterns, but subtle differences in habitat preference are observed at both intraspecific and intrageneric levels, underlining the need for in-depth investigation of habitat selection by mudskippers. Although most species inhabit littoral mudflats, some show possible habitat expansion: juvenile Periophthalmodon freycineti are found occasionally in pools on a sandy shore, and a population of Periophthalmus minutus is found to be established in a marginal mangrove habitat (a salt flat behind a pioneer mangrove assemblage). Burrow confinement during high tide is confirmed for both species of Boleophthalmus, two Periophthalmus (P. minutus and P. novaeguineaensis) and Scartelaos, but not for Periophthalmodon or the other Periophthalmus species. Territory formation is described for S. histophorus.

In vivo formation of bone and haematopoietic territories by transplanted human bone marrow stromal cells generated in medium with and without osteogenic supplements.

Autologous transplantation of human bone marrow stromal cells (BMSCs) has been successfully used for bone reconstruction. However, in order to advance this approach into the mainstream of bone tissue engineering, the conditions for BMSC cultivation and transplantation must be optimized. In a recent report, cultivation with dexamethasone (Dex) significantly increased bone formation by human BMSCs in vivo. Based on this important conclusion, we analysed the data accumulated by our laboratory, where human BMSCs have been routinely generated using media both with and without a combination of two osteogenic supplements: Dex at 10(-8) m and ascorbic acid phosphate (AscP) at 10(-4) m. Our data demonstrate that for 22/24 donors, BMSC strains propagated with and without Dex/AscP formed similar amounts of bone in vivo. Thus, human BMSCs do not appear to need to be induced to osteogenic differentiation ex vivo prior to transplantation. Similarly, for 12/14 donors, BMSC strains cultured with and without Dex/AscP formed haematopoietic territories to a comparable extent. While Dex/AscP did not increase bone formation, they significantly stimulated BMSC in vitro proliferation without affecting the number of BMSC colonies formed by the colony-forming units-fibroblasts. We conclude that for the substantial majority of donors, Dex/AscP have no effect on the ability of BMSCs to form bone and myelosupportive stroma in vivo. However, due to increased BMSC proliferation, the total osteogenic population obtained from a single marrow sample is larger after cultivation with Dex/AscP than without them. Secondary to increased BMSC proliferation, Dex/AscP may stimulate bone formation if BMSCs and/or the transplantation system are less than optimal. Published 2011. This article is a U.S. Government work and is in the public domain in the USA.