Mate-guarding is performed by many monogamous species, a method used by individuals to physically prevent competitors of the same sex from mating with their partners. This behaviour is most often displayed during the fertile period (i.e. when females can be fertilized). In this study I focused on the genetically and socially monogamous species, the Siberian jay (Perisoreus infaustus), in which I observed mate-guarding behaviour. The Siberian jays did change their behaviour and increased their aggression in the fertile period, a sign of mate-guarding. This result also suggests that even socially and genetically monogamous species do increase their aggression during the fertile period. This indicates that fidelity still requires an investment in mate-guarding to limit extra-pair mating opportunities. Mate-guarding should then be possible to find in species where there is at least a theoretical opportunity for extra-pair matings. / Mate-guarding är en metod använd utav många monogama arter, metoden används för att fysiskt hålla konkurrenter utav samma kön borta ifrån sin partner för att försäkra sin egen parning. Denna metod beskådas oftast under tiden honan är fertil. I denna studie fokuserade jag på den genetiska och sociala monogama arten Lavskrika(Perisoreus infaustus) där jag observerade mate-guarding beteende. Lavskrikans beteende förändrades mellan perioden då honan icke var receptiv och hon var fertil, aggressionen ökade för båda könen under den fertila perioden vilket är ett tecken utav mate-guarding beteende. Detta resultat föreslår att socialt och genetiskt monogama arter ökar sin aggression under tiden honan är fertil, det föreslår även att trofasthet fortfarande kräver hög investering utav mate-guarding för att minska riskerna utav otrohet. Mate-guarding beteende borde då finnas hos arter med en teoretisk möjlighet för otrohet.

<p>In Libellulidae there are two types of egg-laying behaviour, non-contact guarding where the male accompany the female during oviposition and tandem guarding where the male is physically coupled with the female. These egg laying strategies also shows differences in egg size distribution and egg size. In species which perform non-contact guarding the egg size is inversely proportionate to the order of laying. In tandem species on the other hand, the egg size is more randomly distributed and the eggs are slightly larger than in non-contact species. To see if there is a difference in the female internal reproductive organs between the two guarding types, the ovariole number was counted. The result shows that species which perform tandem guarding during oviposition have a fewer number of ovarioles compared to the non-contact species. This difference in ovariole number was also species specific.</p><p> Increasing impact on ecosystems, the survival of dragonflies or any other insects can no longer be taken for granted. Therefore can this information be valuable in conservation biology when new habitats are created for preservation of species.</p>

In Libellulidae there are two types of egg-laying behaviour, non-contact guarding where the male accompany the female during oviposition and tandem guarding where the male is physically coupled with the female. These egg laying strategies also shows differences in egg size distribution and egg size. In species which perform non-contact guarding the egg size is inversely proportionate to the order of laying. In tandem species on the other hand, the egg size is more randomly distributed and the eggs are slightly larger than in non-contact species. To see if there is a difference in the female internal reproductive organs between the two guarding types, the ovariole number was counted. The result shows that species which perform tandem guarding during oviposition have a fewer number of ovarioles compared to the non-contact species. This difference in ovariole number was also species specific. Increasing impact on ecosystems, the survival of dragonflies or any other insects can no longer be taken for granted. Therefore can this information be valuable in conservation biology when new habitats are created for preservation of species.

No description available.

Cooperative breeding is a phenomenon whereby breeding and nonbreeding individuals collectively provision young. Nonbreeding group members ("helpers'') may gain indirect and/or direct fitness benefits by breeding in a group, but there has been conflicting evidence regarding the benefits to breeders. In fact, the presence of helpers may sometimes be detrimental to aspects of breeder fitness. For example, in some species of the chiefly Australian genus Malurus, breeding males with helpers have lower within-pair paternity than do males without helpers. Additionally, indirect benefits to breeding males are often limited by low relatedness to their helpers due to high extrapair paternity rates, and helpers often appear to have minimal impact on breeder reproductive success. However, the presence of helpers may allow breeding males to shift their behaviors from guarding and provisioning young to alternative behaviors that affect other components of fitness, such as extraterritory forays (which might increase extrapair mating success) and self-maintenance (which might increase survival). We investigated these possibilities in the facultatively cooperative Red-backed Fairywren (Malurus melanocephalus). Males with helpers spent significantly less time engaging in guarding behaviors and provisioning of young than did those without helpers, but there was no difference in the frequency of extrapair forays nor the number of young sired by males with vs. without helpers. Additionally, the decreased investment in nesting behaviors did not result in consistently higher survival, but may have increased survival in some years. Overall, the results of this study did not suggest any strong direct fitness benefits to breeding males, which may indicate that the costs of retaining helpers are negligible relative to the indirect benefits of helping a potentially related male.

The reproductive strategies of four intertidal grapsid crabs, Hemigrapsus sexdentatus, H. crenulatus, Cyclograpsus lavauxi, and Helice cressa, were studied in the field and laboratory, with emphasis on mating behaviour, duration of female receptivity, and sperm competition. Mating occurred in all species during the intermoult on the days prior to oviposition, when the gonoporo opercula of females became temporarily mobile. Female Helice crassa mated up to three weeks after oviposition, but in all other species mating typically ceased at egg-laying. Male Hemigrapsus pp. used a female-centered competition strategy in which they searched for and defended receptive females until they laid eggs. In contrast, male C. lavauxi searched for and intercepted receptive females only for the duration of copulation and then pursued other receptive females (a mating system termed encounter rate competition with pure search and interception). Male Helice crassa searched for receptive females in their immediate neighbourhood and mated with them briefly on the substrate or in the burrow after which the female left (a mating system termed encounter rate competition with neighbourhoods of dominance). The mating season was short and highly synchronous for Hemigrapsus exdentatus and Cyclograpsus lavauxi and asynchronous for Hemigrapsus crenulatus and Helice crassa. In the laboratory, the mean duration of receptivity for females housed with three males varied between 4.1 and 12.4 days, and the copulation frequency of females varied before oviposition between 2.1 and 24.3 times (mean) depending on the species. Female Hemigrapsus spp. isolated from males stayed receptive significantly longer than females held continuously with males. This suggests that females are able to control the duration of their receptivity, and therefore the time available for mating, according to the absence or presence of males. The operational sex ratio (OSR) had no effect on the duration of female receptivity, but female Hemigrapsus crenulatus mated more often when several males were competing for access. Therefore, male-male competition increased the number of matings per female and hence sperm competition within the female spermathecae. Larger males mated significantly more often than smaller males in all species. However, male size did not affect ejaculate size, meaning that small and large males transferred similar-sized ejaculates, e.g., in Hemigrapsus spp. Males of the two Hemigrapsus species followed a different strategy of sperm allocation. Male H. crenulatus, which are typically confronted with a high mating frequency of the female and a long, asynchronous mating season, distributed similar-sized ejaculates, irrespective of female size. By contrast, male H. sexdentatus, which experience a comparatively lower risk of sperm competition during a short, synchronised mating season, invested larger ejaculates for larger females than for smaller females. In addition, the size of the first and second ejaculates transferred to a female by a male H. crenulatus were not significantly different, whereas the first was larger than the second for H. sexdentatus. A parasitological survey was undertaken of the four grapsid crabs and the presence, seasonal variation and relationship with host gender and size of parasites determined. Four internal parasites were discovered: Nectonema zealandica n. Sp. (Nematomorpha: Nectonematoidea), portunion sp. (Isopoda: Entoniscidae), Profilicollis novaezelandensis n. sp. and profilicollis antarcticus (Acanthocephala: P olymorphidae). Portunion sp. castrated its female hosts, but not the males thereby creating a more male-biased sex ratio. Males parasitised with portunion sp. were equally successful during male-male competition and the number of matings they achieved. The above findings are important for our current understanding of mating strategies in Grapsidae, which are more diverse than previously thought. Females with a restricted duration of sexual receptivity have some control over their receptive period and can therefore influence the OSR and the extent of male-male competition. As females mated multiple times during their receptive period, sperm competition is a common feature in Grapsidae. However, males employed different tactics in regards to sperm competition such as longer mating duration (e.g., C. lavauxi), high number of matings (Helice crassa), or post-copulatory mate guarding until oviposition (Hemigrapsus spp.).

In this thesis, we design and develop new approximation algorithms and complexity results for three guarding and partitioning problems on orthogonal polygons; namely, guarding orthogonal polygons using sliding cameras, partitioning orthogonal polygons so as to minimize the stabbing number and guarding orthogonal terrains using vertex guards. We first study a variant of the well-known art gallery problem in which sliding cameras are used to guard the polygon. We consider two versions of this problem: the Minimum- Cardinality Sliding Cameras (MCSC) problem in which we want to guard P with the minimum number of sliding cameras, and the Minimum-Length Sliding Cameras (MLSC) problem in which the goal is to compute a set S of sliding cameras for guarding P so as to minimize the total length of trajectories along which the cameras in S travel. We answer questions posed by Katz and Morgenstern (2011) by presenting the following results: (i) the MLSC problem is polynomially tractable even for orthogonal polygons with holes, (ii) the MCSC problem is NP-complete when P is allowed to have holes, and (iii) an O(n)-time exact algorithm for the MCSC problem on monotone polygons. We then study a conforming variant of the problem of computing a partition of an orthogonal polygon P into rectangles whose stabbing number is minimum over all such partitions of P. The stabbing number of such a partition is the maximum number of rectangles intersected by any orthogonal line segment inside the polygon. In this thesis, we first give an O(n log n)-time algorithm that solves this problem exactly on histograms. We then show that the problem is NP-hard for orthogonal polygons with holes, providing the first hardness result for this problem. To complement the NP-hardness result, we give a 2-approximation algorithm for the problem on both polygons with and without holes. Finally, we study a variant of the terrain guarding problem on orthogonal terrains in which the objective is to guard the vertices of an orthogonal terrain with the minimum number of vertex guards. We give a linear-time algorithm for this problem under a directed visibility constraint. / February 2016

No description available.

Ett samhälle kan sägas bestå av dels ovissa, oförutsägbara och oberäkneliga respektive planerade, beräknade och förutsägbara händelser. I denna studie undersöks hur detta som vi inte vet något om, såsom plötsliga och oförväntade händelser, organiseras socialt. Sverige och en del andra delar av världen kan sägas vara platser där en säkerhetskultur med fokus på att försäkra sig om skydd av olika slag utspelar sig. Jourbranschen är ett område där denna kultur skulle kunna analyseras. Dessa organisationer kan ses som värdefulla informanter utifrån att det ständigt dyker upp oförutsägbara händelser där människor behöver assistans och hjälp av olika slag. Tidigare forskning i ämnet behandlar fenomen som risk, rationalitet, kris, kaos och katastrof. Även meningsskapande fenomenologiska studier av organisationer som arbetar med dessa typer av händelser har gåtts igenom. Denna uppsats teoretiska utgångspunkt har hämtats från konceptet om system och livsvärld, formulerat i Jürgen Habermas verk The Theory of Communicative Action1. I anslutning till detta koncept berörs också den strukturella meso-sociala dimensionen som ett mellanting eller sammanblandning av en övergripande makrostruktur och en närmare mikro-social interaktion. Två jourorganisationer, med något olika verksamhetsområden, har här utgjort det empiriska datamaterialet bestående av semi-strukturerade intervjuer och deltagande observationer för att undersöka hur oförutsägbarhet organiseras socialt. Resultatet visar att jourverksamheter kan förklara en del skillnader i hur oförutsägbarhet hanteras utifrån modellen om system och livsvärld vilket ses som tydligast via digitaliserat arbetsinnehåll på systemnivå och direktkommunikation i en mellanmänsklig verbal kommunikation. 1 Jürgen Habermas, The Theory of Communicative Action. (Cambridge: Polity Press, 1987). / A society handle on one hand uncertain, unpredictable and incalculable events and on the other hand planned, calculated and predictable occasions. In this essay, I will investigate how these events and situations that we do not know anything about are socially organized. Sweden, among other developed countries worldwide, may be an interesting field of a new upcoming discourse of security and safety. New agencies in the form of alarm centres with on-call and on-site services are popping up more often these days. Two of those agencies are analysed in this essay. Earlier research on this theme handle phenomenon such as rationality, crisis, chaos and catastrophes. Also, phenomenological sense-making studies of organizations working with these kinds of events have been gone through. The sociological theoretical framework of system and lifeworld, developed by Jürgen Habermas in his work of Theories of Communicative Action1 is the theoretical outset in this study. With mentioned organizations, at somewhat different domains, I have used the qualitative methodologies of semi-structural interviews and participant observations. Interpersonal verbal communication is here problematized together with technological and digital forms of communication. The result gave that some forms of systematic organized processes, but also reflexive and intuitive forms of action can explain the dichotomy of system and lifeworld in the structural middle level (meso) for investigated organizations. 1 Jürgen Habermas 1987.

ABSTRACT Usually, real game problems encountered in our daily lives are so complicated that the existing methods are no longer sufficient to deal with them. This motivates us to investigate several kinds of differential game problems, which have not been considered or solved yet, including a pursuit-evasion game with n pursuers and one evader, a problem of guarding a territory with two guarders and two invaders, and a payoff-switching differential game. In this thesis, firstly the geometric method is used to consider the pursuit-evasion game with n pursuers and one evader. Two criteria used to find the solutions of the game in some cases are given. It will be shown that the one-on-one pursuit-evasion game is a special case of this game. Secondly, the problem of guarding a territory with two guarders and two invaders is considered both qualitatively and quantitatively. The investigation of this problem reveals a variety of situations never occurring in the case with one guarder and one invader. An interesting thing found in this investigation is that some invader may play the role as a pursuer for achieving a more favorable payoff in some cases. This will make the problem more complicated and more difficult to be solved. The payoff-switching differential game, first proposed by us, is a kind of differential game with incomplete information. The main difference between this problem and traditional differential games is that in a payoff-switching differential game, any one player at any time may have several choices of payoffs for the future. The optimality in such a problem becomes questionable. Some reasoning mechanisms based on different methods will be provided to determine a reasoning strategy for some player in a payoff-switching differential game. A practical payoff-switching differential game problem, i.e., the guarding three territories with one guarder against one invader, is presented to illustrate the situations of such a game problem. Many computer simulations of this example are given to show the performances of different reasoning strategies. The proposition of the payoff-switching differential game is an important breakthrough in dealing with some kinds of differential games with incomplete information.