Trends in research on the possible effects of climate change concerning aquatic ecosystems with special emphasis on the modelling approach

Knowledge on the expected effects of climate change on aquatic ecosystems is defined by three ways. On the one hand, long-term observation in the field serves as a basis for the possible changes; on the other hand, the experimental approach may bring valuable pieces of information to the research field. The expected effects of climate change cannot be studied by empirical approach; rather mathematical models are useful tools for this purpose. Within this study, the main findings of field observations and their implications for future were summarized; moreover, the modelling approaches were discussed in a more detailed way. Some models try to describe the variation of physical parameters in a given aquatic habitat, thus our knowledge on their biota is confined to the findings based on our present observations. Others are destined for answering special issues related to the given water body. Complex ecosystem models are the keys of our better understanding of the possible effects of climate change. Basically, these models were not created for testing the influence of global warming, rather focused on the description of a complex system (e. g. a lake) involving environmental variables, nutrients. However, such models are capable of studying climatic changes as well by taking into consideration a large set of environmental variables. Mostly, the outputs are consistent with the assumptions based on the findings in the field. Since synthetized models are rather difficult to handle and require quite large series of data, the authors proposed a more simple modelling approach, which is capable of examining the effects of global warming. This approach includes weather dependent simulation modelling of the seasonal dynamics of aquatic organisms within a simplified framework.

Intraspecific Behavioural Diversity in a Freshwater Zooplankton: A study of the fitness consequences of vertical migration behaviour for distinct morphs of Daphnia pulicaria

The literature on niche separation and coexistence between species is large, but there is widespread variation in behavioural strategy between individuals of the same species that has received much less attention. Understanding what maintains this diversity is important because intraspecific behavioural diversity can affect population dynamics and community interactions. Multiple behavioural strategies can arise either as phenotype-dependent ‘conditional strategies’, where phenotypic variation causes individuals to adopt different strategies for optimizing fitness, or as internally-independent ‘alternative strategies’, where multiple fitness peaks exist for individuals and strategic ‘choice’ remains plastic. Though intraspecific variation in stable phenotypes is known to maintain intraspecific behavioural diversity through conditional strategies, when internal conditions are highly plastic or reversible, it is not clear whether individual behaviours are maintained as conditional strategies, or as alternative strategies of equal fitness. In this study, I combine an observational and experimental approach to identify the likely mechanisms maintaining behavioural diversity between hemoglobin-rich and hemoglobin-poor morphs in a natural population of Daphnia pulicaria. In Round Lake, individuals with low hemoglobin migrate daily from the hypolimnion to the epilimnion, whereas individuals with high hemoglobin remain in the hypolimnion. Using high-resolution depth and time sampling, I discovered behavioural diversity both within and among hemoglobin phenotypes. I tested the role of hemoglobin phenotype in maintaining behavioural diversity using automated migration robots that move individuals across the natural environmental gradients in the lake. By measuring the fitness of each morph undergoing either a natural migration behaviour, or the migration of the opposite morph, I found that the fitness of hemoglobin rich and poor morphs in their natural behaviour does not differ, but that Hb-rich individuals can obtain equal fitness from either behaviour, while Hb-poor morphs suffer substantial drops in survivorship in the alternate migration behaviour. Thus, migration behaviour in this system exists as a conditional strategy for some individuals, and as alternative strategies of equal fitness for others. The results of this study suggest that individual limits in the expression of highly flexible internal conditions can reinforce intraspecific behavioural diversity. Few studies have measured the fitness consequences of switching migration strategies and this study provides a rare example in the field.

Contested dominance modifies the anovulatory consequences of social subordination in female marmosets

Dominance status among female marmosets is reflected in agonistic behavior and ovarian function. Socially dominant females receive submissive behavior from subordinates, while exhibiting normal ovulatory function. Subordinate females, however, receive agonistic behavior from dominants, while exhibiting reduced or absent ovulatory function. Such disparity in female fertility is not absolute, and groups with two breeding females have been described. The data reported here were obtained from 8 female-female pairs of captive female marmosets, each housed with a single unrelated male. Pairs were classified into two groups: “uncontested” dominance (UD) and “contested” dominance (CD), with 4 pairs each. Dominant females in UD pairs showed significantly higher frequencies (4.1) of agonism (piloerection, attack and chasing) than their subordinates (0.36), and agonistic behaviors were overall more frequently displayed by CD than by UD pairs. Subordinates in CD pairs exhibited more agonistic behavior (2.9) than subordinates in UD pairs (0.36), which displayed significantly more submissive (6.97) behaviors than their dominants (0.35). The data suggest that there is more than one kind of dominance relationship between female common marmosets. Assessment of progesterone levels showed that while subordinates in UD pairs appeared to be anovulatory, the degree of ovulatory disruption in subordinates of CD pairs was more varied and less complete. We suggest that such variation in female-female social dominance relationships and the associated variation in the degree and reliability of fertility suppression may explain variations of the reproductive condition of free-living groups of common marmosets

Contested dominance modifies the anovulatory consequences of social subordination in female marmosets

Dominance status among female marmosets is reflected in agonistic behavior and ovarian function. Socially dominant females receive submissive behavior from subordinates, while exhibiting normal ovulatory function. Subordinate females, however, receive agonistic behavior from dominants, while exhibiting reduced or absent ovulatory function. Such disparity in female fertility is not absolute, and groups with two breeding females have been described. The data reported here were obtained from 8 female-female pairs of captive female marmosets, each housed with a single unrelated male. Pairs were classified into two groups: “uncontested” dominance (UD) and “contested” dominance (CD), with 4 pairs each. Dominant females in UD pairs showed significantly higher frequencies (4.1) of agonism (piloerection, attack and chasing) than their subordinates (0.36), and agonistic behaviors were overall more frequently displayed by CD than by UD pairs. Subordinates in CD pairs exhibited more agonistic behavior (2.9) than subordinates in UD pairs (0.36), which displayed significantly more submissive (6.97) behaviors than their dominants (0.35). The data suggest that there is more than one kind of dominance relationship between female common marmosets. Assessment of progesterone levels showed that while subordinates in UD pairs appeared to be anovulatory, the degree of ovulatory disruption in subordinates of CD pairs was more varied and less complete. We suggest that such variation in female-female social dominance relationships and the associated variation in the degree and reliability of fertility suppression may explain variations of the reproductive condition of free-living groups of common marmosets

Size and power properties of the AH test of evolutionary change

We investigate the size and power properties of the AH test of evolutionary change. This involves examining whether the size results are sensitive to both the number of individual frequencies estimated and the spectral shape adopted under the null hypothesis. The power tests examine whether the test has good power to detect shifts in both spectral position (variance) and spectral shape (autocovariance structure).

The Dark Side of Organizational Change: The Moderating Role of Political Behavior and Organizational Cynicism

Workplace aggression is a factor that shapes the interaction between individuals and their work environment and produces many undesirable outcomes, sometimes introducing heavy costs for organizations. Only through a comprehensive understanding of the genesis of workplace aggression is possible to develop strategies and interventions to minimize its nefarious effects. The existent body of knowledge has already identified several individual, situational and contextual antecedents of workplace aggression, although this is a research area where significant gaps occur and many issues were still not addressed Dupré and Barling (2006). According to Baron and Neuman (1998) one of these predictors is organizational change, since certain changes in the work environment (e.g., changes in management) can lead to increased aggression. This paper intends to contribute to workplace aggression research by studying its relationship with organizational change, considering a moderating role of political behaviors and organizational cynicism (Ammeter et al., 2002, Ferris et al., 2002). The literature review suggests that mediators and moderators that intervene in the relationships between workplace aggression and its antecedents are understudied topics. James (2005) sustains that organizational politics is related to cynicism and the empirical research of Miranda (2008) has identified leadership political behavior as an antecedent of cynicism but these two variables were not yet investigated regarding their relationship with workplace aggression. This investigation was operationalized using several scales including the Organizational Change Questionnaire-climate of change, processes, and readiness (Bouckenooghe, Devos and Broeck, 2009), a Workplace Aggression Scale (Vicente and D’Oliveira, 2008, 2009, 2010), an Organizational Cynicism Scale (Wanous, Reichers and Austin, 1994) and a Political Behavior Questionnaire (Yukl and Falbe, 1990). Participants representing a wide variety of jobs across many organizations were surveyed. The results of the study and its implications will be presented and discussed. This study contribution is also discussed in what concerns organizational change practices in organizations.

The Distributional Consequences of Supply-Side Reforms in General Equilibrium

This paper addresses the issue on whether tax reforms consisten with lower public debt-to-GDP in the long-run can lead to a more efficient and equitable economy. To this end we solve a heterogeneous agent model comprised of a government, a representative capitalist and representative skilled and unskilled workers, under both rational expectations and adaptive learning. Our main ndings are that (i) reductions in capital taxation, while bene cial at the aggregate level, lead to increased inequality mainly due to the substitutability of un- skilled labour and capital; (ii) a fall in taxation for skilled labour is Pareto improving, which is largely explained by its complementarity with the other factor inputs; (iii) all agents would prefer increasing the tax rate on capital to increasing the tax rate on skilled and un- skilled labour since it leads to relatively lower welfare losses; and (iv) heterogeneity in initial beliefs under adaptive learning quantitatively matters for welfare.

The distributional consequences of tax reforms under market distortions

In this paper we examine the importance of imperfect competition in product and labour markets in determining the long-run welfare e¤ects of tax reforms assuming agent heterogeneneity in capital hold- ings. Each of these market failures, independently, results in welfare losses for at least a segment of the population, after a capital tax cut and a concurrent labour tax increase. However, when combined in a realistic calibration to the UK economy, they imply that a capital tax cut will be Pareto improving in the long run. Consistent with the the- ory of second-best, the two distortions in this context work to correct the negative distributional e¤ects of a capital tax cut that each one, on its own, creates.