1,305 research outputs found

    Mating order-dependent female mate choice in the polygynandrous common lizard Lacerta vivipara.

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    Recent studies indicate that directional female mate choice and order-dependent female mate choice importantly contribute to non-random mating patterns. In species where females prefer larger sized males, disentangling different hypotheses leading to non-random mating patterns is especially difficult, given that male size usually correlates with behaviours that may lead to non-random mating (e.g. size-dependent emergence from hibernation, male fighting ability). Here we investigate female mate choice and order-dependent female mate choice in the polygynandrous common lizard (Lacerta vivipara). By sequentially presenting males in random order to females, we exclude non-random mating patterns potentially arising due to intra-sexual selection (e.g. male-male competition), trait-dependent encounter probabilities, trait-dependent conspicuousness, or trait-dependent emergence from hibernation. To test for order-dependent female mate choice we investigate whether the previous mating history affects female choice. We show that body size and body condition of the male with which a female mated for the first time were bigger and better, respectively, than the average body size and body condition of the rejected males. There was a negative correlation between body sizes of first and second copulating males. This indicates that female mate choice is dependent on the previous mating history and it shows that the female's choice criteria are non-static, i.e. non-directional. Our study therefore suggests that context-dependent female mate choice may not only arise due to genotype-environment interactions, but also due to other female mating strategies, i.e. order-dependent mate choice. Thus context-dependent female mate choice might be more frequent than previously thought

    The co-evolution of multiply-informed dispersal: information transfer across landscapes from neighbors and immigrants

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    Dispersal plays a key role in natural systems by shaping spatial population and evolutionary dynamics. Dispersal has been largely treated as a population process with little attention to individual decisions and the influence of information use on the fitness benefits of dispersal despite clear empirical evidence that dispersal behavior varies among individuals. While information on local density is common, more controversial is the notion that indirect information use can easily evolve. We used an individual-based model to ask under what conditions indirect information use in dispersal will evolve. We modeled indirect information provided by immigrant arrival into a population which should be linked to overall metapopulation density. We also modeled direct information use of density which directly impacts fitness. We show that immigrant-dependent dispersal evolves and does so even when density dependent information is available. Use of two sources of information also provides benefits at the metapopulation level by reducing extinction risk and prolonging the persistence of populations. Our results suggest that use of indirect information in dispersal can evolve under conservative conditions and thus could be widespread

    Experimental enhancement of corticosterone levels positively affects subsequent male survival.

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    Corticosterone is an important hormone of the stress response that regulates physiological processes and modifies animal behavior. While it positively acts on locomotor activity, it may negatively affect reproduction and social activity. This suggests that corticosterone may promote behaviors that increase survival at the cost of reproduction. In this study, we experimentally investigate the link between corticosterone levels and survival in adult common lizards (Lacerta vivipara) by comparing corticosterone-treated with placebo-treated lizards. We experimentally show that corticosterone enhances energy expenditure, daily activity, food intake, and it modifies the behavioral time budget. Enhanced appetite of corticosterone-treated individuals compensated for increased energy expenditure and corticosterone-treated males showed increased survival. This suggests that corticosterone may promote behaviors that reduce stress and it shows that corticosterone per se does not reduce but directly or indirectly increases longer-term survival. This suggests that the production of corticosterone as a response to a stressor may be an adaptive mechanism that even controls survival

    Cooperative social clusters are not destroyed by dispersal in a ciliate

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    <p>Abstract</p> <p>Background</p> <p>The evolution of social cooperation is favored by aggregative behavior to facilitate stable social structure and proximity among kin. High dispersal rates reduce group stability and kin cohesion, so it is generally assumed that there is a fundamental trade-off between cooperation and dispersal. However, empirical tests of this relationship are rare. We tested this assumption experimentally using ten genetically isolated strains of a ciliate, <it>Tetrahymena thermophila</it>.</p> <p>Results</p> <p>The propensity for social aggregation was greater in strains with reduced cell quality and lower growth performance. While we found a trade-off between costly aggregation and local dispersal in phenotypic analyses, aggregative strains showed a dispersal polymorphism by producing either highly sedentary or long-distance dispersive cells, in contrast to less aggregative strains whose cells were monomorphic local dispersers.</p> <p>Conclusion</p> <p>High dispersal among aggregative strains may not destroy group stability in <it>T. thermophila </it>because the dispersal polymorphism allows social strains to more readily escape kin groups than less aggregative strains, yet still benefit from stable group membership among sedentary morphs. Such dispersal polymorphisms should be common in other social organisms, serving to alter the nature of the negative impact of dispersal on social evolution.</p

    Conflict over multiple-partner mating between males and females of the polygynandrous common lizards.

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    The optimal number of mate partners for females rarely coincides with that for males, leading to a potential sexual conflict over multiple-partner mating. This suggests that the population sex ratio may affect multiple-partner mating and thus multiple paternity. We investigate the relationship between multiple paternity and the population sex ratio in the polygynandrous common lizard (Lacerta vivipara). In six populations the adult sex ratio was biased toward males, and in another six populations the adult sex ratio was biased toward females, the latter corresponding to the average adult sex ratio encountered in natural populations. In males the frequency and the degree of polygyny were lower in male-biased populations, as expected if competition among males determines polygyny. In females the frequency of polyandry was not different between treatments, and polyandrous females produced larger clutches, suggesting that polyandry might be adaptive. However, in male-biased populations females suffered from reduced reproductive success compared to female-biased populations, and the number of mate partners increased with female body size in polyandrous females. Polyandrous females of male-biased populations showed disproportionately more mating scars, indicating that polyandrous females of male-biased populations had more interactions with males and suggesting that the degree of multiple paternity is controlled by male sexual harassment. Our results thus imply that polyandry may be hierarchically controlled, with females controlling when to mate with multiple partners and male sexual harassment being a proximate determinant of the degree of multiple paternity. The results are also consistent with a sexual conflict in which male behaviors are harmful to females

    Female common lizards (Lacerta vivipara) do not adjust their sex-biased investment in relation to the adult sex ratio.

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    Sex allocation theory predicts that facultative maternal investment in the rare sex should be favoured by natural selection when breeders experience predictable variation in adult sex ratios (ASRs). We found significant spatial and predictable interannual changes in local ASRs within a natural population of the common lizard where the mean ASR is female-biased, thus validating the key assumptions of adaptive sex ratio models. We tested for facultative maternal investment in the rare sex during and after an experimental perturbation of the ASR by creating populations with female-biased or male-biased ASR. Mothers did not adjust their clutch sex ratio during or after the ASR perturbation, but produced sons with a higher body condition in male-biased populations. However, this differential sex allocation did not result in growth or survival differences in offspring. Our results thus contradict the predictions of adaptive models and challenge the idea that facultative investment in the rare sex might be a mechanism regulating the population sex ratio

    Age- and sex-specific response to population density and sex ratio

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    Both population density and sex ratio shape competition for mates, resources and mating costs. Thus they may critically affect the intensity of sexual selection in the populations. Susceptibility to inter- and intrasexual competition, which changes with age in a large number of species, may additionally influence population response to these demographic factors. In this study, we monitored 16 seminatural populations of common lizards (Lacerta vivipara) to determine whether the reproductive output varied with male and female densities as a function of the individual sex and age. Our results suggest that the intensity of sexual selection was weaker in male-biased populations, supporting new theoretical models. In populations with a male-biased sex ratio, reproductive success was more equally distributed between males and, unlike female-biased populations, the choosiest females (middle-aged) did not obtain sires of higher quality than low-performance females. Our results also suggest that age may influence the intensity of sexual conflict. Middle-aged females (the class with the best performance) produced offspring with a lower body condition in male-biased populations, suggesting that they may be the preferred target of male harassment. By contrast, a male-biased sex ratio appeared to be beneficial for low-quality females, allowing these females to obtain higher quality sires and to produce offspring with a better body condition. These age- and sex-dependent responses to population density and sex ratio have important implications for population ecology and sexual selectio

    Proposta de critérios para o processo de seleção de incubação de empresas de base tecnológica, a partir do modelo cerne : um estudo na incubadora tecnológica de Curitiba (INTEC)

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    Orientadora : Profª Drª Izabel Cristina ZattarDissertação (mestrado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduação em Engenharia de Produção. Defesa: Curitiba, 28/02/2014Inclui referênciasÁrea de concentraçãoResumo: Incubadoras de empresas representam uma grande fonte de estímulo para empreendimentos inovadores, possibilitando o desenvolvimento de novas tecnologias, disponibilizando infraestrutura, assessoria e apoio, os quais são aspectos fundamentais para o sucesso de novos empreendimentos. As incubadoras de empresas de base tecnológica (EBTs) somam 154 no país, sendo que cada uma possui seu próprio mecanismo de seleção de empresas para incubação. Em virtude das diferentes formas de gestão das incubadoras, foi criado pela Anprotec e Sebrae, o modelo de gestão CERNE - Centro de Referência para Apoio a Novos Empreendimentos - com o intuito de uniformizar os procedimentos e favorecer o aumento das chances de sucesso nas incubações. O objetivo deste trabalho foi propor critérios de seleção para incubação, considerando as 5 dimensões do CERNE, visando auxiliar a tomada de decisão na avaliação do potencial de sucesso das empresas candidatas, em uma incubadora de EBTs. O trabalho foi desenvolvido a partir de editais de 20 incubadoras de EBTs, as quais tiveram 38 critérios de seleção identificados e classificados. Destes, foram validados 26 critérios, considerando o grau de importância atribuído por gestores de incubadoras de EBTs, por meio de questionários online. Como resultado, foram obtidas avaliações favoráveis a 25 critérios; apenas um foi avaliado desfavoravelmente. Palavras-chave: Inovação. Incubadoras. Critérios de seleção. Empresas de base tecnológica.Abstract: Business incubators are a great source of encouragement for innovative projects, enabling the development of new technologies, providing infrastructure, advice and support, which are key elements for the success of new business. The technologybased firm incubators (TBFs), which are 154 in Brazil. Each one of them has its own mechanism for the selection of the incubation companies. Because of the different forms of management of incubators, the business model CERNE - Reference Center for Support for New Projects - was created by Anprotec and Sebrae, in order to standardize procedures and promote the increase of chances for success in the incubations. The objective of this study is to propose selection criteria for the incubation, considering CERNE's five dimensions and aiming to help on the decision-making in the assessment of candidate companies in a TBF incubator. The research was conducted from the public notices of 20 TBF incubators, where 38 selection criteria were identified and classified. Managers of TBF incubators validated 26 criteria by its importance via online questionnaires. As a result, favorable ratings were obtained to 25 of them. Only one criterion differed from the others, with a unfavorable rating. Keywords: Innovation. Incubators. Selection criteria. Technology-based firms

    Outgroup Attitudes as a Function of East Asian Religiousness: Marked by High or Low Prejudice?

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    Research on religion and prejudice has mostly been limited to Western Christian participants and beliefs. Evidence, overall, favors the idea of a religion-prejudice link. Does this also hold for East Asian religions, usually perceived as tolerant, and cultures, characterized by holistic thinking and tolerance of contradictions? We review here four recent studies and provide meta-analytic estimation of the East Asian interreligious prejudice. East Asian religiosity was associated with low explicit prejudice against religious outgroups in general (Study 1; adults from Japan, South Korea, and Taiwan) and three specific religious outgroups, i.e. Christians, Jews, and Muslims, but not atheists (Study 2; Taiwanese students), and low implicit prejudice against ethnic (Africans) and religious (Muslims) outgroups (Study 3; Taiwanese students). The mean effect size of the East Asian religious (low) prejudice was r = -.21. Moreover, Westerners from a Christian background primed with Buddhist pictures showed higher prosociality and, those valuing universalism, lower ethnic prejudice compared to the control, no pictures, condition (Study 4). Thus, the general idea that religion promotes prejudice lacks cross-cultural sensitivity: East Asian religion seems to be followed by low prejudice with regard to many, though not all, kinds of outgroups
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