Effects of Spring Temperatures on the Strength of Selection on Timing of Reproduction in a Long-Distance Migratory Bird

Climate change has differentially affected the timing of seasonal events for interacting trophic levels, and this has often led to increased selection on seasonal timing. Yet, the environmental variables driving this selection have rarely been identified, limiting our ability to predict future ecological impacts of climate change. Using a dataset spanning 31 years from a natural population of pied flycatchers (Ficedula hypoleuca), we show that directional selection on timing of reproduction intensified in the first two decades (1980-2000) but weakened during the last decade (2001-2010). Against expectation, this pattern could not be explained by the temporal variation in the phenological mismatch with food abundance. We therefore explored an alternative hypothesis that selection on timing was affected by conditions individuals experience when arriving in spring at the breeding grounds: arriving early in cold conditions may reduce survival. First, we show that in female recruits, spring arrival date in the first breeding year correlates positively with hatch date; hence, early-hatched individuals experience colder conditions at arrival than late-hatched individuals. Second, we show that when temperatures at arrival in the recruitment year were high, early-hatched young had a higher recruitment probability than when temperatures were low. We interpret this as a potential cost of arriving early in colder years, and climate warming may have reduced this cost. We thus show that higher temperatures in the arrival year of recruits were associated with stronger selection for early reproduction in the years these birds were born. As arrival temperatures in the beginning of the study increased, but recently declined again, directional selection on timing of reproduction showed a nonlinear change. We demonstrate that environmental conditions with a lag of up to two years can alter selection on phenological traits in natural populations, something that has important implications for our understanding of how climate can alter patterns of selection in natural populations.

Repositórios de recursos educacionais livres : desafios para implantação em instituições públicas de ensino superior (IPES) a partir da perspectiva de professores conteudistas em EaD

A arquitetura distributiva da Internet amplia as possibilidades de produção e transmissão de recursos educacionais livres (REL). Assim, a pesquisa focaliza a implantação de repositórios de recursos educacionais livres (RREL) em instituições públicas de ensino superior, de maneira a garantir a integridade, a qualidade e a disponibilidade desses recursos no ciberespaço. Nesta perspectiva, identificam-se os fatores intervenientes para consecução desse objetivo, a partir da perspectiva de professores conteudistas na modalidade EaD. Para tanto, adota-se a pesquisa qualitativa e como técnica de coleta de dados, a entrevista. Com base no conjunto de respostas dos professores investigados, a partir da técnica de análise de conteúdo, são elaboradas recomendações para implantação e expansão de RREL no ensino superior. Os resultados apontam que na dimensão governamental se deve:a) incentivar a adoção de licenças abertas para a elaboração de REL, b) fomentar investimentos públicos para o desenvolvimento de pesquisas nessa área c) alocar recursos financeiros de forma constante e crescente na implantação de infraestrutura tecnológica de ponta em nível nacional; na dimensão institucional é necessário: a)promover amplo debate,de modo a elaborar diretrizes para formulação de política com o objetivo de implantar RREL e b) desenvolver programas de incentivos e benefícios para progressão acadêmica do docente; na dimensão informacional a) incentivar o trabalho colaborativo com a constituição de equipe multidisciplinar e b) estimular a participação das bibliotecas universitárias na gestão dos conteúdos. Busca-se, assim, expandir os RREL de maneira compartilhada com vistas à inovação e ao aprimoramento da educação superior no país

Sources of variability in the free-ball micro-scale abrasion test

In the 'free-ball' version of the micro-scale abrasion or ball-cratering test the rotating ball rests against a tilted sample and a grooved drive shaft. Tests under nominally identical conditions with different apparatus commonly show small but significant differences in measured wear rate. An indirect method has been developed and demonstrated for continuous on-line measurement of the coefficient of friction in the free-ball test. Experimental investigation of the effects of sample tilt angle and drive shaft groove width shows that both these factors influence the stability of the rotation of the ball, and the shape of the abrasive slurry pool, which in turn affect the coefficient of friction in the wear scar area and the measured wear rate. It is suggested that in order to improve the reproducibility of this method the geometry of the apparatus should be specified. For the apparatus used in this work with a steel ball of 25 mm diameter, a sample tilt angle of 60-75° and a shaft groove width of about 10mm provided the most stable ball motion and a wear rate which showed least variability. © 2004 Elsevier B.V. All rights reserved.