RESUMEN
This study investigates the effect of water temperature on the development rate of eggs and larvae, the duration of the endogenous feeding period and its consequences for recruitment of smelt (Osmerus eperlanus) in Dutch lakes IJsselmeer and Markermeer. This study measured temperature-dependent egg and larval development rates as well as mortality rates from fertilization till the moment of absorption of the yolk-sac and from yolk-sac depletion onwards in temperature-controlled indoor experiments. Using multinomial modelling the authors found significant differences in development time of egg development stages under different temperature regimes. Based on historic water temperatures, the model predicted that the larval endogenous feeding period has advanced at a rate of about 2.9 days per decade in a more than 50 year period since 1961, yet there was no change in the duration of the endogenous feeding period. As zooplankton is more responsive to daylight than water temperature cues, a mismatch between the peak of the onset of exogenous feeding of smelt and the peak of zooplankton blooms could lead to high mortality and therefore low recruitment of smelt. Such a mismatch might contribute to a decline in the smelt population in Lake IJsselmeer and Lake Markermeer.
Asunto(s)
Osmeriformes/crecimiento & desarrollo , Temperatura , Cigoto/crecimiento & desarrollo , Animales , LagosRESUMEN
Workplace bullying is associated with a host of negative outcomes for the worker who is the target of bullying, as well as for the organization where the bullying occurs. Moreover, we know that rates of bullying are particularly high in health care settings; however, we are less familiar with the factors that may reduce workplace bullying in hospitals. Thus, this study was conducted to determine whether the humor orientation styles of individuals, including nurses working in hospitals, as well as their managers' leadership styles, can influence perceptions of bullying in the workplace. Using data from 459 workers employed in a large hospital in the Southern United States, we examined associations between the Multidimensional Sense of Humor Scale, which has four dimensions, as well as the Multifactor Leadership Questionnaire, with three leadership substyles, and their associations with the risk of being bullied. We observed that one of the four humor subscales, Humor Appreciation, did affect perceptions of bullying in the workplace. The other three, Humor Recognition, Humor Production, and Humor for Coping, did not. However, the leadership styles of managers did affect reports of negative acts. In fact, transformational leadership was associated with 22% of the variance in reports of decreased bullying activity. This work is consistent with previous work on the importance of leadership styles for creating positive work environments, particularly in hospital settings. Given these findings, we offer suggestions for leaders to further improve nursing communication.
Asunto(s)
Acoso Escolar/psicología , Relaciones Interprofesionales , Liderazgo , Cuerpo Médico de Hospitales/psicología , Ingenio y Humor como Asunto , Adulto , Anciano , Femenino , Hospitales , Humanos , Masculino , Cuerpo Médico de Hospitales/estadística & datos numéricos , Persona de Mediana Edad , Personal de Enfermería en Hospital/psicología , Personal de Enfermería en Hospital/estadística & datos numéricos , Encuestas y Cuestionarios , Estados Unidos , Adulto JovenRESUMEN
Smelt Osmerus eperlanus has two different life history strategies in The Netherlands. The migrating population inhabits the Wadden Sea and spawns in freshwater areas. After the closure of the Afsluitdijk in 1932, part of the smelt population became landlocked. The fresh water smelt population has been in severe decline since 1990, and has strongly negatively impacted the numbers of piscivorous water birds relying on smelt as their main prey. The lakes that were formed after the dike closure, IJsselmeer and Markermeer have been assigned as Natura 2000 sites, based on their importance for (among others) piscivorous water birds. Because of the declining fresh water smelt population, the question arose whether this population is still supported by the diadromous population. Opportunities for exchange between fresh water and the sea are however limited to discharge sluices. The relationship between the diadromous and landlocked smelt population was analysed by means of otolith microchemistry. Our interpretation of otolith strontium ((88)Sr) patterns from smelt specimens collected in the fresh water area of Lake IJsselmeer and Markermeer, compared to those collected in the nearby marine environment, is that there is currently no evidence for a substantial contribution from the diadromous population to the spawning stock of the landlocked population.
Asunto(s)
Microquímica/métodos , Osmeriformes , Animales , Peces , Países BajosRESUMEN
The earlier mean adult emergence between males and females, protandry, has been well studied mathematically and in comparative studies. However, quantitative and evolutionary genetic research on protandry is scarce. The butterfly, Bicyclus anynana exhibits protandry and here we selected for each of the different combinations of male and female development time in this species, thus including direct selection on protandry (i.e., FAST, fast males and fast females; SLOW, slow males and slow females; FMSF, fast males and slow females; and SMFF, slow males and fast females). After eight generations of selection there was no significant response for increased or decreased protandry, whereas selection for increased or decreased development time in both sexes (FAST or SLOW) was successful. Continued selection (> 30 generations) for decreased or increased protandry showed a significant difference between the FMSFC and SMFFC lines (subscript c for continued selection), which was of the same magnitude as the nonsignificant difference observed between the FMSF and SMFF lines at generation eight. This indicated that the initial selection was successful, but that the difference between the lines did not increase with continued selection. Our results also indicate that the genetic covariance across sexes for development time is near unity. Interestingly, lines selected for decreased protandry (SMFF) had lower egg-to-adult survival, and broods from these lines had lower rates of egg hatching. This suggests that interactions with fertility might constrain certain directions of change in patterns of protandry. Moreover, selection yielded a change in the ratio of male to female development time for slow lines, suggesting that some amount of sex-specific genetic variance for development time is still present in this population. The FMSFC line showed the largest effect of selection on protandry, mainly through an effect on female developmental time. Lastly, our results show that temperature has an effect on the amount of protandry in the selected lines. These results are discussed in relation to the ecology of this species and the evolution of protandry.