978 resultados para sowing date
Resumo:
Crédito variable de complemento del área de Lengua inglesa para tercero y-mo cuarto de la etapa 12-16 destinado a alumnos que disponiendo de una base gramatical están preparados para avanzar en el aprendizaje de una forma más globalizada, intuitiva y menos sistematizada. Utiliza el lenguaje periodístico y el publicitario como herramienta de aprendizaje. El crédito se estructura en dos partes: en la primera se presentan textos didácticos con el objetivo de captar las diferencias entre Gran Bretaña y Estados Unidos de América. En la segunda parte, a partir de anuncios publicitarios y artículos de prensa inglesa se presentan diferentes actividades con el objetivo que se capte el sentido general del texto. Se describen los contenidos, objetivos y 42 actividades de aprendizaje con el material de soporte necesario.
Correlating Bayesian date estimates with climatic events and domestication using a bovine case study
Resumo:
The tribe Bovini contains a number of commercially and culturally important species, such as cattle. Understanding their evolutionary time scale is important for distinguishing between post-glacial and domestication-associated population expansions, but estimates of bovine divergence times have been hindered by a lack of reliable calibration points. We present a Bayesian phylogenetic analysis of 481 mitochondrial D-loop sequences, including 228 radiocarbon-dated ancient DNA sequences, using a multi-demographic coalescent model. By employing the radiocarbon dates as internal calibrations, we co-estimate the bovine phylogeny and divergence times in a relaxed-clock framework. The analysis yields evidence for significant population expansions in both taurine and zebu cattle, European aurochs and yak clades. The divergence age estimates support domestication-associated expansion times (less than 12 kyr) for the major haplogroups of cattle. We compare the molecular and palaeontological estimates for the Bison-Bos divergence.
Resumo:
Questions: How is succession on ex-arable land affected by sowing high and low diversity mixtures of grassland species as compared to natural succession? How long do effects persist? Location: Experimental plots installed in the Czech Republic, The Netherlands, Spain, Sweden and the United Kingdom. Methods: The experiment was established on ex-arable land, with five blocks, each containing three 10 m x 10 m experiment tal plots: natural colonization, a low- (four species) and high-diversity (15 species) seed mixture. Species composition and biomass was followed for eight years. Results: The sown plants considerably affected the whole successional pathway and the effects persisted during the whole eight year period. Whilst the proportion of sown species (characterized by their cover) increased during the study period, the number of sown species started to decrease from the third season onwards. Sowing caused suppression of natural colonizing species, and the sown plots had more biomass. These effects were on average larger in the high diversity mixtures. However, the low diversity replicate sown with the mixture that produced the largest biomass or largest suppression of natural colonizers fell within the range recorded at the five replicates of the high diversity plots. The natural colonization plots usually had the highest total species richness and lowest productivity at the end of the observation period. Conclusions: The effect of sowing demonstrated dispersal limitation as a factor controlling the rate of early secondary succession. Diversity was important primarily for its 'insurance effect': the high diversity mixtures were always able to compensate for the failure of some species.