近年来国内外橡胶树育种研究新进展

从常规育种、高产育种和抗性育种方面综述近年来国外橡胶树育种研究的新进展,并结合我国橡胶树育种现状,提出我国橡胶树育种的方向,以期为我国橡胶树产量性状、遗传改良和抗逆性育种等提供借鉴.     

Growth and decline of a penguin colony and the influence on nesting density and reproductive success

Colonial breeding is characteristic of seabirds but nesting at high density has both advantages and disadvantages and may reduce survival and fecundity. African penguins (Spheniscus demersus) initiated breeding at Robben Island, South Africa in 1983. The breeding population on the island increased in the late 1990s and early 2000s before decreasing rapidly until 2010. Before the number breeding peaked, local nest density in the areas where the colony was initiated plateaued, suggesting that preferred nests sites were mostly occupied, and the area used by breeding birds expanded. However, it did not contract again as the population decreased, so that nesting density varied substantially. Breeding success was related positively to the prey available to the breeding birds and negatively to local nest density, particularly during the chick-rearing period, suggesting a density-dependence operating through social interactions in the colony, possibly exacerbated by poor prey availability when the breeding population was large. Although nest density at Robben Island was not high, nesting burrows, which probably reduce the incidence of aggressive encounters in the colony, are scarce and our results suggest that habitat alteration has modified the strength of density-dependent relationships for African penguins. Gaining a better understanding of how density dependence affects fecundity and population growth rates in colonial breeders is important for informing conservation management of the African penguin and other threatened taxa.     

ISSR分子标记在棉花遗传育种上的应用

ISSR是一种近些年发展起来的基于微卫星序列的新型分子标记。阐述了ISSR的基本原理、特点及其在棉花遗传多样性与亲缘关系分析、种质鉴定、遗传图谱构建、基因定位及标记辅助选择育种等方面的应用和进展。     

Lathyrus diversity: available resources with relevance to crop improvement – L. sativus and L. cicera as case studies

Background

The Lathyrus genus includes 160 species, some of which have economic importance as food, fodder and ornamental crops (mainly L. sativus, L. cicera and L. odoratus, respectively) and are cultivated in >1·5 Mha worldwide. However, in spite of their well-recognized robustness and potential as a source of calories and protein for populations in drought-prone and marginal areas, cultivation is in decline and there is a high risk of genetic erosion.

Scope

In this review, current and past taxonomic treatments of the Lathyrus genus are assessed and its current status is examined together with future prospects for germplasm conservation, characterization and utilization. A particular emphasis is placed on the importance of diversity analysis for breeding of L. sativus and L. cicera.

Conclusions

Efforts for improvement of L. sativus and L. cicera should concentrate on the development of publicly available joint core collections, and on high-resolution genotyping. This will be critical for permitting decentralized phenotyping. Such a co-ordinated international effort should result in more efficient and faster breeding approaches, which are particularly needed for these neglected, underutilized Lathyrus species.     

Genetic analysis of return over feed in Canadian Holsteins

The objective of this study was to investigate genetic merit of return over feed (ROF), which is a herd profit index defined by CanWest Dairy Herd Improvement as a difference between milk income and feed cost. A multiple-trait (MT) model and random regression model (RRM) were used. The traits analyzed in MT were rearing cost and ROF of the first three lactations. In RRM, a cumulative ROF was fitted as function of age and rearing cost was treated as a correlated trait. Variance components were estimated within a Bayesian framework by Gibbs sampling using a subsample of data. Breeding values were then estimated for 3 041 078 animals using records of 1 951 893 cows. Estimates of heritability for rearing cost from MT and RRM were 0.23 and 0.22, respectively. ROF per lactation and cumulative ROF were negatively correlated with rearing cost. Estimates of heritability of ROF through the first, second and third lactation from MT were 0.27, 0.10 and 0.08, respectively. Estimates of heritability of ROF from RRM increased with age and ranged from 0.08 through 0.31. Estimated breeding values (EBVs) for ROF from MT and RRM were moderately correlated with official EBV for production traits and the Canadian selection index (Lifetime Profit Index). Herd life EBV had -0.07 and 0.19 correlations with EBVs for ROF from MT and RRM, respectively. From both MT and RRM, small favorable correlations were reported between EBVs for ROF and for bone quality and angularity, whereas low unfavorable correlations were reported with EBV for udder depth, front end and chest width. Majority of correlations between EBVs for ROF and for reproduction traits were near 0, with the exception of EBV for gestation length, calf size and calving ease, where small favorable correlations were reported. The ROF is a good indicator of cow profitability despite the fact that it is a simplified profit index that does not account for animal-specific health and reproductive cost. However, because ROF does not account for differences in heritabilities between components of profit, ROF is not recommended to be used for direct selection for profit.     

The Trophic Diatom Index: a new index for monitoring eutrophication in rivers

A index for monitoring the trophic status of rivers based on diatom composition (‚trophic diatom index’, TDI) has been developed, in response to the National Rivers Authority (England & Wales)'s needs under the terms of the Urban Wastewater Treatment Directive of the European Community. The index is based on a suite of 86 taxa selected both for their indicator value and ease of identification. When tested on a dataset from 70 sites free of significant organic pollution, this index was more highly correlated with aqueous P concentrations than previous diatom indices. However, where there was heavy organic pollution, it was difficult to separate the effects of eutrophication from other effects. For this reason, the value of TDI is supplemented by an indication of the proportion of the sample that is composed of taxa tolerant to organic pollution. The index was tested on the R. Browney, N-E. England, above and below a major sewage discharge. TDI values indicated that the effect of inorganic nutrients on the river downstream of the discharge was slight as the river was already nutrient-rich, but there was a large increase in the proportion of organic pollution-tolerant taxa. This indicates that the river was already so eutrophic upstream of the discharge that tertiary treatment to remove P would not be effective unless other aspects of the discharge were also improved.     

More and more generalists: two decades of changes in the European avifauna

Biotic homogenization (BH) is a process whereby some species (losers) are systematically replaced by others (winners). While this process has been related to the effects of anthropogenic activities, whether and how BH is occurring across regions and the role of native species as a driver of BH has hardly been investigated. Here, we examine the trend in the community specialization index (CSI) for 234 native species of breeding birds at 10 111 sites in six European countries from 1990 to 2008. Unlike many BH studies, CSI uses abundance information to estimate the balance between generalist and specialist species in local assemblages. We show that bird communities are more and more composed of native generalist species across regions, revealing a strong, ongoing BH process. Our result suggests a rapid and non-random change in community composition at a continental scale is occurring, most likely driven by anthropogenic activities.     

Climate change and breeding parameters of great and blue tits throughout the western Palaearctic

Increasing evidence suggests that climate change has consequences on avian breeding phenology. Here, variations in laying date and clutch size of great tit Parus major and blue tit Parus caeruleus within and between breeding populations through the western Palaearctic are examined in relation to climatic fluctuations, measured by the winter North Atlantic Oscillation (NAO) index. Within and across breeding sites, laying date was related to winter‐NAO index such that great and blue tit females lay earlier after warmer, moister winters (positive values of winter NAO‐index). The present study shows that for most populations there is an advancement of laying date, but the rate of change with respect to NAO significantly differed geographically across the western Palaearctic and did not differ between species. However, clutch size of great and blue tits was not affected by climatic fluctuations, presumably because the whole season is being shifted, but not in relation to food supplies. These combined analyses for the two species controlled for potentially confounding variables such as latitude, longitude, elevation and habitat of each study site.     

广西龙眼种质资源研究及品种选育

本文概述广西龙眼种质资源的特点,综述广西龙眼种质资源调查、亲缘关系研究和引种、品种选育进展,并提出进一步开展研究利用的建议.