Variation in social organization influences the opportunity for sexual selection in a social lizard

Social monogamy has traditionally been suggested to be maintained because of weak sexual selection on male partner acquisition. However, the ubiquitous incidence of extra-pair paternity suggests that sexual selection can be strong in monogamous systems, although studies partitioning variance in male reproductive success have come to mixed conclusions. Here, we use detailed field data to examine variance in male reproductive success and its implications for the maintenance of sociality in a population of the socially monogamous lizard Egernia whitii. We show that both within-pair and, to a lesser extent, extra-pair partner acquisition contribute to the variance in male reproductive success, resulting in considerable opportunity for sexual selection. Despite this, levels of multiple mating are lower in Egernia compared to other reptiles, suggesting that male partner acquisition is constrained. We suggest that this constraint may be a result of strong territoriality combined with sexual conflict over multiple mating generated by costs of extra-pair paternity to females as a result of facultative male care. This has the potential to limit sexual selection by reducing variance in male reproductive success and therefore contribute to the maintenance of complex social organization.     

How do steppe plants follow their optimal environmental conditions or persist under suboptimal conditions? The differing strategies of annuals and perennials

For a species to be able to respond to environmental change, it must either succeed in following its optimal environmental conditions or in persisting under suboptimal conditions, but we know very little about what controls these capacities. We parameterized species distribution models (SDMs) for 135 plant species from the Algerian steppes. We interpreted low false‐positive rates as reflecting a high capacity to follow optimal environmental conditions and high false‐negative rates as a high capacity to persist under suboptimal environmental conditions. We also measured functional traits in the field and built a unique plant trait database for the North‐African steppe. For both perennial and annual species, we explored how these two capacities can be explained by species traits and whether relevant trait values reflect species strategies or biases in SDMs. We found low false‐positive rates in species with small seeds, flowers attracting specialist pollinators, and specialized distributions (among annuals and perennials), low root:shoot ratios, wide root‐systems, and large leaves (perennials only) (R² = .52–58). We found high false‐negative rates in species with marginal environmental distribution (among annuals and perennials), small seeds, relatively deep roots, and specialized distributions (annuals) or large leaves, wide root‐systems, and monocarpic life cycle (perennials) (R² = .38 for annuals and 0.65 for perennials). Overall, relevant traits are rarely indicative of the possible biases of SDMs, but rather reflect the species' reproductive strategy, dispersal ability, stress tolerance, and pollination strategies. Our results suggest that wide undirected dispersal in annual species and efficient resource acquisition in perennial species favor both capacities, whereas short life spans in perennial species favor persistence in suboptimal environmental conditions and flowers attracting specialist pollinators in perennial and annual species favor following optimal environmental conditions. Species that neither follow nor persist will be at risk under future environmental change.     

Ames试验假阳性的判断方法

目的:确立一种判断Ames试验假阳性的可靠方法。方法:在Ames平皿掺入试验中发现经受试物处理的TA97和TA1535的菌落数相比溶媒对照组明显增加,为了证实其是因为受试物致突变性导致的回变菌落数增加还是由受试物毒性导致的菌落数增加,对分别经受试物和阳性对照物处理的Ames菌落进行增菌培养后接种于无组氨酸的培养基上,观察比较细菌的生长情况。结果:经受试物处理的菌株不能生长在无组氨酸的培养基中,而经阳性对照物处理的菌株则可以生长在无组氨酸的培养基上,说明经受试物处理的菌株没有发生突变。结论:此方法能可靠地验证菌株是否为突变菌株,由本研究可以发现经受试物处理的菌株没有发生突变,Ames平皿掺入试验中所观察到的菌落数增加是由于受试物毒性造成的假阳性。     

Proceedings of the SMBE Tri-National Young Investigators' Workshop 2005. Control of the false discovery rate applied to the detection of positively selected amino acid sites

In this article, we consider the probabilistic identification of amino acid positions that evolve under positive selection as a multiple hypothesis testing problem. The null hypothesis "H0,s: site s evolves under a negative selection or under a neutral process of evolution" is tested at each codon site of the alignment of homologous coding sequences. Standard hypothesis testing is based on the control of the expected proportion of falsely rejected null hypotheses or type-I error rate. As the number of tests increases, however, the power of an individual test may become unacceptably low. Recent advances in statistics have shown that the false discovery rate--in this case, the expected proportion of sites that do not evolve under positive selection among those that are estimated to evolve under this selection regime--is a quantity that can be controlled. Keeping the proportion of false positives low among the significant results generally leads to an increase in power. In this article, we show that controlling the false detection rate is relevant when searching for positively selected sites. We also compare this new approach to traditional methods using extensive simulations.     

Identification of BoLA-DRB3.2 alleles in Korean native cattle (Hanwoo) and Holstein populations using a next generation sequencer

Bovine leucocyte antigen (encoded by BoLA) has been widely studied to identify the association with many traits related to immunity. Exon2 of BoLA-DRB3 is extremely polymorphic, and more than 100 alleles have been identified. We investigated polymorphisms of BoLA-DRB3.2 in Korean native cattle and Holstein populations using a next generation sequencer of the GS-FLX Titanium system. We found 38 alleles including 11 new alleles (BoLA-DRB3*1303, *4702, *7101, *7501, *7201, *7301, *7601, *1104, *7701, *7401 and *50021) in Hanwoo, and nine alleles including one new allele (BoLA-DRB3*7601) in Holstein. The 454 sequencing method is a promising alternative technology for high throughput genotyping of BoLA-DRB3.2 because of its technical advantages that allow it to overcome the disadvantages of sequence-based typing methods.     

金黄色葡萄球菌和单增李斯特菌快检试剂盒(溶液)的评价验证

通过重复第三方实验室的评价方法,分析自主研发的金黄色葡萄球菌和单增李斯特菌溶液快检试剂盒出现假阴性和假阳性的原因.实验验证得出,金黄色葡萄球菌试剂盒测试中出现的假阴性问题可能是试剂在运输、储存以及实验过程中操作不当造成活性降低所引起,可以通过对试剂进行小管分装、干粉化等方式防止试剂活性降低.单增李斯特菌试剂盒果冻阴性对...     

利用竞争性PCR筛选无标记Xa21转基因水稻

PCR是一种简单、迅速、灵敏的检测方法,但假阳性与假阴性却影响了它在常规应用中的准确性。本研究利用竞争性PCR解决无标记Xa21转基因水稻PCR检测中的假阳性与假阴性问题。标记基因潮霉素基因(Hygromycin phosphotransferase,hpt)的竞争模板是外加的日本晴hpt转基因植株基因组DNA,抗白叶枯病基因Xa21的竞争模板是待测水稻内源的位于第11染色体上的Xa21同源基因序列。利用这一方法对双右边界T-DNA载体转化产生的转基因T1代植株进行分析,可以有效地减少或排除假阳性或假阴性样品,选出真正的转基因阳性植株。与常规PCR相比竞争性PCR提高了无标记Xa21转基因植株筛选的准确性。对获得的无标记Xa21转基因植株进行白叶枯抗病鉴定与潮霉素抗性鉴定证实了该方法的可靠性。