Why are birds' eggs colourful? Eggshell pigments co‐vary with life‐history and nesting ecology among British breeding non‐passerine birds

The colourful appearance of bird eggshells has long fascinated biologists and considerable research effort has focused on the structure and biochemistry of the avian eggshell matrix. The presence of tetrapyrrole pigments was identified nearly a century ago. Surprisingly, how the concentrations of avian eggshell pigments vary among related species, and whether this variability is associated with either eggshell appearance and/or species life‐history traits, remains poorly understood. We quantified the concentrations of the two key eggshell pigments, protoporphyrin IX and biliverdin, from a diverse sample of eggshells stored at the Natural History Museum, Tring, UK. We explicitly tested how these two pigments are associated with physical measures of eggshell coloration and whether the pigment concentrations and colour diversity co‐vary with phylogenetic affiliations among species. We also tested a series of comparative hypotheses regarding the association between the concentrations of the two pigments and specific life‐history and breeding ecology traits. Across species, the average concentrations of protoporphyrin and biliverdin were positively correlated, and both strongly co‐varied with phylogenetic relatedness. Controlling for phylogeny, protoporphyrin concentration was associated with a higher likelihood of cavity nesting and ground nesting, whereas biliverdin concentration was associated with a higher likelihood of non‐cavity nesting habit and bi‐parental provisioning. Although unlikely to be explained by a single function, the breeding ecology and life history‐dependence of eggshell pigment concentrations in these comparative analyses implies that related species share pigment strategies, and that those strategies relate to broad adaptive roles in the evolution of variation in avian eggshell coloration and its underlying mechanisms. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 657–672.     

Improved statistical tests for differential gene expression by shrinking variance components estimates

Combining information across genes in the statistical analysis of microarray data is desirable because of the relatively small number of data points obtained for each individual gene. Here we develop an estimator of the error variance that can borrow information across genes using the James-Stein shrinkage concept. A new test statistic (FS) is constructed using this estimator. The new statistic is compared with other statistics used to test for differential expression: the gene-specific F test (F1), the pooled-variance F statistic (F3), a hybrid statistic (F2) that uses the average of the individual and pooled variances, the regularized t-statistic, the posterior odds statistic B, and the SAM t-test. The FS-test shows best or nearly best power for detecting differentially expressed genes over a wide range of simulated data in which the variance components associated with individual genes are either homogeneous or heterogeneous. Thus FS provides a powerful and robust approach to test differential expression of genes that utilizes information not available in individual gene testing approaches and does not suffer from biases of the pooled variance approach.     

A Nonparametrical Evaluation of Anova and MANOVA Designs Using Interaction Structure Analysis

The interaction structure analysis (ISA) is proposed as a nonparametric procedure for the evaluation of uni- and multivariate analysis of variance models. Main effects and interactions of (independent) treatment variables are replaced by interaction-types where types are defined as those treatment-response combinations which occur significantly more often than expected under a null hypothesis (H_o) of no treatment effects. The application of ISA and the typological interpretation of ISA results are illustrated for an ANOVA design from toxicology and for a MANOVA design from psychopharmacology.     

双列杂交分析估算遗传参数两种方法的比较

本文就遗传参数的估算,对双列杂交分析中应用最广的Griffing法和Hayman法作了比较。结果表明,Hayman法估算非加性方差的结果比Griffing法小(p-1)/P~2_5~2, 而估算加性方差和遗传方差的结果则分别比Griffing法大2(p-1)/P~2_s~2和(p-1)/P~2_s~2。另外,本文还就造成两种方法分析结果不同的原因作了讨论。     

单种群生长的广义Logistic模型中参数的一种估值方法

本文提出种群生长的实测数据与广义Logistic模型的相容性条件,给出估计环境容纳量K的数学方法,利用常微分方程反问题的处理方法与麦夸特方法,对模型中参数进行近似估计与优化估计,其方法简便、通用性强．     

不同程度人为干扰对古田山森林群落谱系结构的影响

群落谱系结构包含群落发育的历史信息,能从新的角度反映群落形成的生态过程.作者在浙江古田山自然保护区亚热带常绿阔叶林中选择了人为干扰强度不同的4种群落类型,以20 m×20 m为研究尺度探讨了不同干扰程度对群落谱系结构的影响.结果表明,人工林(类型Ⅰ)谱系结构发散;但间伐林(类型Ⅱ)、自然恢复林(类型Ⅲ)以及自然老龄林(类型Ⅳ)谱系结构聚集,且以类型Ⅱ和Ⅳ聚集度最高.进一步分析不同径级谱系结构发现,在中小径级(DBH≤5 cm和5 cm10 cm时,除了类型Ⅳ,其他3种群落都是谱系结构发散,这反映了在恢复早期种子扩散对这些林型群落构建影响较大:而皆伐后的演替和间伐增加了群落生境异质性,生境过滤作用增强,使类型Ⅱ、Ⅲ群落中小径级谱系结构表现为聚集;类型Ⅳ群落不同径级谱系结构均表现为聚集,可能与其稳定的生境过滤作用有关.