Population differentiation in Crepis tectorum (Asteraceae): patterns of correlation among characters

This study examines the relationship among traits distinguishing populations of C. tectorum and the extent to which existing trait associations reflect underlying (genetic) tradeoffs. Highly consistent trait associations were found in a comparison of 52 populations representing the western part of the geographical range of the species. In addition to a tight integration of traits reflecting plant stature and inflorescence development, there were consistent links between vegetative and reproductive traits; populations characterized by individuals with large leaves and tall stems with terminal branches usually had larger heads, flowers and fruits (achenes) than those whose individuals had small leaves and a short stem branched from the base. There was a weak negative relationship between the extent of leaf dissection and plant stature; short and compact plants had more deeply lobed leaves than tall plants with terminal branches. Few of these associations were present among families representing a single population of C. tectorum , but there was remarkable similarity between the correlations at the between-population level and those obtained in two segregating F2 progenies of crosses between contrasting populations. Hence, provided that the F2 correlations have a strong genetic basis, it appears that the course of population divergence has been constrained by the underlying correlation structure, although some trait associations may also be a result of selection operating in a correlated fashion on functionally related traits, perhaps leading to linkage disequilibrium of parental traits in the first segregating generation of a cross between ecologically differentiated populations.     

Phylogeny and evolution of sexually selected tail ornamentation in widowbirds and bishops (Euplectes spp.)

Despite similar ecology, mating systems and female preferences for supernormal tails, the 17 species of African widowbirds and bishops (Euplectes spp.) show astonishing variation in male tail ornamentation. Whereas bishops retain their brown nonbreeding tails in nuptial plumage, widowbirds grow black nuptial tails, varying in length from a few centimetres in E. axillaris to the extreme half metre train of E. progne. Here, we phylogenetically reconstruct the evolution of the discrete trait, nuptial tail and the continuous trait, tail length, using a molecular phylogeny of 33 Euplectes subspecies. Unlike many recent findings of labile evolution of plumage ornaments, our results suggest that the nuptial tail of Euplectes is a derived and phylogenetically conserved ornamental trait that, once gained, shows directional evolution in its expression. Directionality is demonstrated in the trivial sense of a short‐tailed ancestor, and by contingency and randomization tests suggesting that branches with increasing tail length are overrepresented. This supports an early origin and strong retention of directional female mate choice in widowbirds and bishops, as previously indicated by empirical and experimental results, and provides a less labile, yet rapid scenario of sexually selected diversification.     

DNA fingerprinting in horses using a simple (TG)n probe and its application to population comparisons

A synthetic polynucleotide (TG)_n was hybridized to equine DNA digested with HinfI and hypervariable hybridization patterns were obtained. Mendelian inheritance of these DNA fingerprinting patterns was confirmed by pedigree analysis. Estimates of the probabilities of identical band patterns in unrelated individuals of different breeds (Swedish Trotters, North Swedish Trotters, Thoroughbreds and Arabians) were in the range 1 times 10-⁴-7 times 10-⁶ The variability derived with the (TG)_n, probe in horses was higher than what we obtained with several other commmonly used probes for DNA fingerprinting. Individuals within breeds tended to be more similar to each other with regard to DNA fingerprint pattern than to individuals of other breeds. Moreover, a parsimony analysis made on the basis of the hybridization patterns gave clustering of individuals within breeds. The possibility of using hypervariable probes for the identification of breed-specific characters is discussed.     

陕西蓝田晚中新世食肉类

陕西省蓝田地区灞河组与蓝田组产出了大量的古哺乳动物化石。其中,晚中新世哺乳动物化石序列为认识该地区自然环境的变化提供了重要的依据。详细描述和研究了其中的食肉类化石。计有鬣狗科3种(Ictitherium viverrinum、Hyaenictitherium cf.H.wongii、Adcrocuta eximia)和猫科2种(cf.Metailurus major与cf.Metailurus parvulus)。在下部的灞河组与上部的蓝田组界线附近,食肉类动物群落组成发生了改变,但引起这种改变的原因仍有待进一步研究确定。     

Mosaic variation in allozyme and plastid DNA markers in the European ranges of Silene vulgaris and its partially sympatric relative S. uniflora (Caryophyllaceae)

The perennial herbs Silene vulgaris and S. uniflora are closely related, partially sympatric and interfertile, yet morphologically distinct. We used nuclear (allozyme) and plastid (polymerase chain reaction–restriction fragment length polymorphism) DNA markers to investigate whether these species have a shared history of postglacial colonization and hybridization in Europe, as inferred from large‐scale patterns of geographic variation. The majority of plastid haplotypes and allozyme alleles were widespread and patchily distributed within both species and there was no geographic structure in the distributions of shared allozymes or haplotypes. The mosaic variation is consistent with a scenario in which repeated episodes of interspecific hybridization pre‐dated the largely allopatric range expansion of the two species during the postglacial period. Our overall results are not consistent with a scenario of extensive hybridization and introgression during the postglacial range expansion of the species or within their current areas of sympatry, but we found some evidence for local, postglacial evolution and hybridization in the Baltic region. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 166 , 127–148.     

参考家系鸡黑素皮质素受体3基因多态性与体重关系研究

鼠遗传学研究显示黑素皮质素受体3（melanocortin-3 receptor,MC3R）和MC4R在能量平衡控制中具有互补作用。敲除MC3R基因鼠表现为独有的代谢综合征和增加脂肪重量。以8周龄高体重或低体重独立选择的高体重系（high weight,HW）和低体重系（low weight,LW）白洛克鸡3代参考家系群体作为实验材料,发现了5个新的MC3R基因单核苷酸多态性（single nucleotide polymorphisms,SNPs）;建立了基于限制性内切酶Dde I的MC3R基因型的PCR-RFLP分子检测方法。方差分析结果显示MC3R基因型显著影响公鸡和母鸡的体重,以及公鸡腹脂含量。该结果建议MC3R基因可以作为侯选基因解释杂交鸡体重显著差异的原因。     

Fine needle aspiration in nodular fasciitis of the face

Nodular fasciitis (NF) appears typically as a rapidly growing solitary mass which is most commonly located on the extremities, followed by the trunk and then the head and neck. NF is often suitable for fine needle aspiration (FNA), but few reports of NF diagnosed cytologically have been published. The purpose of this paper is to describe FNA cytology in three cases of nodular fasciitis. All three cases were located on the face.     

Increased growth and recruitment of piscivorous perch, Perca fluviatilis, during a transient phase of expanding submerged vegetation in a shallow lake

1. In this study, we examine how a 7‐year period of expanding submerged stonewort (Chara spp.) vegetation during a shift from turbid to clear water in a shallow lake influenced individual growth and population size structure of perch (Perca fluviatilis). We expected that a shift from phytoplankton to macrophyte dominance and clear water would improve feeding conditions for perch during a critical benthivorous ontogenetic stage, and enhance the recruitment of piscivorous perch. 2. Growth analysis based on opercula showed that growth during the second year of life was significantly higher in years with abundant vegetation than in years with turbid water and sparse vegetation. Growth was not affected during the first, third and fourth year of life. Stable isotope analyses on opercula from 2‐year‐old perch showed that the increase in growth coincided with a change in carbon source in the diet. Stable nitrogen ratio did not change, indicating that the increased growth was not an effect of any change in trophic position. 3. Following the expansion of submerged vegetation, perch size range and abundance of piscivorous perch increased in central, unvegetated areas of the lake. In stands of stoneworts, however, mainly benthivorous perch were caught, and size range did not change with time. 4. Our findings provide empirical support for the notion that establishment of submerged vegetation may lead to increased recruitment of piscivorous perch, because of improved competitive conditions for perch during the benthivorous stage. This is likely to constitute a benthic‐pelagic feedback coupling, in which submerged vegetation and clear water promote the recruitment of piscivorous perch, which, in turn, may increase water clarity through top‐down effects in the pelagic.