Factors influencing seasonal and monthly changes in the group size of chital or axis deer in southern India

Chital or axis deer (Axis axis) form fluid groups that change in size temporally and in relation to habitat. Predictions of hypotheses relating animal density, rainfall, habitat structure, and breeding seasonality, to changes in chital group size were assessed simultaneously using multiple regression models of monthly data collected over a 2 yr period in Guindy National Park, in southern India. Over 2,700 detections of chital groups were made during four seasons in three habitats (forest, scrubland and grassland). In scrubland and grassland, chital group size was positively related to animal density, which increased with rainfall. This suggests that in these habitats, chital density increases in relation to food availability, and group sizes increase due to higher encounter rate and fusion of groups. The density of chital in forest was inversely related to rainfall, but positively to the number of fruiting tree species and availability of fallen litter, their forage in this habitat. There was little change in mean group size in the forest, although chital density more than doubled during the dry season and summer. Dispersion of food items or the closed nature of the forest may preclude formation of larger groups. At low densities, group sizes in all three habitats were similar. Group sizes increased with chital density in scrubland and grassland, but more rapidly in the latter—leading to a positive relationship between openness and mean group size at higher densities. It is not clear, however, that this relationship is solely because of the influence of habitat structure. The rutting index (monthly percentage of adult males in hard antler) was positively related to mean group size in forest and scrubland, probably reflecting the increase in group size due to solitary males joining with females during the rut. The fission-fusion system of group formation in chital is thus interactively influenced by several factors. Aspects that need further study, such as interannual variability, are highlighted.     

Woody plant encroachment in granite barrens on the Frontenac Arch,eastern Ontario,Canada

Aims

Woody plant encroachment is a widespread phenomenon affecting treeless or sparsely treed habitats. We aimed to determine the extent and timing of tree and shrub encroachment into rock barrens of eastern Ontario over the last century, and to assess implications for their ongoing management.

Location

Queen's University Biological Station in the Frontenac Arch ecoregion.

Methods

We quantified the extent of change in woody vegetation in 290 rock barrens using aerial photography from 1925, 1965, and 2008. Composition and structure of woody plant communities in 10 barrens was subsequently quantified in the field using plot-based sampling. Cores or cross-sections were obtained from individuals >1.5 m height and dendrochronological techniques were used to determine their age and identify temporal patterns of any woody encroachment.

Results

Aerial photography indicated that the mean proportion of woody plant cover in barrens increased 22.5% from 1925 to 2008. Dendroecological analysis supported this. Few trees were present prior to 1900 and most established since 1960. Fraxinus americana, Juniperus virginiana, and Juniperus communis were the most common woody species colonizing the barrens. Remnants of large Pinus strobus stumps with extensive charring were found in 90% of the sampled barrens at a mean density of 22.6 stumps ha⁻¹.

Conclusions

Rock barrens on the Frontenac Arch have changed substantially over the past century; gradually being colonized by trees and shrubs and losing their distinctly open character. Active management — including prescribed fire and mechanical thinning — may be necessary if there is a desire to maintain these barrens and the rare species they support as components of the region's biodiversity. However, identification of a reference state for restoration is complicated by the fact that the structure and composition of these habitats were undoubtedly altered by European land clearance in the 19th century, and that some of these areas likely existed as pine woodlands before that.     

豚鹿MHC-DOA基因克隆及其外显子2遗传多样性研究

主要组织相容性复合物(MHC)在脊椎动物的免疫系统中起着重要的作用,MHC-DOA基因是MHCⅡ类的非经典基因,其外显子2多态性丰富。豚鹿Axis porcinus是我国极度濒危的动物。本研究以成都动物园圈养的38头豚鹿为研究对象,提取豚鹿血液总RNA,反转录合成cDNA为模板,利用PCR方法克隆到豚鹿MHC-DOA序列;同时利用PCR方法扩增38头豚鹿的MHC-DOA基因外显子2基因并测序,再进行多态性分析。结果显示:豚鹿MHC-DOA基因开放阅读框长753 bp,编码250个氨基酸残基;蛋白质同源性分析表明,豚鹿MHC-DOA基因与东欧马鹿Cervus elaphus hippelaphus的同源性最高(98.4%);38头豚鹿的MHC-DOA外显子2共有10种单倍型,整体遗传多样性水平中等;MHC-DOA外显子2部分序列中发生了核苷酸的缺失和插入,进而引起DOA蛋白序列发生改变。豚鹿MHC-DOA多态性的研究对豚鹿种群遗传结构调查、遗传资源的保护具有重要意义。     

Metric and morphological study of the upper cervical spine from the Sima de los Huesos site (Sierra de Atapuerca, Burgos, Spain)

In this article, the upper cervical spine remains recovered from the Sima de los Huesos (SH) middle Pleistocene site in the Sierra de Atapuerca (Burgos, Spain) are described and analyzed. To date, this site has yielded more than 5000 human fossils belonging to a minimum of 28 individuals of the species Homo heidelbergensis. At least eleven individuals are represented by the upper cervical (C1 and C2) specimens: six adults and five subadults, one of which could represent an adolescent individual. The most complete adult vertebrae (three atlases and three axes) are described, measured, and compared with other fossil hominins and modern humans. These six specimens are associated with one another and represent three individuals. In addition, one of these sets of cervical vertebrae is associated with Cranium 5 (Individual XXI) from the site. The metric analysis demonstrates that the Sima de los Huesos atlases and axes are metrically more similar to Neandertals than to our modern human comparative sample. The SH atlases share with Neandertals a sagittally elongated canal. The most remarkable feature of the SH (and Neandertal) axes is that they are craniocaudally low and mediolaterally wide compared to our modern male sample. Morphologically, the SH sample shares with Neandertals a higher frequency of caudally projected anterior atlas arch, which could reflect greater development of the longus colli muscle. In other features, such as the frequency of weakly developed tubercles for the attachment of the transverse ligament of the atlas, the Sima de los Huesos fossils show intermediate frequencies between our modern comparative samples and the Neandertals, which could represent the primitive condition. Our results are consistent with the previous phylogenetic interpretation of H. heidelbergensis as an exclusively European species, ancestral only to H. neanderthalensis.     

基于微卫星位点的人工圈养豚鹿亲子关系鉴定

豚鹿属我国国家I级重点保护动物,目前国内野生种群已经灭绝,人工圈养数量少,已极度濒危。成都动物园是国内最大的豚鹿饲养单位,对该园内豚鹿进行亲子鉴定及遗传谱系建立是我国豚鹿拯救工程中一重要环节。本文利用7个微卫星标记对成都动物园27只豚鹿个体进行了基因分型,在母本已知情况下成功鉴定了13对父子关系,其中排除法鉴定8对,似然法鉴定5对且置信度达95%。将亲子鉴定的结果辅以动物园豚鹿圈养的历史记录,我们构建了该园豚鹿的遗传谱系图。本文的研究成果将为后续人工繁殖中亲本雌雄配对的个体选择以及种群的遗传管理提供参考。     

Symmetry breaking and convergent extension in early chordate development

The initiation of axis, polarity, cell differentiation, and gastrulation in the very early chordate development is due to the breaking of radial symmetry. It is believed that this occurs by an external signal. We suggest instead spontaneous symmetry breaking through the agency of the Turing-Child field. Increased size or decreased diffusivity, both brought about by mitotic activity, cause the spontaneous loss of stability of the homogeneous state and the evolution of the metabolic pattern during development. The polar metabolic pattern is the cause of polar gene expression, polar morphogenesis (gastrulation), and polar mitotic activity. The Turing-Child theory explains not only the spontaneous formation of the invagination in gastrulation but also the coherent cell movement observed in convergence and extension during gastrulation and neurulation. The theory is demonstrated with respect to experimental observations on the early development of fish, amphibian, and the chick. The theory can explain a multitude of experimental details. For example, it explains the splayed polar progression of reduction in the fish blastoderm. Reduction starts on that side of the blastoderm margin, which will initiate invagination several hours later. It progresses toward the blastoderm center and somewhat laterally from this future "dorsal lip". This is precisely as predicted by a Turing-Child system in a circle. And for a fish like zebrafish with a blastoderm that is slightly oval, reduction is observed to progress along the long axis of the ellipse, which is what Turing-Child theory predicts. In general the shape and the chemical nature of the experimental patterns are the same as predicted by the Turing couple (cAMP, ATP). Embryological polarity and convergent extension are based on polar eigenfunction and saddle-shaped eigenfunction, respectively.     

A Conformational Change of the γ Subunit Indirectly Regulates the Activity of Cyanobacterial F1-ATPase

The central shaft of the catalytic core of ATP synthase, the γ subunit consists of a coiled-coil structure of N- and C-terminal α-helices, and a globular domain. The γ subunit of cyanobacterial and chloroplast ATP synthase has a unique 30–40-amino acid insertion within the globular domain. We recently prepared the insertion-removed α₃β₃γ complex of cyanobacterial ATP synthase (Sunamura, E., Konno, H., Imashimizu-Kobayashi, M., and Hisabori, T. (2010) Plant Cell Physiol. 51, 855–865). Although the insertion is thought to be located in the periphery of the complex and far from catalytic sites, the mutant complex shows a remarkable increase in ATP hydrolysis activity due to a reduced tendency to lapse into ADP inhibition. We postulated that removal of the insertion affects the activity via a conformational change of two central α-helices in γ. To examine this hypothesis, we prepared a mutant complex that can lock the relative position of two central α-helices to each other by way of a disulfide bond formation. The mutant obtained showed a significant change in ATP hydrolysis activity caused by this restriction. The highly active locked complex was insensitive to N-dimethyldodecylamine-N-oxide, suggesting that the complex is resistant to ADP inhibition. In addition, the lock affected ϵ inhibition. In contrast, the change in activity caused by removal of the γ insertion was independent from the conformational restriction of the central axis component. These results imply that the global conformational change of the γ subunit indirectly regulates complex activity by changing both ADP inhibition and ϵ inhibition.     

Clonal splitting in desert shrubs

Axis splitting is a widespread phenomenon in desert shrubs, and has been reported for shrubs from several plant families, both in old- and new-world deserts. It is so common in dwarf shrubs of arid environments as to be a defining characteristic of this growth form. Although anatomists described this phenomenon several decades ago, there has been only one ecological study of one species, Ambrosia dumosa. The anatomical nature of the various splitting mechanisms that have been found suggests axis splitting to be an extreme form of hydraulic segmentation. The adaptive advantage of clonal splitting in desert shrubs has yet to be determined, but it appears to be largely a risk-spreading mechanism that enables independent mortality of integrated hydraulic units (IHUs) or ramets. This should be especially advantageous in heterogeneous, water-limited environments, where soil water occurs in pockets too small to support a large shrub-genet. Clonal splitting may cause an increase in intraclonal competition among ramets, but there are also indications that at least some species possess mechanisms to reduce competition by minimizing root system overlap among ramets. Many desert shrub species that undergo clonal splitting maintain a dense clump growth form, possibly because such a growth form has positive effects on water and nutrient status of the soil and long-term effects on other soil properties.     

Gene expression suggests conserved mechanisms patterning the heads of insects and myriapods

Segmentation, i.e. the subdivision of the body into serially homologous units, is one of the hallmarks of the arthropods. Arthropod segmentation is best understood in the fly Drosophila melanogaster. But different from the situation in most arthropods in this species all segments are formed from the early blastoderm (so called long-germ developmental mode). In most other arthropods only the anterior segments are formed in a similar way (so called short-germ developmental mode). Posterior segments are added one at a time or in pairs of two from a posterior segment addition zone. The segmentation mechanisms are not universally conserved among arthropods and only little is known about the genetic patterning of the anterior segments. Here we present the expression patterns of the insect head patterning gene orthologs hunchback (hb), orthodenticle (otd), buttonhead-like (btdl), collier (col), cap-n-collar (cnc) and crocodile (croc), and the trunk gap gene Krüppel (Kr) in the myriapod Glomeris marginata. Conserved expression of these genes in insects and a myriapod suggests that the anterior segmentation system may be conserved in at least these two classes of arthropods. This finding implies that the anterior patterning mechanism already existed in the last common ancestor of insects and myriapods.