Early Cambrian radiation of brachiopods: A perspective from South China

Brachiopods, a group of benthic suspension-feeding marine invertebrates, made their first appearance in the Lower Cambrian. In the Yangtze Platform (South China), well-exposed Lower Cambrian stratigraphic succession represents shallow to deeper water environments. Strata from eastern Yunnan, southern Shaanxi and the Yangtze gorges areas of western Hubei Province, deposited in muddy-siltstone and carbonate lithofacies, contained an abundant variety of brachiopods, including all the representatives of the subphylum Linguliformea and the calcareous-shelled genera of Kutorgina and Nisusia from the subphylum Rhynchonelliformea. Thus the fossil assemblage bears witness to the first major phase of evolutionary radiation of brachiopods during the ‘Cambrian explosion’ interval of metazoans. Brachiopods from the celebrated Chengjiang fauna have exquisitely preserved soft-tissues, which reveal the body plans and evolutionary acquisition of morphological novelties of the early stocks, and also provide a good opportunity for testing the analogies with the stem groups from the extant representatives. These fossils have corroborated the view that brachiopods developed complex organization of tissues, and achieved considerable evolutionary success already by the onset of ‘Cambrian Explosion’. Thus it is not improbable that a large part of this radiation occurred within, or only just before early Cambrian time. Studies of Chengjiang brachiopods suggest that attachment by a pedicle to the substrate was probably the most common relationship of Cambrian brachiopods with the substrate where they inhabited.     

Building sustainable livelihoods in Laos: untangling farm from non-farm, progress from distress

Laos is one of the poorest countries in the world. The majority of households continue to rely on farming to meet their needs. However the country is also going through an important transition as the market extends into formerly remote rural areas. Drawing on surveys of nine villages in three districts, the paper elucidates how households are managing the transition from subsistence to market. Agriculturally resilient communities with considerable potential are contrasted with villages where the scope for increases in farm output are sharply constrained. The growing role of non-farm activities is highlighted and a distinction drawn between `distress' and `progressive' diversification. The paper argues that diversification is propelled by very different forces and has markedly different implications in livelihood terms. It is also suggested that while general statements can be made about livelihood transitions in the country, and the production and reproduction of poverty, at a household level it is often not possible to `read-off' likely livelihood conditions from a mere assessment of resources.     

The household economy of pastoralists and wage-labourers in the Richtersveld, South Africa

The Richtersveld is situated in an arid environment and its inhabitants are confronted with various hazards. Based on data collected during 22 months of ethnographic fieldwork, the livelihood strategies of Richtersvelders are explored. Besides a thorough examination of the diversified economy, the internal institutional arrangements for pooling and redistributing resources within households are analysed in this paper. Encouraging household members to engage in different activities and to share their income—as well as skills to manage the household budget properly—are integral to diversification and reducing the vulnerability of households. This study has shown that even in a community marked by considerable dependence on wage labour, almost three-quarters of the households are directly involved in stock farming. Although pastoralism still plays an important role for households, it has shifted from being the core economic activity to being an insurance against unemployment and contributing to subsistence. Stock farming serves to build up resilience through the diversification of economic activities inside the household. In the South African context, the relevance of activities dependent on land has implications not only for rural development, but also for post-apartheid land and agrarian reform.     

Speciation in gall-inducing thrips on Acacia in arid and non-arid areas of Australia

Habitat modification mediated by abiotic processes imposes consequences for the diversification of plants and plant specialists. Host plant diversification is expected to be dependent on environmental and ecological constraints that are fundamentally connected to physiography (physical geography). A phylogenetic approach is used to reconstruct ancestral host plant affiliation of gall-inducing thrips that specialize on Australian Acacia. Diversification rate models are applied to gall-thrips clades that are affiliated with different Acacia host lineages. Gall-thrips diversification is reconciled with contemporary patterns of species diversity relating to the different host lineages. Results indicate that diversification on host lineages that are mostly distributed in non-arid areas are best explained by a rate-constant model. However, this model disguised additive effects of rate-variable lineage accumulation that indicated diversification decreases in sub-clades within this larger group. Gall-thrips affiliated with hosts distributed mostly in arid areas were best characterized by rate-variable decreasing net diversification. The work infers parent gall-thrips lineages are less species diverse compared to daughter lineages that tend to be distributed away from the arid interior of Australia. Contrasting ecological and environmental interactions unique to parent and daughter lineages are suggested to influence the mode of speciation and phenotypic diversity represented by each.     

Origin, diversification, and relationships of Cambrian lobopods

As an extinct group, the origin, diversification and relationships of Cambrian lobopods have long been one of the most hotly-debated subjects. Lobopods used to be regarded as closely related to modern onychophorans and tardigrades, but the similarities are based on the few species of Cambrian lobopods and often on a fairly general level. With the discovery of new creatures and based on new observations on fossil lobopods, we consider that Cambrian lobopods show great diversity and reveal a close relationship between Cambrian lobopods and arthropods. In addition, comparison between the dorsal spines of Cambrian lobopods and small shelly fossils suggest that Cambrian lobopods might have originated from the Meishucun radiation and diversified in the Qiongzhusi radiation.     

Livelihood diversification as an adaptation approach to change in the pastoral Hindu-Kush Himalayan region

Migratory livestock raising has been one of the most important livelihood options for people residing in high mountain areas and has made a significant contribution to the economy of the Hindu Kush Himalayan（HKH） region, both in terms of supporting households and in export earnings. However, in recent decades, changes in the socioeconomic situation and increasing climate variability have led to a need to enhance adaptation by building the resilience of local socio-ecological systems, including economic diversification and sustainable management of natural resources. Based on semistructured interviews with pastoral communities in six countries within the pastoral HKH region, this paper discusses the situation, trends and driving forces behind the diversification of pastoral livelihood. For internal diversification the study highlights the need for enhancement of pastoral livelihoods through value-adding activities in the pastoral sectors. For external diversification changes on policy changes are needed to support free out-migration, market exploitation, and multiple resource use. Finally the paper highlights the role of education in determining household adaptation strategies in the face of various socio-ecological pressures and recommends integrating innovative and indigenous knowledge to develop appropriate methods for risk management and resource management in the pastoral HKH region.     

Evidence for eukaryotic diversification in the 1800 million-year-old Changzhougou Formation, North China

Shales and silty shales of the 1800 million-year-old Changzhougou Formation (lowermost Changcheng Group) in the Pangjiapu Region of North China contain well-preserved, acritarchs. These microbial body fossils, although sphaeromorphs, have a size and fine-scale morphological complexity that would attribute them to the eukaryotic domain on the tree of life. Sphaeromorphs range in size from 62 μm to 216 μm. Shapes include spheroidal, ellipsoidal, and fusiform. Some have medial splits indicating excystment and others have a complex wall structure with three or more wall layers. Thirteen distinct morphological entities have been identified. These results indicate that eukaryotic microbial life was well established by close of the Paleoproterozoic and had already undergone a moderate amount of diversification.     

层序界面-驱动层序地层模式多样化

研究层序地层学的重点在于层序划分,而层序划分的前提是识别和对比岩石记录中代表沉积趋势变化的地层界面。地层界面作为基准面与沉积速率相互作用产生不同沉积成因类型（强迫型海退、低水位和高水位正常海退以及海进）的响应,一部分可以提升至具有层序地层学意义的层序界面。目前,不同学者对层序界面的理解及使用存在着明显的差异和混乱,其导致的模式多样化也造成了解决实际问题时的混乱。     

Micro-economic drivers of profitability in an ITQ-managed fishery: An analysis of the Queensland Coral Reef Fin-Fish Fishery

An economic survey of the commercial operators currently active in the Queensland Coral Reef Fin-Fish Fishery has been carried out, as part of a research project aimed at evaluating alternative management options for this fishery. This paper presents the background analysis used as a basis to develop the sampling design for this survey. The background analysis focuses on activity patterns of the fleet based on effort and catch information, as well as patterns of quota ownership. Based on this information, a fishing business profile describing the micro-economic structure of fishing operations is developed. This profile, in conjunction with the qualitative information gained in undertaking the economic surveys, allows preliminary understanding of the key drivers of profitability in the CRFFF, and possible impacts of external factors on fishing operations.     

‘Where is the life in farming?’: The viability of smallholder farming on the margins of the Kalahari, Southern Africa

This paper investigates the ways in which national and regional policies relate to farming activities and concerns amongst the rural population in an area of southern Africa. The struggle to make a living through farming was a common theme to emerge from research about changing livelihoods in response to both variability in the environment and changes in policy. This local discourse echoed regional debates about land and agrarian reform in post-apartheid South Africa and the uncertain future of mixed farming in Botswana. It also raised broader questions about the viability of the future of small-medium-scale farming systems in rural areas in Africa, especially those within dynamic dryland environments such as the Kalahari. This paper looks specifically at the links between poverty and asset holding and aims to identify the ways in which people are or are not able to utilise or mobilise these assets in times of need. We argue that this can vary significantly between seemingly similar settlements, and similar households and that understanding this complexity is the key to recognising how future interventions many impact upon people’s lives. Too often, in the quest to produce understandings of poverty and livelihoods, the complexity, incongruity and reality of day-to-day practices are overlooked. Thus we seek to draw out the interactions between policy and natural resource use, and the capital asset changes involved in these interactions, which influence the sustainability of livelihoods and the differing levels of poverty and vulnerability.