High Level Of Connectivity Research Articles

基于系统演化视角的可持续性评价方法

PDF HTML阅读 XML下载 导出引用 引用提醒 基于系统演化视角的可持续性评价方法 DOI: 10.5846/stxb201403120425 作者: 作者单位: 中国科学院成都山地灾害与环境研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目(41201603);中国科学院成都山地灾害与环境研究所"一三五"方向性项目专题(SDS-135-1204-03) A new method to assess sustainability: from the perspective of system evolution Author: Affiliation: Institute of Mountain Disaster and Environment, Chinese Academy of Sciences Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:可持续发展水平的衡量是可持续发展研究的重要内容,它可以为政府的可持续发展决策提供重要的科学依据。现有的可持续性评价方法可分为指标列举法、流量分析法和系统分析法。前两类方法应用广泛,但理论基础较为薄弱,在指标的选取、标准化和赋权等方面存在一定的缺陷。基于系统运行机理的系统分析法尚不多见,但能弥补前两种方法的部分不足,Ulanowicz于2009年提出的演化模型是此类方法的代表。该模型从系统演化角度出发,以网络流为研究对象,以信息论为手段,指出系统的可持续性是系统上升性(效率)和恢复力平衡的结果,并提出了可持续性评价指标R。回顾了现有研究方法的优缺点。介绍了从演化视角分析可持续性的原理和数学模型,可持续发展的阈值范围以及该方法的应用案例。总结了该方法的应用步骤及尚需解决的问题。 Abstract:Sustainability assessment is an important subject in the field of sustainable development. Indicators of sustainability can provide policy-makers with clues as to whether a region is moving toward or away from sustainability: this can be helpful for decision-making. Sustainability assessment methodologies can be classified into three indicators: enumeration, flow analysis and systemic analysis. The standard used to classify methodologies considers whether the relationships between components in the system alone or whether the relationships between components in the system and the outside environment are considered. The indicators enumeration and flow analysis are widely used; however, they contain some disadvantages. These methods have a poor theoretical basis. Moreover, criteria to choose, standardize and integrate indicators are not ascertained unanimously. Different results may be derived for the same data if different methods of standardization or integration are used. Hence, sustainability assessment from the perspective of system dynamics has emerged as the optimal assessment method. In 2009, the American theoretical ecologist Ulanowicz proposed a typical system analysis method known as the evolution model. The evolution model-taking flow networks as the study object vand information theory as the measurement-shows that the sustainability of a system is determined by the balance between ascendency (efficiency) and resiliency. The model states that the capacity for a system to undergo evolutionary change or self-organization consists of two factors: 1) ascendency: the network's capacity to perform in a sufficiently organized and efficient manner to maintain its integrity over time; and 2) resilience: the network's reserve of flexible fallback positions and diversity of actions that can be used to meet the exigencies of novel disturbances and the novelty needed for ongoing development and evolution. These two factors are complementary with respect to diversity and connectivity in the network. A system's resilience is enhanced by high levels of diversity and connectivity, while ascendency is augmented by low levels of diversity and connectivity. In other words, too much ascendency (resilience) means too little resilience (ascendency). A system lacking ascendency has neither the extent of activity nor the internal organization needed to survive. By contrast, a system lacking resilience appears brittle in the face of novel disturbances. Both too much ascendency and too much resilience negatively affect sustainable development. Both ascendency and resilience are important for long-term sustainability: a system's sustainability is depending on the tradeoff between ascendency and resilience. According to this result, the sustainability indicator R is proposed. The paper is organized as follows. First, the advantages and disadvantages of current sustainability assessment methodologies are reviewed. Section 1 describes the principles used to analyze sustainability from the perspective of system's evolution. In section 2, the evolution model is described in the language of information theory. Section 3 describes the range of sustainable development and the optimal sustainable development state for ecosystems. This section also examines how to analyze the range of sustainable development in an economic system. The evolution model is applied to a water system and an economic system; these applications are described in section 4. Finally, the key steps to applying the evolution model are summarized and its disadvantages are discussed. 参考文献 相似文献 引证文献

Vertical and horizontal genetic connectivity in Chromis verater, an endemic damselfish found on shallow and mesophotic reefs in the Hawaiian Archipelago and adjacent Johnston Atoll.

Understanding vertical and horizontal connectivity is a major priority in research on mesophotic coral ecosystems (30–150 m). However, horizontal connectivity has been the focus of few studies, and data on vertical connectivity are limited to sessile benthic mesophotic organisms. Here we present patterns of vertical and horizontal connectivity in the Hawaiian Islands-Johnston Atoll endemic threespot damselfish, Chromis verater, based on 319 shallow specimens and 153 deep specimens. The mtDNA markers cytochrome b and control region were sequenced to analyze genetic structure: 1) between shallow (<30 m) and mesophotic (30–150 m) populations and 2) across the species' geographic range. Additionally, the nuclear markers rhodopsin and internal transcribed spacer 2 of ribosomal DNA were sequenced to assess connectivity between shallow and mesophotic populations. There was no significant genetic differentiation by depth, indicating high levels of vertical connectivity between shallow and deep aggregates of C. verater. Consequently, shallow and deep samples were combined by location for analyses of horizontal connectivity. We detected low but significant population structure across the Hawaiian Archipelago (overall cytochrome b: ΦST = 0.009, P = 0.020; control region: ΦST = 0.012, P = 0.009) and a larger break between the archipelago and Johnston Atoll (cytochrome b: ΦST = 0.068, P<0.001; control region: ΦST = 0.116, P<0.001). The population structure within the archipelago was driven by samples from the island of Hawaii at the southeast end of the chain and Lisianski in the middle of the archipelago. The lack of vertical genetic structure supports the refugia hypothesis that deep reefs may constitute a population reservoir for species depleted in shallow reef habitats. These findings represent the first connectivity study on a mobile organism that spans shallow and mesophotic depths and provide a reference point for future connectivity studies on mesophotic fishes.

Analysis of pig movements across eastern Indonesia, 2009–2010

Knowledge of live animal movement through markets and from farm-to-farm is needed to inform strategies for control of trans-boundary animal diseases (TADs) in south-east Asia, particularly due to consumer preference for fresh meat. In eastern Indonesia a TAD of principal interest for control is classical swine fever (CSF) due to its impacts on smallholder farmers. Pig movement is considered a contributor to failure of current CSF control efforts but pig movement patterns are not well understood. This study investigated movement of live pigs in West Timor, Flores and Sumba islands during 2009–2010, with the aim of informing CSF control policies for Nusa Tenggara Timor province. A market survey of 292 pig sellers and 281 pig buyers across nine live pig markets and a farmer survey across 18 villages with 289 smallholder farmers were conducted and information collected on pig movements. The data obtained was used for social network analysis (SNA) on formal (via a market) and informal (village-to-village) movements using information on trading practices, source and destination locations, and the number of pigs being moved. Both inter- and intra-island movements were identified, however inter-island movement was only observed between Flores and Sumba islands. West Timor and Sumba had highly connected networks where large numbers of villages were directly and indirectly linked through pig movement. Further for West Timor, both formal and informal pig movements linked the capital Kupang, on the eastern end of the island to the western districts bordering East Timor connecting all five districts and demonstrating that informal movement transports pigs over distances similar to formal movement on this island. Sumba had a higher potential for pigs to move to a greater number of sequential locations across the entire island. Flores was found to have a more fragmented network, with pig movements concentrated in its eastern or western regions, influenced by terrain. Markets were confirmed as high-risk locations for the introduction and spread of disease, having over 20 contacts (based on in- and out-degree values) depending on operational day. Villages considered high-risk for CSF spread via informal movements were characterised by higher volume of pig exits and/or linkage to higher numbers of other villages. These findings demonstrate that informal movement (often related to cultural practices) can be extensive and the high level of connectivity dictates that control strategies for CSF and other highly transmissible diseases must be formulated at the provincial level and in collaboration with East Timor.

Genetic evidence from the spiny lobster fishery supports international cooperation among Central American marine protected areas

Marine protected areas (MPAs) are an important ecosystem-based management approach to help improve the sustainability of the spiny lobster fishery (Panulirus argus), but information is lacking concerning levels of lobster population connectivity among MPAs. Given their prolonged (~6 months) pelagic larval duration, population connectivity must be considered in any spatial management plan for P. argus. We used genetic techniques to uncover spatial patterns of connectivity among MPAs along the Mesoamerican Barrier Reef (MBRS) of Central America. We hypothesized that connectivity would be greater and genetic differentiation diminished among lobster populations within MPAs in the southern MBRS, which is dominated by a retentive oceanographic environment, as compared to MPAs in the more advective environment further north. We found that levels of connectivity are high among spiny lobster populations residing in MPAs in Central America, although overall F ST was low (F ST = 0.00013) but significant (P = 0.037). MPAs in the northern MBRS contained significantly more individuals that were genetically determined outliers or migrants than southern MPAs (P = 0.008, R 2 = 0.61), which may have contributed to the higher levels of genetic differentiation observed in northern MPAs. Direct genetic testing of larvae and adults will be required to confirm this hypothesis. The high level of connectivity among MPAs provides additional evidence of the importance of international cooperation in the management of Caribbean lobster fisheries. However, uncertainty regarding the ecological and physical drivers of genetic differentiation in Northern MPAs implies that managers should hedge against uncertainty.

Dispatches

Dispatches

Population structure of istiophorid billfishes

The phylogeny of istiophorid billfishes was recently revised based on analyses of nuclear and mitochondrial DNA loci, and a variety of molecular genetic characters has been used to investigate population structuring within several species of billfish. Despite these efforts, the population structure of most istiophorid billfishes is not well understood. This paper reviews genetic insights into the phylogeny and population structure of the billfishes with an emphasis on recent studies. In general, the results of genetic studies indicate significant heterogeneity between Atlantic and Indo-Pacific samples of circumtropical species. Within ocean basins, levels of population structure range among the species from no statistically significant heterogeneity detected among samples to small, but statistically significant genetic divergence between geographically distant samples. The apparent high level of genetic connectivity within oceans for some species seems to contrast with inferences derived from studies employing conventional and satellite tags that suggest limited trans-equatorial or trans-oceanic movements. This disparity may result, in part, from the different time scales underpinning evolutionary and ecological population structure; however, the power of previous genetic studies to elucidate population structuring has been limited by opportunistic sampling. To effectively assess population structure within the highly migratory billfishes, future genetic research will not only require larger sample sizes, both in terms of individuals and molecular markers, but also the development of biologically meaningful sampling designs that incorporate information on the movement patterns and life histories of these pelagic fishes.

Nanotechnology knowledge diffusion: measuring the impact of the research networking and a strategy for improvement

Given the global increase in public funding for nanotechnology research and development, it is even more important to support projects with promising return on investment. A main return is the benefit to other researchers and to the entire field through knowledge diffusion, invention, and innovation. The social network of researchers is one of the channels through which this happens. This study considers the scientific publication network in the field of nanotechnology, and evaluates how knowledge diffusion through coauthorship and citations is affected in large institutions by the location and connectivity of individual researchers in the network. The relative position and connectivity of a researcher is measured by various social network metrics, including degree centrality, Bonacich Power centrality, structural holes, and betweenness centrality. Leveraging the Cox regression model, we analyzed the temporal relationships between knowledge diffusion and social network measures of researchers in five leading universities in the United States using papers published from 2000 to 2010. The results showed that the most significant effects on knowledge diffusion in the field of nanotechnology were from the structural holes of the network and the degree centrality of individual researchers. The data suggest that a researcher has potential to perform better in knowledge creation and diffusion on boundary-spanning positions between different communities and when he or she has a high level of connectivity in the knowledge network. These observations may lead to improved strategies in planning, conducting, and evaluating multidisciplinary nanotechnology research. The paper also identifies the researchers who made most significant contributions to nanotechnology knowledge diffusion in the networks of five leading U.S. universities.

Geographic differences in vertical connectivity in the Caribbean coral Montastraea cavernosa despite high levels of horizontal connectivity at shallow depths.

The deep reef refugia hypothesis proposes that deep reefs can act as local recruitment sources for shallow reefs following disturbance. To test this hypothesis, nine polymorphic DNA microsatellite loci were developed and used to assess vertical connectivity in 583 coral colonies of the Caribbean depth-generalist coral Montastraea cavernosa. Samples were collected from three depth zones (≤10, 15-20 and ≥25 m) at sites in Florida (within the Upper Keys, Lower Keys and Dry Tortugas), Bermuda, and the U.S. Virgin Islands. Migration rates were estimated to determine the probability of coral larval migration from shallow to deep and from deep to shallow. Finally, algal symbiont (Symbiodinium spp.) diversity and distribution were assessed in a subset of corals to test whether symbiont depth zonation might indicate limited vertical connectivity. Overall, analyses revealed significant genetic differentiation by depth in Florida, but not in Bermuda or the U.S. Virgin Islands, despite high levels of horizontal connectivity between these geographic locations at shallow depths. Within Florida, greater vertical connectivity was observed in the Dry Tortugas compared to the Lower or Upper Keys. However, at all sites, and regardless of the extent of vertical connectivity, migration occurred asymmetrically, with greater likelihood of migration from shallow to intermediate/deep habitats. Finally, most colonies hosted a single Symbiodinium type (C3), ruling out symbiont depth zonation of the dominant symbiont type as a structuring factor. Together, these findings suggest that the potential for shallow reefs to recover from deep-water refugia in M. cavernosa is location-specific, varying among and within geographic locations likely as a consequence of local hydrology.

Seagrass radiation after Messinian salinity crisis reflected by strong genetic structuring and out-of-Africa scenario (Ruppiaceae).

Many aquatic plant and seagrass species are widespread and the origin of their continent-wide ranges might result from high gene flow levels. The response of species when extending northwards since the Last Glacial Maximum can be opposed to the structuring of their populations that survived glaciation cycles in southern regions. The peri-Mediterranean is a complex series of sea basins, coastlines, islands and river deltas with a unique history since the Messinian Crisis that potentially influenced allopatric processes of aquatic life. We tested whether vast ranges across Europe and the peri-Mediterranean of a global seagrass group (Ruppia species complexes) can be explained by either overall high levels of gene flow or vicariance through linking population genetics, phylogeography and shallow phylogenetics. A multigene approach identified haplogroup lineages of two species complexes, of ancient and recent hybrids with most of the diversity residing in the South. High levels of connectivity over long distances were only observed at recently colonized northern ranges and in recently-filled seas following the last glaciation. A strong substructure in the southern Mediterranean explained an isolation-by-distance model across Europe. The oldest lineages of the southern Mediterranean Ruppia dated back to the period between the end of the Messinian and Late Pliocene. An imprint of ancient allopatric origin was left at basin level, including basal African lineages. Thus both vicariance in the South and high levels of connectivity in the North explained vast species ranges. Our findings highlight the need for interpreting global distributions of these seagrass and euryhaline species in the context of their origin and evolutionary significant units for setting up appropriate conservation strategies.

Exploring Parental Factors Related to Weight Management in Survivors of Childhood Central Nervous System Tumors

Childhood central nervous system tumor survivors (CCNSTS) are at risk for adverse health issues. Little research has been conducted to explore the role of parental factors in weight management to mitigate adverse health outcomes. We conducted 9 group interviews (n=20) with CCNSTS, their parents, and health care providers to ascertain parental factors that may influence weight management practices in CCNSTS. Three main themes were identified: parenting style, parent-child connectedness, and food and physical activity (PA) environment. Although most parents adopted an authoritative parenting style related to diet and PA practices, some adopted a permissive parenting style. Participants expressed high levels of connection that may hinder the development of peer relationships and described the food and PA environments that promote or hinder weight management through parental modeling of healthy eating and PA and access to healthy food and activities. Weight management interventions for CCNSTS may experience greater benefit from using a family-focused approach, promoting positive food and PA environments, parental modeling of healthy eating and exercise, and partnering with youth to adopt weight management behaviors.

Gene flow and immigration: genetic diversity and population structure of lions (Panthera leo) in Hwange National Park, Zimbabwe

The genetic diversity and population structure of a population of African lions in Hwange National Park, Zimbabwe, was studied using 17 microsatellite loci. Spatial genetic analysis using Bayesian methods suggested a weak genetic structure within the population and high levels of gene flow across the study area. We were able to identify a few individuals with aberrant or admixed ancestry, which we interpreted as either immigrants or as descendants thereof. This, together with relatively high genetic diversity, suggests that immigrants from beyond the study area have influenced the genetic structure within the park. We suggest that the levels of genetic diversity and the observed weak structure are indicative of the large and viable Okavango-Hwange population of which our study population is a part. Genetic patterns can also be attributed to still existing high levels of habitat connectivity between protected areas. Given expected increases in human populations and anthropogenic impacts, efforts to identify and maintain existing movement corridors between regional lion populations will be important in retaining the high genetic diversity status of this population. Our results show that understanding existing levels of genetic diversity and genetic connectivity has implications, not only for this lion population, but also for managing large wild populations of carnivores.

Evolutionary consequences of shifts to bird-pollination in the Australian pea-flowered legumes (Mirbelieae and Bossiaeeae).

BackgroundInteractions with pollinators are proposed to be one of the major drivers of diversity in angiosperms. Specialised interactions with pollinators can lead to specialised floral traits, which collectively are known as a pollination syndrome. While it is thought that specialisation to a pollinator can lead to either an increase in diversity or in some cases a dead end, it is not well understood how transitions among specialised pollinators contribute to changes in diversity. Here, we use evolutionary trait reconstruction of bee-pollination and bird-pollination syndromes in Australian egg-and-bacon peas (Mirbelieae and Bossiaeeae) to test whether transitions between pollination syndromes is correlated with changes in species diversity. We also test for directionality in transitions that might be caused by selection by pollinators or by an evolutionary ratchet in which reversals to the original pollination syndrome are not possible.ResultsTrait reconstructions of Australian egg-and-bacon peas suggest that bee-pollination syndrome is the ancestral form and that there has been replicated evolution of bird-pollination syndromes. Reconstructions indicate potential reversals from bird- to bee-pollination syndromes but this is not consistent with morphology. Species diversity of bird-pollination syndrome clades is lower than that of their bee-pollination syndrome sisters.We estimated the earliest transitions from bee- to bird-pollination syndrome occurred between 30.8 Ma and 10.4 Ma. Geographical structuring of pollination syndromes was found; there were fewer bird-pollination species in the Australian southeast temperate region compared to other regions of Australia.ConclusionsA consistent decrease in diversification rate coincident with switches to bird pollination might be explained if greater dispersal by bird pollinators results in higher levels of connectivity among populations and reduced chances of allopatric speciation.The earliest transitions overlap with the early diversification of Australian honeyeaters – the major lineage of pollinating birds in Australia. Our findings are consistent with the idea that environment and availability of pollinators are important in the evolution of pollination syndromes. Changes in flower traits as a result of transitions to bird-pollination syndrome might also limit reversals to a bee-pollination syndrome.

Molecular evidence for co-occurring cryptic lineages within the Sepioteuthis cf. lessoniana species complex in the Indian and Indo-West Pacific Oceans

The big-fin reef squid, Sepioteuthis cf. lessoniana (Lesson 1930), is an important commodity species within artisanal and near-shore fisheries in the Indian and Indo-Pacific regions. While there has been some genetic and physical evidence that supports the existence of a species complex within S. cf. lessoniana, these studies have been extremely limited in scope geographically. To clarify the extent of cryptic diversity within S. cf. lessoniana, this study examines phylogenetic relationships using mitochondrial genes (cytochrome oxidase c, 16s ribosomal RNA) and nuclear genes (rhodopsin, octopine dehydrogenase) from nearly 400 individuals sampled from throughout the Indian, Indo-Pacific, and Pacific Ocean portions of the range of this species. Phylogenetic analyses using maximum likelihood methods and Bayesian inference identified three distinct lineages with no clear geographic delineations or morphological discriminations. Phylogeographic structure analysis showed high levels of genetic connectivity in the most widespread lineage, lineage C and low levels of connectivity in lineage B. This study provides significant phylogenetic evidence for cryptic lineages within this complex and confirms that cryptic lineages of S. cf. lessoniana occur in sympatry at both small and large spatial scales. Furthermore, it suggests that two closely related co-occurring cryptic lineages have pronounced differences in population structure, implying that underlying differences in ecology and/or life history may facilitate co-occurrence. Further studies are needed to assess the range and extent of cryptic speciation throughout the distribution of this complex. This information is extremely useful as a starting point for future studies exploring the evolution of diversity within Sepioteuthis and can be used to guide fisheries management efforts.

MP Transparency, Communication Links and Social Media: A Comparative Assessment of 184 Parliamentary Websites

Parliamentary websites (PWs) can potentially enhance the quality of government by providing information and communication links that stimulate political awareness, deliberation and participation. This article focuses on two particular uses of PWs that can facilitate communication between constituents and their Members of Parliament: provision of MP contact and background information; and links to social media. Through a seminal empirical examination of all 184 functioning lower house and unicameral PWs around the world, this study found that although PWs in wealthy democracies generally provide more MP information, the majority of PWs are deficient in providing basic MP information to citizens and utilizing linkages to social media. By contrast, some non-democratic states and newly democratized countries, especially those with compulsory voting, display a relatively high level of MP transparency and social media connectivity.

Effects of landscape, demographic and behavioral factors on kin structure: testing ecological predictions in a mesopredator with high dispersal capability

AbstractKin structure, the spatial aggregation of related individuals, impacts many processes important to conservation (e.g. inbreeding), and patterns of kin structure could be impacted by human‐mediated habitat fragmentation and loss. While kin structure is expected to increase with habitat fragmentation (reduced connectivity), the effects of habitat loss (reduced resource availability) remain unclear. Disentangling the effects of habitat fragmentation and loss is challenging because they usually are spatially correlated, and because most species are negatively affected by both processes. Raccoons Procyon lotor is a model species to test how habitat loss affects kin structure because, although relatively unaffected by habitat fragmentation (because of high dispersal ability), they are negatively affected by habitat loss (forest‐related resources being important for female reproductive success). To elucidate the causes and consequences of kin structure in raccoons, we utilized genetic and demographic data collected from 998 individuals trapped from 27 spatially distinct habitat patches (local populations) situated in an agricultural ecosystem. Our results highlight an important, but often ignored fact: structural connectivity does not necessarily predict functional dispersal patterns in natural populations. Thus, in raccoons, local populations with low kin structure were associated with high landscape disturbance (i.e. high levels of habitat loss and low connectivity), and were characterized by demographic instability (i.e. high immigration, emigration and/or mortality). Alternatively, local populations exhibiting high kin structure were associated with low landscape disturbance and high demographic stability (i.e. high natality and philopatry). We propose that such increased philopatry in resource‐rich patches could lead to a functional isolation (‘isolation by resource’) exacerbating the negative effects of landscape modification because of isolation by distance and/or resistance, especially in species with low dispersal capability. Our results also indicate that high levels of genetic diversity may be associated with low (rather than high) patch quality because populations in such patches could be composed predominantly of (unrelated) immigrants.

Characterization and Prediction of Haploinsufficiency Using Systems-Level Gene Properties in Yeast

Variation in gene copy number can significantly affect organism fitness. When one allele is missing in a diploid, the phenotype can be compromised because of haploinsufficiency. In this work, we identified associations between Saccharomyces cerevisiae gene properties and genome-scale haploinsufficiency phenotypes from previous work. We compared the haploinsufficiency profiles against 23 gene properties and found that genes with higher level of connectivity (degree) in a protein–protein interaction network, higher genetic interaction degree, greater gene sequence conservation, and higher protein expression were significantly more likely to be haploinsufficient. Additionally, haploinsufficiency showed negative relationships with cell cycle regulation and promoter sequence conservation.

Landscapes of midwifery practice

undergraduate midwifery programmes offer opportunities for school leavers and young people (aged less than 21 years) to enter the profession. There is limited research exploring this age groups experience of their Bachelor of Midwifery programme. In order to retain these students we need to ensure that their experiences of undertaking a Bachelor of Midwifery program are positive and barriers and challenges are minimised.this study explored young midwifery students' experience of their Bachelor of Midwifery program.a descriptive exploratory qualitative approach was used to explore the experiences of eleven students aged 20 years or less on enrolment. Data was collected using face-to-face or telephone-recorded interviews. Thematic analysis was used to analysis the data set.three major themes described the young students' experiences. The first labelled ‘The challenges of being young’ presented a number of age related challenges including transport issues with on-call commitments as some students had not gained a driver's license. Students experienced some degree of prejudice relating to their age from their older student peers and some clinical staff during placements. ‘Finding your way’ was the second theme and described the strategies students used to buildconfidence and competence both in the university and clinical environment. The young students reported a strong commitment to the profession. They demonstrated high levels of connection with women and found the continuity of care experiences invaluable to their learning. The final theme ‘Making the transition from teenager to midwife’ demonstrated some unique insights into how studying to become a midwife impacted upon their personal and professional growth.the young students in this study encountered some unique issues related to their age. However as they progressed through the program they developed confidence in themselves and visualised themselves as having a long midwifery career. They were strongly motivated towards providing woman-centred maternity care and considered their continuity of care experiences fundamental to them developing a strong sense of themselves as midwives. Attracting and retaining young students is essential if the profession is to realise its goal of ensuring all women have access to a known midwife.

A panmictic fiddler crab from the coast of Brazil? Impact of divergent ocean currents and larval dispersal potential on genetic and morphological variation in Uca maracoani

Marine species tend to exhibit relatively less population structuring than terrestrial species owing to fewer barriers to gene flow and increased connectivity resulting from greater dispersal abilities. Thus, in many cases, life history plays a more important role in phylogeography of marine taxa than do oceanographic features. Littoral species are of particular phylogeographic interest because they possess life histories that have both marine and terrestrial characteristics. This study evaluates the synergistic impact of divergent ocean currents and a high larval dispersal potential on the phylogeography of the fiddler crab, Uca maracoani, distributed along the coast of Brazil. Patterns of genetic variation were assessed with sequence data for a portion of the mitochondrial COI gene and AFLPs. Geometric morphometric techniques were used to evaluate morphological variation. Results revealed a lack of discernible genetic subdivision. However, geometric morphometrics showed statistically significant morphological differentiation. The absence of a clear phylogeographic pattern appears to be determined primarily by life history characteristics permitting a high level of connectivity. One, or a combination of several factors, may explain the incongruity between genetic and morphologic signatures, including phenotypic plasticity, incomplete lineage sorting, or recent and ongoing genetic divergence.

High genetic connectivity in the Atlantic sharpnose shark, Rhizoprionodon terraenovae, from the southeast Gulf of Mexico inferred from AFLP fingerprinting

Elasmobranch species represent valuable fishery resources worldwide. Even though their life-history characteristics make them vulnerable to overfishing, there is insufficient fundamental knowledge about their stock structure in many exploited species. The Atlantic sharpnose shark Rhizoprionodon terraenovae is a small shark representing up to 45.9% of the annual landings from the artisanal elasmobranch fishery in the Gulf of Mexico. There is a need to assess the biological and genetic status of its populations to provide a basis for their proper management and conservation. We examined the genetic diversity and population genetic structure of R. terraenovae landed in three locations in the southeast Gulf of Mexico using amplified fragment length polymorphisms (AFLPs) fingerprinting. A total of 465 loci were detected using 3 primer combinations, 410 of which were polymorphic. The percentage of polymorphic loci was 96.3% and average expected heterozygosity was 0.327 for all localities. AMOVA and Bayesian analyses of genetic structure did not reveal significant genetic differentiation among the three localities. Our results are consistent with the migratory behavior and the lack of significant barriers to dispersal that may cause the high levels of genetic connectivity. We suggest that Atlantic sharpnose shark catches landed in the southeast Gulf of Mexico come from a large and well-mixed population, probably mating offshore; however, determining the spatial extent of this population requires a geographically wider genetic survey.

Putative selected markers in the Chionodraco genus detected by interspecific outlier tests

The identification of loci under selection (outliers) is a major challenge in evolutionary biology, being critical to comprehend evolutionary processes leading to population differentiation and speciation, and for conservation purposes, also in light of recent climate change. However, detection of selected loci can be difficult when populations are weakly differentiated. This is the case of marine fish populations, often characterized by high levels of gene flow and connectivity, and particularly of fish living in the Antarctic marine environment, characterized by a complex and strong circulating system promoting individual dispersal all around the continent. With the final aim of identifying outlier loci putatively under selection in the Chionodraco genus, we used 21 microsatellites, including both genomic (Type II) and EST-linked loci (Type I), to investigate the genetic differentiation among the three recently derived Chionodraco species that are endemic to the freezing Antarctic waters. Neutrality tests were applied in interspecific comparisons in order to identify candidate loci showing high levels of genetic differentiation, which might reveal imprints of past selection. Three outlier loci were identified, detecting a higher differentiation between species than did neutral loci. Outliers showed sequence similarity to a calmodulin gene, to an antifreeze glycoprotein/trypsinogen-like protease gene and to nonannotated fish mRNAs. Selective pressures acting on outlier loci identified in this study might reflect past evolutionary processes, which led to species divergence and local adaptation in the Chionodraco genus. Used loci will provide a valuable tool for future population genetic studies in Antarctic notothenioids.