Strong genetic population structure in the boring giant clam, Tridacna crocea, across the Indo-Malay Archipelago: implications related to evolutionary processes and connectivity

Even though the Indo-Malay Archipelago hosts the world's greatest diversity of marine species, studies on the genetic population structure and gene flow of marine organisms within this area are rather rare. Consequently, not much is known about connectivity of marine populations in the Indo-Malay Archipelago, despite the fact that such information is important to understand evolutionary and ecological processes in the centre of marine biodiversity. This study aims to investigate the genetic population structure of the boring giant clam, Tridacna crocea . The analysis is based on a 456-bp fragment of the cytochrome oxidase I gene from 300 individuals collected from 15 localities across the Indo-Malay Archipelago. Tridacna crocea shows a very strong genetic population structure and isolation by distance, indicating restricted gene flow between almost all sample sites. The observed Φ_ST-value of 0.28 is very high compared to other studies on giant clams. According to the pronounced genetic differences, the sample sites can be divided into four groups from West to East: (i) Eastern Indian Ocean, (ii) Java Sea, (iii) South China Sea, Indonesian throughflow, as well as seas in the East of Sulawesi, and (iv) Western Pacific. This complex genetic population structure and pattern of connectivity, characterised by restricted gene flow between some sites and panmixing between others can be attributed to the geological history and prevailing current regimes in the Indo-Malay Archipelago.     

Pacific Coral-reef Fishes: The Implications of Behaviour and Ecology of Larvae for Biodiversity and Conservation, and a Reassessment of the Open Population Paradigm

The two-phase life history of most marine fishes and invertebrates has enormous implications for dispersal, population connectivity, and resource management. Pelagic dispersal larvae of marine animals traditionally thought to ensure that populations are widespread, that chances of local extinction are low, and that marine protected areas (MPA) can easily function to replenish both their own populations and those of unprotected areas. Traditionally, dispersal is considered to depend primarily on two variables: pelagic larva duration and far-field currents. These conclusions arise from the open population paradigm and are usually accompanied by a simplifying assumption: larvae are distributed passively by far-field currents. Unfortunately, they ignore the complex reality of circulation and hydrological connectivity of reefs, and do not consider newly-demonstrated behavioural capabilities of coral-reef fish larvae. Far-field circulation varies with depth and often excludes water bodies where propagules are released, and this has important implications for predicting trajectories of even passive larvae. However, larvae are not passive: late-stage larvae of coral-reef fishes can swim faster than currents for long periods, can probably detect reefs at some distance, and can actively find them. This behaviour is flexible, which greatly complicates modelling of larval fish trajectories. Populations at ecological (as opposed to evolutionary) scales are probably less open and more subdivided than previously assumed. All this means that dispersal predictions based solely on far-field water circulation are probably wrong. An emerging view of larval-fish dispersal is articulated that takes these new data and perspectives into account. This emerging view shows that re-evaluation of traditional views in several areas is required, including the contribution of larval-fish biology and dispersal to biodiversity patterns, the way reef fishes are managed, and the way in which MPA are thought to operate. At evolutionary and zoogeographic scales, reef-fish populations are best considered to be open.     

Socioeconomic Metabolism and Colonization of Natural Processes in SangSaeng Village: Material and Energy Flows, Land Use, and Cultural Change in Northeast Thailand

Conceptualizing environmental problems as sustainability problems contributing to local and global environmental change requires an understanding of how societies cope with their natural environment. Indicators for society–nature interactions are fairly well developed for national-level analyses. This study adapts some of these indicators to the local level and relates them to a qualitative assessment of economic and cultural change in a single community. Indicators are derived from material and energy flow accounting methods and address two major objectives: Firstly, to identify mutual influences between the global and the local level. Secondly, to assess future potentials of environmental pressures and impacts that can be expected to occur as such communities follow a path of further modernization. This study of a small rice-farming community in Northeast Thailand deals with physical as well as sociocultural aspects in order to produce a broad picture of society–nature relations. The indicators developed portray a society in the midst of transition and rapid modernization. This becomes apparent when comparing the results to those of similar studies in traditional and industrial societies. What we see is a community struggling to adapt to global influences, while at the same time maintaining subsistence with traditional coping mechanisms.     

Population structure and colonization of Bactrocera dorsalis (Diptera: Tephritidae) in China,inferred from mtDNA COI sequences

The oriental fruit fly, Bactrocera dorsalis, is a serious pest of fruits and vegetables in South‐east Asia, and, because of quarantine restrictions, impedes international trade and economic development in the region. Revealing genetic variation in oriental fruit fly populations will provide a better understanding of the colonization process and facilitate the quarantine and management of this species. The genetic structure in 15 populations of oriental fruit fly from southern China, Laos and Myanmar in South‐east Asia was examined with a 640‐bp sequence of the mitochondrial cytochrome oxidase subunit I (COI) gene. The highest levels of genetic diversity were found in Laos and Myanmar. Low to medium levels of genetic differentiation (F_ST ≤ 0.134) were observed among populations. Pooled populations from mainland China differed from those in Laos and Myanmar (F_ST = 0.024). Genetic structure across the region did not follow the isolation‐by‐distance model. The high genetic diversity observed in Laos and Myanmar supports the South‐east Asian origin of B. dorsalis. High genetic diversity and significant differentiation between some populations within mainland China indicate B. dorsalis populations have been established in the region for an extended period of time. High levels of genetic diversity observed among the five populations from Hainan Island and similarity between the Island and Chinese mainland populations indicate that B. dorsalis was introduced to Hainan from the mainland and has been on the island for many years. High genetic diversity in the recently established population in Shanghai (Pudong) suggests multiple introductions or a larger number of founders.     

沿海地区应对气候变化和人口快速增长的韧性土地利用规划——以美国佛罗里达州马坦萨斯河流域为例

气候变化引起的海平面上升以及人口快速增长引起的土地利用变化为新时期全球沿海低洼地区的土地利用规划带来了新的挑战。有别于传统的土地利用规划理念与方法,引入韧性城市的概念,以美国佛罗里达州马坦萨斯河入海口地区应对气候变化和人口快速增长的韧性土地利用规划为例,通过构建基于地理信息系统的综合模型,整合海平面上升影响模型、物种栖息地模型和土地利用预测模型来预测适应海平面上升的土地利用规划方案。研究的结果可为中国沿海地区特别是三角洲地区应对气候变化提供借鉴。