East Asian Monsoon Signals Reflected in Temperature and Precipitation Changes over the Past 300 Years in the Middle and Lower Reaches of the Yangtze River

Based on observational data and Asian monsoon intensity datasets from China, the relationships between the East Asian winter monsoon index and winter temperature, the East Asian summer monsoon index and Meiyu precipitation over the middle and lower reaches of the Yangtze River, were analyzed. We found that the monsoon signals were reflected in the temperature and Meiyu precipitation variations. Thus, we used the reconstructed Meiyu precipitation and winter temperature series for the past 300 years and detected the summer/winter monsoon intensity signals using multi-taper spectral estimation method and wavelet analysis. The main periodicities of Meiyu precipitation and winter temperature, such as interannual cycle with 2–7-year, interdecadal-centennial cycles with 30–40-year and 50–100-year, were found. The good relationships between the East Asian summer and winter monsoons suggested that they were in phase at 31-year cycle, while out of phase at 100-year cycle, but with 20-year phase difference. In addition, the winter monsoon intensity may be regulated by the North Atlantic Oscillation, the Arctic Oscillation and the Atlantic Multidecadal Oscillation, and the summer monsoon is closely related to the signal intensities of the Pacific Decadal Oscillation.     

Anti-phase oscillation of Asian monsoons during the Younger Dryas period: Evidence from peat cellulose δC of Hani, Northeast China

Significant changes in the global atmospheric and oceanic circulation system occurred during the Younger Dryas cold period. Several researchers have demonstrated a weakening of intensity of the Indian Ocean Summer Monsoon during that period. However, the exact characteristics of the East Asian Summer Monsoon still remain vague. Here we present a late-glacial precipitation proxy record of the East Asian Summer Monsoon, based on the peat cellulose δ¹³C found in Hani, Northeast China. Both the peat cellulose record and a pollen record from Lake Sihailongwan sediment indicate an abrupt increase in precipitation in the region during the Younger Dryas period. These results support the occurrence of wet conditions in the north and of dry conditions in the south of the Chinese Mainland during that period. By examining the activity of the East Asian Summer Monsoon on an interannual timescale, we propose a theory for the anomalous precipitation distribution that we attribute to the occurrence of an El Niño-like phenomenon in the Equatorial Pacific Ocean during the Younger Dryas. In this case, the intensity of the Western Pacific subtropical high may strengthen, and its position over the western Pacific Ocean may move northward. This could cause an enhancement of the East Asian Summer Monsoon and migration of a monsoonal rainbelt towards the northern region of the Chinese mainland, resulting in a precipitation distribution of wet conditions in the north and dry conditions in the south. Therefore, this anomalous rainfall distribution should be considered to indicate the strengthening of the East Asian Summer Monsoon, in anti-phase with the Indian Ocean Summer monsoon that weakened during the same period. This agrees with the previously revealed anti-phase variations of the two monsoons during the ice-rafted debris cold events of the North Atlantic Ocean. It appears that, in relation to the abrupt temperature drop in the Northern Hemisphere on centennial to millennial time scales, anti-phase variations of the two Asian summer monsoons occurred.     

Approximate Bayesian analysis of Drosophila melanogaster polymorphism data reveals a recent colonization of Southeast Asia

Southeast Asian populations of the fruit fly Drosophila melanogaster differ from ancestral African and derived European populations by several morphological characteristics. It has been argued that this morphological differentiation could be the result of an early colonization of Southeast Asia that predated the migration of D. melanogaster to Europe after the last glacial period (around 10,000 years ago). To investigate the colonization process of Southeast Asia, we collected nucleotide polymorphism data for more than 200 X-linked fragments and 50 autosomal loci from a population of Malaysia. We analyzed this new single nucleotide polymorphism data set jointly with already existing data from an African and a European population by employing an Approximate Bayesian Computation approach. By contrasting different demographic models of these three populations, we do not find any evidence for an early divergence between the African and the Asian populations. Rather, we show that Asian and European populations of D. melanogaster share a non-African most recent common ancestor that existed about 2,500 years ago.     

Phylogenetic Position of Mammoth and Steller's Sea Cow Within Tethytheria Demonstrated by Mitochondrial DNA Sequences

Here we report DNA sequences from mitochondrial cytochrome b gene segments (1,005 base pairs per species) for the extinct woolly mammoth (Mammuthus primigenius) and Steller's sea cow (Hydrodamalis gigas) and the extant Asian elephant (Elephas maximus), the Western Indian manatee (Trichechus manatus), and the hyrax (Procavia capensis). These molecular data have allowed us to construct the phylogeny for the Tethytheria. Our molecular data resolve the trichotomy between the two species of living elephants and the mammoth and confirm that the mammoth was more closely related to the Asian elephant than to the African elephant. Our data also suggest that the sea cow–dugong divergence was likely as ancient as the dugong–manatee split, and it appears to have been much earlier (22 million years ago) than had been previously estimated (4–8 million years ago) by immunological comparison. Received: 8 August 1996 / Accepted: 30 September 1996     

Urgent call for further breeding of the relic zoo population of the critically endangered Barbary lion (Panthera leo leo Linnaeus 1758)

The Barbary lion became extinct in the wild around 1942. Since the end of the 19th century, a last purebred captive breeding stock existed at the court of Morocco. The rest of these animals became the core exhibition of the new Rabat Zoo after passing through repeated bottlenecks and possibly some introgression events by foreign lions. This study uses mitochondrial DNA sequencing data to clarify the relationship among these lions and their sub-Saharan and Asian relatives. We analysed mitochondrial cytochrome b sequences obtained from a sample from a Barbary lion descended from a young female of the Barbary lion breeding group at the Rabat Zoo and various other members of the genus Panthera. In our cytochrome-b-based phylogenetic tree, the North African Barbary lion, represented by a biopsy sample from the Neuwied Zoo, joins the Asian lion clade, although it is slightly different from its Asian sister group. However, it is clearly distinct from sub-Saharan lions and can be considered as a genetically defined phylogeographic group of its own. Molecular dating of the extant sub-Saharan and Asian lion groups shows that the split between North African Barbary lions and Asian lions must be considerably more recent than 74–203 kilo years ago.     

Conservation Implications of Rapid Shifts in the Trade of Wild African and Asian Pythons

Pythons are harvested for the international leather industry and pet trade. We analyzed the CITES export records (1999–2008) of the most intensively commercialized wild pythons (Python regius, Python sebae, Python reticulatus, Python molurus, Python curtus species complex) from African and Asian countries where reliable data on trade rates and ecology are available. Mean declared annual numbers of exported pythons were 30,000 in five African countries and 164,000 in Indonesia. Trade intensity tripled in Indonesia over the last decade, but declined in Africa. African international trade is exclusively associated with the pet market (mainly United States and Europe), whereas Asian pythons are sold mostly for luxury leather, albeit more recently also for the pet trade. A negative correlation between the annual numbers of pythons traded in Africa vs. Asia suggests a rapid and recent shift of the pressure exerted on wild populations in the two main exporting continents. We also found a strong effect of the currency exchange rate (i.e., U.S.$/€, the currencies used by the major importing countries) on African python exports: when the cost per African python increased, importers relied increasingly on Asian providers for pet trade. Overall, our data indicate that Asian pythons (especially P. reticulatus) might be threatened due to the rapidly increasing pressure, whereas the decreasing international trade in African pythons is likely more sustainable.     

Discovery and genetic assessment of wild bottle Gourd [Lagenaria siceraria (Mol.) Standley; Cucurbitaceae] from Zimbabwe

Bottle gourd /Lagenaria siceraria (Mol.) Standley] is an edible, medicinal, and otherwise utilitarian domesticated cucurbit with an ancient pantropical distribution. This African native reached Asia and the Americas 9000 years ago, probably as a wild species whose fruits had floated across the seas. Independent domestications from wild populations are believed to have occurred in both the Old and New Worlds. However, few wild populations of L. siceraria have been found during recorded history and none has been verified or studied in detail. In 1992, Mary Wilkins-Ellert discovered an unusual free-living plant of Lagenaria in a remote region of southeastern Zimbabwe. Her morphological observations during several plantings of the collected seed, as well as results from two genetic analyses (random amplified polymorphic DNA and chloroplast sequencing), indicate that the Zimbabwe collection is part of a genetically distinct and wild lineage ofL. siceraria.     

西北地区降水稳定同位素的云下二次蒸发效应

利用GNIP提供的我国西北地区的8个站点和本研究的2个站点的降水同位素数据以及相应的气象数据,结合HYSPLIT模型和水滴蒸发模型,分析了我国西北地区降水δ¹⁸O和d的时空分布,对该区二次蒸发效应进行了存在性判定与定量讨论,并探讨了二次蒸发效应的敏感因子.结果表明: 夏季风期间,新疆地区δ¹⁸O和d值由南向北均走低,陕甘宁地区由南向北,由东向西δ¹⁸O值整体上升,d值呈现下降趋势;冬季风期间,西北地区由南到北,由东向西δ¹⁸O值整体上逐渐减小,新疆地区d值由南向北升高,陕甘宁地区由南向北d值呈现下降趋势,由东向西有微弱的增大.我国西北地区夏季风时期的大气降水线的斜率、截距(6.80,-0.07)显著低于研究区全年的大气降水线方程的斜率、截距(7.27,3.37)和冬季风时期的大气降水线的斜率、截距(7.46,6.07),表明夏季风期间二次蒸发作用较强.研究区夏季风时期的蒸发比率均值为4.49%,高于冬季风时的3.65%,而黄土高原周边站点冬季风时期的蒸发比率高于夏季风时期,这与黄土高原近年来干旱加剧密不可分.另外,二次蒸发作用的强度随相对湿度、降水量和水汽压的增大而减弱,随温度(大于0 ℃)的升高而增强,但各因子在不同范围时对二次蒸发作用的影响有差异.     

Climate Dynamics: A Network-Based Approach for the Analysis of Global Precipitation

Precipitation is one of the most important meteorological variables for defining the climate dynamics, but the spatial patterns of precipitation have not been fully investigated yet. The complex network theory, which provides a robust tool to investigate the statistical interdependence of many interacting elements, is used here to analyze the spatial dynamics of annual precipitation over seventy years (1941–2010). The precipitation network is built associating a node to a geographical region, which has a temporal distribution of precipitation, and identifying possible links among nodes through the correlation function.The precipitation network reveals significant spatial variability with barely connected regions, as Eastern China and Japan, and highly connected regions, such as the African Sahel, Eastern Australia and, to a lesser extent, Northern Europe. Sahel and Eastern Australia are remarkably dry regions, where low amounts of rainfall are uniformly distributed on continental scales and small-scale extreme events are rare. As a consequence, the precipitation gradient is low, making these regions well connected on a large spatial scale. On the contrary, the Asiatic South-East is often reached by extreme events such as monsoons, tropical cyclones and heat waves, which can all contribute to reduce the correlation to the short-range scale only.Some patterns emerging between mid-latitude and tropical regions suggest a possible impact of the propagation of planetary waves on precipitation at a global scale. Other links can be qualitatively associated to the atmospheric and oceanic circulation. To analyze the sensitivity of the network to the physical closeness of the nodes, short-term connections are broken. The African Sahel, Eastern Australia and Northern Europe regions again appear as the supernodes of the network, confirming furthermore their long-range connection structure. Almost all North-American and Asian nodes vanish, revealing that extreme events can enhance high precipitation gradients, leading to a systematic absence of long-range patterns.     

Genetic Evidence of Postglacial Population Expansion in Puget Sound Rockfish (Sebastes emphaeus)

Several rockfish species (genus Sebastes) along the northeastern Pacific Ocean have rapidly declined in abundance owing in part to overfishing. A striking exception is the dwarf-like Puget Sound rockfish Sebastes emphaeus, whose densities have increased by several orders of magnitude over the last several decades. To describe their genetic structure, we sequenced 395 bp from the mitochondrial control region of 128 S. emphaeus adults from 5 locations spanning approximately 120 km of the Northwest Straits of Washington state. We detected no significant genetic differentiation among these populations and substantial genetic variation within populations, a pattern that may indicate high levels of ongoing gene flow. Preliminary data from 2 microsatellite loci are also consistent with panmixia. The mtDNA sequences also suggest that Puget Sound rockfish populations have expanded substantially since the retreat of Pleistocene glaciers made habitat in Puget Sound region available approximately 12,000 years ago.     

Changing patterns of the East Asian monsoon drive shifts in migration and abundance of a globally important rice pest

Numerous insects including pests and beneficial species undertake windborne migrations over hundreds of kilometers. In East Asia, climate-induced changes in large-scale atmospheric circulation systems are affecting wind-fields and precipitation zones and these, in turn, are changing migration patterns. We examined the consequences in a serious rice pest, the brown planthopper (BPH, Nilaparvata lugens) in East China. BPH cannot overwinter in temperate East Asia, and infestations there are initiated by several waves of windborne spring or summer migrants originating from tropical areas in Indochina. The East Asian summer monsoon, characterized by abundant rainfall and southerly winds, is of critical importance for these northward movements. We analyzed a 42-year dataset of meteorological parameters and catches of BPH from a standardized network of 341 light-traps in South and East China. We show that south of the Yangtze River during summer, southwesterly winds have weakened and rainfall increased, while the summer precipitation has decreased further north on the Jianghuai Plain. Together, these changes have resulted in shorter migratory journeys for BPH leaving South China. As a result, pest outbreaks of BPH in the key rice-growing area of the Lower Yangtze River Valley (LYRV) have declined since 2001. We show that these changes to the East Asian summer monsoon weather parameters are driven by shifts in the position and intensity of the Western Pacific subtropical high (WPSH) system that have occurred during the last 20 years. As a result, the relationship between WPSH intensity and BPH immigration that was previously used to predict the size of the immigration to the LYRV has now broken down. Our results demonstrate that migration patterns of a serious rice pest have shifted in response to the climate-induced changes in precipitation and wind pattern, with significant consequences for the population management of migratory pests.     

Indian Siddis: African descendants with Indian admixture

The Siddis (Afro-Indians) are a tribal population whose members live in coastal Karnataka, Gujarat, and in some parts of Andhra Pradesh. Historical records indicate that the Portuguese brought the Siddis to India from Africa about 300-500 years ago; however, there is little information about their more precise ancestral origins. Here, we perform a genome-wide survey to understand the population history of the Siddis. Using hundreds of thousands of autosomal markers, we show that they have inherited ancestry from Africans, Indians, and possibly Europeans (Portuguese). Additionally, analyses of the uniparental (Y-chromosomal and mitochondrial DNA) markers indicate that the Siddis trace their ancestry to Bantu speakers from sub-Saharan Africa. We estimate that the admixture between the African ancestors of the Siddis and neighboring South Asian groups probably occurred in the past eight generations (～200 years ago), consistent with historical records.     

A 9,000 Year History of Seal Hunting on Lake Baikal,Siberia: The Zooarchaeology of Sagan-Zaba II

Sagan-Zaba II, a habitation site on the shore of Siberia’s Lake Baikal, contains a record of seal hunting that spans much of the Holocene, making it one of the longest histories of seal use in North Asia. Zooarchaeological analyses of the 16,000 Baikal seal remains from this well-dated site clearly show that sealing began here at least 9000 calendar years ago. The use of these animals at Sagan-Zaba appears to have peaked in the Middle Holocene, when foragers used the site as a spring hunting and processing location for yearling and juvenile seals taken on the lake ice. After 4800 years ago, seal use declined at the site, while the relative importance of ungulate hunting and fishing increased. Pastoralists began occupying Sagan-Zaba at some point during the Late Holocene, and these groups too utilized the lake’s seals. Domesticated animals are increasingly common after about 2000 years ago, a pattern seen elsewhere in the region, but spring and some summer hunting of seals was still occurring. This use of seals by prehistoric herders mirrors patterns of seal use among the region’s historic and modern groups. Overall, the data presented in the paper demonstrate that Lake Baikal witnessed thousands of years of human use of aquatic resources.     

Summer monsoon precipitation variations in central China over the past 750 years derived from a high-resolution absolute-dated stalagmite

A 2–3-year resolution record of stalagmite oxygen isotope variations from the south flank of the Qinling Mountains, central China, has revealed the Asian summer monsoon (ASM) precipitation variations in the investigated area over the past 750 years. The summer monsoon precipitation gradually increased since 1249 AD, reaching its highest values in the period 1535–1685 AD, and then decreased with substantial decadal- to centennial-scale fluctuations. The monsoon precipitation increased again between 1920 and 1970 AD. Three intervals of high monsoon precipitation were identified: 1535–1685 AD, 1755–1835 AD, and 1920–1970 AD. Three intervals of low precipitation were inferred in 1249–1325 AD, 1390–1420 AD, and 1890–1915 AD. The δ¹⁸O composition and lithological features of the stalagmite coincidently indicate a wetter climate during the Little Ice Age (LIA), which is also confirmed by climate records from Chinese historical documents within this area. A comparison with other high-resolution speleothem records indicates regional differences in monsoon precipitation variability from the south to the north of central China in the last 750 years on decadal- to centennial-scale. Power spectrum analysis of the δ¹⁸O record shows significant 117.8-, 34.6-, 14-, 10.3-, and ~ 6-year periodicities. These periodicities are widely observed in the climate records from ASM-controlled areas of China and are consistent with the Gleissburg periodicity, Brϋckner periodicity, sunspot periodicity of solar activity, and El Nińo–Southern Oscillation (ENSO) periodicity. These correlations suggest that both solar activity and ENSO periodicity may have had important influences on ASM precipitation in China over the past 750 years.     

Calculation of longevity and life expectancy in captive elephants

The concepts of longevity (longest lived) and life expectancy (typical age at death) are common demographic parameters that provide insight into a population. Defined as the longest lived individual, longevity is easily calculated but is not representative, as only one individual will live to this extreme. Longevity records for North American Asian elephants (Elephas maximus) and African elephants (Loxodonta africana) have not yet been set, as the oldest individuals (77 and 53 years, respectively) are still alive. One Asian elephant lived to 86 years in the Taipei Zoo. This is comparable to the maximum (though not typical) longevity estimated in wild populations. Calculation of life expectancy, however, must use statistics that are appropriate for the data available, the distribution of the data, and the species' biology. Using a simple arithmetic mean to describe the non‐normally distributed age at death for elephant populations underestimates life expectancy. Use of life‐table analysis to estimate median survivorship or survival analysis to estimate average survivorship are more appropriate for the species' biology and the data available, and provide more accurate estimates. Using a life‐table, the median life expectancy for female Asian elephants (Lx=0.50) is 35.9 years in North America and 41.9 years in Europe. Survival analysis estimates of average life expectancy for Asian elephants are 47.6 years in Europe and 44.8 years in North America. Survival analysis estimates for African elephants are less robust due to less data. Currently the African elephant average life expectancy estimate in North America is 33.0 years, but this is likely to increase with more data, as it has over the past 10 years. Zoo Biol 23:365–373, 2004. © 2004 Wiley‐Liss, Inc.     

Uncovering the tracks of a recent and rapid invasion: the case of the fruit fly pest Bactrocera invadens (Diptera: Tephritidae) in Africa

Phytophagous insects of the genus Bactrocera are among the most economically important invasive fruit fly pests. In 2003, an unknown Bactrocera species was found in Kenya. First identified as an ‘aberrant form’ of the Asian B. dorsalis complex, it was later recognized as a new species, Bactrocera invadens. Within 2 years of its discovery, the species was recorded in several African countries, becoming an important quarantine pest. As this invasive fly was discovered only recently, no data are available on its invasion pattern in Africa. This pilot study attempts to infer from genetic data the dynamic aspects of the African invasion of this pest. Using microsatellite markers, we evaluated the level of genetic diversity and the extent of common ancestry among several African populations collected across the invaded areas. A sample from the Asian Sri Lankan population was analysed to confirm the Asian origin of this pest. Genetic data cast no doubt that Sri Lanka belongs to the native range, but only a small percentage of its genotypes can be found in Africa. African populations display relatively high levels of genetic diversity associated with limited geographical structure and no genetic footprints of bottlenecks. These features are indicative of processes of rapid population growth and expansion with possible multiple introductions. In the span of relatively few years, the African invasion registered the presence of at least two uncorrelated outbreaks, both starting from the East. The results of the analyses support that invasion started in East Africa, where B. invadens was initially isolated.     

Detection and characterization of the African citrus greening Liberobacter by amplification,cloning, and sequencing of the rplKAJL-rpoBC operon

Greening disease of citrus is caused by a phloem-restricted, uncultured bacterium, recently characterized and named Liberobacter. As shown previously, a probe encoding ribosomal protein genes (rplKAJL-rpoBC operon) from an Asian liberobacter could detect all Asian liberobacter strains tested, but not African strains. Using the sequence of the rplKAJL-rpoBC operon of the Asian liberobacter strain from Poona (India), we have defined primers for PCR amplification of the equivalent genes of an African liberobacter strain. The amplified fragment was cloned in pUC18 and successfully used as a probe to detect African liberobacter strains by Southern and dot hybridizations. Sequence comparisons of the African and Asian liberobacter operons indicate that they represent two different species in the proposed genus Liberobacter.     

Mitochondrial genetic variation in European, African and Indian cattle populations

Mitochondrial DNA from representative animals of 13 different cattle breeds was assayed for restriction fragment length polymorphisms (RFLP) to determine phylogenetic relationships and levels of variation among breeds; 16 different mitotypes were found, described by 20 polymorphisms. Within these 16 mitotypes two major lineages were apparent: an Afro-European and an Asian type. These were found to differ at over 2.3% of sites surveyed. None of the mitotypes found in the Asian lineage was detectable in the Afro-European lineage and vice versa. Within each of the major mitotypes there were no further significant differences within or among breeds. Using rates of mitochondrial evolution estimated from other species, the two lineages were estimated to have diverged between 575000 and 1150000 years ago; well outside the 10000 years bp timeframe postulated by a single domestication hypothesis. The results presented are concordant with those generated in other studies and provide strong evidence for an independent domestication of Asian Bos indicus. Furthermore, the grouping of all African indicine populations within the clade containing all Bos taurus lineages points to the hybrid origins of the humped cattle of that continent.     

Global invasion history of the Mediterranean recluse spider: a concordance with human expansion

The dispersal of modern humans from their African origins to the rest of the occupied world is a topic of lively debate centering principally on single versus multiple dispersals. The Mediterranean recluse spider Loxosceles rufescens, a significant pest, has gained much of its current distribution through commensalism with humans. Therefore, the matrilineal history of this spider should reflect dispersal patterns of human females. Here, an assessment of genetic variation at mitochondrial markers in 347 colonies of L. rufescens from 104 geographic sites worldwide reveals a north African origin of the global populations of L. rufescens. This involves at least three separate events among which two involve coincidental dispersals, including one to north Africa, Europe, Asia, North America, and Australia and the other to north Africa, Europe, and Asia only. North African L. rufescens appear to have expanded initially into Israel and subsequently spread into Greece, where a subset of these populations went eastward into Iran and southeastern Asia. This corresponds to the modern human southern dispersal theory. Chinese populations appear to have expanded approximately 42 710–46 008 yr ago. The initial split between the Greek and Chinese populations dates to 41 412–44 444 yr ago, which coincides with the expansion of modern humans into Southeast and East Asia. Thus, the matrilineal history of Asian L. rufescens tracks the history of human dispersals over tens of thousands of years.     

Chromosome Painting Shows That Pygathrix nemaeus Has the Most Basal Karyotype Among Asian Colobinae

We mapped the chromosomal homology of Pygathrix namaeus (douc) with human and other primates by in situ hybridization of human chromosome paints. The synteny of 3 human chromosomes (1, 2, 19) is fragmented in the douc karyotype and the 23 human probes (autosomes plus X) provided 26 signals. There are associations between human chromosomes 14/15, 21/22, and 1/19. Human chromosomes 1 and 19 are divided in two segments and associated on douc chromosomes 8 and 10. The fragmentation and association of human chromosomes 1 and 19 is best explained as the result of a reciprocal translocation, which occurs in all documented Asian colobines studied, but not in the African species Colobus guereza. However, the homologs to douc chromosome 10 in all other Asian documented colobines show an additional pericentric inversion. Our results indicate that Pygathrix nemeus is karyologically the most conservative colobine species yet studied and that this species probably diverged early after the separation of Asian and African Colobinae. The data reinforce the monophyly of the Colobinae and their division into an African and an Asian clade.