针对热带树种陆均松Dacrydium pierrei de Laubenfels分布在海南的12个天然种群进行取样,测定了叶绿体DNA(cpDNA)trnL-F非编码区序列。序列长度介于868—876 bp.显示出长度多态性。碱基组成A+T含量较高,百分比值为64.17%-64.95%。通过...针对热带树种陆均松Dacrydium pierrei de Laubenfels分布在海南的12个天然种群进行取样,测定了叶绿体DNA(cpDNA)trnL-F非编码区序列。序列长度介于868—876 bp.显示出长度多态性。碱基组成A+T含量较高,百分比值为64.17%-64.95%。通过统计简约算法共鉴定出30个单倍型。根据种群间分化度FST(=0.00)、基因流Nm(介于1.92—2.50)、AMOVA(24.17%的遗传变异发生在种群间,P>0.05)以及邻接树中单倍型的分支式样,发现海南的陆均松种群尚未发生遗传分化。另一方面,依统计简约算法构建的单倍型网图具“星状”特征,而且邻接树中多数单倍型合并于树的顶端。这些基因谱系结果提示海南陆均松种群在近期历史上发生过种群扩张。Tajima的D检验和错配分析结果也支持这种推测。结合地质和古孢粉学证据,认为残存于“避难所”的陆均松种群在全新世时,伴随全球气候转暖,在海南岛内可能实行了扩张。展开更多
Insects are ectotherms and their ability to resist temperature stress is limited. The immediate effects of sub-lethal heat stress on insects are well documented, but longer- term effects of such stresses are rarely re...Insects are ectotherms and their ability to resist temperature stress is limited. The immediate effects of sub-lethal heat stress on insects are well documented, but longer- term effects of such stresses are rarely reported. In this study, survival, development and reproduction of the whitefly, Bemisia tabaci （Gennadius） （Hemiptera： Aleyrodidae） biotype B, were compared over five consecutive generations at 27, 31 and 35℃ and for one generation at 37 ℃. Both temperature and generation significantly affected the fitness of the whitefly. These impacts were more dramatic with increasing generations and temperatures. Among the experimental temperatures, the most favorable for development and reproduction were 27 ℃ and 31 ℃. At 27 ℃, survival, development and fecundity were all stable over these five generations. At 31 ℃, immature survival rate was the highest in the fifth generation, but female fecundities decreased in the fourth and fifth generations. At 35 ℃, egg hatching rate, immature survival rate and female fecundity decreased significantly in the fourth and fifth generations. At 37 ℃, survival ofB. tabaci was not adversely affected, but female fecundity at 37 ℃ was less than 10% of that at 27 ℃ or 31 ℃. These results demonstrate that the lethal high temperature for B. tabaci is over 37 ℃, and the whitefly population continued expanding in the five generations at 35 ℃. The ability orB. tabaci biotype B to survive high temperature stress will play an important role in its population extension under global warming.展开更多
The melon fruit fly, Bactrocera cucurbitae （Coquillett） （Diptera： Tephritidae）, has been the subject of worldwide quarantine and management efforts due to its widespread agricultural impact and potential for rapi...The melon fruit fly, Bactrocera cucurbitae （Coquillett） （Diptera： Tephritidae）, has been the subject of worldwide quarantine and management efforts due to its widespread agricultural impact and potential for rapid range expansion. From its presumed native distribution in India, this species has spread throughout the hot-humid regions of the world. We provide information that reveals population structure, invasion history and population connectivity from 23 locations covering nine countries based on DNA sequences of the mitochondrial cytochrome oxidase I （COI） gene. Forty-two polymorphic sites were described among 38 haplotypes. The most common haplotype, H1, was observed in 73% of the samples distributed among all populations. Highest genetic diversity was seen within populations, and no isolation-by-distance was detected. The western regions （Nepal, Bangladesh, Thailand, Burma and China-west） showed higher haplotype diversity than eastern regions （China-east）. China-Yunnan showed highest levels of genetic diversity in China. Haplotype diversity decreased with longitude from west to east. Together, these analyses suggest that B. cueurbitae has expanded from west to east within a limited geographic scale and recently invaded China through Yunnan Province.展开更多
文摘针对热带树种陆均松Dacrydium pierrei de Laubenfels分布在海南的12个天然种群进行取样,测定了叶绿体DNA(cpDNA)trnL-F非编码区序列。序列长度介于868—876 bp.显示出长度多态性。碱基组成A+T含量较高,百分比值为64.17%-64.95%。通过统计简约算法共鉴定出30个单倍型。根据种群间分化度FST(=0.00)、基因流Nm(介于1.92—2.50)、AMOVA(24.17%的遗传变异发生在种群间,P>0.05)以及邻接树中单倍型的分支式样,发现海南的陆均松种群尚未发生遗传分化。另一方面,依统计简约算法构建的单倍型网图具“星状”特征,而且邻接树中多数单倍型合并于树的顶端。这些基因谱系结果提示海南陆均松种群在近期历史上发生过种群扩张。Tajima的D检验和错配分析结果也支持这种推测。结合地质和古孢粉学证据,认为残存于“避难所”的陆均松种群在全新世时,伴随全球气候转暖,在海南岛内可能实行了扩张。
文摘Insects are ectotherms and their ability to resist temperature stress is limited. The immediate effects of sub-lethal heat stress on insects are well documented, but longer- term effects of such stresses are rarely reported. In this study, survival, development and reproduction of the whitefly, Bemisia tabaci （Gennadius） （Hemiptera： Aleyrodidae） biotype B, were compared over five consecutive generations at 27, 31 and 35℃ and for one generation at 37 ℃. Both temperature and generation significantly affected the fitness of the whitefly. These impacts were more dramatic with increasing generations and temperatures. Among the experimental temperatures, the most favorable for development and reproduction were 27 ℃ and 31 ℃. At 27 ℃, survival, development and fecundity were all stable over these five generations. At 31 ℃, immature survival rate was the highest in the fifth generation, but female fecundities decreased in the fourth and fifth generations. At 35 ℃, egg hatching rate, immature survival rate and female fecundity decreased significantly in the fourth and fifth generations. At 37 ℃, survival ofB. tabaci was not adversely affected, but female fecundity at 37 ℃ was less than 10% of that at 27 ℃ or 31 ℃. These results demonstrate that the lethal high temperature for B. tabaci is over 37 ℃, and the whitefly population continued expanding in the five generations at 35 ℃. The ability orB. tabaci biotype B to survive high temperature stress will play an important role in its population extension under global warming.
文摘The melon fruit fly, Bactrocera cucurbitae （Coquillett） （Diptera： Tephritidae）, has been the subject of worldwide quarantine and management efforts due to its widespread agricultural impact and potential for rapid range expansion. From its presumed native distribution in India, this species has spread throughout the hot-humid regions of the world. We provide information that reveals population structure, invasion history and population connectivity from 23 locations covering nine countries based on DNA sequences of the mitochondrial cytochrome oxidase I （COI） gene. Forty-two polymorphic sites were described among 38 haplotypes. The most common haplotype, H1, was observed in 73% of the samples distributed among all populations. Highest genetic diversity was seen within populations, and no isolation-by-distance was detected. The western regions （Nepal, Bangladesh, Thailand, Burma and China-west） showed higher haplotype diversity than eastern regions （China-east）. China-Yunnan showed highest levels of genetic diversity in China. Haplotype diversity decreased with longitude from west to east. Together, these analyses suggest that B. cueurbitae has expanded from west to east within a limited geographic scale and recently invaded China through Yunnan Province.
