Phylogeography and Sex-Biased Dispersal across Riverine Manatee Populations (Trichechus inunguis and Trichechus manatus) in South America

Phylogeographic patterns and sex-biased dispersal were studied in riverine populations of West Indian (Trichechus manatus) and Amazonian manatees (T. inunguis) in South America, using 410bp D-loop (Control Region, Mitochondrial DNA) sequences and 15 nuclear microsatellite loci. This multi-locus approach was key to disentangle complex patterns of gene flow among populations. D-loop analyses revealed population structuring among all Colombian rivers for T. manatus, while microsatellite data suggested no structure. Two main populations of T. inunguis separating the Colombian and Peruvian Amazon were supported by analysis of the D-loop and microsatellite data. Overall, we provide molecular evidence for differences in dispersal patterns between sexes, demonstrating male-biased gene flow dispersal in riverine manatees. These results are in contrast with previously reported levels of population structure shown by microsatellite data in marine manatee populations, revealing low habitat restrictions to gene flow in riverine habitats, and more significant dispersal limitations for males in marine environments.     

Dispersal Behavior and the Connectivity Between Wolf Populations in Northern Europe

ABSTRACT The isolated gray wolf (Canis lupus) population of the Scandinavian Peninsular is suffering from inbreeding depression. We studied dispersal of 35 wolves fitted with very high frequency (20) or Global Positioning System—global system for mobile (15) radiocollars in the neighboring Finnish wolf population. The growing wolf population in Finland has high numbers of dispersing individuals that could potentially disperse into the Scandinavian population. About half (53%) of the dispersing wolves moved total distances that could have reached the Scandinavian population if they had been straight-line moves, but because of the irregular pattern of movements, we detected no wolves successfully dispersing to the Scandinavian population. Dispersal to the Scandinavian population was also limited by high mortality of wolves in reindeer (Rangifer tarandus) management areas and by dispersal to Bothnian Bay at times of the year when ice was not present. We suggest that when a small wolf population is separated from source populations by distance, barriers, and human exploitation, wildlife managers could promote the population's viability by limiting harvest in the peripheral areas or by introducing wolves from the source population.     

Dispersal and distribution in Leopoldinia (Palmae)

The Amazon palm genus Leopoldinia exemplifies the transition from a terrestrial to an amphibious life-style, accompanied by a switch from synzoochorous dispersal to hydrochory. Leopoldinia piassaba produces heavy fruits with a fleshy, sweet mesocarp and is presumed to be dispersed by terrestrial animals. This species enters aquatic habitats only so far as these are submersed for a short while. The other two species, L. major and L. pulchra , resist long-lasting submersion and have much smaller, buoyant fruits, which are dispersed by water and are produced in proportionately larger guantities. They are eaten and mostly destroyed, but occasionally probably also dispersed by fish. L. pulchra , the species with the smallest fruits, has acquired the widest geographical distribution.     

Dispersal Pathways and Genetic Differentiation among Worldwide Populations of the Invasive Weed Centaurea solstitialis L. (Asteraceae)

The natural history of introduced species is often unclear due to a lack of historical records. Even when historical information is readily available, important factors of the invasions such as genetic bottlenecks, hybridization, historical relationships among populations and adaptive changes are left unknown. In this study, we developed a set of nuclear, simple sequence repeat markers and used these to characterize the genetic diversity and population structure among native (Eurasian) and non-native (North and South American) populations of Centaurea solstitialis L., (yellow starthistle). We used these data to test hypotheses about the invasion pathways of the species that were based on historical and geographical records, and we make inferences about historical relationships among populations and demographic processes following invasion. We confirm that the center of diversity and the native range of the species is likely the eastern Mediterranean region in the vicinity of Turkey. From this region, the species likely proceeded to colonize other parts of Europe and Asia via a slow, stepwise range expansion. Spanish populations were the primary source of seed to invade South America via human-mediated events, as was evident from historical records, but populations from the eastern Mediterranean region were also important. North American populations were largely derived from South America, but had secondary contributors. We suggest that the introduction history of non-native populations from disparate parts of the native range have allowed not just one, but multiple opportunities first in South America then again in North America for the creation of novel genotypes via intraspecific hybridization. We propose that multiple intraspecific hybridization events may have created especially potent conditions for the selection of a noxious invader, and may explain differences in genetic patterns among North and South America populations, inferred differences in demographic processes, as well as morphological differences previously reported from common garden experiments.     

Patterns of Variation in the Rdna Cistron within and among World Populations of a Mosquito, Aedes Albopictus (Skuse)

A restriction map was constructed of the ribosomal cistron in a mosquito, Aedes albopictus (Skuse). The 18s, 28s and nontranscribed spacer (NTS) regions were subcloned and used to probe for intraspecific variation. Seventeen populations were examined throughout the world range of the species. No variation was detected in the coding regions but extensive and continuous variation existed in the NTS. The NTS consisted of two nonhomologous regions. The first region contained multiple 190-bp AluI repeats nested within larger XhoI repeats of various sizes. There was a large number of length variants in the AluI repeat region of the NTS. No repeats were found in the second region and it gave rise to relatively fewer variants. An analysis of NTS diversity in individual mosquitoes indicated that most of the diversity arose at the population level. Discriminant analysis was performed on spacer types in individual mosquitoes and demonstrated that individuals within a population carried a unique set of spacers. In contrast with studies of the NTS in Drosophila populations, there seems to be little conservation of spacers in a population. The importance of molecular drive relative to drift and selection in the generation of local population differentiation is discussed.     

Population Dynamic and Genetic Consequences of Spatial Density-Dependent Dispersal in Patchy Populations

Predictions about sex-specific, spatial density-dependent dispersal and their demographic and genetic consequences were tested in experimental populations of root voles (Microtus oeconomus). Each population consisted of two demes inhabiting equal-sized habitat patches imbedded in a barren matrix area. We used a neutral two-allele allozyme marker to monitor gene flow. Initially, the two demes were genetically distinct and had different densities so that the size of a high-density deme (genotype bb) was four times larger than that of a low-density deme (genotype aa). The sex-specific dispersal pattern was in accordance with our prediction. Male dispersal was unconditional on deme-specific densities, and the majority of the first-generation males became dispersed from both demes, whereas female dispersal was strongly density dependent, so that dispersal took place exclusively from the high-density to the low-density deme. The demographic implication of this dispersal pattern was that the initial density difference between the demes was quickly canceled out. We built a mathematical model that predicted that the initially rare allele (a) would increase in frequency given the dispersal pattern, and this was supported by our experimental data. This result relies mostly on the density-independent male-dispersal strategy, which presumably stems from inbreeding avoidance. Our study highlights the importance of incorporating sex-specific dispersal strategies in population genetic models. Sex-biased dispersal may act as a deterministic force counteracting the tendency for stochastic loss of alleles in small and fragmented populations.     

Dynamics of Baculovirus Growth and Dispersal in Mamestra brassicae L. (LepidopteraNoctuidae) Larval Populations Introduced into Small Cabbage Plots

The nuclear polyhedrosis virus of Mamestra brassicae has been studied in larval populations of the moth introduced into small plots of cabbages. Primary dispersal of virus from single foci of infected larvae resulted from enhanced movement of the larvae, which colonized new plants logarithmically. Virus growth within the host population was quantified, and infection of young larvae in the following generation was related directly to the concentration of virus produced during the primary phase. Secondary cycling of virus resulted in dispersal of inoculum from multiple foci, and a large proportion of plants were ultimately colonized by infected larvae. The dynamics of virus growth during secondary dispersal were quantified and contrasted with results from the primary phase. The significance of these results is discussed in relation to possible control of insect pests through dispersal of virus by the host insect.     

Journal of Mosquito Research(JMR)

正Journal of Mosquito Research(ISSN 1927-646X)is an open access,peer reviewed journal published online by Bio Publisher.The journal is publishing high quality original research on all aspects of mosquito and its affecting the living organisms,as well as environmental risk and public policy relevant to mosquito modified     

Journal of Mosquito Research(JMR)

正Journal of Mosquito Research(ISSN 1927-646X)is an open access,peer reviewed journal published online by Bio Publisher.The journal is publishing high quality original research on all aspects of mosquito and its affecting the living organisms,as well as environmental risk and public policy relevant to mosquito modified     

Journal of Mosquito Research(JMR)

正Journal of Mosquito Research(ISSN 1927-646X)is an open access,peer reviewed journal published online by Bio Publisher.The journal is publishing high quality original research on all aspects of mosquito and its affecting the living organisms,as well as environmental risk and public policy relevant to mosquito modified     

Journal of Mosquito Research(JMR)

正Journal of Mosquito Research(ISSN 1927-646X)is an open access,peer reviewed journal published online by Bio Publisher.The journal is publishing high quality original research on all aspects of mosquito and its affecting the living organisms,as well as environmental risk and public policy relevant to mosquito modified organisms.Topics include(but are not limited to)the research at molecular or protein     

Journal of Mosquito Research(JMR)

正Journal of Mosquito Research (ISSN 1927-646X) is an open access,peer reviewed journal published online by Bio Publisher.The journal is publishing high quality original research on all aspects of mosquito and its affecting the living organisms,as well as environmental risk and public policy relevant to mosquito modified organisms.Topics include(but are not limited to)the research at molecular or protein     

Journal of Mosquito Research(JMR)

正Journal of Mosquito Research (ISSN 1927-646X) is an open access, peer reviewed journal published online by Bio Publisher. The journal is publishing high quality original research on all aspects of mosquito and its affecting the living organisms,as well as environmental risk and public policy relevant to mosquito modified organisms. Topics include (but are not limited to) the research at molecular or protein     

Journal of Mosquito Research(JMR)

正Journal of Mosquito Research(ISSN 1927-646X)is an open access,peer reviewed journal published online by Bio Publisher.The journal is publishing high quality original research on all aspects of mosquito and its affecting the living organisms,as well as environmental risk and public policy relevant to mosquito modified organisms.Topics include(but are not limited to)the research at molecular or protein     

Journal of Mosquito Research(JMR)

正Journal of Mosquito Research(ISSN 1927-646X)is an open access,peer reviewed journal published online by Bio Publisher.The journal is publishing high quality original research on all aspects of mosquito and its affecting the living organisms,as well as environmental risk and public policy relevant to mosquito modified     

Journal of Mosquito Research(JMR)

正Journal of Mosquito Research(ISSN 1927-646X)is an open access,peer reviewed journal published online by Bio Publisher.The journal is publishing high quality original research on all aspects of mosquito and its affecting the living organisms,as well as environmental risk and public policy relevant to mosquito modified organisms.Topics include(but are not limited to)the research at molecular or protein     

Journal of Mosquito Research(JMR)

正Journal of Mosquito Research(ISSN 1927-646X)is an open access,peer reviewed journal published online by Bio Publisher.The journal is publishing high quality original research on all aspects of mosquito and its affecting the living organisms,as well as environmental risk and public policy relevant to mosquito modified organisms.Topics include(but are not limited to)the research at molecular or protein