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Xu M.,Chinese Academy of Fishery Sciences | Xu M.,Key Laboratory of Tropical and Subtropical Fishery Resource Application and Cultivation | Luo D.,Chinese Academy of Fishery Sciences | Luo D.,Key Laboratory of Tropical and Subtropical Fishery Resource Application and Cultivation | And 9 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2015

There is increasing recognition that spatial scale(s), in terms of ecological processes, are critical to construct general ecological predictions. Ecological processes act at a variety of spatial and temporal scales and the variation of scale may lead to changes in ecological patterns. To understand a particular ecosystem, it is important to study the system at the appropriate scale(s), and to develop models that bridge the required scale(s). The aquatic golden apple snail(Pomacea canaliculata, Ampullariidae) was introduced from South America to mainland China around 1980s for commercial use. P. canaliculata has been listed as one of the 100 most invasive species by the Invasive Species Specialist Group of the International Union for Conservation of Nature. Given that the variation of traits in invasive species plays an important role in the establishment and spread of a population, it is necessary to examine trait variation at the spatial scale of the invasive species and to elucidate the possible underlying mechanisms. Using a nested sampling method, we collected individuals of P. canaliculata at different spatial scales in the Guangdong Province, southern China. We measured the phenotypic traits and conducted a variance component analysis. The variance in four phenotypic traits(body-mass, -height, -width and mouth width) was partitioned across five different nested spatial scales(in decreasing order of size: city, town, habitat, plot and individual). The results indicated that the four selected phenotypic traits had a similar variation pattern across spatial scales, with most of the variation occurring below the habitat level. The most phenotypic variation occurred at the individual and plot level, explaining nearly 80% of all the variation in phenotype. We found that the habitat level accounted for the remaining variation, with the exception of body-mass. At the larger scale, such as the town and city, there was no significant increase in trait variation. Consistent with the variance partitioning, the coefficient of trait variation decreased as scale increased. The lowest trait variation value occurred at the city scale, declining sharply from the town level, while the individual level showed the largest value. This result was confirmed when we analyzed the frequency distributions of phenotypic traits among different towns within the city scale. Towns within a city have similar trait-value frequency distributions, indicating that the overall trait distribution is conserved at the town-level, with no large variance occurring at the town-scale. We can speculate on the likely processes of scale where P. canaliculata phenotype traits changed. Our results suggest that processes acting at the regional scale e.g., the influence of climate played no significant role in trait variation. To effectively manage and predict biological invasions, attention should be focused on the genetic characteristics and the effect of local environmental factors. Finally, our study provided a general model for investigating trait variation across different ecological scales where samples are collected across nested spatial structures and analyzed using variance component analysis. In the future, incorporating the theory of eco-evolutionary dynamics to study trait variability in invasive species will enhance our ability to predict and manage the incursion. © 2015, Ecological Society of China. All rights reserved.


Yu L.,Key Laboratory of Tropical and Subtropical Fishery Resource Application and Cultivation | Yu L.,Chinese Academy of Fishery Sciences | Bai J.,Key Laboratory of Tropical and Subtropical Fishery Resource Application and Cultivation | Bai J.,Chinese Academy of Fishery Sciences | And 10 more authors.
Fisheries Science | Year: 2014

The grass carp, which is one of the most important farmed fish species in China, is widely distributed in different river basins. In this study, 21 single nucleotide polymorphism markers, developed in the grass carp expressed sequence tag database, were used with the snapshot genotyping method to analyze the genetic structure of six grass carp populations (SS, JL, HH, YJ, NX, and FS) from the Yangtze River and the Pearl River. The effective numbers of alleles (Ne) of the six grass carp populations was 1.7680-1.8038, the observed heterozygosity (Ho) was 0.5938-0.6305, the expected heterozygosity (He) was 0.4420-0.4443, and the polymorphic information content (PIC) was 0.3241-0.3403. The PIC, Ne, and He of the JL population were the highest among all populations, whereas those of the YJ population were the lowest. The NJ tree analysis based on genetic distance of the grass carp populations revealed that the six populations clustered into two branches: the SS, JL, and HH populations clustered first into one branch, which then clustered with YJ population; the FS and NX populations constituted a separate branch. The established genetic structures and phylogenetic relationships of some of the grass carp populations of the Yangtze River and Pearl River may lay the foundation for selecting core breeding populations. © 2014 The Japanese Society of Fisheries Science.

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