Pacific white shrimp (Litopenaeus vannamei) is the leading species farmed in the Western Hemisphere and an economically important aquaculture species in China. In this project, a genetic linkage map was constructed using amplified fragment length polymorphism (AFLP) and microsatellite markers. One hundred and eight select AFLP primer combinations and 30 polymorphic microsatellite markers produced 2071 markers that were polymorphic in either of the parents and segregated in the progeny. Of these segregating markers, 319 were mapped to 45 linkage groups of the female framework map, covering a total of 4134.4 cM; and 267 markers were assigned to 45 linkage groups of the male map, covering a total of 3220.9 cM. High recombination rates were found in both parental maps. A sex-linked microsatellite marker was mapped on the female map with 6.6 cM to sex and a LOD of 17.8, two other microsatellite markers were also linked with both 8.6 cM to sex and LOD score of 14.3 and 16.4. The genetic maps presented here will serve as a basis for the construction of a high-resolution genetic map, quantitative trait loci (QTLs) detection, marker-assisted selection (MAS) and comparative genome mapping.

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Abstract:Stream water temperature (t s ) is a critical water quality parameter for aquatic ecosystems. However, t s records are sparse or nonexistent in many river systems. In this work, we present an empirical model to predict t s at the site scale across the USA. The model, derived using data from 171 reference sites selected from the Geospatial Attributes of Gages for Evaluating Streamflow database, describes the linear relationship between monthly mean air temperature (t a ) and t s . Multiple linear regression models are used to predict the slope (m) and intercept (b) of the t a -t s linear relation as a function of climatic, hydrologic and land cover characteristics. Model performance to predict t s resulted in a mean Nash-Sutcliffe efficiency coefficient of 0.78 across all sites. Application of the model to predict t s at additional 89 nonreference sites with a higher human alteration yielded a mean NashSutcliffe value of 0.45. We also analysed seasonal thermal sensitivity (m) and found strong hysteresis in the t a -t s relation. Drainage area exerts a strong control on m in all seasons, whereas the cooling effect of groundwater was only evident for the spring and fall seasons. However, groundwater contributions are negatively related to mean t s in all seasons. Finally, we found that elevation and mean basin slope are negatively related to mean t s in all seasons, indicating that steep basins tend to stay cooler because of shorter residence times to gain heat from their surroundings. This model can potentially be used to predict climate change impacts on t s across the USA.