Intra-specific variation of sperm length in the malaria vector Anopheles gambiae: males with shorter sperm have higher reproductive success

<p>Abstract</p> <p>Background</p> <p>Intra-specific variation in sperm length influences male reproductive success in several species of insects. In males of the malaria vector <it>Anopheles gambiae</it>, sperm length is highly variable but the significance of this variation is unknown. Understanding what determines the reproductive success of male mosquitoes is critical for controlling malaria, and in particular for replacing natural populations with transgenic, malaria-resistant mosquitoes.</p> <p>Methods</p> <p>A laboratory population of <it>A. gambiae </it>males was tested for intra-specific variation in sperm length. A full-sib quantitative genetic design was used to test for a genetic component of sperm length in <it>A. gambiae </it>males and estimate its heritability. This study also tested for a relationship between sperm length and male reproductive success in <it>A. gambiae</it>. Male reproductive success was measured as the proportions of inseminated and ovipositing females.</p> <p>Results</p> <p>There was intra-specific variation of sperm length in <it>A. gambiae</it>. There was no significant genetic variation in sperm length and its heritability was low (h²= 0.18) compared to other insects. Sperm length was correlated with male body size (measured as wing length). Males with short sperm had significantly higher reproductive success than males with long sperm and this was independent of body size.</p> <p>Conclusion</p> <p>This is the first study to demonstrate intra-specific variation in sperm length in <it>A. gambiae </it>and that males with short sperm have higher reproductive success. That sperm length influences female oviposition is important for any strategy considering the release of transgenic males.</p

Methodology For Evaluating Atis Impacts On Air Quality

This paper presents an analytical method for evaluating the impact of rerouting traffic guided with Advanced Traveler Information Systems (ATIS) on air quality. The method is applied to a simple road network composed of two routes with one of the routes experiencing incident congestion. The methodology can be extended to more complex networks. Total emissions of three air pollutants (CO, VOC, and NOx) on the two routes are evaluated with and without ATIS. Emissions are evaluated for three time periods: 199398, 1998-2003, and the time period beyond year 2003. The findings indicate that a systemwide reduction of CO and VOC can be achieved through the implementation of ATIS. Further, more reduction in emissions of CO and VOC can be achieved with higher ATIS market-penetration levels. However, except for small market-penetration levels, ATIS may have a negative impact on NOx emissions. It is also found that ATIS alone cannot compete with improved emission controls in reducing emissions. Emission controls and ATIS together can achieve greater reductions of emissions than can be achieved by emission controls alone, which is likely to eliminate the negative impact of ATIS on NOx emissions. © ASCE