Voordouw Maarten J, Koella Jacob C, Hurd Hilary
Department of Biology, University of Victoria, PO Box 3020, Station CSC, Victoria, British Columbia, V8W 3N5, Canada.
Malar J. 2008 Oct 21;7:214. doi: 10.1186/1475-2875-7-214.
Intra-specific variation in sperm length influences male reproductive success in several species of insects. In males of the malaria vector Anopheles gambiae, 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.
A laboratory population of A. gambiae 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 A. gambiae males and estimate its heritability. This study also tested for a relationship between sperm length and male reproductive success in A. gambiae. Male reproductive success was measured as the proportions of inseminated and ovipositing females.
There was intra-specific variation of sperm length in A. gambiae. 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.
This is the first study to demonstrate intra-specific variation in sperm length in A. gambiae 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.
精子长度的种内变异会影响几种昆虫物种中雄性的繁殖成功率。在疟蚊媒介冈比亚按蚊的雄性个体中，精子长度高度可变，但其变异的意义尚不清楚。了解决定雄性蚊子繁殖成功的因素对于控制疟疾至关重要，特别是对于用转基因抗疟蚊子取代自然种群而言。
对实验室饲养的冈比亚按蚊雄性群体进行精子长度的种内变异测试。采用全同胞定量遗传设计来测试冈比亚按蚊雄性精子长度的遗传成分并估计其遗传力。本研究还测试了冈比亚按蚊精子长度与雄性繁殖成功率之间的关系。雄性繁殖成功率通过已受精和产卵雌性的比例来衡量。
冈比亚按蚊存在精子长度的种内变异。精子长度没有显著的遗传变异，并且与其他昆虫相比其遗传力较低（h2 = 0.18）。精子长度与雄性体型（以翅长衡量）相关。精子短的雄性比精子长的雄性具有显著更高的繁殖成功率，且这与体型无关。
这是第一项证明冈比亚按蚊精子长度存在种内变异且精子短的雄性具有更高繁殖成功率的研究。精子长度影响雌性产卵这一发现对于任何考虑释放转基因雄性的策略都很重要。
