|Linthicum, Kenneth - Ken|
Submitted to: American Mosquito Control Association
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/30/2006
Publication Date: 6/15/2006
Citation: Rongnoparut, P., Rodpradit, P., Kongsawadworakul, P., Sithiprasasna, R., Linthicum, K. 2006. Population genetic structure of Anopheles maculatus in Thailand. American Mosquito Control Association. 22:192-197. Interpretive Summary: Anopheles maculatus is a mosquito that transmits malaria in much of Asia. As part of the process to understand if mosquitoes carrying a malaria-refractive gene could be introduced into a natural population and spread the beneficial gene we evaluated how natural gene flow occurs in peninsular Thailand. We discovered that many genes are exchanged between populations separated by as far as 650 km. However, mountain ranges could serve as significant barriers to gene flow, even among populations separated by as little as 50 km. Successful introductions of transgenic mosquitoes into natural populations will need to consider impediments to gene flow such as mountain ranges.
Technical Abstract: Anopheles (Cellia) maculatus Theobald is a major malaria vector in southern Thailand and peninsular Malaysia, and previous studies on the population genetics of this mosquito suggested that mountain ranges reduced gene flow among some populations. In this study we examine the genetic variance among 12 collections of natural populations in southern Thailand by analyzing 7 microsatellite loci. Based on Analysis of Molecular Variance (AMOVA), three geographic populations of An. maculatus can be recognized. The northern population consists of 3 collections situated in western Thailand north of 120 north latitude. The collections located south of 120 north latitude can be separated into two genetic populations: (1) the middle southern which includes 3 collections located on the west side of the Phuket mountain range between 80 and 100 north latitude, (2) the southern which includes 2 collections located on the east of the Phuket mountain range located between approximately 6.50 and 11.50 north latitude. AMOVA revealed significant genetic differentiation between northern and middle southern populations. The middle southern also demonstrated moderate differentiation from the southern population. Furthermore, gene flow is restricted between proximal collections when located on different sides of the Phuket mountain range (mean values of FST and RST = 0.046 and 0.132, respectively, between Chumphon and Ranong). Collections separated by distances as little as 50 km exhibit restriction of gene flow when separated by geographic barriers, while collections separated by more than 650 km without geographic barriers exhibit greater gene flow.