biostudies-literatureBalcazar DNational Institutes of Health (NIH)National Institutes of HealthNational Science Foundation of Sri Lanka91https://www.ebi.ac.uk/biostudies/studies/S-EPMC12915009biostudies-literatureUnknown19(1)<h4>Background</h4>Aedes aegypti is typically regarded as a freshwater mosquito; however, recent studies have documented its development in brackish water habitats in coastal regions, including Sri Lanka's Jaffna Peninsula. Compared with freshwater populations, brackish water samples in Jaffna display enhanced salt tolerance throughout larval-to-adult development, along with differences in gene expression, cuticle morphology and composition, and insecticide susceptibility.<h4>Methods</h4>To explore the genetic basis of these differences, we performed a comparative genomic analysis using 5135 genome-wide single nucleotide polymorphisms (SNPs) from Ae. aegypti inhabiting freshwater and brackish water sites in the Jaffna Peninsula. Genetic diversity, population structure, and demographic paraParasites & vectorsInvestigating genetic differentiation between brackish and fresh water collections of the arboviral vector Aedes aegypti.PMC12915009RG/HS/2019/02RO1 AI155562Surendran SNGloria-Soria ABalcazar DRamasamy RAdams EPowell JRfalseInvestigating genetic differentiation between brackish and fresh water collections of the arboviral vector Aedes aegypti.<h4>Background</h4>Aedes aegypti is typically regarded as a freshwater mosquito; however, recent studies have documented its development in brackish water habitats in coastal regions, including Sri Lanka's Jaffna Peninsula. Compared with freshwater populations, brackish water samples in Jaffna display enhanced salt tolerance throughout larval-to-adult development, along with differences in gene expression, cuticle morphology and composition, and insecticide susceptibility.<h4>Methods</h4>To explore the genetic basis of these differences, we performed a comparative genomic analysis using 5135 genome-wide single nucleotide polymorphisms (SNPs) from Ae. aegypti inhabiting freshwater and brackish water sites in the Jaffna Peninsula. Genetic diversity, population structure, and demographic para2026-01-01T00:00:00Z2026 Jan2026-07-16T06:35:53.427Z2026-07-09T10:40:14.77ZS-EPMC129150094159379010.1186/s13071-025-07239-3