INTRODUCTION. Anopheles coluzzii and An. gambiae are the main malaria vectors in sub-Saharan Africa. The two species have recently diverged and are strongly reproductively isolated throughout Africa, but stable frequencies of putative hybrids >20% have been reported from the far-west of the species range. Whole genome sequencing data by theAnopheles gambiae 1000 genomes project (Ag1000G; www.malariagen.net/projects/ag1000g) have attributed an “uncertain species status” to far-west populations. MATERIALS AND METHODS. We carried out population genomic analyses (i.e. PCA, Admixture, Tess, Fst, F3 statistics, Patterson’s D statistics, TreeMix) on a dataset including 112 An. coluzzii and An. gambiaeindividuals from 7 far-west populations and 1,069 individuals from 20 populations from west and central Africa sequenced by Illumina technology within Ag1000G. We focused on the euchromatic regions of chromosome-3 (3L region 15-41 Mbp; 3R region 1-24 Mbp) which are considered neutral regions not affected by low recombination due to vicinity to centromere or presence of paracentric inversions. RESULTS AND CONCLUSIONS. Results show evidence of a putative “far-west taxon” characterized by i) polymorphic chromosome-X IGS diagnostic markers; ii) An. gambiae-like chromosome-X pericentromeric region of interspecific divergence; iii) admixture of specie-specific autosomal ancestry informative markers. In addition, the putative “far-west taxon” shows i) a chromosome-3 unique gene-pool highly differentiated from west-African An. coluzzii and An. gambiae populations (PCA, Admixture, Tess, Fst, F3); ii) an origin not due to admixture between An. coluzzii and An. gambiae (Patterson’s D statistics, TreeMix); iii) evidence of gene-flow with west-African An. coluzzii populations, predating the insurgence of kdr resistant mutation conferring resistance to insecticides in this species (F3-statistics and kdr genotyping). Further demographic/phylogenetic and ecological/malariologial characterizations are needed to better clarify the actual taxonomic status of the “far-west taxon” and its role as malaria vector.
Whole-genome sequencing analysis of populations with an uncertain species status at the Far-West of Anopheles gambiae range / Caputo, Beniamino; Maria De Marco, Carlo; Miles, Alistair; della Torre, Alessandra. - (2021). (Intervento presentato al convegno XXXI Congresso Nazionale della Società Italiana di Parassitologia: ”I parassiti del terzo millennio” tenutosi a Teramo).
Whole-genome sequencing analysis of populations with an uncertain species status at the Far-West of Anopheles gambiae range
Beniamino Caputo;Carlo Maria De Marco;
2021
Abstract
INTRODUCTION. Anopheles coluzzii and An. gambiae are the main malaria vectors in sub-Saharan Africa. The two species have recently diverged and are strongly reproductively isolated throughout Africa, but stable frequencies of putative hybrids >20% have been reported from the far-west of the species range. Whole genome sequencing data by theAnopheles gambiae 1000 genomes project (Ag1000G; www.malariagen.net/projects/ag1000g) have attributed an “uncertain species status” to far-west populations. MATERIALS AND METHODS. We carried out population genomic analyses (i.e. PCA, Admixture, Tess, Fst, F3 statistics, Patterson’s D statistics, TreeMix) on a dataset including 112 An. coluzzii and An. gambiaeindividuals from 7 far-west populations and 1,069 individuals from 20 populations from west and central Africa sequenced by Illumina technology within Ag1000G. We focused on the euchromatic regions of chromosome-3 (3L region 15-41 Mbp; 3R region 1-24 Mbp) which are considered neutral regions not affected by low recombination due to vicinity to centromere or presence of paracentric inversions. RESULTS AND CONCLUSIONS. Results show evidence of a putative “far-west taxon” characterized by i) polymorphic chromosome-X IGS diagnostic markers; ii) An. gambiae-like chromosome-X pericentromeric region of interspecific divergence; iii) admixture of specie-specific autosomal ancestry informative markers. In addition, the putative “far-west taxon” shows i) a chromosome-3 unique gene-pool highly differentiated from west-African An. coluzzii and An. gambiae populations (PCA, Admixture, Tess, Fst, F3); ii) an origin not due to admixture between An. coluzzii and An. gambiae (Patterson’s D statistics, TreeMix); iii) evidence of gene-flow with west-African An. coluzzii populations, predating the insurgence of kdr resistant mutation conferring resistance to insecticides in this species (F3-statistics and kdr genotyping). Further demographic/phylogenetic and ecological/malariologial characterizations are needed to better clarify the actual taxonomic status of the “far-west taxon” and its role as malaria vector.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
