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The fate of genes that cross species boundaries after a major hybridization event in a natural mosquito population
Author(s) -
Hanemaaijer Mark J.,
Collier Travis C.,
Chang Allison,
Shott Chloe C.,
Houston Parker D.,
Schmidt Hanno,
Main Bradley J.,
Cornel Anthony J.,
Lee Yoosook,
Lanzaro Gregory C.
Publication year - 2018
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1111/mec.14947
Subject(s) - biology , introgression , population , anopheles gambiae , genetics , allele , population genomics , natural population growth , gene pool , natural selection , gene flow , evolutionary biology , genetic variation , gene , genome , genomics , genetic diversity , malaria , demography , sociology , immunology
Animal species are able to acquire new genetic material via hybridization and subsequent introgression. However, little is known about how foreign genomic material is incorporated into a population over time and what genes are susceptible to introgression. Here, we follow the closely related mosquito sister species Anopheles coluzzii and Anopheles gambiae in a sympatric natural population in Mali at multiple time points spanning a period of 25 years. During this period, we observed the temporary breakdown of mating barriers, which allowed us to explore the fate of alleles that crossed the species boundary in a natural population. Whole genome sequencing of 74 individuals revealed introgression within only 34 genes (0.26% of total genes) from A. gambiae to A. coluzzii , the majority contained within a 4 Mb region on the 2L chromosome which includes the insecticide resistance gene (AGAP004707). We designed a genotyping assay to follow 25 of the 34 introgressed alleles over time and found that all A. gambiae alleles, except four, reached a frequency of 50% in the A. coluzzii population within 4 years (~50 generations) and increased to ~80% within 6 years (~75 generations). However, the frequency of all introgressed alleles, except three, decreased to ~60% in 2016. This suggests an ongoing process of purifying selection in the population against DNA of foreign ancestry, except for alleles that are under positive selection, resulting in a complex genomic landscape . This study shows that stable introgression is limited to only specific genes even within closely related species.