The fate of genes that cross species boundaries after a major hybridization event in a natural mosquito population

Mark J. Hanemaaijer, Travis C. Collier, Allison Chang, Chloe C. Shott, Parker D. Houston, Hanno Schmidt, Bradley Main, Anthony J. Cornel, Yoosook Lee, Gregory C Lanzaro

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)4978-4990
Number of pages13
JournalMolecular Ecology
Volume27
Issue number24
DOIs
StatePublished - Dec 1 2018

Keywords

  • Anopheles
  • evolution
  • gene flow
  • hybridization
  • Introgression
  • population genomics
  • selection

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Genetics

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