Malaria is an infectious disease caused by parasites of the genus Plasmodium which is responsible
for approximately 400,000 deaths annually, primarily in sub-Saharan Africa. Malaria is transmitted
by mosquitoes belonging to the Anopheles gambiae species complex. While progress has been made
to reduce the incidence of malaria, the emergence of insecticide resistance necessitates the
development of novel vector control strategies. Gene drive technologies have seen significant
advances in recent years, providing hope for their implementation in the near future.
While gene flow has been identified between sibling species of the An. gambiae species complex,
they are reproductively isolated by both pre- and post-zygotic isolation mechanisms. Interspecific
crosses between most member species produce sterile hybrid males, in accordance with Haldane’s
rule of speciation. The aim of this project was to support the development of gene drive technologies
by investigating hybrid incompatibilities between two of the most significant vector species,
Anopheles gambiae and Anopheles arabiensis. The potential for the introgression of genomic regions
from one species into the genetic background of the other was investigated to help inform models
regarding the spread of gene drives between sibling species. In addition, the identification of genetic
elements involved in hybrid male sterility could provide potential targets for vector control strategies.
Large autosomal regions were found to introgress and persist in interspecific genomes without a
detectable fertility cost. In addition, the introduction of distinct autosomal regions of conspecific DNA
into otherwise heterospecific genomes of hybrid males was found to overcome hybrid
incompatibilities and partially restore fertility. While no specific genetic factors involved in hybrid
incompatibilities could be identified, the results indicate that such factors are present at least on the
X chromosome. Furthermore, the evidence suggests that asynapsis between interspecific homologous
autosomes during gametogenesis plays a role in the manifestation of hybrid male sterility.