Gene flow between island populations of the malaria mosquito, Anopheles
hinesorum, may have contributed to the spread of divergent host
preference phenotypes
Abstract
Anopheles hinesorum is a mosquito species with variable host preference.
Throughout New Guinea and northern Australia, An. hinesorum feeds on
humans (it is opportunistically anthropophagic) while in the southwest
Pacific’s Solomon Archipelago, the species is abundant but has rarely
been found biting humans (it is exclusively zoophagic in most
populations). There are at least two divergent zoophagic (non-human
biting) mitochondrial lineages of An. hinesorum in the Solomon
Archipelago. Since zoophagy is a derived (non-ancestral) trait in this
species, this leads to the question: has zoophagy evolved independently
in these divergent lineages? Or conversely: has nuclear gene flow or
connectivity resulted in the transfer of zoophagy? Although we cannot
conclusively answer this, we find close nuclear relationships between
Solomon Archipelago populations indicating that recent nuclear gene flow
has occurred between zoophagic populations from the divergent
mitochondrial lineages. Recent work on isolated islands of the Western
Province (Solomon Archipelago) has also revealed an anomalous,
anthropophagic island population of An. hinesorum. We find a common
shared mitochondrial haplotype between this Solomon Island population
and another anthropophagic population from New Guinea. This finding
suggests that there has been recent migration from New Guinea into the
only known anthropophagic population from the Solomon Islands. Although
currently localized to a few islands in the Western Province of the
Solomon Archipelago, if anthropophagy presents a selective advantage, we
may see An. hinesorum emerge as a new malaria vector in a region that is
now working on malaria elimination.