Evolution of a mosquito’s hatching behavior to match its human-provided habitat

A subspecies of the yellow fever mosquito, Aedes aegypti, has recently
evolved to specialize in biting and living alongside humans. It prefers
human odor and breeds in human-provided artificial containers rather than
the forest tree holes of its ancestors. Here, we report one way this human
specialist has adapted to the distinct ecology of human environments.
While eggs of the ancestral subspecies rarely hatch in pure water, those
of the derived human-specialist do so readily. We trace this novel
behavior to a shift in how eggs respond to dissolved oxygen, low levels of
which may signal food abundance. Moreover, we show that while tree holes
are consistently low in dissolved oxygen, artificial containers often have
much higher levels. There is thus a concordance between the hatching
behavior of each subspecies and the aquatic habitat it uses in the wild.
We find this behavioral variation is heritable, with both maternal and
zygotic effects. The zygotic effect depends on dissolved oxygen
concentration (i.e., GxE), pointing to potential changes in
oxygen-sensitive circuits. Together, our results suggest that a shift in
hatching response contributed to the pernicious success of this
human-specialist mosquito and illustrate how animals may rapidly adapt to
human-driven changes in the environment.