Data from: Origin, acquisition and diversification of heritable bacterial endosymbionts in louse flies and bat flies

The γ-proteobacterium Arsenophonus and its close relatives (Arsenophonus
and like organisms, ALOs) are emerging as a novel clade of endosymbionts,
which are exceptionally widespread in insects. The biology of ALOs is,
however, in most cases entirely unknown, and it is unclear how these
endosymbionts spread across insect populations. Here, we investigate this
aspect through the examination of the presence, the diversity and the
evolutionary history of ALOs in 25 related species of blood-feeding flies:
tsetse flies (Glossinidae), louse flies (Hippoboscidae) and bat flies
(Nycteribiidae and Streblidae). While these endosymbionts were not found
in tsetse flies, we identify louse flies and bat flies as harbouring the
highest diversity of ALO strains reported to date, including a novel ALO
clade, as well as Arsenophonus and the recently described Candidatus
Aschnera chinzeii clade. We further show that the origin of ALO
endosymbiosies extends deep into the evolutionary past of louse flies and
bat flies, and that it likely played a major role in the ecological
specialization of their hosts. The evolutionary history of ALOs is notably
complex and was shaped by both vertical transmission and horizontal
transfers with frequent host turnover and apparent symbiont replacement in
host lineages. In particular, ALOs have evolved repeatedly and
independently close relationships with diverse groups of louse flies and
bat flies, as well as phylogenetically more distant insect families,
suggesting that ALO endosymbioses are exceptionally dynamic systems.