Data from: Current geography masks dynamic history of gene flow during speciation in northern Australian birds

Genome divergence is greatly influenced by gene flow during early stages
of speciation. As populations differentiate, geographical barriers can
constrain gene flow and so affect the dynamics of divergence and
speciation. Current geography, specifically disjunction and continuity of
ranges, is often used to predict the historical gene flow during the
divergence process. We test this prediction in eight meliphagoid bird
species complexes codistributed in four regions. These regions are
separated by known biogeographic barriers across northern Australia and
Papua New Guinea. We find that bird populations currently separated by
terrestrial habitat barriers within Australia and marine barriers between
Australia and Papua New Guinea have a range of divergence levels and
probability of gene flow not associated with current range connectivity.
Instead, geographic distance and historical range connectivity better
predict divergence and probability of gene flow. In this dynamic
environmental context, we also find support for a nonlinear decrease of
the probability of gene flow during the divergence process. The
probability of gene flow initially decreases gradually after a certain
level of divergence is reached. Its decrease then accelerates until the
probability is close to zero. This implies that although geographic
connectivity may have more of an effect early in speciation, other factors
associated with higher divergence may play a more important role in
influencing gene flow midway through and later in speciation. Current
geographic connectivity may then mislead inferences regarding potential
for gene flow during speciation under a complex and dynamic history of
geographic and reproductive isolation.