Data from: More than bindin divergence: reproductive isolation between sympatric subspecies of a sea urchin by asynchronous spawning

The evolution of reproductive barriers is crucial to the process of
speciation. In the Echinoidea, studies have focused on divergence in the
gamete recognition protein, bindin, as the primary isolating mechanism
among species. As such, the capacity of alternate mechanisms to be
effective reproductive barriers and the phylogenetic context in which they
arise is unclear. Here, we examine the evolutionary histories and factors
limiting gene exchange between two subspecies of Heliocidaris
erythrogramma that occur sympatrically in Western Australia. We found low,
but significant differentiation between the subspecies in two
mitochondrial genes. Further, coalescent analyses suggest that they
diverged in isolation on the east and west coasts of Australia, with a
subsequent range expansion of H. e. erythrogramma into Western Australia.
Differentiation in bindin was minimal, indicating gamete incompatibility
is an unlikely reproductive barrier. We did, however, detect strong
asynchrony in spawning seasons; H. e. erythrogramma spawned over summer
while H. e. armigera spawned in autumn. Taken together, we provide
compelling evidence for a recent divergence of these subspecies and their
reproductive isolation without gamete incompatibility. Western Australian
H. erythrogramma may therefore present an intriguing case of incipient
speciation, which depends on long-term persistence of the factors
underlying this spawning asynchrony.

Sex
RatioSpawning
DataGSI
Data