Data from: Parent-of-origin growth effects and the evolution of hybrid inviability in dwarf hamsters

Mammalian hybrids often show abnormal growth, indicating that
developmental inviability may play an important role in mammalian
speciation. Yet, it is unclear if this recurrent phenotype reflects a
common genetic basis. Here, we describe extreme parent-of-origin-dependent
growth in hybrids from crosses between two species of dwarf hamsters,
Phodopus campbelli and Phodopus sungorus. One cross type resulted in
massive placental and embryonic overgrowth, severe developmental defects,
and maternal death. Embryos from the reciprocal cross were viable and
normal sized, but adult hybrid males were relatively small. These effects
are strikingly similar to patterns from several other mammalian hybrids.
Using comparative sequence data from dwarf hamsters and several other
hybridizing mammals, we argue that extreme hybrid growth can contribute to
reproductive isolation during the early stages of species divergence.
Next, we tested if abnormal growth in hybrid hamsters was associated with
disrupted genomic imprinting. We found no association between imprinting
status at several candidate genes and hybrid growth, though two
interacting genes involved in embryonic growth did show reduced expression
in overgrown hybrids. Collectively, our study indicates that
growth-related hybrid inviability may play an important role in mammalian
speciation but that the genetic underpinnings of these phenotypes remain
unresolved.