It seems to me that such speciation supports the assumption of endurance. Over time you'd see selection for species which are patient, diligent, fecund star colonizers. Just like medieval Europeans spent decades or centuries building a cathedral, over time you'd select for species which spend centuries working on their next starshot.
Depends on if the explorers are the ones doing the bulk of the breeding. On planet earth, educated people actually tend to have fewer kids. There is therefore selective pressure against intelligence on earth.
