I only had time to give the first article a quick glance, but it doesn’t seem surprising that if the parental lines don’t have adaptability for the conditions that the progeny are grown in, that this would reduce heterosis or vigor generally in the hybrid population. It’s interesting though that as long as the hybrids are possible, that there doesn’t appear to be a point where genetic distance reduces heterosis. I suspect the story will be a little different when you look at inter species hybrid—take Joseph’s squash for example, maximoss has more genetically divergent parents than mospermia but it s mospermia that has stronger heterosis. There you get into more transposon phenomena which complicates things.
