Funny thing is, in studies, hardiness is hard to track genetically. They found there are 3 primary clusters of polygenetics for hardiness. Too many genes involved to track as singularly responsible. Those clusters are heat hardiness, adaptive/general hardiness, and cold hardiness. Often, in the most hardiness 2 to 3 of those clusters would heavily overlap. Not always though, but enough so that patterns emerged. Some rugosa hybrids are a good example of those that have both general and cold hardiness, but languish and sometimes burn in high desert. However, many roses that are cold hardy are also heat hardy.

In other words, we cannot see this traits (heat and cold hardy) as exclusive. Sometimes its a more complex story.