Couple of Questions about Hybridization

Please, two questions on hybridization,

  1. Species roses readily cross with themselves or any other rose in their vacinity and yet still remain speciies roses. So why are hybrid roses distinguished from speciies roses other than by chance (i.e., any given sequence of rose breeding could conceivably take place in a native habitate over the eons) or is it related to the specific gene set and ploidness of the genes?

  2. Any given set of parents do give rise to specific roses, but does not any given pollination of the same parents give rise to different rose offspring? i.e. each pollination or even each seed of a rose is unique genetically? Sometimes even the same plant gives rise to different genetic offspring (sports and environment effects)?

To question number one–

In the past many members here have agreed and disagreed about the word “species.”

Does it mean a rose growing and occuring in the wild naturally?

Does it mean a rose that breeds true from seed?

Can people breed “species” such as R. kordesii, or should they be called “species hybrid?” Dr. Robert Bayse created a similar tetraploid rose much like R. kordesii, but he never called it a species rose.

Roses such as R. californica, R. nutkana, and R. blanda often have variations because they breed with each other frequently.

I guess everyone has a definition.

For me, a species rose has two requirements: 1.) breeds in the wild naturally, and 2.) have little variation but dominant characteristics.

Mike, to your 2nd question, modern roses are like people in a sense. Each of their children is unique. Each seed will produce a unique rose. Like families, there will be seedlings that resemble each other to a certain degree, but also in the same family, seedlings may look very different from one another.

Even among species roses self crosses you will get variation, though the differences are more subtle.

Jim Sproul

As to 1, I’ve often been irked at the definition of “species” given in school biology classes, as distinct from “varieties”. The definition never held, as it pertained to the ability to interbreed. Even differing genera of orchids can interbreed. But if the definition is applied to “in their natural habitat” it does elimanate distinct varieties seperated by geological barriers. Still, it’s sloppy at best…

As to 2, the classic example involves Mr. Lincoln, Papa Meilland, and Oklahoma, all of which descend from the exact same cross. But like brothers and sisters, they have some distinctions. And parentage does not necessarily dictate offspring’s superiority. As Jim says, the people genetics is a fair parallel. The complexity of the genome is comparable. Einstein would not necessarily sire great physicists. And if crossed with Magic Johnson, the product would not likely be an awesome Basketball player with scientific prowess.

A lame answer, but it’s late, and I’m tired…