a species is something which forms distinct populations with different genetic characteristics. just because something can interbreed does not mean that it ever will in nature. even if they do cross in nature, they form their own distinct populations away from the place where they cross. in many cases, these hybrids are sterile, do not have an even number of chromosomes, or have different sized chromosomes in each pair.
also, the fact that certain plants can interbreed with a common relative does not mean they can interbreed with each other. for example, Grammatophyllum and Ansellia species have both been crossed with Eulophia, but there have been no successful crosses of Grammatophyllum with Ansellia. it would make no sense to include the three in the same species. exactly how they should be categorized is a matter of ongoing debate, and the recent re-classification is mostly due to recent studies of genetics. in some cases, this research shows that certain groups of species are more closely related than previously thought, and should be placed in the same genus or subfamily. this has led to attempts at creating new types of hybrids, which were at one time believed to be impossible. in other cases, the research has shown that species are not as closely related, and explains why certain types of hybrids are impossible. this same type of research is leading to re-organization of all plant families.
|
Hybrid Mode
