**4. Conclusion**

Gene duplication is rampant. It should be noted that the products depicted above show considerable variation both in number of, and distances between, the LRR domains. Where, when and how do the genes listed here function? For most of them there is no evidence that they deliver innate immunity in the plant. Of course, some of them do! For many the function is not known. Gene duplications, carrying amino acid changes resulting from mutations, often end in neofunctionalization even though duplicate genes may also merely provide tissue specific expression for the original ancestral gene. Subsequent alternate splicing of genes, in turn, might also give new roles to the genes. But if domains are the units that built proteins, then domain shuffling provides a more efficient source for expressed gene versatility: (Thereby, nature promotes evolution of disparate proteins for novel functions.) Most of the genes listed in this chapter certainly exist because of duplication. These genes could be grouped further, however, because another domain had first been added for the projected protein molecules, long before the gene duplications occurred. Possibly, domains represent the evolutionary building blocks for all proteins. At present we can only speculate as to the mechanism of such random multi-domain protein formation. Were transposons involved? (Retroprocession, the process that is responsible for pseudogene formation, possibly could have also facilitated the creation of new disparate proteins!). Specific domain combinations might have been built randomly – maybe sometimes just once during the evolution of an organism – and then sometimes only to be rearranged during duplication or even to loose domains by mutating them away thereafter. (.See e.g..the Strubbelig family members 1-8.)
