Dear all,
According to you, if 2 genes are next to each other in the genome (same telomer and near a bigger cluster of similar genes), could it be enough to justify a sister group of them in a phylogenetic tree?
Best regards
If you're thinking that those two genes would be the result of a duplication, then my first thought would be 'no' because two genes could be close to each other after a translocation , a deletion, an inversion....
The only evidence for this relationship is phylogenetic evidence, not position. Don't forget that a recently duplicated locus is between two others, only one of which is it's phylogenetic sister (barring unequal crossing over). Position on the chromosome is not random so although adjacent loci may be more related than average, in practice this won't be much help in coming to the right relationship.
Your question reminds one possibility of "tandom duplication" similar to that of evolution of the homeodomain family of transcription factors. These genes cluster together in various chromosomal locations. It has been hypothesized that the HOX cluster probably originated from tandem duplications resulting in an array of genes linked on a single chromosome in the ancestral metazoan, followed by cluster duplications and rearrangement in early vertebrate evolution
Considering the paucity of information in the question, the only answer is: NO.
That is valid even if the two genes are resulting from a gene duplication and are side by side in the genome. You cannot make a phylogenetic tree with just two sequences. Therefore, the topology of the tree, and whether different groups will be "sister" groups or not, will totally depend on what other sequences are being compared with these two.
In any case, position, as pointed out by Pierre and Dave is not a valid criteria for determining phylogenetic relationship.
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Sorry, but I down-voted your answer: it is not answering the question at all. Also, I find it suggests the possibility that position could justify grouping from a phylogenetic point of view, and that is false as Pierre and Dave have pointed out.