Nice news piece (open access) in Nature about the developing research field of de novo / orphan / taxonomically restricted (TRGs) / lineage specific genes. The article highlights a point I’ve made elsewhere on this discussion board: the methodological youth of the field, and (hence) the widely-varying answers about how many orphans or TRGs a species possesses:
The study gets at one of the field’s biggest preoccupations: how to tell whether a gene is truly de novo. Answers vary wildly, and approaches are still evolving. For example, an early study found 15 de novo genes in the whole primate order; a later attempt found 60 in humans alone. One option for finding candidate de novo genes is to use an algorithm to search for similar genes in related species. If nothing shows up, then it’s possible that the gene arose de novo. But failing to find a relative doesn’t mean no relative is there: the gene could have been lost along the way, or might have shape-shifted far away from its kin.
Worth a look.
Mod edit, adding link: How evolution builds genes from scratch