Is small indel bias a determinant of genome size?

Variation in eukaryotic genome sizes has remained an unsolved puzzle for more than half a century. Most traditional approaches have ignored the mechanisms of genome size change as an important component of the puzzle, or have posited forces capable only of increasing DNA content. In an important recent addition, it has been suggested that DNA loss caused by biases in small insertions and deletions (indels) can be a determinant of genome size. Although genome shrinkage has probably been important in many groups, the data upon which this specific mechanistic theory is based are limited, and must be interpreted with caution.