New insight into leaf shape diversity
Many of us probably remember the punnett squares by which we were introduced to the idea of genetic inheritance in school: a dominant allele in each of my brown-eyed parents hides a recessive allele that explains my blue eyes. Most genetic inheritance, of course, is much more complex. Differences in how we look are usually produced not by a single gene, but rather by interactions between several genes, across a gene regulatory network. Conversely, a single gene can affect not just one but many aspects of an organism's development – and these are often unrelated. This second phenomenon, which scientists call "pleiotropy" from the Greek word for "many ways", is central to one of the more interesting puzzles of evolutionary biology. A paper published in Genes and Development sheds some light on this puzzle.