JOURNAL CLUB

The question of whether sympatric speciation (i.e. reproductive isolation of populations with overlapping distributions) is a source of biodiversity has always been controversial. So far, mounting evidence from only a few species, for example African lacustrine cichlids, African widowbirds and phytophagous insects, supports the notion that it occurs in nature. In the latter two, host shifts can lead to genetic isolation of the population that has shifted. A potential new example comes from Eurasian and North American crossbills. The North American red crossbill (Loxia curvirostra) can be divided into sibling specie