Sympatric plant speciation in islands? (Reply)

Abstract

Arising from: V. Savolainen et al. Nature 441, 210–213 (2006).

Stuessy¹ questions our conclusions of sympatric speciation in a case study of palms on Lord Howe Island² and proposes an alternative hypothesis, whereby the two Howea species evolved allopatrically when the island was larger and less eroded. Stuessy also argues that low genetic divergence does not necessarily indicate speciation in sympatry¹. We agree that it is important not to jump to conclusions, but we have good estimates of the size and geological history of Lord Howe Island at the time of the speciation event^3,4, and both are fully compatible with sympatric speciation. Stuessy also misinterprets the results from our AFLP (amplified DNA-fragment length polymorphism) genome scan: we did not assert that low AFLP divergence per se is evidence for sympatric speciation, but rather that the distribution of these genetic divergence values across the genome is strongly supportive of speciation with gene flow involving disruptive or divergent selection².