Just a hypothesis: a reply to Hanski

Hanski's critique of the habitat amount hypothesis (Hanski, 2015, Journal of Biogeography, 42 , 989–993) does not actually constitute a test of the hypothesis, but rather a series of arguments for why he suspects that it is not correct. But the habitat amount hypothesis is exactly that – a hypothesis. It will remain ‘just’ a hypothesis until it has been rigorously tested against empirical data. To facilitate such testing, in Fahrig (2013, Journal of Biogeography, 40 , 1649–1663) I presented specific, testable predictions of the hypothesis. Here, I reiterate the main tests needed, in the hope that some readers will be encouraged to carry them out. I appreciate this opportunity to emphasize that the habitat amount hypothesis needs to be tested against empirical data, and I look forward to seeing the results of such tests.