Table 1.

Hypotheses to explain the Azores Diversity Enigma

Hypotheses	Justification
1. Linnean shortfall	The differences in diversity patterns of Pericallis between the Azores and the Canaries are explained by differences in taxon concepts and/or taxonomic effort applied between the archipelagos. Recent studies have shown that there is potentially greater diversity in the Azores compared to current species circumscriptions [10, 18, 30]
2. Ecological homogeneity	Adaptive diversification plays a key role in the evolution of island lineages [43]. There is more limited opportunity for diversification in the Azores because they are more ecologically homogenous, compared to the Canaries [15].