The general dynamic model of island biogeography revisited at the level of major flowering plant families

Abstract

Aim The general dynamic model (GDM) proposed by Whittaker et al. (2008) has become a widely accepted theoretical framework in island biogeography. In this study, we explore whether GDM predictions hold when overall plant diversity is deconstructed into major plant families. Location 101 islands from 14 oceanic archipelagos world‐wide. Methods Occurrence data for all species of nine large, cosmopolitan flowering plant families were used to test predictions derived from the GDM. We analysed the effects of island area and age on species richness as well as number and percentage of single‐island endemic species per family using mixed‐effect models. Results Total species and endemic richness as well as the percentage of endemic species showed the predicted hump‐shaped relationship with island age. The overall pattern was mainly driven by few species‐rich plant families. Varying patterns were found for individual families, some of them opposing the general trend. In most cases, native and endemic species richness peaked much earlier in the island life cycle than suggested by the GDM. The contribution of area to the explained variation of all dependent variables was much higher than that of island age. Main conclusions The results suggest that biodiversity‐age relationships reported for large taxonomic groups like plants are driven by only a few species‐rich clades. The way these families influence the overall patterns of species richness and endemism is related to family‐specific properties, such as evolutionary history or dispersal strategies. Deviances from the GDM predictions can hence largely be explained by family characteristics and considering taxon‐specific traits may help to further improve the explanatory power of the GDM. Families not following the expectations, like Orchidaceae, may be particularly valuable candidates to unveil so far neglected drivers of island biogeographical patterns.