Conclusions
The Aegean continental islands were separated from the mainland for a very long period of time (>2.6 Ma) thus promoting endemism; the extreme and recent paleo-configurations of high connectivity with the mainland that started with the onset of the Quaternary greatly affected their species richness and speciation patterns. These connections with the mainland manifested as “shocks” of sorts, when isolated islands became connected with the mainland (Sondaar and Van der Geer 2005). We hypothesise that increasing lower sea levels over the Quaternary period led to migration waves of continental species to ever more continental islands disrupting allopatric evolutionary processes, induced extinctions in single island endemic species, ultimately leading to signals of endemic underrepresentation and native supersaturation tuned to the most extreme (LGM) configurations prevalent at the end of the Pleistocene. We noted for some multiple endemic chorotypes, the high z-values on land-bridge islands and a dependency on present day distance, which may reflect a relict response to the pre-Quaternary conditions, when these land-bridge islands still were true islands. Continental systems therefore hold ample evidence of the effect of paleogeography on the species richness, speciation and biogeographical patterns of the Aegean islands. The noted principal differences in geographic and evolutionary mechanisms between oceanic and continental islands make statistical assessments of endemic species data of combined oceanic and continental islands fundamentally problematic and studies involving both systems should explicitly incorporate their differences in statistical models.