Figure 3. Evaluation of the effect of environmental changes on diversification processes in the evolutionary history of birdwing butterflies.
(a) Major trends in global climate change46, and (b) major trends in global sea level17 during the last 26 Myr, estimated from relative proportions of different oxygen isotopes. (c) Best model for temperature-dependent diversification with a positive relationship between extinction rate and palaeo-temperatures. (d) Best model for a sea level-dependent diversification with a positive relationship between extinction rate and past sea levels. Dotted lines indicate the maximum and minimum limits of the confidence interval obtained from 500 phylogenies, and the continuous line represents the average. (e) The Indomalayan-Australasian Archipelago when sea level varied in the past, and under two projections of sea-level decrease. Pictured is Ornithoptera alexandrae, a threatened species living in the coastlines of Southeast Papua New Guinea. Oligo., Oligocene; Pli., Pliocene; and Q, Quaternary. Picture of the birdwing butterfly made by Fabien Condamine. Map drawn with PowerPoint by Fabien Condamine.