Past responses to environmental change provide vital baseline data for estimating
the potential resilience of extant taxa to future change. Here, we investigate the
latitudinal range contraction that terrestrial and fresh-water turtles (Testudinata)
experienced from the Late Cretaceous to the Paleogene (100.5-23.03 mya) in response
to major climatic changes. We apply ecological niche modeling (ENM) to reconstruct
turtle niches, using ancient and modern distribution data, paleogeographic reconstructions,
and the HadCM3L climate model to quantify their range shifts in the Cretaceous and
late Eocene. We then use the insights provided by these models to infer their probable
ecological responses to future climate scenarios at different represen-tative concentration
pathways (RCPs 4.5 and 8.5 for 2100), which project globally increased temperatures
and spreading arid biomes at lower to mid-latitudes. We show that turtle ranges are
predicted to expand poleward in the Northern Hemisphere, with decreased habitat suitability
at lower latitudes, inverting a trend of latitudinal range contraction that has been
prevalent since the Eocene. Trionychids and freshwater turtles can more easily track
their niches than Testudinidae and other terrestrial groups. However, habitat destruc-tion
and fragmentation at higher latitudes will probably reduce the capability of turtles
and tortoises to cope with future climate changes.
