Assessing the impacts of climate change on amphibians

Climatic changes have had profound impacts on species distributions throughout time. In response, species
have shifted ranges, adapted genetically and behaviourally or become extinct. Using species distribution
models, we examined how changes in suitable climatic space could affect the distributions of 37 endemic
frog species in the Cape Floristic Region (CFR) – an area proposed to have evolved its megadiversity under
a stable climate, which is expected to change substantially in future. Species distributions were projected
onto mean climate for a current period (1950 to 2000), hindcasted to palaeoclimate (Last Glacial Maximum;
LGM ≈ 21 kya and Holocene Glacial Minimum; HGM ≈ 6 kya) and forecasted for two emissions scenarios
(A2a and B2a) for the year 2080. We then determined the changes in area sizes, direction (longitude
and latitude), fragmentation index and biotic velocity, and assessed if these were affected by life-history
traits and altitude. We found that the biotic velocity at which the CFR amphibian community is expected to
shift north (A2a ≈ 540.5 km/kya) and east (B2a ≈ 198 km/kya) far exceeds historical background rates
(≈1.05 km/kya, north and west ≈ 2.36 km/kya since the LGM). Our models further suggest that the CFR
amphibian community has already lost about 56% of suitable climate space since the LGM and this loss is
expected to accelerate under future emission scenarios (A2a ≈ 70%; B2a ≈ 60%). Lastly, we found that
highland species were more fragmented than lowland species between the LGM and current period, but that
the fragmentation of lowland species between current and future climates is expected to increase.