Williams-Climate-change-refugia-for-terrestrial-biodiversity_0

5. CASE STUDY 2: PLEISTOCENE STABILITY & DIVERSITY OF
HERPETOFAUNA
5.1 Authors and contributors
Authors:
Dan F. Rosauer and Craig Moritz (Australian National University)
Contributors:
Jeremy VanDerWal, April E. Reside (James Cook University)
Renee A. Catullo (CSIRO Ecosystem Sciences & Australian National University)
5.2 Introduction
The importance of evolutionary refugia in maintaining species and lineages through
late Pleistocene climate change is well known. Understanding their location and
function is directly relevant to approaches that identify areas that may act as refugia for
biodiversity through current and anticipated climate change. Evolutionary refugia are
expected to be hotspots of both species and genetic diversity, so the ability to identify
likely refugia will help to better target areas needing further biological research or
conservation action. Evidence of the location and behaviour of refugia through past
climate change is also important for improving our understanding of the likely response
of species distributions to anticipated climate change and the effectiveness of refugia in
mitigating loss of biodiversity over the coming century.
We modelled the distribution of independent lineages within rainforest lizard species,
and identified their centres of endemism as indicators of places that may have
functioned as evolutionary refugia, retaining local diversity through late Pleistocene
climate cycles. Infraspecific endemism provides a sensitive measure of persistence,
because even where species are widespread, they may contain locally endemic
lineages which imply local persistence of the species in particular areas. In contrast,
areas which a species has occupied more recently when expanding its range from
refugia, would be expected to harbour less infraspecific diversity. We compiled a large
body of published and unpublished research on the phylogeography of lizards in
eastern Australia to model the distribution of evolutionarily distinct lineages within these
species, and identify areas of greatest lineage endemism. We also identified centres of
diversity and endemism of rainforest specialist reptiles and frogs at species level.
We also assessed the effect of changing paleo-climate over the past 120 000 years on
the distribution of rainforest on Australia’s eastern seaboard, to identify areas which
have been most continuously suitable for rainforest, and thus for the rainforest lizards.
Stability of climate since the last glacial maximum (LGM) has been shown to relate
strongly to current endemism of species (Graham et al. 2006, Davies et al. 2009) and
genetic variation within a range of species (Carnaval et al. 2009, De Mello Martins
2011) via its effect on the distribution of vegetation types.
The patchwork of rainforest areas that span Australia’s east and south-east from Cape
York Peninsula (CYP) to Tasmania provide an excellent case study for this approach.
Compared to the surrounding biomes, they represent areas which are environmentally
and compositionally distinct which, with changing climate, have varied repeatedly in
size and connectivity. We used paleo-climate models to assess climate stability of
these areas over the past 120 000 years to identify comparatively stable areas, where
climate has been most continuously suitable for rainforest, and which may function as
evolutionary refugia for rainforest specialist taxa.
Climate change refugia for terrestrial biodiversity 77