Diversification across biomes in a continental lizard radiation.

Area of Science:

• Evolutionary Biology
• Ecology
• Herpetology

Background:

• Ecological opportunity is a known driver of evolutionary diversification.
• Alternatively, topographic or environmental heterogeneity may generate and sustain diversity.
• The Gehyra variegata lizard group in Australia provides a model to test these hypotheses.

Purpose of the Study:

• To explore the drivers of evolutionary diversification in the Gehyra variegata lizard group.
• To investigate the roles of ecological opportunity versus environmental heterogeneity in lineage diversification.
• To resolve the evolutionary relationships and diversity patterns within the Australian arid zone (AAZ) Gehyra.

Main Methods:

• Phylogenomic data and coalescent analyses were used to resolve lineages and relationships in the AAZ taxa.
• Comparative analysis of diversification rates between the Australian monsoonal tropics (AMT) and AAZ.
• Morphological and geographic range comparisons between rock-dwelling and generalist taxa.

Main Results:

• The AMT and AAZ radiations represent separate evolutionary events with similar speciation rates.
• High lizard diversity was found in the western AAZ (Pilbara region), with most taxa restricted to rocks.
• Rock-dwelling and generalist taxa exhibit morphological differences, but accelerated evolution was only observed in lineage-poor central AAZ taxa.

Conclusions:

• Environmental heterogeneity and refugial dynamics appear to be more significant drivers of lineage diversity than ecological release in this lizard group.
• Lineage and morphological diversity are not always correlated.
• The findings challenge the universal applicability of the ecological opportunity hypothesis for diversification.