Mass turnover and recovery dynamics of a diverse Australian continental radiation

Abstract

Trends in global and local climate history have been linked to observed macroevolutionary patterns across a variety of organisms. These climatic pressures may unilaterally or asymmetrically influence the evolutionary trajectory of clades. To test and compare signatures of changing global (Eocene-Oligocene boundary cooling) and continental (Miocene aridification) environments on a continental fauna, we investigated the macroevolutionary dynamics of one of Australia's most diverse endemic radiations, pygopodoid geckos. We generated a time-calibrated phylogeny (>90% taxon coverage) to test whether (i) asymmetrical pygopodoid tree shape may be the result of mass turnover deep in the group's history, and (ii) how Miocene aridification shaped trends in biome assemblages. We find evidence of mass turnover in pygopodoids following the isolation of the Australian continental plate ∼30 million years ago, and in contrast, gradual aridification is linked to elevated speciation rates in the young arid zone. Surprisingly, our results suggest that invasion of arid habitats was not an evolutionary end point. Instead, arid Australia has acted as a source for diversity, with repeated outward dispersals having facilitated diversification of this group. This pattern contrasts trends in richness and distribution of other Australian vertebrates, illustrating the profound effects historical biome changes have on macroevolutionary patterns.

Diversification across biomes in a continental lizard radiation

“…; Oliver et al. ; Brennan and Oliver ). Habitat use appears to be more plastic, with several shifts between rocks and trees (generalists) inferred in the main AAZ clade.…”

“…Biogeographic analyses indicate that there has been relatively little movement between biomes, a pattern that contrasts with several other codistributed lineages Oliver et al 2014a;Brennan and Oliver 2017). Habitat use appears to be more plastic, with several shifts between rocks and trees (generalists) inferred in the main AAZ clade.…”

Diversification rates are more strongly related to microhabitat than climate in squamate reptiles (lizards and snakes)

“…). On the other hand, an analysis of Australian geckoes found higher diversification rates in arid regions (Brennan and Oliver ), but this result may be quite atypical given that Australia is dominated by arid regions (unlike the rest of the world). Nevertheless, this might be a useful topic to explore further in future analyses.…”

“…Detailed analyses of the most species-rich group of North and Middle American lizards (Phrynosomatidae), which have higher richness in more arid regions, found no evidence that drier climates promoted diversification ). On the other hand, an analysis of Australian geckoes found higher diversification rates in arid regions (Brennan and Oliver 2017), but this result may be quite atypical given that Australia is dominated by arid regions (unlike the rest of the world). Nevertheless, this might be a useful topic to explore further in future analyses.…”

Increased diversification rates are coupled with higher rates of climate space exploration in Australian Acacia (Caesalpinioideae)

“…At that time only the north-west displayed aridity, though central Australia likely had seasonal dryness (Martin, 2006;Huber & Goldner, 2012). Since the Eocene, Australia's climate has progressively dried, presenting ecological opportunities and resulting in spectacular radiations within one or more of the Australian biomes (Crayn et al, 2006;Rabosky et al, 2007;Crisp et al, 2009;Sanders et al, 2008;Watanabe et al, 2006;Catullo & Keogh, 2014;Toon et al, 2015;Lamont et al, 2016;Brennan & Oliver, 2017). For example, Australian rainforests now occupy a small fraction of their former extent, and many rainforest lineages are now extinct (Hill et al, 1999;Martin, 2006;Byrne et al, 2008Byrne et al, , 2011.…”