Wattles and Wombats: Molecular rate variation and Biodiversity Xavier Goldie The University of Auckland The Australian National University

Outline: Biodiversity and Evolution Evolutionary Speed in Australian Plants Evolutionary Speed Hypothesis Productivity and the Water-Energy Balance Outcomes Molecular rates in Mammals Diversification and molecular rates: crash course Outcomes

Biodiversity and Evolution What drives diversification? SPECIATION - EXTINCTION Why are species unevenly distributed - Spatially? Phylogenetically? Temporally?

Rodents Lagomorphs Primates + Cetartiodactyla + Carnivora + Chiroptera Shrews and stuff Xenarthra Afrotheria Metatheria

Evolutionary Speed in Australian Plants Climate and Biodiversity

Rohde’s Evolutionary Speed Hypothesis (ESH) Bromham and Cardillo 2003

Rohde’s ESH deals specifically with the relationship between global temperature and biodiversity However… Terrestrial biodiversity is linked most tightly to the interaction of temperature and the physical state of water “Water-Energy Balance” (Hawkins et al 2003) “Productivity” (Gillman and Wright, 2006)

Is Rohde’s ESH applicable to gradients of water availability?

Species RichnessRainfallProductivity

Amyema congener Amyema maidenii “Wet” “Dry”

30 Phylogenetically Independent contrasts   Branch length  Trait P.A.  Branch length  Trait

Significantly more (23 of 30) comparisons resulted in longer “Wet” branch lengths (Sign Test: P = 0.005) The rate of nucleotide substitution in “Wet” zone taxa was on average more than twice that of closely related “Dry” zone congeners (Wilcoxon Signed Rank Test: W = 93, P = 0.003). Goldie et al., 2010

Results are consistent with the evolutionary speed hypothesis Optimised water-energy balance may act to increase micro-evolutionary rates in mesic areas Arid conditions may lead to slower tempo of micro-evolution

Bromham and Cardillo 2003 Rohde’s Evolutionary Speed Hypothesis

Molecular Rates Speciation Rates Wright et al 2006 Lanfear et al In Prep Webster et al 2003 Pagel et al 2006

Molecular Rates in Mammals

What is the relationship between the rate of molecular evolution, and diversification, in mammals?

Whole Mitochondrial Genomes and Nuclear Genes Estimated Synonymous, Non-Synonymous and total substitution rates (MG94_REV_3x4 in HyPHY) Mitochondrial Sister-clades at roughly ordinal, familial and generic level Nuclear Sister-Clades in Mammalia, Eutheria, Metatheria, Euarchontoglires and Laurasiatheria Sign-Tests and Parametric Regression Included Body Size in Multiple Regression

N e and/or Selection Mutation Clade A Clade B Clade A Clade B dN  dS --  dN/dS  -- Brlen 

No consistent relationship between molecular rates and clade size - mitochondrial or nuclear Body Size Effect detected in nuclear genes, but not in mitochondrial Saturated Synonymous Rates in mitochondrial genes “RY” Coded four-fold degenerate sites - record only synonymous Transversions (T or C ↔ G or A) No relationship (Goldie et al, In Prep)

Eutheria ML Brlen versus Clade Size P = But not repeated in dN or dS

Welch et al 2007 P = Mitochondrial dS

BUT WHAT DOES IT ALL MEAN?

Lack of apparent relationship between mammalian molecular rates and diversification rates? Molecular rates are not central to the diversification process in mammals Different process operating between plants and mammals - has been suggested But why birds, and not mammals?

Gillman et al 2009 Higher rates of molecular evolution in tropical mammals versus temperate PICs Interpreted as support for Evolutionary Speed Hypothesis driving Latitudinal Species Gradients Bassariscus astustusBassariscus sumichrasti

Rohde’s ESH Bromham and Cardillo, 2003

Acknowledgements: Shane Wright Len Gillman Lindell Bromham Rob Lanfear Nga Pae O Te Maramatanga Maori Centre of Research Excellence The Australian National University

Questions?