Summary Large intraspecific functional trait variation strongly impacts many aspects of communities and ecosystems, and is the medium upon which evolution works. Yet intraspecific trait variation is inconsistent and hard to predict across traits, species and locations. We measured within‐species variation in leaf mass per area (LMA), leaf dry matter content (LDMC), branch wood density (WD), and allocation to stem area vs leaf area in branches (branch Huber value (HV)) across the aridity range of seven Australian eucalypts and a co‐occurring Acacia species to explore how traits and their variances change with aridity. Within species, we found consistent increases in LMA, LDMC and WD and HV with increasing aridity, resulting in consistent trait coordination across leaves and branches. However, this coordination only emerged across sites with large climate differences. Unlike trait means, patterns of trait variance with aridity were mixed across populations and species. Only LDMC showed constrained trait variation in more xeric species and drier populations that could indicate limits to plasticity or heritable trait variation. Our results highlight that climate can drive consistent within‐species trait patterns, but that patterns might often be obscured by the complex nature of morphological traits, sampling incomplete species ranges or sampling confounded stress gradients.

Aridity drives coordinated trait shifts but not decreased trait variance across the 1 geographic range of eight Australian trees 2 3 4 5 Abstract: 58Context: Large intraspecific functional trait variation strongly impacts many aspects of natural 59 communities and ecosystems, yet is inconsistent across traits and species. 60Approach: We measured within-species variation in leaf mass per area (LMA), leaf dry matter 61 content (LDMC), branch wood density (WD), and allocation to stem area vs. leaf area in 62 branches (branch Huber value, HV) across the aridity range of seven Australian eucalypts and an 63Acacia species to explore how traits and their variances change with aridity. 64 Results and Conclusions:Within-species, we found consistent increases in LMA, LDMC and 65 WD, and HV with increasing aridity, resulting in consistent trait coordination across tissues. 66However, this coordination only emerged across sites with large climate differences. Unlike trait 67 means, patterns of trait variance with aridity were mixed across populations and species and 68 showed limited support for constrained trait variation in dryer populations or more xeric species. 69 Synthesis:Our results highlight that climate can drive consistent within-species trait patterns, 70 but that these patterns might often be obscured by the complex nature of morphological traits and 71 sampling incomplete species ranges or sampling confounded stress gradients. 72 73 74 John et al. 2017). The ratio of stem sapwood area to leaf area or Huber value (HV) reflects the 129 balance of hydraulic supply (sapwood area) relative to hydraulic demand (leaf area), with high 130