Testing the niche breadth-range size hypothesis: habitat specialization versus performance in Australian alpine daisies

Relatively common species within a clade are expected to perform well across a wider range of conditions than their rarer relatives, yet experimental tests of this “niche breadth—range size” hypothesis remain surprisingly scarce. Rarity may arise due to trade-offs between specialization and performance across a wide range of environments. Here we use common garden and reciprocal transplant experiments to test the niche breadth—range size hypothesis, focusing on four common and three rare endemic alpine daisies (Brachyscome spp.) from the Australian Alps. We used three experimental contexts: 1) alpine reciprocal seedling experiment: a test of seedling survival and growth in three alpine habitat types differing in environmental quality and species diversity, 2) warm environment common garden: a test of whether common daisy species have higher growth rates and phenotypic plasticity, assessed in a common garden in a warmer climate and run simultaneously with experiment 1, and 3) alpine reci...