Diversification and trait evolution in New Zealand woody lineages across changing biomes

Abstract

Diversification of woody plant lineages in New Zealand has unfolded in complex physiographic, climatic, and environmental contexts. Many tree and shrub lineages have existed in New Zealand since the late Cenozoic when Forest was the dominant biome, subsequently diversifying (or continuing to diversify) during the Pliocene/Pleistocene as Open (below treeline) and Alpine biomes emerged. We examine the links between biomes occupied, traits, and diversification. In particular, whether traits are phylogenetically conserved or ecologically constrained and their relationship to biomes occupied. We focus on Melicytus, Myrsine and Pseudopanax which occur across Forest, Open, and Alpine biomes. Our approach combines measured traits and modelled niche traits of extant species to examine the importance of biome occupancy and biome shifts on trait evolution in these lineages. Our results demonstrate trait values are filtered by biomes in these lineages and can predict biomes occupied. However, few biome shifts were associated with trait evolution, typically only biome shifts into extreme environments (Alpine) involved trait innovations. In addition to biomes, trait evolution can also be influenced by species age, trait lability and broad climatic change. Integrating functional traits in a phylogenetic framework can identify how evolutionary and ecological features create modern biogeographic patterns in New Zealand.