EAPSI:Assessing Seed Dispersal Limitation as a Cause of Abrupt Treelines in New Zealand

Johnson Jeremy S, Bryan TX

Investigators

Abstract

This research will identify if seed dispersal at New Zealand alpine treelines is limited and a cause of their abrupt and striking form. The abrupt alpine treeline in New Zealand is a system that has experienced warming over the last 50 years without a corresponding change in alpine treeline position. In a closely linked vegetation-climate system, we would expect that the treeline should track climate relatively closely over periods as short as a decade. Unlike animals that can respond quickly to changing environmental conditions, plants are fixed in space and must respond inter-generationally through seed dispersal. This research will address the issue by 1) characterizing gene flow at mountain beech treelines and 2) assessing the degree to which the treeline is dispersal limited resulting in their abrupt form. The research will analyze genomic data allowing the researchers to dissect genetic similarity between treeline forming individuals and forest individuals below, teasing apart the ecological factors influencing dispersal and the potential for treelines to track future climate variation. This research will be conducted in collaboration with New Zealand researchers Dr. Brad Case at Lincoln University and Dr. Ellen Cieraad at Landcare Research, both experts on New Zealand treeline dynamics. Specifically, a genotyping by sequencing approach, double digest restriction site associated DNA discovery, will be used to simultaneously sequence and identify highly informative molecular markers, single nucleotide polymorphisms, across the mountain beech (Nothofagus solandri var. cliffortioides (Hook.f.) Poole.) genome. Genome wide datasets are rare in forest species but next generation sequencing is allowing large genomic regions to be analyzed efficiently. The genomic variation will be assessed along three elevational transects to identify if seed dispersal limitation is a cause of abrupt alpine treelines. This NSF EAPSI award is funded in collaboration with the Royal Society of New Zealand.