Seed provenance for changing climates: early growth traits of nonlocal seed are better adapted to future climatic scenarios, but not to current field conditions

Abstract

The urgency to repair degraded ecosystems is challenged by the need to future-proof populations to deal with changing climates. Therefore, it is necessary to know if source gene-pools are resilient to both current and future climatic conditions. We tested this question with the pioneer shrub 'Hardenbergia violacea' (Fabaceae), an important species for restoration in eastern Australia. We evaluated in situ and ex situ performance of seed from eight provenances, two local and six from regions receiving hotter and wetter spring to autumn conditions and/or drier winters and we included wild and commercial collections. We compared survivorship of seedlings in climate-houses that emulated current and predicted temperature and rainfall. In the field, we measured germination and seedling survivorship. We used neutral codominant markers to provide inbreeding and heterozygosity estimates to evaluate against health and survivorship. All provenances survived the current conditions, but local provenances were the poorest performers in the predicted hotter and wetter scenario compared with nonlocal provenances. No provenance survived more than a fortnight of a climate-house simulated, but predicted, extreme weather event of a drought (35/22°C 12 hours day/night, 50 mL/week=220mm rainfall). Heterozygosity was positively associated with plant health in surviving plants, and plants in poor condition had high inbreeding estimates. In the field, nonlocal provenances performed poorly and most survivors were from local provenances. The contribution of individual genetic variation to stress tolerance will be an important consideration when selecting provenances for future climates.