No abstract

Sympatric tree species are subject to similar climatic drivers, posing a question as to whether they display comparable adaptive responses. However, no study has explicitly examined local adaptation of co‐occurring parasitic and autotrophic plant species to the abiotic environment. Here we test the hypotheses that a generalist parasitic tree would display a weaker signal of selection and that genomic variation would associate with fewer climatic variables (particularly precipitation) but have similar spatial patterns to a sympatric autotrophic tree species. To test these hypotheses, we collected samples from 17 sites across the range of two tree species, the hemiparasite Nuytsia floribunda (n = 264) and sympatric autotroph Melaleuca rhaphiophylla (n = 272). We obtained 5,531 high‐quality genome‐wide single nucleotide polymorphisms (SNPs) for M. rhaphiophylla and 6,727 SNPs for N. floribunda using DArTseq genome scan technology. Population differentiation and environmental association approaches were used to identify signals of selection. Generalized dissimilarly modelling was used to detect climatic and spatial patterns of local adaptation across climatic gradients. Overall, 322 SNPs were identified as putatively adaptive for the autotroph, while only 57 SNPs were identified for the parasitic species. We found genomic variation to associate with different sets of bioclimatic variables for each species, with precipitation relatively less important for the parasite. Spatial patterns of predicted adaptive variability were different and indicate that co‐occurring species with disparate life history traits may not respond equally to selective pressures (i.e., temperature and precipitation). Together, these findings provide insight into local adaptation of sympatric parasitic and autotrophic tree species to abiotic environments.

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Restoration interventions require knowledge on the suitability of seed sources. Provenance delineation for ecological restoration of degraded environments has begun to incorporate genome-wide information on adaptive variation, but this has only been completed on a small number of plant species. Rarely is provenance delineation using a genomics approach applied to species occurring across different habitats, and in the context of future climate scenarios, despite their potential importance for successful long-term restoration. Here, we use neutral genetic data to investigate patterns of genetic differentiation and a landscape genomics approach to model putatively adaptive genetic variation under multiple climate scenarios for two species cooccurring in a predominantly mesic environment, and two species co-occurring in a semi-arid environment. We then determine the genetic similarity of seed sourcing locations to hypothetical restoration sites, both under current and future climate scenarios. We found that the geographical extent of provenances and the amount of genetic change required to track the projected climatic conditions over time differed within the pairs of co-occurring species, and between habitats. Additionally, future climate scenarios had differing effects on provenance patterns between the two landscapes indicating a differential response to changing climate between species from mesic and arid habitats. This implies that provenance guidelines can be both species and habitat dependent. We discuss how these results can be utilized to design seed sourcing strategies for successful restoration, and how these methods could be more broadly applied to delineate provenances of other species and locations.

No abstract