IAP2-23-087

The importance of location of origin for wildflower seed mixes

Wildflower seed mixes have been popularised as an ecologically conscientious way for the public to preserve native flora and their associated pollinators (1). Beyond gardens, larger scale planting of wildflowers are increasingly added to public landscaping schemes, such as roadsides and parks (2). New farming subsidies for environmental land management schemes (ELMs) linked to increasing biodiversity on set-aside land might make this practise even more widespread soon (3). However, species choices are frequently prioritised by aesthetic and horticultural considerations rather than their ecology and restorative roles (4) and demand is such that seeds are often produced on farms at a commercial scale rather than over-harvesting from the wild (5). However, when mass-produced and sown without consideration of local provenance, wildflower species will experience selection for non-adaptive traits such as large size, long flowering time, and seed retention (4, 6) that negates and homogenises within-species local adaptation (7, 8). The evolutionary and ecological impacts of these plantings need to be studied in a UK context.
This project will develop case studies of focal wildflower species that are frequently planted in the UK to quantify the genetic differentiation, local adaptation, and ecological impacts of naturally established populations compared to commercial sources of these species. We hypothesise that rare or specialist species are more vulnerable to genetic swamping or mal-adaptive gene flow. Therefore, a mix of contrasting species will be considered from relatively common red campion to the meadow grassland hemi-parasite yellow-rattle. We will compare populations of these mix species originating from commercially available seed mixes and natural populations from across the UK to determine the suitability of current wildflower seed mixes for use in conservation and restoration projects and to guide best-practise for UK wildflower restoration with evidence-based results.

A review will be conducted to gather published sources of evidence for the consequences and importance of location of origin of translocated meadow species. Data will be collected in a carefully planned and systematic way in order to perform a metastudy of the available evidence.
Suitable focal species will be chosen for additional study based on criteria related to popularity in UK wildflower mixes, range distribution that is likely to include plantings outside of the typical range, results from previous studies in this field, and existing resources for research. Pilot studies have already been performed for red campion and additional case study species will also be included to increase the general applicability of the study.
Field work and sample requests will be conducted to build suitable study collections of focal species representing seed from multiple commercially available wildflower mixes and native populations from throughout the UK range and beyond.
Seed from distant and local natural populations, and populations from commercial sources will be grown in a common garden at Durham Botanic Garden and a Plantlife site elsewhere in the UK to measure trait differences potentially related local adaptation or recent domestication. Ecological benefits of pollinator attractiveness and soil biodiversity will be compared between natural and commercial plots. The experiment will be repeated during multiple growing seasons to allow for the influence of weather variation.
Population genomics techniques will be applied to sample populations and commercial sources of each species to measure and compare genetic diversity and genetic differentiation. Genetic tests for local adaptation will be applied by searching for genetic associations with traits measured in the field trials and between population of origin characteristics and climate.

Year 1

The systematic review and associated meta study will be conducted. The results will be written up into a publication. Focal species will be confirmed and targeted fieldwork will be conducted to complete range gaps in sample collections that cannot be filled through seed requests. Genomic resources for focal species will be explored and initial tests of genetic markers performed. Field trials will be planned and a small-scale pilot study conducted to assess feasibility and to troubleshoot.

Year 2

Any remaining gaps in sample collections will be filled. Developed genetic markers will be used to genotype the sample collections. A full scale field trial will be performed measuring plant fitness traits and associated soil and invertebrate biodiversity will be assessed using environmental genomics approaches.

Year 3

Population genetics analysis will be performed. Field trial results will be analysed. Combined genetics and environment analyses will be performed. A second full-scale field trial will be performed.

Year 3.5

New data from the final year will be incorporated into existing analyses. Research publications will be completed for submission.

This project will provide practical experience in the fields of molecular genetic analysis and ecological approaches. It will generate valuable perspectives on restoration and conservation that are transferable to the wider environmental sector.