IAP2-22-387

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). Native but non-dominant species are recommended from the perspective of successful establishment without becoming invasive (3, 4). However, species choices are frequently prioritised by aesthetic considerations such as the popular “annual cornfield” mixes offered in the UK consisting of poppies, corn chamomile, corncockle, cornflower, corn marigold and campion. Naturally occurring populations of some of these cornfield specialists are very rare due to modern herbicide use and are greatly outnumbered by planted populations. Little is known about the ecological impact of these plantings.
Focusing on red campion (Silene dioica), natural populations show genetic differentiation at relatively small scales due to natural barriers in Sweden (4). Local adaptation and reduced fitness of hybrids between native and foreign parents has been demonstrated for this species in Switzerland (5). Hybridization with closely related white campion (Silene latifolia) also results in reduced fitness hybrids (6)
This project will quantify genetic differentiation and local adaptation and ecological benefits of red campion and/or other popular wildflower seed mix species originating from commercially available seed mixes and natural populations across the UK and Europe to determine the suitability of current wildflower seed mixes for use in conservation and restoration projects and to guide best-practise with evidence-based results.

Methodology

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. We have already identified red campion as a suitable focus, but 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 selected local and non-local populations will be grown in a common garden at Durham Botanic Garden to measure the extent of local adaptation in Northern UK and to compare ecological benefits such as pollinator and soil biodiversity. The experiment will be repeated during multiple growing seasons to allow for the influence of weather variation.
Genomic resources for focal species will be explored for genetic markers for population genetic analysis. Samples will be genotyped with multiple genetic markers to measure and compare genetic diversity and genetic differentiation and to determine any genetic associations with ecological variables measured in the field trials.

Project Timeline

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.

Training
& Skills

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.

References & further reading

(1) Dively et al. 2020 Ecol. Eng. 144:105703 https://doi.org/10.1016/j.ecoleng.2019.105703
(2) Aldrich 2002 Native Plants J. 3:67 https://doi.org/10.3368/npj.3.1.67
(3) https://www.plantlife.org.uk/application/files/4614/8483/5178/Keeping_the_wild_in_wildflower_FAQ_WEB.pdf
(4) Giles et al. 1998 Heredity 80:715 https://doi.org/10.1046/j.1365-2540.1998.00348.x
(5) Keller et al. 2000 J. Appl. Ecol. 37:647 https://doi.org/10.1046/j.1365-2664.2000.00517.x
(6) Karrenberg & Favre 2008 Evolution 62:763 https://doi.org/10.1111/j.1558-5646.2008.00330.x

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