Examples of three species conservation assessments
To illustrate the general patterns observed in our assessments, we provide three examples of assessments (Tables 3 and 4) from those reported in Supplement 1. Armeria maritima subsp. elongata (Hoffm.) Bonnier was selected as examples to an assessment of a Critically Endangered species that was recommended management to increase genetic diversity. Silene latifolia Poir was selected to illustrate an assessment in which management to decrease inbreeding was recommended. Achillea millefolium L. was selected to show a Least Concern species where no management was recommended.
Armeria maritima subsp. elongata is a threatened species and has been included in the UK Biodiversity Action Plan (BAP 2007) as well as England’s Biodiversity List (Natural England 2013). It is a diploid native herbaceous and perennial plant without available genetic data for its UK distribution, and usually grows in rough grasslands overlying river gravels or alluvium, formerly one site in limestone grassland, altitude 0-300 m. In Great Britain, it is Red Listed as Critically Endangered, A2a, with decline noted in its locations. In the UK, it is found in England only; and its range is declining, having been found in the 1950s in at least 12 localities of one county but now lost from all but one location due to ploughing, reseeding and agricultural improvement. Its conservation management recommendation is to increase genetic diversity as it is unlikely to have connected gene flow due to a scattered distribution and poor seed dispersal ability. It has a high risk of sampling limited diversity. The species also reproduces sexually so it is more likely to have higher differentiation and consequently has a high risk of mixing (Table 4). Given the high risk of genetic fragmentation and inbreeding in Armeria maritima, our framework recommends increasing genetic diversity through translocations. However, we emphasize that such interventions should be preceded by targeted genetic studies to confirm fragmentation levels and mitigate risks of outbreeding depression.
Silene latifolia is a Least Concern species in the UK with a probable decline in range, particularly in its western range (Leach 2019). It has been identified as a species of potential interest for ecological restoration for European grasslands and has five subspecies described and currently accepted (Ladoucer et al. 2018). Silene latifolia itself has little evidence for hybridisation, but one subspecies (S. latifolia subsp. alba) hybridises with S. dioica (L.) Clairv. creating the hybrid S. x hampeana Meusel & K.Werner (S. dioica x S. latifolia subsp. alba (Mill.) Greuter & Burdet). It is a diploid native herbaceous hemicryptophytic plant that grows on free draining mildly acidic to mildly alkaline soils, tolerant to drought and frost but intolerant to heavy metals. Connected gene flow is somewhat unlikely as despite its effective dispersal method, S. latifolia has a patchy distribution in Wales, Scotland and Ireland but is not rare throughout England. It is therefore likely to have a moderate risk of sampling limited diversity. There are also likely to be some risks associated with mixing as the species is outcrossing and occurs in divergent ecological conditions. The hybridisation of intraspecific taxa also increases this risk. This species is an example of a species with low-moderate differentiation, higher diversity and moderate-high risk of inbreeding. In this case, management to reduce inbreeding was recommended (Tables 3 and 4) while genetic information is gathered for this species.
Achillea millefolium is a Least Concern species with six subspecies described and currently accepted. Hexaploid cytotypes have been found in the UK (2n = 54), and outside of the UK diploids (2n = 28) and tetraploids (2n = 36) have been described. It is widespread; frequent and abundant where occurring. It has a soil seedbank longevity of 1-5 years; a stable range with no significant change since the 1962 Atlas Survey. It was identified as a species of potential interest for ecological restoration within European grasslands (Ladoucer et al. 2018). It grows in a range of grassland types; waysides and waste grounds; coastal sand dunes and stabilised shingle, in an altitude range of 0-1210 m (Botanical Society of the British Isles 2024b). It is likely to have connected gene flow as the species shows no evidence of fragmentation and it has an effective dispersal method. Despite reproducing sexually, the species is long-lived and common. It is therefore likely to have higher diversity and lower differentiation with a low risk of sampling limited diversity and a low risk of mixing. Based on this evidence, the species does not require management at this time (Tables 3 and 4); however, we recommend gathering genetic data to confirm these recommendations.