1 INTRODUCTION
Alpine environments, dominated by perennial herbs, face severe impacts
from global climate change (Seddon et al. , 2016). Global warming
has led to significant changes, such as the encroachment of woody
subalpine plants, narrowing of alpine ecosystems (Capers & Stone, 2011)
or the increase of diversity in European summits (Steinbauer et
al. , 2018). While the loss of alpine habitat could be compensated by
glacier retreatment (Whittaker, 1993; Losapio et al. , 2021), the
snowline has been wholly lost in the lower and southern mountain regions
where alpine plants are currently refuged in their ridges and peaks
facing potential local extinction (Rumpf et al. , 2022). Global
warming also affects alpine plant reproduction, including
plant-pollinator interactions (Inouye, 2020) and seed germination
(Mondoni et al. , 2012). Moreover, human disturbance in
mountainous areas, such as civil infrastructures or recreation
resources, leads to alpine habitat fragmentation and quality decline
(Winkler, 2020; Chardon et al. , 2023). Therefore, alpine
ecosystems and their species are considered vulnerable to environmental
changes (Schwager & Berg, 2019).
By 2100, 36-55% of the alpine species in European mountains are
predicted to lose more than 80% of their habitats (Inouye, 2020).
However, limited information is available regarding the current
conservation status of many European alpine species, such as those
included in the Androsace L. section Aretia (L.). SectionAretia includes narrow endemics with low dispersal ability
(Anderberg & Kelso, 1996), with 34 recognized species (Boucher et
al. , 2021) mainly distributed in the ”European Alpine System” (Ozenda,
1995). Only a handful of Aretia species have undergone threat
assessments (Fasciani & Pace, 2015; Eustacchio et al. , 2023). In
Spain, Androsace cantabrica (Losa & P. Monts.) Kress has been
included in the list of priority species for conservation (Moreno Saizet al. , 2008).
Androsace cantabrica is an endemic species to the central region
of the North Iberian Cordillera Cantábrica (Fig. 1A; Kress, 1997). It is
a perennial, monoecious, and allogamous plant with small, densely
clustered rosettes. The stem is usually less than 5cm long, and the
flower corolla is deep pink (Figs. 1B and C; Kress, 1997).Androsace cantabrica is known to occur in seven localities;
however, population size estimates are only known in four of them (Fig.
1A, in red), with less than 6,000 individuals estimated across 20 1x1km
UTM quadrats (Baudet et al. (2004). This species is found on
siliceous or acidic substrates in mountainous areas above 2000m,
typically in ridges, and often associated with low shrubs or pastures
(Tejero et al. , 2022). The central distribution core is centred
around the Tres Mares area, partially overlapping with the Alto Campoo
ski resort. All population sites have traditionally been subjected to
controlled burning to promote pasture development. Global warming will
likely affect its reproductive output, like Tejero et al. (2022)
observed lower germination rates in experiments with warmer
temperatures. Baudet et al. (2004) proposed to categoriseA. cantabrica as ”Endangered” in the Spanish Red List, later
confirmed by Moreno Saiz et al. (2008). However, A.
cantabrica is not an accepted species name
(https://powo.science.kew.org/, accessed 14th July 2024); instead,
it is treated as a synonym of A. adfinis subsp. adfinis Biroli. This taxonomic uncertainty has conservation implications because
the European conservation framework does not consider it a species, thus
not categorised as threatened. Scientific evidence is urgently needed to
resolve this taxonomic conflict as a first step to provide effective
conservation (Godfray et al. , 2004).
Molecular phylogenetics has emerged as a crucial tool for addressing
taxonomic challenges (de Queiroz & Gauthier, 1992), and its resolution
has greatly enhanced with the advent of high-throughput sequencing
methodologies (Campos et al. , 2023). However, attempts to clarify
species boundaries in this complex of Androsace species were
mostly based on traditional molecular approaches. Previous morphological
studies suggested that A. cantabrica was closely related toA. laggeri A.Huet (Kress, 1997). Genetic data using different
molecular markers, such as the plastid trn L-F region and the
internal transcribed spacer (ITS, Schneeweiss et al. , 2004),
amplified fragment length polymorphism (AFLPs, Dixon et al. ,
2008), and double digest restriction-site associated DNA (ddRAD-seq,
Boucher et al. , 2021), proposed that A. cantabrica andA. adfinis are sister taxa, forming a cantabrica-adfinis clade sister to a clade formed by A. halleri L. and A.
laggeri (/halleri clade hereafter), but with low bootstrap
support. However, a more recent phylogenetic tree reconstructed
with full plastome sequences suggests that the clade formed by A. cantabrica and A. adfinis is not sister to the /halleri
clade (Smyčka et al., 2022). Therefore, the evolutionary
relationships among the Iberian Androsace section Aretia taxa and A. adfinis remain uncertain and still need to be
resolved.
Targeted sequencing using the universal Angiosperms353 probe set can
generate hundreds of homologous low-copy nuclear loci sequences,
establishing it as a powerful tool in plant evolutionary studies
(Johnson et al. , 2019). This approach is cost-effective and
allows the use of herbarium materials in phylogenomic analysis (Breweret al. , 2019). Nuclear genes can yield a distinct phylogenetic
topology compared to plastid genes (Stubbs et al. , 2023). By
combining these two genomic sources, researchers can explore reticulate
evolution and potential hybrid origins more effectively (Vriesendorp &
Bakker, 2005). However, most previous studies using Angiosperms353 data
have primarily focused on clade boundaries at the genus, family, and
order levels (e.g., Nepenthes (Nepenthaceae), Murphy et
al. , 2020; Gentianales, Antonelli et al. , 2021; Primulaceae,
Larson et al. , 2023), with few addressing species-level taxonomic
conflicts (e.g., Campos et al. , 2023). In addition to its
application in phylogenomics, Angiosperms353 data can be utilised in
population genetic studies (Slimp et al. , 2021), which is
invaluable for designing effective conservation plans for threatened
species (Liu & Zhao, 1999; Xiong et al. , 2024). Compared to
RAD-Seq (Davey & Blaxter, 2010), Angiosperms353 offers a more
cost-effective alternative with reduced missing data, and it can be used
in plants with different genome sizes (Slimp et al. , 2021).
However, to our knowledge, the application of Angiosperms353 in
practical conservation genetics has yet to be reported.
Our research objectives are threefold: to clarify the taxonomic status
of A. cantabrica using nuclear Angiosperms353 loci and plastid
data; to evaluate its threatened status and IUCN category; and to
provide conservation recommendations for A. cantabrica based on
population genetics analysis. This approach will also enable us to
evaluate the effectiveness of Angiosperms353 in conservation genetics
research.