Conserving on the edge: genetic variation and structure in northern populations of the endangered plant Dracocephalum ruyschiana L. (Lamiaceae)

Abstract

Loss of biodiversity is accelerating, including the loss of genetic diversity. Conservation of small, isolated populations may be important, as they can provide valuable contributions to overall genetic variation and long-term viability of species. Furthermore, such populations may play an essential role in adaptation to new environments following changes in e.g. land-use and climate. Dracocephalum ruyschiana is a threatened plant species throughout its European distribution, but 25% of the European populations are situated within Norway. Therefore, the species has its own action plan in Norway, which includes demographic monitoring. However, this monitoring does not cover genetic variation nor is the selection of monitored populations based on genetic differentiation, therefore this fundamental level of biodiversity is overlooked. We analyzed 43 sites using 96 SNPs developed for D. ruyschiana, to investigate whether the monitored populations cover the genetic variation and differentiation found within the Norwegian distribution. The results show structuring and differentiation between populations and indicate that there are at least four distinct genetic groups, of which only two are covered extensively by current demographic monitoring. We suggest that two sites representing the two other genetic groups should be included in the national monitoring program to better conserve the genetic variation found in the Norwegian population of D. ruyschiana. Overall, our results highlight the importance of an integrated, interdisciplinary framework to better monitor and conserve biodiversity at several levels.

Spatiotemporal monitoring of the rare northern dragonhead (Dracocephalum ruyschiana, Lamiaceae) — SNP genotyping and environmental niche modeling herbarium specimens

“…Northern dragonhead is a diploid (2 n = 2 x = 14), insect‐pollinated, perennial herb (Fægri & Danielsen, 1996 ; Kyrkjeeide et al, 2020 ). It grows from a rhizome with limited vegetative branching, resulting in small clones of about 30‐cm‐tall stems with multi‐flowered racemes.…”

“…An average fruit set rate of 0.27 has been reported for 20 populations in Sweden (Milberg & Bertilsson, 1997 ). Seeds are dry nutlets lacking modifications for long‐distance dispersal and, hence, most likely are passively dispersed (Kyrkjeeide et al, 2020 ; Solstad et al, 2021 ).…”

“…(2) The abundance availability of specimens through time and space in Norwegian herbaria. (3) The availability of a 96 SNP microfluidic array for northern dragonhead (Kleven et al, 2019 ), which had already been used for analyzing contemporary samples from Norway (Kyrkjeeide et al, 2020 ). And, (4) the species' high level of priority in Norway, being threatened by habitat loss.…”

“…And, (4) the species' high level of priority in Norway, being threatened by habitat loss. Kyrkjeeide et al ( 2020 ) added a genomic level to the monitoring regime of northern dragonhead in Norway. They found that only two of the revealed genetic groups were covered by the demographic monitoring and conservation efforts at the time.…”

Do marginal plant populations enhance the fitness of larger core units under ongoing climate change? Empirical insights from a rare carnation

“…Plant populations isolated at the margin of the geographic range can greatly contribute to local biodiversity and to the evolutionary potential of species (e.g. Pfeifer et al 2010 ; Kyrkjeeide et al 2020 ); therefore, they often inspired the interest of conservation and evolutionary biologists. The effects of geographical marginality vary substantially across species ( Pfeifer et al 2009 ; Abeli et al 2015 ), as a function of the ecological relationships between central and peripheral sites (i.e.…”