Molecular evidence of species- and subspecies-level distinctions in the rare Orchis patens s.l. and implications for conservation

Abstract

Characterizing genetic diversity and structure of populations is essential for the effective conservation of threatened species. Orchis patens sensu lato is a narrowly distributed tetraploid species with a disjunct distribution (i.e., Northern Italy, North Africa and the Canary Islands), which is facing a severe decline. In this study, we evaluated levels of genetic diversity and population structuring using 12 new nuclear microsatellite markers. Our analyses of genetic differentiation based on multiple approaches (Structure analysis, PCA analysis, and F-statistics using the ploidy-independent Rho-index) showed that gene flow is low across the range of O. patens s.l., particularly in the Canary Islands. Clear differences in allele frequencies between Italy, Algeria and the Canary Islands underlie the genetic differentiation retrieved. Our study provides support for the recognition of O. canariensis as a sister species to O. patens and the separation of the Italian populations as a new subspecies of O. patens. Despite the high heterozygosity values found in all populations (ranging from 0.4 to 0.7), compatible with the tetraploid status of the species, small population sizes and reduced gene flow will be likely detrimental for the different populations in the long term, and we recommend immediate conservation actions to counteract further fragmentation and population decline.

Microsatellites and petal morphology reveal new patterns of admixture in Orchis hybrid zones

“…The 11 newly isolated microsatellites in this study, alongside the set of loci for Orchis subgenus Masculae developed in parallel by Calevo et al (2021), are the first nuclear microsatellite markers characterized in the genus Orchis. Our molecular and morphological data collectively indicate that contemporary hybridization has occurred in O. militaris-O.…”

“…The 11 newly isolated microsatellites in this study, alongside the set of loci for Orchis subgenus Masculae developed in parallel by Calevo et al (2021)…”

“…The 11 newly isolated microsatellites in this study, alongside the set of loci for Orchis subgenus Masculae developed in parallel by Calevo et al (2021) Table S3. Characteristics and PCR amplification conditions of loci isolated from Orchis species.…”

Little hope for the polyploid endemic Pyrenean Larkspur (Delphinium montanum): Evidences from population genomics and Ecological Niche Modeling

“…Thus, species endemic to specific mountain ranges represent a major conservation issue, if only for their heritage interest. It is critical to characterize the distribution of genetic diversity within‐ and between‐ their populations to evaluate the inbreeding risk and study population structure to better understand how isolated they really are, in order to undertake effective conservation actions (Calevo et al, 2021).…”

Little hope for the polyploid endemic Pyrenean Larkspur (Delphinium montanum): evidences from population genomics and Ecological Niche Modelling

“…Thus, species endemic to specific mountain ranges represent a major conservation issue, if only for their heritage interest. It is critical to characterize the distribution of genetic diversity within- and between-their populations to evaluate the inbreeding risk and study population structure to better understand how isolated they really are, in order to undertake effective conservation actions (Calevo et al 2021).…”