J Plant Ecol ›› 2017, Vol. 10 ›› Issue (4): 649-659.

• Research Articles •

### Population isolation shapes plant genetics, phenotype and germination in naturally patchy ecosystems

Laurent De Vriendt1,2,5, Marc-André Lemay1, Martine Jean1,3, Sébastien Renaut2,4, Stéphanie Pellerin2,4,5, Simon Joly2,4,5, François Belzile1,3 and Monique Poulin1,2,*

1. 1 Département de Phytologie, Faculté des Sciences de l'Agriculture et de l'Alimentation, Université Laval, 2425 rue de l'agriculture Québec, Québec G1V 0A6, Canada; 2 Québec Center for Biodiversity Science, Department of Biology, McGill University, Stewart Biology Building, 1205 Dr. Penfield Avenue, Montréal H3A 1B1, Canada; 3 Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, 1030 avenue de la Médecine, Québec G1V 0A6, Canada; 4 Institut de recherche en biologie végétale, Département des Sciences biologiques, Université de Montréal, 4101 Sherbrooke Est, Montréal H1X 2B2, Canada; 5 Jardin botanique de Montréal, 4101 Sherbrooke Est, Montréal H1X 2B2, Canada
• Received:2016-02-01 Accepted:2016-07-03 Published:2017-07-24
• Contact: De Vriendt, Laurent

Abstract: Aims Habitat connectivity is important in conservation since isolation can diminish the potential of a population for adaptation and increase its risk of extinction. However, conservation of naturally patchy ecosystems such as peatlands has mainly focused on preserving specific sites with exceptional characteristics, neglecting the potential interconnectivity between patches. In order to better understand plant dynamics within a peatland network, we assessed the effect of population isolation on genetic distinctiveness, phenotypic variations and germination rates using the peatland-obligate white-fringed orchid (Platanthera blephariglottis).
Methods Fifteen phenotypic traits were measured for 24 individuals per population (20 distinct populations, Quebec, Canada) and germination rates of nearly 20000 seeds were assessed. Genetic distinctiveness was quantified for 26 populations using single nucleotide polymorphism markers obtained via a pooled genotyping-by-sequencing approach. Geographic isolation was measured as the distance to the nearest population and as the number of populations occurring in concentric buffer zones (within a radius of 2, 5 and 10 km) around the studied populations.
Important findings All phenotypic traits showed significant differences among populations. Genetic results also indicated a pattern of isolation-by-distance, which suggests that seed and/or pollen exchange is restricted geographically. Finally, all phenotypic traits, as well as a reduced germination rate, were correlated with either geographic isolation or genetic distance. We conclude that geographic isolation likely restricts gene flow, which in turn may affect germination. Consequently, it is imperative that conservation programs take into account the patchy nature of such ecosystems, rather than targeting a few specific sites with exceptional character for preservation.

Aims Habitat connectivity is important in conservation since isolation can diminish the potential of a population for adaptation and increase its risk of extinction. However, conservation of naturally patchy ecosystems such as peatlands has mainly focused on preserving specific sites with exceptional characteristics, neglecting the potential interconnectivity between patches. In order to better understand plant dynamics within a peatland network, we assessed the effect of population isolation on genetic distinctiveness, phenotypic variations and germination rates using the peatland-obligate white-fringed orchid (Platanthera blephariglottis).
Methods Fifteen phenotypic traits were measured for 24 individuals per population (20 distinct populations, Quebec, Canada) and germination rates of nearly 20000 seeds were assessed. Genetic distinctiveness was quantified for 26 populations using single nucleotide polymorphism markers obtained via a pooled genotyping-by-sequencing approach. Geographic isolation was measured as the distance to the nearest population and as the number of populations occurring in concentric buffer zones (within a radius of 2, 5 and 10 km) around the studied populations.
Important findings All phenotypic traits showed significant differences among populations. Genetic results also indicated a pattern of isolation-by-distance, which suggests that seed and/or pollen exchange is restricted geographically. Finally, all phenotypic traits, as well as a reduced germination rate, were correlated with either geographic isolation or genetic distance. We conclude that geographic isolation likely restricts gene flow, which in turn may affect germination. Consequently, it is imperative that conservation programs take into account the patchy nature of such ecosystems, rather than targeting a few specific sites with exceptional character for preservation.